draft-ietf-sidr-bgpsec-protocol-23.txt   rfc8205.txt 
Network Working Group M. Lepinski, Ed. Internet Engineering Task Force (IETF) M. Lepinski, Ed.
Internet-Draft NCF Request for Comments: 8205 NCF
Intended status: Standards Track K. Sriram, Ed. Category: Standards Track K. Sriram, Ed.
Expires: October 29, 2017 NIST ISSN: 2070-1721 NIST
April 27, 2017 September 2017
BGPsec Protocol Specification BGPsec Protocol Specification
draft-ietf-sidr-bgpsec-protocol-23
Abstract Abstract
This document describes BGPsec, an extension to the Border Gateway This document describes BGPsec, an extension to the Border Gateway
Protocol (BGP) that provides security for the path of autonomous Protocol (BGP) that provides security for the path of Autonomous
systems (ASes) through which a BGP update message passes. BGPsec is Systems (ASes) through which a BGP UPDATE message passes. BGPsec is
implemented via an optional non-transitive BGP path attribute that implemented via an optional non-transitive BGP path attribute that
carries digital signatures produced by each autonomous system that carries digital signatures produced by each AS that propagates the
propagates the update message. The digital signatures provide UPDATE message. The digital signatures provide confidence that every
confidence that every AS on the path of ASes listed in the update AS on the path of ASes listed in the UPDATE message has explicitly
message has explicitly authorized the advertisement of the route. authorized the advertisement of the route.
Status of This Memo Status of This Memo
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provisions of BCP 78 and BCP 79.
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Internet Standards is available in Section 2 of RFC 7841.
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and how to provide feedback on it may be obtained at
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Copyright (c) 2017 IETF Trust and the persons identified as the Copyright (c) 2017 IETF Trust and the persons identified as the
document authors. All rights reserved. document authors. All rights reserved.
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Table of Contents Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 3 1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 3
1.1. Requirements Language . . . . . . . . . . . . . . . . . . 3 1.1. Requirements Language . . . . . . . . . . . . . . . . . . 3
2. BGPsec Negotiation . . . . . . . . . . . . . . . . . . . . . 3 2. BGPsec Negotiation . . . . . . . . . . . . . . . . . . . . . 3
2.1. The BGPsec Capability . . . . . . . . . . . . . . . . . . 4 2.1. The BGPsec Capability . . . . . . . . . . . . . . . . . . 4
2.2. Negotiating BGPsec Support . . . . . . . . . . . . . . . 5 2.2. Negotiating BGPsec Support . . . . . . . . . . . . . . . 5
3. The BGPsec_Path Attribute . . . . . . . . . . . . . . . . . . 6 3. The BGPsec_PATH Attribute . . . . . . . . . . . . . . . . . . 6
3.1. Secure_Path . . . . . . . . . . . . . . . . . . . . . . . 8 3.1. Secure_Path . . . . . . . . . . . . . . . . . . . . . . . 8
3.2. Signature_Block . . . . . . . . . . . . . . . . . . . . . 10 3.2. Signature_Block . . . . . . . . . . . . . . . . . . . . . 10
4. BGPsec Update Messages . . . . . . . . . . . . . . . . . . . 11 4. BGPsec UPDATE Messages . . . . . . . . . . . . . . . . . . . 11
4.1. General Guidance . . . . . . . . . . . . . . . . . . . . 11 4.1. General Guidance . . . . . . . . . . . . . . . . . . . . 11
4.2. Constructing the BGPsec_Path Attribute . . . . . . . . . 14 4.2. Constructing the BGPsec_PATH Attribute . . . . . . . . . 14
4.3. Processing Instructions for Confederation Members . . . . 18 4.3. Processing Instructions for Confederation Members . . . . 18
4.4. Reconstructing the AS_PATH Attribute . . . . . . . . . . 19 4.4. Reconstructing the AS_PATH Attribute . . . . . . . . . . 19
5. Processing a Received BGPsec Update . . . . . . . . . . . . . 21 5. Processing a Received BGPsec UPDATE Message . . . . . . . . . 21
5.1. Overview of BGPsec Validation . . . . . . . . . . . . . . 22 5.1. Overview of BGPsec Validation . . . . . . . . . . . . . . 22
5.2. Validation Algorithm . . . . . . . . . . . . . . . . . . 23 5.2. Validation Algorithm . . . . . . . . . . . . . . . . . . 23
6. Algorithms and Extensibility . . . . . . . . . . . . . . . . 27 6. Algorithms and Extensibility . . . . . . . . . . . . . . . . 27
6.1. Algorithm Suite Considerations . . . . . . . . . . . . . 27 6.1. Algorithm Suite Considerations . . . . . . . . . . . . . 27
6.2. Considerations for the SKI Size . . . . . . . . . . . . . 28 6.2. Considerations for the SKI Size . . . . . . . . . . . . . 28
6.3. Extensibility Considerations . . . . . . . . . . . . . . 28 6.3. Extensibility Considerations . . . . . . . . . . . . . . 28
7. Operations and Management Considerations . . . . . . . . . . 29 7. Operations and Management Considerations . . . . . . . . . . 29
7.1. Capability Negotiation Failure . . . . . . . . . . . . . 29 7.1. Capability Negotiation Failure . . . . . . . . . . . . . 29
7.2. Preventing Misuse of pCount=0 . . . . . . . . . . . . . . 29 7.2. Preventing Misuse of pCount=0 . . . . . . . . . . . . . . 29
7.3. Early Termination of Signature Verification . . . . . . . 30 7.3. Early Termination of Signature Verification . . . . . . . 30
7.4. Non-Deterministic Signature Algorithms . . . . . . . . . 30 7.4. Non-deterministic Signature Algorithms . . . . . . . . . 30
7.5. Private AS Numbers . . . . . . . . . . . . . . . . . . . 30 7.5. Private AS Numbers . . . . . . . . . . . . . . . . . . . 30
7.6. Robustness Considerations for Accessing RPKI Data . . . . 32 7.6. Robustness Considerations for Accessing RPKI Data . . . . 32
7.7. Graceful Restart . . . . . . . . . . . . . . . . . . . . 32 7.7. Graceful Restart . . . . . . . . . . . . . . . . . . . . 32
7.8. Robustness of Secret Random Number in ECDSA . . . . . . . 32 7.8. Robustness of Secret Random Number in ECDSA . . . . . . . 32
7.9. Incremental/Partial Deployment Considerations . . . . . . 33 7.9. Incremental/Partial Deployment Considerations . . . . . . 33
8. Security Considerations . . . . . . . . . . . . . . . . . . . 33 8. Security Considerations . . . . . . . . . . . . . . . . . . . 33
8.1. Security Guarantees . . . . . . . . . . . . . . . . . . . 33 8.1. Security Guarantees . . . . . . . . . . . . . . . . . . . 33
8.2. On the Removal of BGPsec Signatures . . . . . . . . . . . 34 8.2. On the Removal of BGPsec Signatures . . . . . . . . . . . 34
8.3. Mitigation of Denial of Service Attacks . . . . . . . . . 35 8.3. Mitigation of Denial-of-Service Attacks . . . . . . . . . 36
8.4. Additional Security Considerations . . . . . . . . . . . 36 8.4. Additional Security Considerations . . . . . . . . . . . 36
9. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 38 9. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 38
10. Contributors . . . . . . . . . . . . . . . . . . . . . . . . 39 10. References . . . . . . . . . . . . . . . . . . . . . . . . . 39
10.1. Authors . . . . . . . . . . . . . . . . . . . . . . . . 39 10.1. Normative References . . . . . . . . . . . . . . . . . . 39
10.2. Acknowledgements . . . . . . . . . . . . . . . . . . . . 40 10.2. Informative References . . . . . . . . . . . . . . . . . 41
11. References . . . . . . . . . . . . . . . . . . . . . . . . . 40 Acknowledgements . . . . . . . . . . . . . . . . . . . . . . . . 43
11.1. Normative References . . . . . . . . . . . . . . . . . . 40 Contributors . . . . . . . . . . . . . . . . . . . . . . . . . . 44
11.2. Informative References . . . . . . . . . . . . . . . . . 42 Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 45
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 44
1. Introduction 1. Introduction
This document describes BGPsec, a mechanism for providing path This document describes BGPsec, a mechanism for providing path
security for Border Gateway Protocol (BGP) [RFC4271] route security for Border Gateway Protocol (BGP) [RFC4271] route
advertisements. That is, a BGP speaker who receives a valid BGPsec advertisements. That is, a BGP speaker who receives a valid BGPsec
update has cryptographic assurance that the advertised route has the UPDATE message has cryptographic assurance that the advertised route
following property: Every AS on the path of ASes listed in the update has the following property: every Autonomous System (AS) on the path
message has explicitly authorized the advertisement of the route to of ASes listed in the UPDATE message has explicitly authorized the
the subsequent AS in the path. advertisement of the route to the subsequent AS in the path.
This document specifies an optional (non-transitive) BGP path This document specifies an optional (non-transitive) BGP path
attribute, BGPsec_Path. It also describes how a BGPsec-compliant BGP attribute, BGPsec_PATH. It also describes how a BGPsec-compliant BGP
speaker (referred to hereafter as a BGPsec speaker) can generate, speaker (referred to hereafter as a BGPsec speaker) can generate,
propagate, and validate BGP update messages containing this attribute propagate, and validate BGP UPDATE messages containing this attribute
to obtain the above assurances. to obtain the above assurances.
BGPsec is intended to be used to supplement BGP Origin Validation BGPsec is intended to be used to supplement BGP origin validation
[RFC6483][RFC6811] and when used in conjunction with origin [RFC6483] [RFC6811], and when used in conjunction with origin
validation, it is possible to prevent a wide variety of route validation, it is possible to prevent a wide variety of route
hijacking attacks against BGP. hijacking attacks against BGP.
BGPsec relies on the Resource Public Key Infrastructure (RPKI) BGPsec relies on the Resource Public Key Infrastructure (RPKI)
certificates that attest to the allocation of AS number and IP certificates that attest to the allocation of AS number and IP
address resources. (For more information on the RPKI, see RFC 6480 address resources. (For more information on the RPKI, see RFC 6480
[RFC6480] and the documents referenced therein.) Any BGPsec speaker [RFC6480] and the documents referenced therein.) Any BGPsec speaker
who wishes to send, to external (eBGP) peers, BGP update messages who wishes to send, to external (eBGP) peers, BGP UPDATE messages
containing the BGPsec_Path needs to possess a private key associated containing the BGPsec_PATH needs to possess a private key associated
with an RPKI router certificate [I-D.ietf-sidr-bgpsec-pki-profiles] with an RPKI router certificate [RFC8209] that corresponds to the
that corresponds to the BGPsec speaker's AS number. Note, however, BGPsec speaker's AS number. Note, however, that a BGPsec speaker
that a BGPsec speaker does not need such a certificate in order to does not need such a certificate in order to validate received UPDATE
validate received update messages containing the BGPsec_Path messages containing the BGPsec_PATH attribute (see Section 5.2).
attribute (see Section 5.2).
1.1. Requirements Language 1.1. Requirements Language
The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT", The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
"SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this "SHOULD", "SHOULD NOT", "RECOMMENDED", "NOT RECOMMENDED", "MAY", and
document are to be interpreted as described in RFC 2119 [RFC2119]. "OPTIONAL" in this document are to be interpreted as described in
BCP 14 [RFC2119] [RFC8174] when, and only when, they appear in all
capitals, as shown here.
2. BGPsec Negotiation 2. BGPsec Negotiation
This document defines a BGP capability [RFC5492] that allows a BGP This document defines a BGP capability [RFC5492] that allows a BGP
speaker to advertise to a neighbor the ability to send or to receive speaker to advertise to a neighbor the ability to send or to receive
BGPsec update messages (i.e., update messages containing the BGPsec UPDATE messages (i.e., UPDATE messages containing the
BGPsec_Path attribute). BGPsec_PATH attribute).
2.1. The BGPsec Capability 2.1. The BGPsec Capability
This capability has capability code: TBD This capability has capability code 7.
The capability length for this capability MUST be set to 3. The capability length for this capability MUST be set to 3.
The three octets of the capability format are specified in Figure 1. The 3 octets of the capability format are specified in Figure 1.
0 1 2 3 4 5 6 7 0 1 2 3 4 5 6 7
+---------------------------------------+ +---------------------------------------+
| Version | Dir | Unassigned | | Version | Dir | Unassigned |
+---------------------------------------+ +---------------------------------------+
| | | |
+------ AFI -----+ +------ AFI -----+
| | | |
+---------------------------------------+ +---------------------------------------+
Figure 1: BGPsec Capability format. Figure 1: BGPsec Capability Format
The first four bits of the first octet indicate the version of BGPsec The first 4 bits of the first octet indicate the version of BGPsec
for which the BGP speaker is advertising support. This document for which the BGP speaker is advertising support. This document
defines only BGPsec version 0 (all four bits set to zero). Other defines only BGPsec version 0 (all 4 bits set to 0). Other versions
versions of BGPsec may be defined in future documents. A BGPsec of BGPsec may be defined in future documents. A BGPsec speaker MAY
speaker MAY advertise support for multiple versions of BGPsec by advertise support for multiple versions of BGPsec by including
including multiple versions of the BGPsec capability in its BGP OPEN multiple versions of the BGPsec capability in its BGP OPEN message.
message.
The fifth bit of the first octet is a direction bit which indicates The fifth bit of the first octet is a Direction bit, which indicates
whether the BGP speaker is advertising the capability to send BGPsec whether the BGP speaker is advertising the capability to send BGPsec
update messages or receive BGPsec update messages. The BGP speaker UPDATE messages or receive BGPsec UPDATE messages. The BGP speaker
sets this bit to 0 to indicate the capability to receive BGPsec sets this bit to 0 to indicate the capability to receive BGPsec
update messages. The BGP speaker sets this bit to 1 to indicate the UPDATE messages. The BGP speaker sets this bit to 1 to indicate the
capability to send BGPsec update messages. capability to send BGPsec UPDATE messages.
The remaining three bits of the first octet are unassigned and for The remaining 3 bits of the first octet are unassigned and for future
future use. These bits are set to zero by the sender of the use. These bits are set to 0 by the sender of the capability and
capability and ignored by the receiver of the capability. ignored by the receiver of the capability.
The second and third octets contain the 16-bit Address Family The second and third octets contain the 16-bit Address Family
Identifier (AFI) which indicates the address family for which the Identifier (AFI), which indicates the address family for which the
BGPsec speaker is advertising support for BGPsec. This document only BGPsec speaker is advertising support for BGPsec. This document only
specifies BGPsec for use with two address families, IPv4 and IPv6, specifies BGPsec for use with two address families, IPv4 and IPv6,
AFI values 1 and 2 respectively [IANA-AF]. BGPsec for use with other with AFI values 1 and 2, respectively [IANA-AF]. BGPsec for use with
address families may be specified in future documents. other address families may be specified in future documents.
2.2. Negotiating BGPsec Support 2.2. Negotiating BGPsec Support
In order to indicate that a BGP speaker is willing to send BGPsec In order to indicate that a BGP speaker is willing to send BGPsec
update messages (for a particular address family), a BGP speaker UPDATE messages (for a particular address family), a BGP speaker
sends the BGPsec Capability (see Section 2.1) with the Direction bit sends the BGPsec capability (see Section 2.1) with the Direction bit
(the fifth bit of the first octet) set to 1. In order to indicate (the fifth bit of the first octet) set to 1. In order to indicate
that the speaker is willing to receive BGP update messages containing that the speaker is willing to receive BGP UPDATE messages containing
the BGPsec_Path attribute (for a particular address family), a BGP the BGPsec_PATH attribute (for a particular address family), a BGP
speaker sends the BGPsec capability with the Direction bit set to 0. speaker sends the BGPsec capability with the Direction bit set to 0.
In order to advertise the capability to both send and receive BGPsec In order to advertise the capability to both send and receive BGPsec
update messages, the BGP speaker sends two copies of the BGPsec UPDATE messages, the BGP speaker sends two copies of the BGPsec
capability (one with the direction bit set to 0 and one with the capability (one with the Direction bit set to 0 and one with the
direction bit set to 1). Direction bit set to 1).
Similarly, if a BGP speaker wishes to use BGPsec with two different Similarly, if a BGP speaker wishes to use BGPsec with two different
address families (i.e., IPv4 and IPv6) over the same BGP session, address families (i.e., IPv4 and IPv6) over the same BGP session,
then the speaker includes two instances of this capability (one for then the speaker includes two instances of this capability (one for
each address family) in the BGP OPEN message. A BGP speaker MUST NOT each address family) in the BGP OPEN message. A BGP speaker MUST NOT
announce BGPsec capability if it does not support the BGP announce BGPsec capability if it does not support the BGP
multiprotocol extension [RFC4760]. Additionally, a BGP speaker MUST multiprotocol extension [RFC4760]. Additionally, a BGP speaker
NOT advertise the capability of BGPsec support for a particular AFI MUST NOT advertise the capability of BGPsec support for a particular
unless it has also advertised the multiprotocol extension capability AFI unless it has also advertised the multiprotocol extension
for the same AFI [RFC4760]. capability for the same AFI [RFC4760].
In a BGPsec peering session, a peer is permitted to send update In a BGPsec peering session, a peer is permitted to send UPDATE
messages containing the BGPsec_Path attribute if, and only if: messages containing the BGPsec_PATH attribute if and only if:
o The given peer sent the BGPsec capability for a particular version o The given peer sent the BGPsec capability for a particular version
of BGPsec and a particular address family with the Direction bit of BGPsec and a particular address family with the Direction bit
set to 1; and set to 1, and
o The other (receiving) peer sent the BGPsec capability for the same o The other (receiving) peer sent the BGPsec capability for the same
version of BGPsec and the same address family with the Direction version of BGPsec and the same address family with the Direction
bit set to 0. bit set to 0.
In such a session, it can be said that the use of the particular In such a session, it can be said that the use of the particular
version of BGPsec has been negotiated for a particular address version of BGPsec has been negotiated for a particular address
family. Traditional BGP update messages (i.e. unsigned, containing family. Traditional BGP UPDATE messages (i.e., unsigned, containing
AS_PATH attribute) MAY be sent within a session regardless of whether the AS_PATH attribute) MAY be sent within a session regardless of
or not the use of BGPsec is successfully negotiated. However, if whether or not the use of BGPsec is successfully negotiated.
BGPsec is not successfully negotiated, then BGP update messages However, if BGPsec is not successfully negotiated, then BGP UPDATE
containing the BGPsec_Path attribute MUST NOT be sent. messages containing the BGPsec_PATH attribute MUST NOT be sent.
This document defines the behavior of implementations in the case This document defines the behavior of implementations in the case
where BGPsec version zero is the only version that has been where BGPsec version 0 is the only version that has been successfully
successfully negotiated. Any future document which specifies negotiated. Any future document that specifies additional versions
additional versions of BGPsec will need to specify behavior in the of BGPsec will need to specify behavior in the case that support for
case that support for multiple versions is negotiated. multiple versions is negotiated.
BGPsec cannot provide meaningful security guarantees without support BGPsec cannot provide meaningful security guarantees without support
for four-byte AS numbers. Therefore, any BGP speaker that announces for 4-byte AS numbers. Therefore, any BGP speaker that announces the
the BGPsec capability, MUST also announce the capability for four- BGPsec capability, MUST also announce the capability for 4-byte AS
byte AS support [RFC6793]. If a BGP speaker sends the BGPsec support [RFC6793]. If a BGP speaker sends the BGPsec capability but
capability but not the four-byte AS support capability then BGPsec not the 4-byte AS support capability, then BGPsec has not been
has not been successfully negotiated, and update messages containing successfully negotiated, and UPDATE messages containing the
the BGPsec_Path attribute MUST NOT be sent within such a session. BGPsec_PATH attribute MUST NOT be sent within such a session.
3. The BGPsec_Path Attribute 3. The BGPsec_PATH Attribute
The BGPsec_Path attribute is an optional non-transitive BGP path The BGPsec_PATH attribute is an optional non-transitive BGP path
attribute. attribute.
This document registers an attribute type code for this attribute: This document registers an attribute type code for this attribute:
BGPsec_Path (see Section 9). BGPsec_PATH (see Section 9).
The BGPsec_Path attribute carries the secured information regarding The BGPsec_PATH attribute carries the secured information regarding
the path of ASes through which an update message passes. This the path of ASes through which an UPDATE message passes. This
includes the digital signatures used to protect the path information. includes the digital signatures used to protect the path information.
The update messages that contain the BGPsec_Path attribute are The UPDATE messages that contain the BGPsec_PATH attribute are
referred to as "BGPsec Update messages". The BGPsec_Path attribute referred to as "BGPsec UPDATE messages". The BGPsec_PATH attribute
replaces the AS_PATH attribute in a BGPsec update message. That is, replaces the AS_PATH attribute in a BGPsec UPDATE message. That is,
update messages that contain the BGPsec_Path attribute MUST NOT UPDATE messages that contain the BGPsec_PATH attribute MUST NOT
contain the AS_PATH attribute, and vice versa. contain the AS_PATH attribute, and vice versa.
The BGPsec_Path attribute is made up of several parts. The high- The BGPsec_PATH attribute is made up of several parts. The
level diagram in Figure 2 provides an overview of the structure of high-level diagram in Figure 2 provides an overview of the structure
the BGPsec_Path attribute. of the BGPsec_PATH attribute. ("SKI" as used in Figure 2 means
"Subject Key Identifier".)
+---------------------------------------------------------+ +---------------------------------------------------------+
| +-----------------+ | | +-----------------+ |
| | Secure Path | | | | Secure_Path | |
| +-----------------+ | | +-----------------+ |
| | pCount X | | | | pCount X | |
| | Flags X | | | | Flags X | |
| | AS X | | | | AS X | |
| | pCount Y | | | | pCount Y | |
| | Flags Y | | | | Flags Y | |
| | AS Y | | | | AS Y | |
| | ... | | | | ... | |
| +-----------------+ | | +-----------------+ |
| | | |
| +-----------------+ +-----------------+ | | +---------------------+ +---------------------+ |
| | Sig Block 1 | | Sig Block 2 | | | | Signature_Block 1 | | Signature_Block 2 | |
| +-----------------+ +-----------------+ | | +---------------------+ +---------------------+ |
| | Alg Suite 1 | | Alg Suite 2 | | | | Algorithm Suite 1 | | Algorithm Suite 2 | |
| | SKI X1 | | SKI X2 | | | | SKI X1 | | SKI X2 | |
| | Signature X1 | | Signature X2 | | | | Signature X1 | | Signature X2 | |
| | SKI Y1 | | SKI Y2 | | | | SKI Y1 | | SKI Y2 | |
| | Signature Y1 | | Signature Y2 | | | | Signature Y1 | | Signature Y2 | |
| | ... | | .... | | | | ... | | .... | |
| +-----------------+ +-----------------+ | | +---------------------+ +---------------------+ |
| | | |
+---------------------------------------------------------+ +---------------------------------------------------------+
Figure 2: High-level diagram of the BGPsec_Path attribute. Figure 2: High-Level Diagram of the BGPsec_PATH Attribute
Figure 3 provides the specification of the format for the BGPsec_Path Figure 3 provides the specification of the format for the BGPsec_PATH
attribute. attribute.
+-------------------------------------------------------+ +-------------------------------------------------------+
| Secure_Path (variable) | | Secure_Path (variable) |
+-------------------------------------------------------+ +-------------------------------------------------------+
| Sequence of one or two Signature_Blocks (variable) | | Sequence of one or two Signature_Blocks (variable) |
+-------------------------------------------------------+ +-------------------------------------------------------+
Figure 3: BGPsec_Path attribute format. Figure 3: BGPsec_PATH Attribute Format
The Secure_Path contains AS path information for the BGPsec update The Secure_Path contains AS path information for the BGPsec UPDATE
message. This is logically equivalent to the information that is message. This is logically equivalent to the information that is
contained in a non-BGPsec AS_PATH attribute. The information in contained in a non-BGPsec AS_PATH attribute. The information in the
Secure_Path is used by BGPsec speakers in the same way that Secure_Path is used by BGPsec speakers in the same way that
information from the AS_PATH is used by non-BGPsec speakers. The information from the AS_PATH is used by non-BGPsec speakers. The
format of the Secure_Path is described below in Section 3.1. format of the Secure_Path is described below in Section 3.1.
The BGPsec_Path attribute will contain one or two Signature_Blocks, The BGPsec_PATH attribute will contain one or two Signature_Blocks,
each of which corresponds to a different algorithm suite. Each of each of which corresponds to a different algorithm suite. Each of
the Signature_Blocks will contain a Signature Segment for each AS the Signature_Blocks will contain a Signature Segment for each AS
number (i.e., Secure_Path Segment) in the Secure_Path. In the most number (i.e., Secure_Path Segment) in the Secure_Path. In the
common case, the BGPsec_Path attribute will contain only a single most common case, the BGPsec_PATH attribute will contain only a
Signature_Block. However, in order to enable a transition from an single Signature_Block. However, in order to enable a transition
old algorithm suite to a new algorithm suite (without a flag day), it from an old algorithm suite to a new algorithm suite (without a
will be necessary to include two Signature_Blocks (one for the old flag day), it will be necessary to include two Signature_Blocks (one
algorithm suite and one for the new algorithm suite) during the for the old algorithm suite and one for the new algorithm suite)
transition period. (See Section 6.1 for more discussion of algorithm during the transition period. (See Section 6.1 for more discussion
transitions.) The format of the Signature_Blocks is described below of algorithm transitions.) The format of the Signature_Blocks is
in Section 3.2. described below in Section 3.2.
3.1. Secure_Path 3.1. Secure_Path
A detailed description of the Secure_Path information in the A detailed description of the Secure_Path information in the
BGPsec_Path attribute is provided here. BGPsec_PATH attribute is provided here. The specification for the
Secure_Path field is provided in Figures 4 and 5.
+-----------------------------------------------+ +-----------------------------------------------+
| Secure_Path Length (2 octets) | | Secure_Path Length (2 octets) |
+-----------------------------------------------+ +-----------------------------------------------+
| One or More Secure_Path Segments (variable) | | One or more Secure_Path Segments (variable) |
+-----------------------------------------------+ +-----------------------------------------------+
Figure 4: Secure_Path format. Figure 4: Secure_Path Format
The specification for the Secure_Path field is provided in Figure 4 The Secure_Path Length contains the length (in octets) of the entire
and Figure 5. The Secure_Path Length contains the length (in octets) Secure_Path (including the 2 octets used to express this length
of the entire Secure_Path (including the two octets used to express field). As explained below, each Secure_Path Segment is 6 octets
this length field). As explained below, each Secure_Path Segment is long. Note that this means the Secure_Path Length is two greater
six octets long. Note that this means the Secure_Path Length is two than six times the number of Secure_Path Segments (i.e., the number
greater than six times the number Secure_Path Segments (i.e., the of AS numbers in the path).
number of AS numbers in the path).
The Secure_Path contains one Secure_Path Segment (see Figure 5) for The Secure_Path contains one Secure_Path Segment (see Figure 5) for
each Autonomous System in the path to the originating AS of the each AS in the path to the originating AS of the prefix specified in
prefix specified in the update message. (Note: Repeated Autonomous the UPDATE message. (Note: Repeated ASes are "compressed out" using
Systems are compressed out using the pCount field as discussed the pCount field, as discussed below.)
below.)
+------------------------------------------------------+ +------------------------------------------------------+
| pCount (1 octet) | | pCount (1 octet) |
+------------------------------------------------------+ +------------------------------------------------------+
| Confed_Segment flag (1 bit) | Unassigned (7 bits) | (Flags) | Confed_Segment flag (1 bit) | Unassigned (7 bits) | (Flags)
+------------------------------------------------------+ +------------------------------------------------------+
| AS Number (4 octets) | | AS Number (4 octets) |
+------------------------------------------------------+ +------------------------------------------------------+
Figure 5: Secure_Path Segment format. Figure 5: Secure_Path Segment Format
The AS Number (in Figure 5) is the AS number of the BGP speaker that The AS Number (in Figure 5) is the AS number of the BGP speaker that
added this Secure_Path Segment to the BGPsec_Path attribute. (See added this Secure_Path Segment to the BGPsec_PATH attribute. (See
Section 4 for more information on populating this field.) Section 4 for more information on populating this field.)
The pCount field contains the number of repetitions of the associated The pCount field contains the number of repetitions of the associated
autonomous system number that the signature covers. This field AS number that the signature covers. This field enables a BGPsec
enables a BGPsec speaker to mimic the semantics of prepending speaker to mimic the semantics of prepending multiple copies of their
multiple copies of their AS to the AS_PATH without requiring the AS to the AS_PATH without requiring the speaker to generate multiple
speaker to generate multiple signatures. Note that Section 9.1.2.2 signatures. Note that Section 9.1.2.2 ("Breaking Ties (Phase 2)") in
("Breaking Ties") in [RFC4271] mentions "number of AS numbers" in the [RFC4271] mentions the "number of AS numbers" in the AS_PATH
AS_PATH attribute that is used in the route selection process. This attribute that is used in the route selection process. This metric
metric (number of AS numbers) is the same as the AS path length (number of AS numbers) is the same as the AS path length obtained in
obtained in BGPsec by summing the pCount values in the BGPsec_Path BGPsec by summing the pCount values in the BGPsec_PATH attribute.
attribute. The pCount field is also useful in managing route servers The pCount field is also useful in managing route servers (see
(see Section 4.2), AS confederations (see Section 4.3), and AS Number Section 4.2), AS confederations (see Section 4.3), and AS Number
migrations (see [I-D.ietf-sidr-as-migration] for details). migrations (see [RFC8206] for details).
The left most (i.e. the most significant) bit of the Flags field in The leftmost (i.e., the most significant) bit of the Flags field in
Figure 5 is the Confed_Segment flag. The Confed_Segment flag is set Figure 5 is the Confed_Segment flag. The Confed_Segment flag is set
to one to indicate that the BGPsec speaker that constructed this to 1 to indicate that the BGPsec speaker that constructed this
Secure_Path Segment is sending the update message to a peer AS within Secure_Path Segment is sending the UPDATE message to a peer AS within
the same Autonomous System confederation [RFC5065]. (That is, a the same AS confederation [RFC5065]. (That is, a sequence of
sequence of consecutive Confed_Segment flags are set in a BGPsec consecutive Confed_Segment flags are set in a BGPsec UPDATE message
update message whenever, in a non-BGPsec update message, an AS_PATH whenever, in a non-BGPsec UPDATE message, an AS_PATH segment of type
segment of type AS_CONFED_SEQUENCE occurs.) In all other cases the AS_CONFED_SEQUENCE occurs.) In all other cases, the Confed_Segment
Confed_Segment flag is set to zero. flag is set to 0.
The remaining seven bits of the Flags are unassigned and MUST be set The remaining 7 bits of the Flags field are unassigned. They MUST be
to zero by the sender, and ignored by the receiver. Note, however, set to 0 by the sender and ignored by the receiver. Note, however,
that the signature is computed over all eight bits of the flags that the signature is computed over all 8 bits of the Flags field.
field.
As stated earlier in Section 2.2, BGPsec peering requires that the As stated earlier in Section 2.2, BGPsec peering requires that the
peering ASes MUST each support four-byte AS numbers. Currently- peering ASes MUST each support 4-byte AS numbers. Currently assigned
assigned two-byte AS numbers are converted into four-byte AS numbers 2-byte AS numbers are converted into 4-byte AS numbers by setting the
by setting the two high-order octets of the four-octet field to zero two high-order octets of the 4-octet field to 0 [RFC6793].
[RFC6793].
3.2. Signature_Block 3.2. Signature_Block
A detailed description of the Signature_Blocks in the BGPsec_Path A detailed description of the Signature_Blocks in the BGPsec_PATH
attribute is provided here using Figure 6 and Figure 7. attribute is provided here using Figures 6 and 7.
+---------------------------------------------+ +---------------------------------------------+
| Signature_Block Length (2 octets) | | Signature_Block Length (2 octets) |
+---------------------------------------------+ +---------------------------------------------+
| Algorithm Suite Identifier (1 octet) | | Algorithm Suite Identifier (1 octet) |
+---------------------------------------------+ +---------------------------------------------+
| Sequence of Signature Segments (variable) | | Sequence of Signature Segments (variable) |
+---------------------------------------------+ +---------------------------------------------+
Figure 6: Signature_Block format. Figure 6: Signature_Block Format
The Signature_Block Length in Figure 6 is the total number of octets The Signature_Block Length in Figure 6 is the total number of octets
in the Signature_Block (including the two octets used to express this in the Signature_Block (including the 2 octets used to express this
length field). length field).
The Algorithm Suite Identifier is a one-octet identifier specifying The Algorithm Suite Identifier is a 1-octet identifier specifying the
the digest algorithm and digital signature algorithm used to produce digest algorithm and digital signature algorithm used to produce the
the digital signature in each Signature Segment. An IANA registry of digital signature in each Signature Segment. An IANA registry of
algorithm identifiers for use in BGPsec is specified in the BGPsec algorithm suite identifiers for use in BGPsec is specified in the
algorithms document [I-D.ietf-sidr-bgpsec-algs]. BGPsec algorithms document [RFC8208].
A Signature_Block in Figure 6 has exactly one Signature Segment (see A Signature_Block in Figure 6 has exactly one Signature Segment (see
Figure 7) for each Secure_Path Segment in the Secure_Path portion of Figure 7) for each Secure_Path Segment in the Secure_Path portion of
the BGPsec_Path Attribute. (That is, one Signature Segment for each the BGPsec_PATH attribute (that is, one Signature Segment for each
distinct AS on the path for the prefix in the Update message.) distinct AS on the path for the prefix in the UPDATE message).
+---------------------------------------------+ +---------------------------------------------+
| Subject Key Identifier (SKI) (20 octets) | | Subject Key Identifier (SKI) (20 octets) |
+---------------------------------------------+ +---------------------------------------------+
| Signature Length (2 octets) | | Signature Length (2 octets) |
+---------------------------------------------+ +---------------------------------------------+
| Signature (variable) | | Signature (variable) |
+---------------------------------------------+ +---------------------------------------------+
Figure 7: Signature Segment format. Figure 7: Signature Segment Format
The Subject Key Identifier (SKI) field in Figure 7 contains the value The Subject Key Identifier (SKI) field in Figure 7 contains the value
in the Subject Key Identifier extension of the RPKI router in the Subject Key Identifier extension of the RPKI router
certificate [RFC6487] that is used to verify the signature (see certificate [RFC6487] that is used to verify the signature (see
Section 5 for details on validity of BGPsec update messages). The Section 5 for details on the validity of BGPsec UPDATE messages).
SKI field has a fixed 20 octets size. See Section 6.2 for The SKI field has a fixed size of 20 octets. See Section 6.2 for
considerations for the SKI size. considerations for the SKI size.
The Signature Length field contains the size (in octets) of the value The Signature Length field contains the size (in octets) of the value
in the Signature field of the Signature Segment. in the Signature field of the Signature Segment.
The Signature in Figure 7 contains a digital signature that protects The Signature field in Figure 7 contains a digital signature that
the prefix and the BGPsec_Path attribute (see Section 4 and Section 5 protects the prefix and the BGPsec_PATH attribute (see Sections 4 and
for details on signature generation and validation, respectively). 5 for details on signature generation and validation, respectively).
4. BGPsec Update Messages 4. BGPsec UPDATE Messages
Section 4.1 provides general guidance on the creation of BGPsec Section 4.1 provides general guidance on the creation of BGPsec
Update Messages -- that is, update messages containing the UPDATE messages -- that is, UPDATE messages containing the
BGPsec_Path attribute. BGPsec_PATH attribute.
Section 4.2 specifies how a BGPsec speaker generates the BGPsec_Path Section 4.2 specifies how a BGPsec speaker generates the BGPsec_PATH
attribute to include in a BGPsec Update message. attribute to include in a BGPsec UPDATE message.
Section 4.3 contains special processing instructions for members of Section 4.3 contains special processing instructions for members of
an autonomous system confederation [RFC5065]. A BGPsec speaker that an AS confederation [RFC5065]. A BGPsec speaker that is not a member
is not a member of such a confederation MUST NOT set the of such a confederation MUST NOT set the Confed_Segment flag in its
Confed_Segment flag in its Secure_Path Segment (i.e. leave the flag Secure_Path Segment (i.e., leave the Confed_Segment flag at the
bit at default value zero) in all BGPsec update messages it sends. default value of 0) in all BGPsec UPDATE messages it sends.
Section 4.4 contains instructions for reconstructing the AS_PATH Section 4.4 contains instructions for reconstructing the AS_PATH
attribute in cases where a BGPsec speaker receives an update message attribute in cases where a BGPsec speaker receives an UPDATE message
with a BGPsec_Path attribute and wishes to propagate the update with a BGPsec_PATH attribute and wishes to propagate the UPDATE
message to a peer who does not support BGPsec. message to a peer who does not support BGPsec.
4.1. General Guidance 4.1. General Guidance
The information protected by the signature on a BGPsec update message The information protected by the signature on a BGPsec UPDATE message
includes the AS number of the peer to whom the update message is includes the AS number of the peer to whom the UPDATE message is
being sent. Therefore, if a BGPsec speaker wishes to send a BGPsec being sent. Therefore, if a BGPsec speaker wishes to send a BGPsec
update to multiple BGP peers, it MUST generate a separate BGPsec UPDATE message to multiple BGP peers, it MUST generate a separate
update message for each unique peer AS to whom the update message is BGPsec UPDATE message for each unique peer AS to whom the UPDATE
sent. message is sent.
A BGPsec update message MUST advertise a route to only a single A BGPsec UPDATE message MUST advertise a route to only a single
prefix. This is because a BGPsec speaker receiving an update message prefix. This is because a BGPsec speaker receiving an UPDATE message
with multiple prefixes would be unable to construct a valid BGPsec with multiple prefixes would be unable to construct a valid BGPsec
update message (i.e., valid path signatures) containing a subset of UPDATE message (i.e., valid path signatures) containing a subset of
the prefixes in the received update. If a BGPsec speaker wishes to the prefixes in the received update. If a BGPsec speaker wishes to
advertise routes to multiple prefixes, then it MUST generate a advertise routes to multiple prefixes, then it MUST generate a
separate BGPsec update message for each prefix. Additionally, a separate BGPsec UPDATE message for each prefix. Additionally, a
BGPsec update message MUST use the MP_REACH_NLRI [RFC4760] attribute BGPsec UPDATE message MUST use the MP_REACH_NLRI attribute [RFC4760]
to encode the prefix. to encode the prefix.
The BGPsec_Path attribute and the AS_PATH attribute are mutually The BGPsec_PATH attribute and the AS_PATH attribute are mutually
exclusive. That is, any update message containing the BGPsec_Path exclusive. That is, any UPDATE message containing the BGPsec_PATH
attribute MUST NOT contain the AS_PATH attribute. The information attribute MUST NOT contain the AS_PATH attribute. The information
that would be contained in the AS_PATH attribute is instead conveyed that would be contained in the AS_PATH attribute is instead conveyed
in the Secure_Path portion of the BGPsec_Path attribute. in the Secure_Path portion of the BGPsec_PATH attribute.
In order to create or add a new signature to a BGPsec update message In order to create or add a new signature to a BGPsec UPDATE message
with a given algorithm suite, the BGPsec speaker MUST possess a with a given algorithm suite, the BGPsec speaker MUST possess a
private key suitable for generating signatures for this algorithm private key suitable for generating signatures for this algorithm
suite. Additionally, this private key must correspond to the public suite. Additionally, this private key must correspond to the public
key in a valid Resource PKI end-entity certificate whose AS number key in a valid RPKI end entity certificate whose AS number resource
resource extension includes the BGPsec speaker's AS number extension includes the BGPsec speaker's AS number [RFC8209]. Note
[I-D.ietf-sidr-bgpsec-pki-profiles]. Note also that new signatures also that new signatures are only added to a BGPsec UPDATE message
are only added to a BGPsec update message when a BGPsec speaker is when a BGPsec speaker is generating an UPDATE message to send to an
generating an update message to send to an external peer (i.e., when external peer (i.e., when the AS number of the peer is not equal to
the AS number of the peer is not equal to the BGPsec speaker's own AS the BGPsec speaker's own AS number).
number).
The Resource PKI enables the legitimate holder of IP address The RPKI enables the legitimate holder of IP address prefix(es) to
prefix(es) to issue a signed object, called a Route Origination issue a signed object, called a Route Origin Authorization (ROA),
Authorization (ROA), that authorizes a given AS to originate routes that authorizes a given AS to originate routes to a given set of
to a given set of prefixes (see RFC 6482 [RFC6482]). It is expected prefixes (see RFC 6482 [RFC6482]). It is expected that most Relying
that most relying parties will utilize BGPsec in tandem with origin Parties (RPs) will utilize BGPsec in tandem with origin validation
validation (see RFC 6483 [RFC6483] and RFC 6811 [RFC6811]). (see RFC 6483 [RFC6483] and RFC 6811 [RFC6811]). Therefore, it is
Therefore, it is RECOMMENDED that a BGPsec speaker only originate a RECOMMENDED that a BGPsec speaker only originate a BGPsec UPDATE
BGPsec update advertising a route for a given prefix if there exists message advertising a route for a given prefix if there exists a
a valid ROA authorizing the BGPsec speaker's AS to originate routes valid ROA authorizing the BGPsec speaker's AS to originate routes to
to this prefix. this prefix.
If a BGPsec router has received only a non-BGPsec update message If a BGPsec router has received only a non-BGPsec UPDATE message
containing the AS_PATH attribute (instead of the BGPsec_Path containing the AS_PATH attribute (instead of the BGPsec_PATH
attribute) from a peer for a given prefix, then it MUST NOT attach a attribute) from a peer for a given prefix, then it MUST NOT attach a
BGPsec_Path attribute when it propagates the update message. (Note BGPsec_PATH attribute when it propagates the UPDATE message. (Note
that a BGPsec router may also receive a non-BGPsec update message that a BGPsec router may also receive a non-BGPsec UPDATE message
from an internal peer without the AS_PATH attribute, i.e., with just from an internal peer without the AS_PATH attribute, i.e., with just
the NLRI in it. In that case, the prefix is originating from that the Network Layer Reachability Information (NLRI) in it. In that
AS, and if it is selected for advertisement, the BGPsec speaker case, the prefix is originating from that AS, and if it is selected
SHOULD attach a BGPsec_Path attribute and send a signed route (for for advertisement, the BGPsec speaker SHOULD attach a BGPsec_PATH
that prefix) to its external BGPsec-speaking peers.) attribute and send a signed route (for that prefix) to its external
BGPsec-speaking peers.)
Conversely, if a BGPsec router has received a BGPsec update message Conversely, if a BGPsec router has received a BGPsec UPDATE message
(with the BGPsec_Path attribute) from a peer for a given prefix and (with the BGPsec_PATH attribute) from a peer for a given prefix and
it chooses to propagate that peer's route for the prefix, then it it chooses to propagate that peer's route for the prefix, then it
SHOULD propagate the route as a BGPsec update message containing the SHOULD propagate the route as a BGPsec UPDATE message containing the
BGPsec_Path attribute. BGPsec_PATH attribute.
Note that removing BGPsec signatures (i.e., propagating a route Note that removing BGPsec signatures (i.e., propagating a route
advertisement without the BGPsec_Path attribute) has significant advertisement without the BGPsec_PATH attribute) has significant
security ramifications. (See Section 8 for discussion of the security ramifications. (See Section 8 for a discussion of the
security ramifications of removing BGPsec signatures.) Therefore, security ramifications of removing BGPsec signatures.) Therefore,
when a route advertisement is received via a BGPsec update message, when a route advertisement is received via a BGPsec UPDATE message,
propagating the route advertisement without the BGPsec_Path attribute propagating the route advertisement without the BGPsec_PATH attribute
is NOT RECOMMENDED, unless the message is sent to a peer that did not is NOT RECOMMENDED, unless the message is sent to a peer that did not
advertise the capability to receive BGPsec update messages (see advertise the capability to receive BGPsec UPDATE messages (see
Section 4.4). Section 4.4).
Furthermore, note that when a BGPsec speaker propagates a route Furthermore, note that when a BGPsec speaker propagates a route
advertisement with the BGPsec_Path attribute it is not attesting to advertisement with the BGPsec_PATH attribute, it is not attesting to
the validation state of the update message it received. (See the validation state of the UPDATE message it received. (See
Section 8 for more discussion of the security semantics of BGPsec Section 8 for more discussion of the security semantics of BGPsec
signatures.) signatures.)
If the BGPsec speaker is producing an update message which would, in If the BGPsec speaker is producing an UPDATE message that would, in
the absence of BGPsec, contain an AS_SET (e.g., the BGPsec speaker is the absence of BGPsec, contain an AS_SET (e.g., the BGPsec speaker is
performing proxy aggregation), then the BGPsec speaker MUST NOT performing proxy aggregation), then the BGPsec speaker MUST NOT
include the BGPsec_Path attribute. In such a case, the BGPsec include the BGPsec_PATH attribute. In such a case, the BGPsec
speaker MUST remove any existing BGPsec_Path in the received speaker MUST remove any existing BGPsec_PATH in the received
advertisement(s) for this prefix and produce a traditional (non- advertisement(s) for this prefix and produce a traditional
BGPsec) update message. It should be noted that BCP 172 [RFC6472] (non-BGPsec) UPDATE message. It should be noted that BCP 172
recommends against the use of AS_SET and AS_CONFED_SET in the AS_PATH [RFC6472] recommends against the use of AS_SET and AS_CONFED_SET in
of BGP updates. the AS_PATH of BGP UPDATE messages.
The case where the BGPsec speaker sends a BGPsec update message to an The case where the BGPsec speaker sends a BGPsec UPDATE message to an
iBGP peer is quite simple. When originating a new route iBGP (internal BGP) peer is quite simple. When originating a new
advertisement and sending it to a BGPsec-capable iBGP peer, the route advertisement and sending it to a BGPsec-capable iBGP peer, the
BGPsec speaker omits the BGPsec_Path attribute. When originating a BGPsec speaker omits the BGPsec_PATH attribute. When originating a
new route advertisement and sending it to a non-BGPsec iBGP peer, the new route advertisement and sending it to a non-BGPsec iBGP peer, the
BGPsec speaker includes an empty AS_PATH attribute in the update BGPsec speaker includes an empty AS_PATH attribute in the UPDATE
message. (An empty AS_PATH attribute is one whose length field message. (An empty AS_PATH attribute is one whose length field
contains the value zero [RFC4271].) When a BGPsec speaker chooses to contains the value 0 [RFC4271].) When a BGPsec speaker chooses to
forward a BGPsec update message to an iBGP peer, the BGPsec_Path forward a BGPsec UPDATE message to an iBGP peer, the BGPsec_PATH
attribute SHOULD NOT be removed, unless the peer doesn't support attribute SHOULD NOT be removed, unless the peer doesn't support
BGPsec. In the case when an iBGP peer doesn't support BGPsec, then a BGPsec. In the case when an iBGP peer doesn't support BGPsec, then a
BGP update with AS_PATH is reconstructed from the BGPsec update and BGP UPDATE message with AS_PATH is reconstructed from the BGPsec
then forwarded (see Section 4.4). In particular, when forwarding to UPDATE message and then forwarded (see Section 4.4). In particular,
a BGPsec-capable iBGP (or eBGP) peer, the BGPsec_Path attribute when forwarding to a BGPsec-capable iBGP (or eBGP) peer, the
SHOULD NOT be removed even in the case where the BGPsec update BGPsec_PATH attribute SHOULD NOT be removed even in the case where
message has not been successfully validated. (See Section 5 for more the BGPsec UPDATE message has not been successfully validated. (See
information on validation, and Section 8 for the security Section 5 for more information on validation and Section 8 for the
ramifications of removing BGPsec signatures.) security ramifications of removing BGPsec signatures.)
All BGPsec UPDATE messages MUST conform to BGP's maximum message
All BGPsec update messages MUST conform to BGP's maximum message
size. If the resulting message exceeds the maximum message size, size. If the resulting message exceeds the maximum message size,
then the guidelines in Section 9.2 of RFC 4271 [RFC4271] MUST be then the guidelines in Section 9.2 of RFC 4271 [RFC4271] MUST be
followed. followed.
4.2. Constructing the BGPsec_Path Attribute 4.2. Constructing the BGPsec_PATH Attribute
When a BGPsec speaker receives a BGPsec update message containing a When a BGPsec speaker receives a BGPsec UPDATE message containing a
BGPsec_Path attribute (with one or more signatures) from an (internal BGPsec_PATH attribute (with one or more signatures) from an (internal
or external) peer, it may choose to propagate the route advertisement or external) peer, it may choose to propagate the route advertisement
by sending it to its other (internal or external) peers. When by sending it to its other (internal or external) peers. When
sending the route advertisement to an internal BGPsec-speaking peer, sending the route advertisement to an internal BGPsec-speaking peer,
the BGPsec_Path attribute SHALL NOT be modified. When sending the the BGPsec_PATH attribute SHALL NOT be modified. When sending the
route advertisement to an external BGPsec-speaking peer, the route advertisement to an external BGPsec-speaking peer, the
following procedures are used to form or update the BGPsec_Path following procedures are used to form or update the BGPsec_PATH
attribute. attribute.
To generate the BGPsec_Path attribute on the outgoing update message, To generate the BGPsec_PATH attribute on the outgoing UPDATE message,
the BGPsec speaker first generates a new Secure_Path Segment. Note the BGPsec speaker first generates a new Secure_Path Segment. Note
that if the BGPsec speaker is not the origin AS and there is an that if the BGPsec speaker is not the origin AS and there is an
existing BGPsec_Path attribute, then the BGPsec speaker prepends its existing BGPsec_PATH attribute, then the BGPsec speaker prepends its
new Secure_Path Segment (places in first position) onto the existing new Secure_Path Segment (places in first position) onto the existing
Secure_Path. Secure_Path.
The AS number in this Secure_Path Segment MUST match the AS number in The AS number in this Secure_Path Segment MUST match the AS number in
the Subject field of the Resource PKI router certificate that will be the Subject field of the RPKI router certificate that will be used to
used to verify the digital signature constructed by this BGPsec verify the digital signature constructed by this BGPsec speaker (see
speaker (see Section 3.1.1 in [I-D.ietf-sidr-bgpsec-pki-profiles] and Section 3.1.1 in [RFC8209] and RFC 6487 [RFC6487]).
RFC 6487 [RFC6487]).
The pCount field of the Secure_Path Segment is typically set to the The pCount field of the Secure_Path Segment is typically set to the
value 1. However, a BGPsec speaker may set the pCount field to a value 1. However, a BGPsec speaker may set the pCount field to a
value greater than 1. Setting the pCount field to a value greater value greater than 1. Setting the pCount field to a value greater
than one has the same semantics as repeating an AS number multiple than 1 has the same semantics as repeating an AS number multiple
times in the AS_PATH of a non-BGPsec update message (e.g., for times in the AS_PATH of a non-BGPsec UPDATE message (e.g., for
traffic engineering purposes). traffic engineering purposes).
To prevent unnecessary processing load in the validation of BGPsec To prevent unnecessary processing load in the validation of BGPsec
signatures, a BGPsec speaker SHOULD NOT produce multiple consecutive signatures, a BGPsec speaker SHOULD NOT produce multiple consecutive
Secure_Path Segments with the same AS number. This means that to Secure_Path Segments with the same AS number. This means that to
achieve the semantics of prepending the same AS number k times, a achieve the semantics of prepending the same AS number k times, a
BGPsec speaker SHOULD produce a single Secure_Path Segment -- with BGPsec speaker SHOULD produce a single Secure_Path Segment -- with a
pCount of k -- and a single corresponding Signature Segment. pCount of k -- and a single corresponding Signature Segment.
A route server that participates in the BGP control plane, but does A route server that participates in the BGP control plane but
not act as a transit AS in the data plane, may choose to set pCount does not act as a transit AS in the data plane may choose to set
to 0. This option enables the route server to participate in BGPsec pCount to 0. This option enables the route server to participate in
and obtain the associated security guarantees without increasing the BGPsec and obtain the associated security guarantees without
length of the AS path. (Note that BGPsec speakers compute the length increasing the length of the AS path. (Note that BGPsec speakers
of the AS path by summing the pCount values in the BGPsec_Path compute the length of the AS path by summing the pCount values in the
attribute, see Section 5.) However, when a route server sets the BGPsec_PATH attribute; see Section 5.) However, when a route server
pCount value to 0, it still inserts its AS number into the sets the pCount value to 0, it still inserts its AS number into the
Secure_Path Segment, as this information is needed to validate the Secure_Path Segment, as this information is needed to validate the
signature added by the route server. See signature added by the route server. See [RFC8206] for a discussion
[I-D.ietf-sidr-as-migration] for a discussion of setting pCount to 0 of setting pCount to 0 to facilitate AS Number migration. Also, see
to facilitate AS Number Migration. Also, see Section 4.3 for the use Section 4.3 for the use of pCount=0 in the context of an AS
of pCount=0 in the context of an AS confederation. See Section 7.2 confederation. See Section 7.2 for operational guidance for
for operational guidance for configuring a BGPsec router for setting configuring a BGPsec router for setting pCount=0 and/or accepting
pCount=0 and/or accepting pCount=0 from a peer. pCount=0 from a peer.
Next, the BGPsec speaker generates one or two Signature_Blocks. Next, the BGPsec speaker generates one or two Signature_Blocks.
Typically, a BGPsec speaker will use only a single algorithm suite, Typically, a BGPsec speaker will use only a single algorithm suite
and thus create only a single Signature_Block in the BGPsec_Path and thus create only a single Signature_Block in the BGPsec_PATH
attribute. However, to ensure backwards compatibility during a attribute. However, to ensure backwards compatibility during a
period of transition from a 'current' algorithm suite to a 'new' period of transition from a 'current' algorithm suite to a 'new'
algorithm suite, it will be necessary to originate update messages algorithm suite, it will be necessary to originate UPDATE messages
that contain a Signature_Block for both the 'current' and the 'new' that contain a Signature_Block for both the 'current' and the 'new'
algorithm suites (see Section 6.1). algorithm suites (see Section 6.1).
If the received BGPsec update message contains two Signature_Blocks If the received BGPsec UPDATE message contains two Signature_Blocks
and the BGPsec speaker supports both of the corresponding algorithm and the BGPsec speaker supports both of the corresponding algorithm
suites, then the new update message generated by the BGPsec speaker suites, then the new UPDATE message generated by the BGPsec speaker
MUST include both of the Signature_Blocks. If the received BGPsec MUST include both of the Signature_Blocks. If the received BGPsec
update message contains two Signature_Blocks and the BGPsec speaker UPDATE message contains two Signature_Blocks and the BGPsec speaker
only supports one of the two corresponding algorithm suites, then the only supports one of the two corresponding algorithm suites, then the
BGPsec speaker MUST remove the Signature_Block corresponding to the BGPsec speaker MUST remove the Signature_Block corresponding to the
algorithm suite that it does not understand. If the BGPsec speaker algorithm suite that it does not understand. If the BGPsec speaker
does not support the algorithm suites in any of the Signature_Blocks does not support the algorithm suites in any of the Signature_Blocks
contained in the received update message, then the BGPsec speaker contained in the received UPDATE message, then the BGPsec speaker
MUST NOT propagate the route advertisement with the BGPsec_Path MUST NOT propagate the route advertisement with the BGPsec_PATH
attribute. (That is, if it chooses to propagate this route attribute. (That is, if it chooses to propagate this route
advertisement at all, it MUST do so as an unsigned BGP update advertisement at all, it MUST do so as an unsigned BGP UPDATE
message. See Section 4.4 for more information on converting to an message. See Section 4.4 for more information on converting to an
unsigned BGP message.) unsigned BGP UPDATE message.)
Note that in the case where the BGPsec_Path has two Signature_Blocks Note that in the case where the BGPsec_PATH has two Signature_Blocks
(corresponding to different algorithm suites), the validation (corresponding to different algorithm suites), the validation
algorithm (see Section 5.2) deems a BGPsec update message to be algorithm (see Section 5.2) deems a BGPsec UPDATE message to be
'Valid' if there is at least one supported algorithm suite (and 'Valid' if there is at least one supported algorithm suite (and
corresponding Signature_Block) that is deemed 'Valid'. This means corresponding Signature_Block) that is deemed 'Valid'. This means
that a 'Valid' BGPsec update message may contain a Signature_Block that a 'Valid' BGPsec UPDATE message may contain a Signature_Block
which is not deemed 'Valid' (e.g., contains signatures that BGPsec that is not deemed 'Valid' (e.g., contains signatures that BGPsec
does not successfully verify). Nonetheless, such Signature_Blocks does not successfully verify). Nonetheless, such Signature_Blocks
MUST NOT be removed. (See Section 8 for a discussion of the security MUST NOT be removed. (See Section 8 for a discussion of the security
ramifications of this design choice.) ramifications of this design choice.)
For each Signature_Block corresponding to an algorithm suite that the For each Signature_Block corresponding to an algorithm suite that the
BGPsec speaker does support, the BGPsec speaker MUST add a new BGPsec speaker does support, the BGPsec speaker MUST add a new
Signature Segment to the Signature_Block. This Signature Segment is Signature Segment to the Signature_Block. This Signature Segment is
prepended to the list of Signature Segments (placed in the first prepended to the list of Signature Segments (placed in the first
position) so that the list of Signature Segments appears in the same position) so that the list of Signature Segments appears in the same
order as the corresponding Secure_Path Segments. The BGPsec speaker order as the corresponding Secure_Path Segments. The BGPsec speaker
populates the fields of this new Signature Segment as follows. populates the fields of this new Signature Segment as follows.
The Subject Key Identifier field in the new segment is populated with The Subject Key Identifier field in the new segment is populated with
the identifier contained in the Subject Key Identifier extension of the identifier contained in the Subject Key Identifier extension of
skipping to change at page 16, line 10 skipping to change at page 16, line 15
BGPsec speaker does support, the BGPsec speaker MUST add a new BGPsec speaker does support, the BGPsec speaker MUST add a new
Signature Segment to the Signature_Block. This Signature Segment is Signature Segment to the Signature_Block. This Signature Segment is
prepended to the list of Signature Segments (placed in the first prepended to the list of Signature Segments (placed in the first
position) so that the list of Signature Segments appears in the same position) so that the list of Signature Segments appears in the same
order as the corresponding Secure_Path Segments. The BGPsec speaker order as the corresponding Secure_Path Segments. The BGPsec speaker
populates the fields of this new Signature Segment as follows. populates the fields of this new Signature Segment as follows.
The Subject Key Identifier field in the new segment is populated with The Subject Key Identifier field in the new segment is populated with
the identifier contained in the Subject Key Identifier extension of the identifier contained in the Subject Key Identifier extension of
the RPKI router certificate corresponding to the BGPsec speaker the RPKI router certificate corresponding to the BGPsec speaker
[I-D.ietf-sidr-bgpsec-pki-profiles]. This Subject Key Identifier [RFC8209]. This Subject Key Identifier will be used by recipients of
will be used by recipients of the route advertisement to identify the the route advertisement to identify the proper certificate to use in
proper certificate to use in verifying the signature. verifying the signature.
The Signature field in the new segment contains a digital signature The Signature field in the new segment contains a digital signature
that binds the prefix and BGPsec_Path attribute to the RPKI router that binds the prefix and BGPsec_PATH attribute to the RPKI router
certificate corresponding to the BGPsec speaker. The digital certificate corresponding to the BGPsec speaker. The digital
signature is computed as follows: signature is computed as follows:
o For clarity, let us number the Secure_Path and corresponding o For clarity, let us number the Secure_Path and corresponding
Signature Segments from 1 to N as follows. Let Secure_Path Signature Segments from 1 to N, as follows. Let Secure_Path
Segment 1 and Signature Segment 1 be the segments produced by the Segment 1 and Signature Segment 1 be the segments produced by the
origin AS. Let Secure_Path Segment 2 and Signature Segment 2 be origin AS. Let Secure_Path Segment 2 and Signature Segment 2 be
the segments added by the next AS after the origin. Continue this the segments added by the next AS after the origin. Continue this
method of numbering and ultimately let Secure_Path Segment N and method of numbering, and ultimately let Secure_Path Segment N and
Signature Segment N be those that are being added by the current Signature Segment N be those that are being added by the current
AS. The current AS (Nth AS) is signing and forwarding the update AS. The current AS (Nth AS) is signing and forwarding the UPDATE
to the next AS (i.e. (N+1)th AS) in the chain of ASes that form message to the next AS (i.e., the (N+1)th AS) in the chain of ASes
the AS path. that form the AS path.
o In order to construct the digital signature for Signature Segment o In order to construct the digital signature for Signature
N (the Signature Segment being produced by the current AS), first Segment N (the Signature Segment being produced by the current
construct the sequence of octets to be hashed as shown in AS), first construct the sequence of octets to be hashed as shown
Figure 8. This sequence of octets includes all the data that the in Figure 8. This sequence of octets includes all the data that
Nth AS attests to by adding its digital signature in the update the Nth AS attests to by adding its digital signature in the
which is being forwarded to a BGPsec speaker in the (N+1)th AS. UPDATE message that is being forwarded to a BGPsec speaker in the
(For the design rationale for choosing the specific structure in (N+1)th AS. (For the design rationale for choosing the specific
Figure 8, please see [Borchert].) structure in Figure 8, please see [Borchert].)
+------------------------------------+ +------------------------------------+
| Target AS Number | | Target AS Number |
+------------------------------------+ ---\ +------------------------------------+----\
| Signature Segment : N-1 | \ | Signature Segment : N-1 | \
+------------------------------------+ | +------------------------------------+ |
| Secure_Path Segment : N | | | Secure_Path Segment : N | |
+------------------------------------+ \ +------------------------------------+ \
... > Data from ... > Data from
+------------------------------------+ / N Segments +------------------------------------+ / N Segments
| Signature Segment : 1 | | | Signature Segment : 1 | |
+------------------------------------+ | +------------------------------------+ |
| Secure_Path Segment : 2 | | | Secure_Path Segment : 2 | |
+------------------------------------+ / +------------------------------------+ /
| Secure_Path Segment : 1 | / | Secure_Path Segment : 1 | /
+------------------------------------+---/ +------------------------------------+---/
| Algorithm Suite Identifier | | Algorithm Suite Identifier |
+------------------------------------+ +------------------------------------+
| AFI | | AFI |
+------------------------------------+ +------------------------------------+
| SAFI | | SAFI |
+------------------------------------+ +------------------------------------+
| Prefix | | NLRI |
+------------------------------------+ +------------------------------------+
Figure 8: Sequence of octets to be hashed. Figure 8: Sequence of Octets to Be Hashed
The elements in this sequence (Figure 8) MUST be ordered exactly The elements in this sequence (Figure 8) MUST be ordered exactly
as shown. The 'Target AS Number' is the AS to whom the BGPsec as shown. The 'Target AS Number' is the AS to whom the BGPsec
speaker intends to send the update message. (Note that the speaker intends to send the UPDATE message. (Note that the
'Target AS Number' is the AS number announced by the peer in the 'Target AS Number' is the AS number announced by the peer in the
OPEN message of the BGP session within which the update is sent.) OPEN message of the BGP session within which the UPDATE message is
The Secure_Path and Signature Segments (1 through N-1) are sent.) The Secure_Path and Signature Segments (1 through N-1) are
obtained from the BGPsec_Path attribute. Finally, the Address obtained from the BGPsec_PATH attribute. Finally, the Address
Family Identifier (AFI), Subsequent Address Family Identifier Family Identifier (AFI), Subsequent Address Family Identifier
(SAFI), and Prefix fields are obtained from the MP_REACH_NLRI (SAFI), and NLRI fields are obtained from the MP_REACH_NLRI
attribute [RFC4760]. Additionally, in the Prefix field all of the attribute [RFC4760]. Additionally, in the Prefix field within the
trailing bits MUST be set to zero when constructing this sequence. NLRI field (see Section 5 in RFC 4760 [RFC4760]), all of the
trailing bits MUST be set to 0 when constructing this sequence.
o Apply to this octet sequence (in Figure 8) the digest algorithm o Apply to this octet sequence (in Figure 8) the digest algorithm
(for the algorithm suite of this Signature_Block) to obtain a (for the algorithm suite of this Signature_Block) to obtain a
digest value. digest value.
o Apply to this digest value the signature algorithm, (for the o Apply to this digest value the signature algorithm (for the
algorithm suite of this Signature_Block) to obtain the digital algorithm suite of this Signature_Block) to obtain the digital
signature. Then populate the Signature Field (in Figure 7) with signature. Then populate the Signature field (in Figure 7) with
this digital signature. this digital signature.
The Signature Length field (in Figure 7) is populated with the length The Signature Length field (in Figure 7) is populated with the length
(in octets) of the value in the Signature field. (in octets) of the value in the Signature field.
4.3. Processing Instructions for Confederation Members 4.3. Processing Instructions for Confederation Members
Members of autonomous system confederations [RFC5065] MUST Members of AS confederations [RFC5065] MUST additionally follow the
additionally follow the instructions in this section for processing instructions in this section for processing BGPsec UPDATE messages.
BGPsec update messages.
When a BGPsec speaker in an AS confederation receives a BGPsec update When a BGPsec speaker in an AS confederation receives a BGPsec UPDATE
from a peer that is external to the confederation and chooses to message from a peer that is external to the confederation and chooses
propagate the update within the confederation, then it first adds a to propagate the UPDATE message within the confederation, it first
signature signed to its own Member-AS (i.e. the Target AS number is adds a signature signed to its own Member-AS (i.e., the 'Target AS
the BGPsec speaker's Member-AS number). In this internally modified Number' is the BGPsec speaker's Member-AS Number). In this
update, the newly added Secure_Path Segment contains the public AS internally modified UPDATE message, the newly added Secure_Path
number (i.e. Confederation Identifier), the Segment's pCount value Segment contains the public AS number (i.e., Confederation
is set to 0, and Confed_Segment flag is set to one. Setting pCount=0 Identifier), the segment's pCount value is set to 0, and
in this case helps ensure that the AS path length is not Confed_Segment flag is set to 1. Setting pCount=0 in this case helps
unnecessarily incremented. The newly added signature is generated ensure that the AS path length is not unnecessarily incremented. The
using a private key corresponding to the public AS number of the newly added signature is generated using a private key corresponding
confederation. The BGPsec speaker propagates the modified update to to the public AS number of the confederation. The BGPsec speaker
its peers within the confederation. propagates the modified UPDATE message to its peers within the
confederation.
Any BGPsec_Path modifications mentioned below in the context of Any BGPsec_PATH modifications mentioned below in the context of
propagation of the update within the confederation are in addition to propagation of the UPDATE message within the confederation are in
the modification described above (i.e. with pCount=0). addition to the modification described above (i.e., with pCount=0).
When a BGPsec speaker sends a BGPsec update message to a peer that When a BGPsec speaker sends a BGPsec UPDATE message to a peer that
belongs within its own Member-AS, the confederation member SHALL NOT belongs within its own Member-AS, the confederation member SHALL NOT
modify the BGPsec_Path attribute. When a BGPsec speaker sends a modify the BGPsec_PATH attribute. When a BGPsec speaker sends a
BGPsec update message to a peer that is within the same confederation BGPsec UPDATE message to a peer that is within the same confederation
but in a different Member-AS, the BGPsec speaker puts its Member-AS but in a different Member-AS, the BGPsec speaker puts its Member-AS
number in the AS Number field of the Secure_Path Segment that it adds Number in the AS Number field of the Secure_Path Segment that it adds
to the BGPsec update message. Additionally, in this case, the to the BGPsec UPDATE message. Additionally, in this case, the
Member-AS that generates the Secure_Path Segment sets the Member-AS that generates the Secure_Path Segment sets the
Confed_Segment flag to one. Further, the signature is generated with Confed_Segment flag to 1. Further, the signature is generated with a
a private key corresponding to the BGPsec speaker's Member-AS Number. private key corresponding to the BGPsec speaker's Member-AS Number.
(Note: In this document, intra-Member-AS peering is regarded as iBGP (Note: In this document, intra-Member-AS peering is regarded as iBGP,
and inter-Member-AS peering is regarded as eBGP. The latter is also and inter-Member-AS peering is regarded as eBGP. The latter is also
known as confederation-eBGP.) known as confederation-eBGP.)
Within a confederation, the verification of BGPsec signatures added Within a confederation, the verification of BGPsec signatures added
by other members of the confederation is optional. Note that if a by other members of the confederation is optional. Note that if a
confederation chooses not to verify digital signatures within the confederation chooses not to verify digital signatures within the
confederation, then BGPsec is able to provide no assurances about the confederation, then BGPsec is not able to provide any assurances
integrity of the Member-AS Numbers placed in Secure_Path Segments about the integrity of the Member-AS Numbers placed in Secure_Path
where the Confed_Segment flag is set to one. Segments where the Confed_Segment flag is set to 1.
When a confederation member receives a BGPsec update message from a When a confederation member receives a BGPsec UPDATE message from a
peer within the confederation and propagates it to a peer outside the peer within the confederation and propagates it to a peer outside the
confederation, it needs to remove all of the Secure_Path Segments confederation, it needs to remove all of the Secure_Path Segments
added by confederation members as well as the corresponding Signature added by confederation members as well as the corresponding Signature
Segments. To do this, the confederation member propagating the route Segments. To do this, the confederation member propagating the route
outside the confederation does the following: outside the confederation does the following:
o First, starting with the most recently added Secure_Path Segment, o First, starting with the most recently added Secure_Path Segment,
remove all of the consecutive Secure_Path Segments that have the remove all of the consecutive Secure_Path Segments that have the
Confed_Segment flag set to one. Stop this process once a Confed_Segment flag set to 1. Stop this process once a
Secure_Path Segment is reached which has its Confed_Segment flag Secure_Path Segment that has its Confed_Segment flag set to 0 is
set to zero. Keep a count of the number of segments removed in reached. Keep a count of the number of segments removed in this
this fashion. fashion.
o Second, starting with the most recently added Signature Segment, o Second, starting with the most recently added Signature Segment,
remove a number of Signature Segments equal to the number of remove a number of Signature Segments equal to the number of
Secure_Path Segments removed in the previous step. (That is, Secure_Path Segments removed in the previous step. (That is,
remove the K most recently added Signature Segments, where K is remove the K most recently added Signature Segments, where K is
the number of Secure_Path Segments removed in the previous step.) the number of Secure_Path Segments removed in the previous step.)
o Finally, add a Secure_Path Segment containing, in the AS field, o Finally, add a Secure_Path Segment containing, in the AS field,
the AS Confederation Identifier (the public AS number of the the AS Confederation Identifier (the public AS number of the
confederation) as well as a corresponding Signature Segment. Note confederation) as well as a corresponding Signature Segment. Note
that all fields other than the AS field are populated as per that all fields other than the AS field are populated as per
Section 4.2. Section 4.2.
Finally, as discussed above, an AS confederation MAY optionally Finally, as discussed above, an AS confederation MAY optionally
decide that its members will not verify digital signatures added by decide that its members will not verify digital signatures added by
members. In such a confederation, when a BGPsec speaker runs the members. In such a confederation, when a BGPsec speaker runs the
algorithm in Section 5.2, the BGPsec speaker, during the process of algorithm in Section 5.2, the BGPsec speaker, during the process of
Signature verifications, first checks whether the Confed_Segment flag signature verifications, first checks whether the Confed_Segment flag
in a Secure_Path Segment is set to one. If the flag is set to one, in a Secure_Path Segment is set to 1. If the flag is set to 1, the
the BGPsec speaker skips the verification for the corresponding BGPsec speaker skips the verification for the corresponding signature
Signature, and immediately moves on to the next Secure_Path Segment. and immediately moves on to the next Secure_Path Segment. Note that
Note that as specified in Section 5.2, it is an error when a BGPsec as specified in Section 5.2, it is an error when a BGPsec speaker
speaker receives from a peer, who is not in the same AS receives, from a peer who is not in the same AS confederation, a
confederation, a BGPsec update containing a Confed_Segment flag set BGPsec UPDATE message containing a Confed_Segment flag set to 1.
to one.
4.4. Reconstructing the AS_PATH Attribute 4.4. Reconstructing the AS_PATH Attribute
BGPsec update messages do not contain the AS_PATH attribute. BGPsec UPDATE messages do not contain the AS_PATH attribute.
However, the AS_PATH attribute can be reconstructed from the However, the AS_PATH attribute can be reconstructed from the
BGPsec_Path attribute. This is necessary in the case where a route BGPsec_PATH attribute. This is necessary in the case where a route
advertisement is received via a BGPsec update message and then advertisement is received via a BGPsec UPDATE message and then
propagated to a peer via a non-BGPsec update message (e.g., because propagated to a peer via a non-BGPsec UPDATE message (e.g., because
the latter peer does not support BGPsec). Note that there may be the latter peer does not support BGPsec). Note that there may be
additional cases where an implementation finds it useful to perform additional cases where an implementation finds it useful to perform
this reconstruction. Before attempting to reconstruct an AS_PATH for this reconstruction. Before attempting to reconstruct an AS_PATH for
the purpose of forwarding an unsigned (non-BGPsec) update to a peer, the purpose of forwarding an unsigned (non-BGPsec) UPDATE message to
a BGPsec speaker MUST perform the basic integrity checks listed in a peer, a BGPsec speaker MUST perform the basic integrity checks
Section 5.2 to ensure that the received BGPsec update is properly listed in Section 5.2 to ensure that the received BGPsec UPDATE
formed. message is properly formed.
The AS_PATH attribute can be constructed from the BGPsec_Path The AS_PATH attribute can be constructed from the BGPsec_PATH
attribute as follows. Starting with a blank AS_PATH attribute, attribute as follows. Starting with a blank AS_PATH attribute,
process the Secure_Path Segments in order from least-recently added process the Secure_Path Segments in order from least recently added
(corresponding to the origin) to most-recently added. For each (corresponding to the origin) to most recently added. For each
Secure_Path Segment perform the following steps: Secure_Path Segment, perform the following steps:
1. If the Secure_Path Segment has pCount=0, then do nothing (i.e. 1. If the Secure_Path Segment has pCount=0, then do nothing (i.e.,
move on to process the next Secure_Path Segment). move on to process the next Secure_Path Segment).
2. If the Secure_Path Segment has pCount greater than 0 and the 2. If the Secure_Path Segment has pCount greater than 0 and the
Confed_Segment flag is set to one, then look at the most-recently Confed_Segment flag is set to 1, then look at the most recently
added segment in the AS_PATH. added segment in the AS_PATH.
* In the case where the AS_PATH is blank or in the case where * In the case where the AS_PATH is blank or in the case where
the most-recently added segment is of type AS_SEQUENCE, add the most recently added segment is of type AS_SEQUENCE, add
(prepend to the AS_PATH) a new AS_PATH segment of type (prepend to the AS_PATH) a new AS_PATH segment of type
AS_CONFED_SEQUENCE. This segment of type AS_CONFED_SEQUENCE AS_CONFED_SEQUENCE. This segment of type AS_CONFED_SEQUENCE
shall contain a number of elements equal to the pCount field shall contain a number of elements equal to the pCount field
in the current Secure_Path Segment. Each of these elements in the current Secure_Path Segment. Each of these elements
shall be the AS number contained in the current Secure_Path shall be the AS number contained in the current Secure_Path
Segment. (That is, if the pCount field is X, then the segment Segment. (That is, if the pCount field is X, then the segment
of type AS_CONFED_SEQUENCE contains X copies of the of type AS_CONFED_SEQUENCE contains X copies of the
Secure_Path Segment's AS Number field.) Secure_Path Segment's AS Number field.)
* In the case where the most-recently added segment in the * In the case where the most recently added segment in the
AS_PATH is of type AS_CONFED_SEQUENCE then add (prepend to the AS_PATH is of type AS_CONFED_SEQUENCE, then add (prepend to
segment) a number of elements equal to the pCount field in the the segment) a number of elements equal to the pCount field in
current Secure_Path Segment. The value of each of these the current Secure_Path Segment. The value of each of these
elements shall be the AS number contained in the current elements shall be the AS number contained in the current
Secure_Path Segment. (That is, if the pCount field is X, then Secure_Path Segment. (That is, if the pCount field is X, then
add X copies of the Secure_Path Segment's AS Number field to add X copies of the Secure_Path Segment's AS Number field to
the existing AS_CONFED_SEQUENCE.) the existing AS_CONFED_SEQUENCE.)
3. If the Secure_Path Segment has pCount greater than 0 and the 3. If the Secure_Path Segment has pCount greater than 0 and the
Confed_Segment flag is set to zero, then look at the most- Confed_Segment flag is set to 0, then look at the most recently
recently added segment in the AS_PATH. added segment in the AS_PATH.
* In the case where the AS_PATH is blank or in the case where * In the case where the AS_PATH is blank or in the case where
the most-recently added segment is of type AS_CONFED_SEQUENCE, the most recently added segment is of type AS_CONFED_SEQUENCE,
add (prepend to the AS_PATH) a new AS_PATH segment of type add (prepend to the AS_PATH) a new AS_PATH segment of type
AS_SEQUENCE. This segment of type AS_SEQUENCE shall contain a AS_SEQUENCE. This segment of type AS_SEQUENCE shall contain a
number of elements equal to the pCount field in the current number of elements equal to the pCount field in the current
Secure_Path Segment. Each of these elements shall be the AS Secure_Path Segment. Each of these elements shall be the AS
number contained in the current Secure_Path Segment. (That number contained in the current Secure_Path Segment. (That
is, if the pCount field is X, then the segment of type is, if the pCount field is X, then the segment of type
AS_SEQUENCE contains X copies of the Secure_Path Segment's AS AS_SEQUENCE contains X copies of the Secure_Path Segment's AS
Number field.) Number field.)
* In the case where the most recently added segment in the * In the case where the most recently added segment in the
AS_PATH is of type AS_SEQUENCE then add (prepend to the AS_PATH is of type AS_SEQUENCE, then add (prepend to the
segment) a number of elements equal to the pCount field in the segment) a number of elements equal to the pCount field in the
current Secure_Path Segment. The value of each of these current Secure_Path Segment. The value of each of these
elements shall be the AS number contained in the current elements shall be the AS number contained in the current
Secure_Path Segment. (That is, if the pCount field is X, then Secure_Path Segment. (That is, if the pCount field is X, then
add X copies of the Secure_Path Segment's AS Number field to add X copies of the Secure_Path Segment's AS Number field to
the existing AS_SEQUENCE.) the existing AS_SEQUENCE.)
As part of the above described procedure, the following additional As part of the procedure described above, the following additional
actions are performed in order not to exceed the size limitations of actions are performed in order not to exceed the size limitations of
AS_SEQUENCE and AS_CONFED_SEQUENCE. While adding the next AS_SEQUENCE and AS_CONFED_SEQUENCE. While adding the next
Secure_Path Segment (with its prepends, if any) to the AS_PATH being Secure_Path Segment (with its prepends, if any) to the AS_PATH being
assembled, if it would cause the AS_SEQUENCE (or AS_CONFED_SEQUENCE) assembled, if it would cause the AS_SEQUENCE (or AS_CONFED_SEQUENCE)
at hand to exceed the limit of 255 AS numbers per segment [RFC4271] at hand to exceed the limit of 255 AS numbers per segment [RFC4271]
[RFC5065], then the BGPsec speaker would follow the recommendations [RFC5065], then the BGPsec speaker would follow the recommendations
in RFC 4271 [RFC4271] and RFC 5065 [RFC5065] of creating another in RFC 4271 [RFC4271] and RFC 5065 [RFC5065] of creating another
segment of the same type (AS_SEQUENCE or AS_CONFED_SEQUENCE) and segment of the same type (AS_SEQUENCE or AS_CONFED_SEQUENCE) and
continue filling that. continue filling that.
Finally, one special case of reconstruction of AS_PATH is when the Finally, one special case of reconstruction of AS_PATH is when the
BGPsec_Path attribute is absent. As explained in Section 4.1, when a BGPsec_PATH attribute is absent. As explained in Section 4.1, when a
BGPsec speaker originates a prefix and sends it to a BGPsec-capable BGPsec speaker originates a prefix and sends it to a BGPsec-capable
iBGP peer, the BGPsec_Path is not attached. So when received from a iBGP peer, the BGPsec_PATH is not attached. So, when received from a
BGPsec-capable iBGP peer, no BGPsec_Path attribute in a BGPsec update BGPsec-capable iBGP peer, no BGPsec_PATH attribute in a BGPsec UPDATE
is equivalent to an empty AS_PATH [RFC4271]. message is equivalent to an empty AS_PATH [RFC4271].
5. Processing a Received BGPsec Update 5. Processing a Received BGPsec UPDATE Message
Upon receiving a BGPsec update message from an external (eBGP) peer, Upon receiving a BGPsec UPDATE message from an external (eBGP) peer,
a BGPsec speaker SHOULD validate the message to determine the a BGPsec speaker SHOULD validate the message to determine the
authenticity of the path information contained in the BGPsec_Path authenticity of the path information contained in the BGPsec_PATH
attribute. Typically, a BGPsec speaker will also wish to perform attribute. Typically, a BGPsec speaker will also wish to perform
origin validation (see RFC 6483 [RFC6483] and RFC 6811 [RFC6811]) on origin validation (see RFC 6483 [RFC6483] and RFC 6811 [RFC6811]) on
an incoming BGPsec update message, but such validation is independent an incoming BGPsec UPDATE message, but such validation is independent
of the validation described in this section. of the validation described in this section.
Section 5.1 provides an overview of BGPsec validation and Section 5.2 Section 5.1 provides an overview of BGPsec validation, and
provides a specific algorithm for performing such validation. (Note Section 5.2 provides a specific algorithm for performing such
that an implementation need not follow the specific algorithm in validation. (Note that an implementation need not follow the
Section 5.2 as long as the input/output behavior of the validation is specific algorithm in Section 5.2 as long as the input/output
identical to that of the algorithm in Section 5.2.) During behavior of the validation is identical to that of the algorithm in
exceptional conditions (e.g., the BGPsec speaker receives an Section 5.2.) During exceptional conditions (e.g., the BGPsec
incredibly large number of update messages at once) a BGPsec speaker speaker receives an incredibly large number of UPDATE messages at
MAY temporarily defer validation of incoming BGPsec update messages. once), a BGPsec speaker MAY temporarily defer validation of incoming
The treatment of such BGPsec update messages, whose validation has BGPsec UPDATE messages. The treatment of such BGPsec UPDATE
been deferred, is a matter of local policy. However, an messages, whose validation has been deferred, is a matter of local
implementation SHOULD ensure that deferment of validation and status policy. However, an implementation SHOULD ensure that deferment of
of deferred messages is visible to the operator. validation and status of deferred messages is visible to the
operator.
The validity of BGPsec update messages is a function of the current The validity of BGPsec UPDATE messages is a function of the current
RPKI state. When a BGPsec speaker learns that RPKI state has changed RPKI state. When a BGPsec speaker learns that the RPKI state has
(e.g., from an RPKI validating cache via the RPKI-to-Router protocol changed (e.g., from an RPKI validating cache via the RPKI-Router
[I-D.ietf-sidr-rpki-rtr-rfc6810-bis]), the BGPsec speaker MUST re-run protocol [RFC8210]), the BGPsec speaker MUST rerun validation on all
validation on all affected update messages stored in its Adj-RIB-In affected UPDATE messages stored in its Adj-RIB-In [RFC4271]. For
[RFC4271]. For example, when a given RPKI router certificate ceases example, when a given RPKI router certificate ceases to be valid
to be valid (e.g., it expires or is revoked), all update messages (e.g., it expires or is revoked), all UPDATE messages containing a
containing a signature whose SKI matches the SKI in the given signature whose SKI matches the SKI in the given certificate MUST be
certificate MUST be re-assessed to determine if they are still valid. reassessed to determine if they are still valid. If this
If this reassessment determines that the validity state of an update reassessment determines that the validity state of an UPDATE message
has changed then, depending on local policy, it may be necessary to has changed, then, depending on local policy, it may be necessary to
re-run best path selection. rerun best path selection.
BGPsec update messages do not contain an AS_PATH attribute. The BGPsec UPDATE messages do not contain an AS_PATH attribute. The
Secure_Path contains AS path information for the BGPsec update Secure_Path contains AS path information for the BGPsec UPDATE
message. Therefore, a BGPsec speaker MUST utilize the AS path message. Therefore, a BGPsec speaker MUST utilize the AS path
information in the Secure_Path in all cases where it would otherwise information in the Secure_Path in all cases where it would otherwise
use the AS path information in the AS_PATH attribute. The only use the AS path information in the AS_PATH attribute. The only
exception to this rule is when AS path information must be updated in exception to this rule is when AS path information must be updated in
order to propagate a route to a peer (in which case the BGPsec order to propagate a route to a peer (in which case the BGPsec
speaker follows the instructions in Section 4). Section 4.4 provides speaker follows the instructions in Section 4). Section 4.4 provides
an algorithm for constructing an AS_PATH attribute from a BGPsec_Path an algorithm for constructing an AS_PATH attribute from a BGPsec_PATH
attribute. Whenever the use of AS path information is called for attribute. Whenever the use of AS path information is called for
(e.g., loop detection, or use of AS path length in best path (e.g., loop detection or the use of the AS path length in best path
selection) the externally visible behavior of the implementation selection), the externally visible behavior of the implementation
shall be the same as if the implementation had run the algorithm in shall be the same as if the implementation had run the algorithm in
Section 4.4 and used the resulting AS_PATH attribute as it would for Section 4.4 and used the resulting AS_PATH attribute as it would for
a non-BGPsec update message. a non-BGPsec UPDATE message.
5.1. Overview of BGPsec Validation 5.1. Overview of BGPsec Validation
Validation of a BGPsec update message makes use of data from RPKI Validation of a BGPsec UPDATE message makes use of data from RPKI
router certificates. In particular, it is necessary that the router certificates. In particular, it is necessary that the
recipient have access to the following data obtained from valid RPKI recipient have access to the following data obtained from valid RPKI
router certificates: the AS Number, Public Key and Subject Key router certificates: the AS Number, Public Key, and Subject Key
Identifier from each valid RPKI router certificate. Identifier from each valid RPKI router certificate.
Note that the BGPsec speaker could perform the validation of RPKI Note that the BGPsec speaker could perform the validation of RPKI
router certificates on its own and extract the required data, or it router certificates on its own and extract the required data, or it
could receive the same data from a trusted cache that performs RPKI could receive the same data from a trusted cache that performs RPKI
validation on behalf of (some set of) BGPsec speakers. (For example, validation on behalf of (some set of) BGPsec speakers. (For example,
the trusted cache could deliver the necessary validity information to the trusted cache could deliver the necessary validity information to
the BGPsec speaker using the router key PDU for the RPKI-to-Router the BGPsec speaker by using the Router Key PDU (Protocol Data Unit)
protocol [I-D.ietf-sidr-rpki-rtr-rfc6810-bis].) for the RPKI-Router protocol [RFC8210].)
To validate a BGPsec update message containing the BGPsec_Path To validate a BGPsec UPDATE message containing the BGPsec_PATH
attribute, the recipient performs the validation steps specified in attribute, the recipient performs the validation steps specified in
Section 5.2. The validation procedure results in one of two states: Section 5.2. The validation procedure results in one of two states:
'Valid' and 'Not Valid'. 'Valid' and 'Not Valid'.
It is expected that the output of the validation procedure will be It is expected that the output of the validation procedure will be
used as an input to BGP route selection. That said, BGP route used as an input to BGP route selection. That said, BGP route
selection, and thus the handling of the validation states is a matter selection, and thus the handling of the validation states, is a
of local policy, and is handled using local policy mechanisms. matter of local policy and is handled using local policy mechanisms.
Implementations SHOULD enable operators to set such local policy on a Implementations SHOULD enable operators to set such local policy on a
per-session basis. (That is, it is expected that some operators will per-session basis. (That is, it is expected that some operators will
choose to treat BGPsec validation status differently for update choose to treat BGPsec validation status differently for UPDATE
messages received over different BGP sessions.) messages received over different BGP sessions.)
BGPsec validation needs only be performed at the eBGP edge. The BGPsec validation need only be performed at the eBGP edge. The
validation status of a BGP signed/unsigned update MAY be conveyed via validation status of a BGP signed/unsigned UPDATE message MAY be
iBGP from an ingress edge router to an egress edge router via some conveyed via iBGP from an ingress edge router to an egress edge
mechanism, according to local policy within an AS. As discussed in router via some mechanism, according to local policy within an AS.
Section 4, when a BGPsec speaker chooses to forward a (syntactically As discussed in Section 4, when a BGPsec speaker chooses to forward a
correct) BGPsec update message, it SHOULD be forwarded with its (syntactically correct) BGPsec UPDATE message, it SHOULD be forwarded
BGPsec_Path attribute intact (regardless of the validation state of with its BGPsec_PATH attribute intact (regardless of the validation
the update message). Based entirely on local policy, an egress state of the UPDATE message). Based entirely on local policy, an
router receiving a BGPsec update message from within its own AS MAY egress router receiving a BGPsec UPDATE message from within its own
choose to perform its own validation. AS MAY choose to perform its own validation.
5.2. Validation Algorithm 5.2. Validation Algorithm
This section specifies an algorithm for validation of BGPsec update This section specifies an algorithm for validation of BGPsec UPDATE
messages. A conformant implementation MUST include a BGPsec update messages. A conformant implementation MUST include a BGPsec update
validation algorithm that is functionally equivalent to the validation algorithm that is functionally equivalent to the
externally visible behavior of this algorithm. externally visible behavior of this algorithm.
First, the recipient of a BGPsec update message performs a check to First, the recipient of a BGPsec UPDATE message performs a check to
ensure that the message is properly formed. Both syntactical and ensure that the message is properly formed. Both syntactical and
protocol violation errors are checked. BGPsec_Path attribute MUST be protocol violation errors are checked. The BGPsec_PATH attribute
present when a BGPsec update is received from an external (eBGP) MUST be present when a BGPsec UPDATE message is received from an
BGPsec peer and also when such an update is propagated to an internal external (eBGP) BGPsec peer and also when such an UPDATE message is
(iBGP) BGPsec peer (see Section 4.2). The error checks specified in propagated to an internal (iBGP) BGPsec peer (see Section 4.2). The
Section 6.3 of [RFC4271] are performed, except that for BGPsec error checks specified in Section 6.3 of [RFC4271] are performed,
updates the checks on the AS_PATH attribute do not apply and instead except that for BGPsec UPDATE messages the checks on the AS_PATH
the following checks on BGPsec_Path attribute are performed: attribute do not apply and instead the following checks on the
BGPsec_PATH attribute are performed:
1. Check to ensure that the entire BGPsec_Path attribute is 1. Check to ensure that the entire BGPsec_PATH attribute is
syntactically correct (conforms to the specification in this syntactically correct (conforms to the specification in this
document). document).
2. Check that AS number in the most recently added Secure_Path 2. Check that the AS number in the most recently added Secure_Path
Segment (i.e. the one corresponding to the eBGP peer from which Segment (i.e., the one corresponding to the eBGP peer from which
the update message was received) matches the AS number of that the UPDATE message was received) matches the AS number of that
peer as specified in the BGP OPEN message. (Note: This check is peer as specified in the BGP OPEN message. (Note: This check is
performed only at an ingress BGPsec routers where the update is performed only at an ingress BGPsec router where the UPDATE
first received from a peer AS.) message is first received from a peer AS.)
3. Check that each Signature_Block contains one Signature Segment 3. Check that each Signature_Block contains one Signature Segment
for each Secure_Path Segment in the Secure_Path portion of the for each Secure_Path Segment in the Secure_Path portion of the
BGPsec_Path attribute. (Note that the entirety of each BGPsec_PATH attribute. (Note that the entirety of each
Signature_Block MUST be checked to ensure that it is well formed, Signature_Block MUST be checked to ensure that it is well formed,
even though the validation process may terminate before all even though the validation process may terminate before all
signatures are cryptographically verified.) signatures are cryptographically verified.)
4. Check that the update message does not contain an AS_PATH 4. Check that the UPDATE message does not contain an AS_PATH
attribute. attribute.
5. If the update message was received from an BGPsec peer that is 5. If the UPDATE message was received from a BGPsec peer that is not
not a member of the BGPsec speaker's AS confederation, check to a member of the BGPsec speaker's AS confederation, check to
ensure that none of the Secure_Path Segments contain a Flags ensure that none of the Secure_Path Segments contain a Flags
field with the Confed_Segment flag set to one. field with the Confed_Segment flag set to 1.
6. If the update message was received from a BGPsec peer that is a 6. If the UPDATE message was received from a BGPsec peer that is a
member of the BGPsec speaker's AS confederation, check to ensure member of the BGPsec speaker's AS confederation, check to ensure
that the Secure_Path Segment corresponding to that peer contains that the Secure_Path Segment corresponding to that peer contains
a Flags field with the Confed_Segment flag set to one. a Flags field with the Confed_Segment flag set to 1.
7. If the update message was received from a peer that is not 7. If the UPDATE message was received from a peer that is not
expected to set pCount=0 (see Section 4.2 and Section 4.3) then expected to set pCount=0 (see Sections 4.2 and 4.3), then check
check to ensure that the pCount field in the most-recently added to ensure that the pCount field in the most recently added
Secure_Path Segment is not equal to zero. (Note: See router Secure_Path Segment is not equal to 0. (Note: See Section 7.2
configuration guidance related to this in Section 7.2.) for router configuration guidance related to this item.)
8. Using the equivalent of AS_PATH corresponding to the Secure_Path 8. Using the equivalent of AS_PATH corresponding to the Secure_Path
in the update (see Section 4.4), check that the local AS number in the UPDATE message (see Section 4.4), check that the local AS
is not present in the AS path (i.e. rule out AS loop). number is not present in the AS path (i.e., rule out an AS loop).
If any of these checks fail, it is an error in the BGPsec_Path If any of these checks fail, it is an error in the BGPsec_PATH
attribute. BGPsec speakers MUST handle any syntactical or protocol attribute. BGPsec speakers MUST handle any syntactical or protocol
errors in the BGPsec_Path attribute using the "treat-as-withdraw" errors in the BGPsec_PATH attribute by using the "treat-as-withdraw"
approach as defined in RFC 7606 [RFC7606]. (Note: Since the AS approach as defined in RFC 7606 [RFC7606]. (Note: Since the AS
number of a transparent route server does appear in the Secure_Path number of a transparent route server does appear in the Secure_Path
with pCount=0, the route server MAY check if its local AS is listed with pCount=0, the route server MAY check to see if its local AS is
in the Secure_Path, and this check MAY be included in the loop listed in the Secure_Path, and this check MAY be included in the
detection check listed above.) loop-detection check listed above.)
Next, the BGPsec speaker examines the Signature_Blocks in the Next, the BGPsec speaker examines the Signature_Blocks in the
BGPsec_Path attribute. A Signature_Block corresponding to an BGPsec_PATH attribute. A Signature_Block corresponding to an
algorithm suite that the BGPsec speaker does not support is not algorithm suite that the BGPsec speaker does not support is not
considered in validation. If there is no Signature_Block considered in the validation process. If there is no Signature_Block
corresponding to an algorithm suite that the BGPsec speaker supports, corresponding to an algorithm suite that the BGPsec speaker supports,
then in order to consider the update in the route selection process, then in order to consider the UPDATE message in the route selection
the BGPsec speaker MUST strip the Signature_Block(s), reconstruct the process, the BGPsec speaker MUST strip the Signature_Block(s),
AS_PATH from the Secure_Path (see Section 4.4), and treat the update reconstruct the AS_PATH from the Secure_Path (see Section 4.4), and
as if it was received as an unsigned BGP update. treat the UPDATE message as if it were received as an unsigned BGP
UPDATE message.
For each remaining Signature_Block (corresponding to an algorithm For each remaining Signature_Block (corresponding to an algorithm
suite supported by the BGPsec speaker), the BGPsec speaker iterates suite supported by the BGPsec speaker), the BGPsec speaker iterates
through the Signature Segments in the Signature_Block, starting with through the Signature Segments in the Signature_Block, starting with
the most recently added segment (and concluding with the least the most recently added segment (and concluding with the
recently added segment). Note that there is a one-to-one least recently added segment). Note that there is a one-to-one
correspondence between Signature Segments and Secure_Path Segments correspondence between Signature Segments and Secure_Path Segments
within the BGPsec_Path attribute. The following steps make use of within the BGPsec_PATH attribute. The following steps make use of
this correspondence. this correspondence:
o (Step 1): Let there be K AS hops in a received BGPsec_Path o Step 1: Let there be K AS hops in a received BGPsec_PATH attribute
attribute that is to be validated. Let AS(1), AS(2), ..., AS(K+1) that is to be validated. Let AS(1), AS(2), ..., AS(K+1) denote
denote the sequence of AS numbers from the origin AS to the the sequence of AS numbers from the origin AS to the validating
validating AS. Let Secure_Path Segment N and Signature Segment N AS. Let Secure_Path Segment N and Signature Segment N in the
in the BGPsec_Path attribute refer to those corresponding to AS(N) BGPsec_PATH attribute refer to those corresponding to AS(N) (where
(where N = 1, 2, ..., K). The BGPsec speaker that is processing N = 1, 2, ..., K). The BGPsec speaker that is processing and
and validating the BGPsec_Path attribute resides in AS(K+1). Let validating the BGPsec_PATH attribute resides in AS(K+1). Let
Signature Segment N be the Signature Segment that is currently Signature Segment N be the Signature Segment that is currently
being verified. being verified.
o (Step 2): Locate the public key needed to verify the signature (in o Step 2: Locate the public key needed to verify the signature (in
the current Signature Segment). To do this, consult the valid the current Signature Segment). To do this, consult the valid
RPKI router certificate data and look up all valid (AS, SKI, RPKI router certificate data and look up all valid (AS Number,
Public Key) triples in which the AS matches the AS number in the Public Key, Subject Key Identifier) triples in which the AS
corresponding Secure_Path Segment. Of these triples that match matches the AS number in the corresponding Secure_Path Segment.
the AS number, check whether there is an SKI that matches the Of these triples that match the AS number, check whether there is
value in the Subject Key Identifier field of the Signature an SKI that matches the value in the Subject Key Identifier field
Segment. If this check finds no such matching SKI value, then of the Signature Segment. If this check finds no such matching
mark the entire Signature_Block as 'Not Valid' and proceed to the SKI value, then mark the entire Signature_Block as 'Not Valid' and
next Signature_Block. proceed to the next Signature_Block.
o (Step 3): Compute the digest function (for the given algorithm o Step 3: Compute the digest function (for the given algorithm
suite) on the appropriate data. suite) on the appropriate data.
In order to verify the digital signature in Signature Segment N, In order to verify the digital signature in Signature Segment N,
construct the sequence of octets to be hashed as shown in Figure 9 construct the sequence of octets to be hashed as shown in Figure 9
(using the notations defined in Step 1). (Note that this sequence (using the notations defined in Step 1). (Note that this sequence
is the same sequence that was used by AS(N) that created the is the same sequence that was used by AS(N) that created the
Signature Segment N (see Section 4.2 and Figure 8).) Signature Segment N (see Section 4.2 and Figure 8).)
+------------------------------------+ +------------------------------------+
| Target AS Number | | Target AS Number |
+------------------------------------+ ---\ +------------------------------------+----\
| Signature Segment : N-1 | \ | Signature Segment : N-1 | \
+------------------------------------+ | +------------------------------------+ |
| Secure_Path Segment : N | | | Secure_Path Segment : N | |
+------------------------------------+ \ +------------------------------------+ \
... > Data from ... > Data from
+------------------------------------+ / N Segments +------------------------------------+ / N Segments
| Signature Segment : 1 | | | Signature Segment : 1 | |
+------------------------------------+ | +------------------------------------+ |
| Secure_Path Segment : 2 | | | Secure_Path Segment : 2 | |
+------------------------------------+ / +------------------------------------+ /
| Secure_Path Segment : 1 | / | Secure_Path Segment : 1 | /
+------------------------------------+---/ +------------------------------------+---/
| Algorithm Suite Identifier | | Algorithm Suite Identifier |
+------------------------------------+ +------------------------------------+
| AFI | | AFI |
+------------------------------------+ +------------------------------------+
| SAFI | | SAFI |
+------------------------------------+ +------------------------------------+
| Prefix | | NLRI |
+------------------------------------+ +------------------------------------+
Figure 9: The Sequence of octets to be hashed for signature Figure 9: Sequence of Octets to Be Hashed for Signature Verification
verification of Signature Segment N; N = 1,2, ..., K, where K is the of Signature Segment N; N = 1,2, ..., K, Where K Is the Number of
number of AS hops in the BGPsec_Path attribute. AS Hops in the BGPsec_PATH Attribute
The elements in this sequence (Figure 9) MUST be ordered exactly The elements in this sequence (Figure 9) MUST be ordered exactly
as shown. For the first segment to be processed (the most as shown. For the first segment to be processed (the
recently added segment (i.e. N = K) given that there are K hops most recently added segment (i.e., N = K) given that there are K
in the Secure_Path), the 'Target AS Number' is AS(K+1), the AS hops in the Secure_Path), the 'Target AS Number' is AS(K+1), the
number of the BGPsec speaker validating the update message. Note AS number of the BGPsec speaker validating the UPDATE message.
that if a BGPsec speaker uses multiple AS Numbers (e.g., the Note that if a BGPsec speaker uses multiple AS Numbers (e.g., the
BGPsec speaker is a member of a confederation), the AS number used BGPsec speaker is a member of a confederation), the AS number used
here MUST be the AS number announced in the OPEN message for the here MUST be the AS number announced in the OPEN message for the
BGP session over which the BGPsec update was received. BGP session over which the BGPsec UPDATE message was received.
For each other Signature Segment (N smaller than K), the 'Target For each other Signature Segment (N smaller than K), the 'Target
AS Number' is AS(N+1), the AS number in the Secure_Path Segment AS Number' is AS(N+1), the AS number in the Secure_Path Segment
that corresponds to the Signature Segment added immediately after that corresponds to the Signature Segment added immediately after
the one being processed. (That is, in the Secure_Path Segment the one being processed (that is, in the Secure_Path Segment that
that corresponds to the Signature Segment that the validator just corresponds to the Signature Segment that the validator just
finished processing.) finished processing).
The Secure_Path and Signature Segment are obtained from the The Secure_Path and Signature Segment are obtained from the
BGPsec_Path attribute. The Address Family Identifier (AFI), BGPsec_PATH attribute. The AFI, SAFI, and NLRI fields are
Subsequent Address Family Identifier (SAFI), and Prefix fields are
obtained from the MP_REACH_NLRI attribute [RFC4760]. obtained from the MP_REACH_NLRI attribute [RFC4760].
Additionally, in the Prefix field all of the trailing bits MUST be Additionally, in the Prefix field within the NLRI field (see
set to zero when constructing this sequence. Section 5 in RFC 4760 [RFC4760]), all of the trailing bits MUST be
set to 0 when constructing this sequence.
o (Step 4): Use the signature validation algorithm (for the given o Step 4: Use the signature validation algorithm (for the given
algorithm suite) to verify the signature in the current segment. algorithm suite) to verify the signature in the current segment.
That is, invoke the signature validation algorithm on the That is, invoke the signature validation algorithm on the
following three inputs: the value of the Signature field in the following three inputs: the value of the Signature field in the
current segment; the digest value computed in Step 3 above; and current segment, the digest value computed in Step 3 above, and
the public key obtained from the valid RPKI data in Step 2 above. the public key obtained from the valid RPKI data in Step 2 above.
If the signature validation algorithm determines that the If the signature validation algorithm determines that the
signature is invalid, then mark the entire Signature_Block as 'Not signature is invalid, then mark the entire Signature_Block as
Valid' and proceed to the next Signature_Block. If the signature 'Not Valid' and proceed to the next Signature_Block. If the
validation algorithm determines that the signature is valid, then signature validation algorithm determines that the signature is
continue processing Signature Segments (within the current valid, then continue processing Signature Segments (within the
Signature_Block). current Signature_Block).
If all Signature Segments within a Signature_Block pass validation If all Signature Segments within a Signature_Block pass validation
(i.e., all segments are processed and the Signature_Block has not yet (i.e., all segments are processed and the Signature_Block has not yet
been marked 'Not Valid'), then the Signature_Block is marked as been marked 'Not Valid'), then the Signature_Block is marked as
'Valid'. 'Valid'.
If at least one Signature_Block is marked as 'Valid', then the If at least one Signature_Block is marked as 'Valid', then the
validation algorithm terminates and the BGPsec update message is validation algorithm terminates and the BGPsec UPDATE message is
deemed to be 'Valid'. (That is, if a BGPsec update message contains deemed 'Valid'. (That is, if a BGPsec UPDATE message contains two
two Signature_Blocks then the update message is deemed 'Valid' if the Signature_Blocks, then the UPDATE message is deemed 'Valid' if the
first Signature_Block is marked 'Valid' OR the second Signature_Block first Signature_Block is marked 'Valid' OR the second Signature_Block
is marked 'Valid'.) is marked 'Valid'.)
6. Algorithms and Extensibility 6. Algorithms and Extensibility
6.1. Algorithm Suite Considerations 6.1. Algorithm Suite Considerations
Note that there is currently no support for bilateral negotiation Note that there is currently no support for bilateral negotiation
(using BGP capabilities) between BGPsec peers to use a particular (using BGP capabilities) between BGPsec peers to use a particular
(digest and signature) algorithm suite. This is because the (digest and signature) algorithm suite. This is because the
algorithm suite used by the sender of a BGPsec update message MUST be algorithm suite used by the sender of a BGPsec UPDATE message MUST be
understood not only by the peer to whom it is directly sending the understood not only by the peer to whom it is directly sending the
message, but also by all BGPsec speakers to whom the route message but also by all BGPsec speakers to whom the route
advertisement is eventually propagated. Therefore, selection of an advertisement is eventually propagated. Therefore, selection of an
algorithm suite cannot be a local matter negotiated by BGP peers, but algorithm suite cannot be a local matter negotiated by BGP peers but
instead must be coordinated throughout the Internet. instead must be coordinated throughout the Internet.
To this end, a mandatory algorithm suites document exists which To this end, [RFC8208] specifies a mandatory-to-use 'current'
specifies a mandatory-to-use 'current' algorithm suite for use by all algorithm suite for use by all BGPsec speakers.
BGPsec speakers [I-D.ietf-sidr-bgpsec-algs].
It is anticipated that, in the future, the mandatory algorithm suites It is anticipated that, in the future, [RFC8208] or its successor
document will be updated to specify a transition from the 'current' will be updated to specify a transition from the 'current' algorithm
algorithm suite to a 'new' algorithm suite. During the period of suite to a 'new' algorithm suite. During the period of transition,
transition, all BGPsec update messages SHOULD simultaneously use both all BGPsec UPDATE messages SHOULD simultaneously use both the
the 'current' algorithm suite and the 'new' algorithm suite. (Note 'current' algorithm suite and the 'new' algorithm suite. (Note that
that Section 3 and Section 4 specify how the BGPsec_Path attribute Sections 3 and 4 specify how the BGPsec_PATH attribute can contain
can contain signatures, in parallel, for two algorithm suites.) Once signatures, in parallel, for two algorithm suites.) Once the
the transition is complete, use of the old 'current' algorithm will transition is complete, the use of the old 'current' algorithm will
be deprecated, use of the 'new' algorithm will be mandatory, and a be deprecated, the use of the 'new' algorithm will be mandatory, and
subsequent 'even newer' algorithm suite may be specified as a subsequent 'even newer' algorithm suite may be specified as
recommended to implement. Once the transition has successfully been "recommended to implement". Once the transition has successfully
completed in this manner, BGPsec speakers SHOULD include only a been completed in this manner, BGPsec speakers SHOULD include only a
single Signature_Block (corresponding to the 'new' algorithm). single Signature_Block (corresponding to the 'new' algorithm).
6.2. Considerations for the SKI Size 6.2. Considerations for the SKI Size
Depending on the method of generating key identifiers [RFC7093], the Depending on the method of generating key identifiers [RFC7093], the
size of the SKI in a RPKI router certificate may vary. The SKI field size of the SKI in an RPKI router certificate may vary. The SKI
in the BGPsec_Path attribute has a fixed 20 octets size (see field in the BGPsec_PATH attribute has a fixed size of 20 octets (see
Figure 7). If the SKI is longer than 20 octets, then use the Figure 7). If the SKI is longer than 20 octets, then use the
leftmost 20 octets of the SKI (excluding the tag and length) leftmost 20 octets of the SKI (excluding the tag and length)
[RFC7093]. If the SKI value is shorter than 20 octets, then pad the [RFC7093]. If the SKI value is shorter than 20 octets, then pad the
SKI (excluding the tag and length) to the right (least significant SKI (excluding the tag and length) to the right (least significant
octets) with octets having zero values. octets) with octets having "0" values.
6.3. Extensibility Considerations 6.3. Extensibility Considerations
This section discusses potential changes to BGPsec that would require This section discusses potential changes to BGPsec that would require
substantial changes to the processing of the BGPsec_Path and thus substantial changes to the processing of the BGPsec_PATH and thus
necessitate a new version of BGPsec. Examples of such changes necessitate a new version of BGPsec. Examples of such changes
include: include:
o A new type of signature algorithm that produces signatures of o A new type of signature algorithm that produces signatures of
variable length variable length
o A new type of signature algorithm for which the number of o A new type of signature algorithm for which the number of
signatures in the Signature_Block is not equal to the number of signatures in the Signature_Block is not equal to the number of
ASes in the Secure_Path (e.g., aggregate signatures) ASes in the Secure_Path (e.g., aggregate signatures)
o Changes to the data that is protected by the BGPsec signatures o Changes to the data that is protected by the BGPsec signatures
(e.g., attributes other than the AS path) (e.g., attributes other than the AS path)
In the case that such a change to BGPsec were deemed desirable, it is In the case that such a change to BGPsec were deemed desirable, it is
expected that a subsequent version of BGPsec would be created and expected that a subsequent version of BGPsec would be created and
that this version of BGPsec would specify a new BGP path attribute, that this version of BGPsec would specify a new BGP path attribute --
let's call it BGPsec_Path_Two, which is designed to accommodate the let's call it "BGPsec_PATH_Two" -- that is designed to accommodate
desired changes to BGPsec. In such a case, the mandatory algorithm the desired changes to BGPsec. In such a case, [RFC8208] or its
suites document would be updated to specify algorithm suites successor would be updated to specify algorithm suites appropriate
appropriate for the new version of BGPsec. for the new version of BGPsec.
At this point a transition would begin which is analogous to the At this point, a transition would begin that is analogous to the
algorithm transition discussed in Section 6.1. During the transition algorithm transition discussed in Section 6.1. During the transition
period all BGPsec speakers SHOULD simultaneously include both the period, all BGPsec speakers SHOULD simultaneously include both the
BGPsec_Path attribute and the new BGPsec_Path_Two attribute. Once BGPsec_PATH attribute and the new BGPsec_PATH_Two attribute. Once
the transition is complete, the use of BGPsec_Path could then be the transition is complete, the use of BGPsec_PATH could then be
deprecated, at which point BGPsec speakers should include only the deprecated, at which point BGPsec speakers should include only the
new BGPsec_Path_Two attribute. Such a process could facilitate a new BGPsec_PATH_Two attribute. Such a process could facilitate a
transition to a new BGPsec semantics in a backwards compatible transition to a new BGPsec semantics in a backwards-compatible
fashion. fashion.
7. Operations and Management Considerations 7. Operations and Management Considerations
Some operations and management issues that are closely relevant to Some operations and management issues that are closely relevant to
BGPsec protocol specification and its deployment are highlighted BGPsec protocol specification and deployment are highlighted here.
here. The Best Current Practices concerning operations and The best practices concerning operations and deployment of BGPsec are
deployment of BGPsec are provided in [I-D.ietf-sidr-bgpsec-ops]. provided in [RFC8207].
7.1. Capability Negotiation Failure 7.1. Capability Negotiation Failure
Section 2.2 describes the negotiation required to establish a BGPsec- Section 2.2 describes the negotiation required to establish a
capable peering session. Not only must the BGPsec capability be BGPsec-capable peering session. Not only must the BGPsec capability
exchanged (and agreed on), but the BGP multiprotocol extension be exchanged (and agreed on), but the BGP multiprotocol extension
[RFC4760] for the same AFI and the four-byte AS capability [RFC6793] [RFC4760] for the same AFI and the 4-byte AS capability [RFC6793]
MUST also be exchanged. Failure to properly negotiate a BGPsec MUST also be exchanged. Failure to properly negotiate a BGPsec
session, due to a missing capability, for example, may still result session -- due to a missing capability, for example -- may still
in the exchange of BGP (unsigned) updates. It is RECOMMENDED that an result in the exchange of BGP (unsigned) UPDATE messages. It is
implementation log the failure to properly negotiate a BGPsec RECOMMENDED that an implementation log the failure to properly
session. Also, an implementation MUST have the ability to prevent a negotiate a BGPsec session. Also, an implementation MUST have the
BGP session from being established if configured for only BGPsec use. ability to prevent a BGP session from being established if configured
to only use BGPsec.
7.2. Preventing Misuse of pCount=0 7.2. Preventing Misuse of pCount=0
A peer that is an Internet Exchange Point (IXP) (i.e. Route Server) A peer that is an Internet Exchange Point (IXP) (i.e., route server)
with a transparent AS is expected to set pCount=0 in its Secure_Path with a transparent AS is expected to set pCount=0 in its Secure_Path
Segment while forwarding an update to a peer (see Section 4.2). Segment while forwarding an UPDATE message to a peer (see
Clearly, such an IXP MUST configure its BGPsec router to set pCount=0 Section 4.2). Clearly, such an IXP MUST configure its BGPsec router
in its Secure_Path Segment. This also means that a BGPsec speaker to set pCount=0 in its Secure_Path Segment. This also means that a
MUST be configured so that it permits pCount=0 from an IXP peer. Two BGPsec speaker MUST be configured so that it permits pCount=0 from an
other cases where pCount is set to zero are in the context AS IXP peer. Two other cases where pCount is set to 0 are in the
confederation (see Section 4.3) and AS migration contexts of an AS confederation (see Section 4.3) and of AS migration
[I-D.ietf-sidr-as-migration]. In these two cases, pCount=0 is set [RFC8206]. In these two cases, pCount=0 is set and accepted within
and accepted within the same AS (albeit the AS has two different the same AS (albeit the AS has two different identities). Note that
identities). Note that if a BGPsec speaker does not expect a peer AS if a BGPsec speaker does not expect a peer AS to set its pCount=0 and
to set its pCount=0, and if an update received from that peer if an UPDATE message received from that peer violates this, then the
violates this, then the update MUST be considered to be in error (see UPDATE message MUST be considered to be in error (see the list of
the list of checks in Section 5.2). See Section 8.4 for a discussion checks in Section 5.2). See Section 8.4 for a discussion of security
of security considerations concerning pCount=0. considerations concerning pCount=0.
7.3. Early Termination of Signature Verification 7.3. Early Termination of Signature Verification
During the validation of a BGPsec update, route processor performance During the validation of a BGPsec UPDATE message, route processor
speedup can be achieved by incorporating the following observations. performance speedup can be achieved by incorporating the following
An update is deemed 'Valid' if at least one of the Signature_Blocks observations. An UPDATE message is deemed 'Valid' if at least one of
is marked as 'Valid' (see Section 5.2). Therefore, if an update the Signature_Blocks is marked as 'Valid' (see Section 5.2).
contains two Signature_Blocks and the first one verified is found Therefore, if an UPDATE message contains two Signature_Blocks and the
'Valid', then the second Signature_Block does not have to be first one verified is found 'Valid', then the second Signature_Block
verified. And if the update is chosen for best path, then the BGPsec does not have to be verified. And if the UPDATE message is chosen
speaker adds its signature (generated with the respective algorithm) for best path, then the BGPsec speaker adds its signature (generated
to each of the two Signature_Blocks and forwards the update. Also, a with the respective algorithm) to each of the two Signature_Blocks
BGPsec update is deemed 'Not Valid' if at least one signature in each and forwards the UPDATE message. Also, a BGPsec UPDATE message is
of the Signature_Blocks is invalid. This principle can also be used deemed 'Not Valid' if at least one signature in each of the
for route processor workload savings, i.e. the verification for a Signature_Blocks is invalid. This principle can also be used for
route processor workload savings, i.e., the verification for a
Signature_Block terminates early when the first invalid signature is Signature_Block terminates early when the first invalid signature is
encountered. encountered.
7.4. Non-Deterministic Signature Algorithms 7.4. Non-deterministic Signature Algorithms
Many signature algorithms are non-deterministic. That is, many Many signature algorithms are non-deterministic. That is, many
signature algorithms will produce different signatures each time they signature algorithms will produce different signatures each time they
are run (even when they are signing the same data with the same key). are run (even when they are signing the same data with the same key).
Therefore, if a BGPsec router receives a BGPsec update from a peer Therefore, if a BGPsec router receives a BGPsec UPDATE message from a
and later receives a second BGPsec update message from the same peer peer and later receives a second BGPsec UPDATE message from the same
for the same prefix with the same Secure_Path and SKIs, the second peer for the same prefix with the same Secure_Path and SKIs, the
update MAY differ from the first update in the signature fields (for second UPDATE message MAY differ from the first UPDATE message in the
a non-deterministic signature algorithm). However, the two sets of signature fields (for a non-deterministic signature algorithm).
signature fields will not differ if the sender caches and reuses the However, the two sets of signature fields will not differ if the
previous signature. For a deterministic signature algorithm, the sender caches and reuses the previous signature. For a deterministic
signature fields MUST be identical between the two updates. On the signature algorithm, the signature fields MUST be identical between
basis of these observations, an implementation MAY incorporate the two UPDATE messages. On the basis of these observations, an
optimizations in update validation processing. implementation MAY incorporate optimizations in update validation
processing.
7.5. Private AS Numbers 7.5. Private AS Numbers
It is possible that a stub customer of an ISP employs a private AS It is possible that a stub customer of an ISP employs a private AS
number. Such a stub customer cannot publish a ROA in the global RPKI number. Such a stub customer cannot publish a ROA in the Global RPKI
for the private AS number and the prefixes that they use. Also, the for the private AS number and the prefixes that they use. Also, the
global RPKI cannot support private AS numbers (i.e. BGPsec speakers Global RPKI cannot support private AS numbers (i.e., BGPsec speakers
in private ASes cannot be issued router certificates in the global in private ASes cannot be issued router certificates in the Global
RPKI). For interactions between the stub customer (with private AS RPKI). For interactions between the stub customer (with the private
number) and the ISP, the following two scenarios are possible: AS number) and the ISP, the following two scenarios are possible:
1. The stub customer sends an unsigned BGP update for a prefix to 1. The stub customer sends an unsigned BGP UPDATE message for a
the ISP's AS. An edge BGPsec speaker in the ISP's AS may choose prefix to the ISP's AS. An edge BGPsec speaker in the ISP's AS
to propagate the prefix to its non-BGPsec and BGPsec peers. If may choose to propagate the prefix to its non-BGPsec and BGPsec
so, the ISP's edge BGPsec speaker MUST strip the AS_PATH with the peers. If so, the ISP's edge BGPsec speaker MUST strip the
private AS number, and then (a) re-originate the prefix without AS_PATH with the private AS number and then (a) re-originate the
any signatures towards its non-BGPsec peer and (b) re-originate prefix without any signatures towards its non-BGPsec peer and
the prefix including its own signature towards its BGPsec peer. (b) re-originate the prefix including its own signature towards
In both cases (i.e. (a) and (b)), the prefix MUST have a ROA in its BGPsec peer. In both cases (i.e., (a) and (b)), the prefix
the global RPKI authorizing the ISP's AS to originate it. MUST have a ROA in the Global RPKI authorizing the ISP's AS to
originate it.
2. The ISP and the stub customer may use a local RPKI repository 2. The ISP and the stub customer may use a local RPKI repository
(using a mechanism such as described in [I-D.ietf-sidr-slurm]). (using a mechanism such as one of the mechanisms described in
Then there can be a ROA for the prefix originated by the stub AS, [SLURM]). Then, there can be a ROA for the prefix originated by
and the eBGP speaker in the stub AS can be a BGPsec speaker the stub AS, and the eBGP speaker in the stub AS can be a BGPsec
having a router certificate, albeit the ROA and router speaker having a router certificate, albeit the ROA and router
certificate are valid only locally. With this arrangement, the certificate are valid only locally. With this arrangement, the
stub AS sends a signed update for the prefix to the ISP's AS. An stub AS sends a signed UPDATE message for the prefix to the ISP's
edge BGPsec speaker in the ISP's AS validates the update using AS. An edge BGPsec speaker in the ISP's AS validates the UPDATE
RPKI data based the local RPKI view. Further, it may choose to message, using RPKI data based on the local RPKI view. Further,
propagate the prefix to its non-BGPsec and BGPsec peers. If so, it may choose to propagate the prefix to its non-BGPsec and
the ISP's edge BGPsec speaker MUST strip the Secure_Path and the BGPsec peers. If so, the ISP's edge BGPsec speaker MUST strip
Signature Segment received from the stub AS with the private AS the Secure_Path and the Signature Segment received from the stub
number, and then (a) re-originate the prefix without any AS with the private AS number and then (a) re-originate the
signatures towards its non-BGPsec peer and (b) re-originate the prefix without any signatures towards its non-BGPsec peer and
prefix including its own signature towards its BGPsec peer. In (b) re-originate the prefix including its own signature towards
both cases (i.e. (a) and (b)), the prefix MUST have a ROA in the its BGPsec peer. In both cases (i.e., (a) and (b)), the prefix
global RPKI authorizing the ISP's AS to originate it. MUST have a ROA in the Global RPKI authorizing the ISP's AS to
originate it.
It is possible that private AS numbers are used in an AS It is possible that private AS numbers are used in an AS
confederation [RFC5065]. BGPsec protocol requires that when a BGPsec confederation [RFC5065]. The BGPsec protocol requires that when a
update propagates through a confederation, each Member-AS that BGPsec UPDATE message propagates through a confederation, each
forwards it to a peer Member-AS MUST sign the update (see Member-AS that forwards it to a peer Member-AS MUST sign the UPDATE
Section 4.3). However, the global RPKI cannot support private AS message (see Section 4.3). However, the Global RPKI cannot support
numbers. In order for the BGPsec speakers in Member-ASes with private AS numbers. In order for the BGPsec speakers in Member-ASes
private AS numbers to have digital certificates, there MUST be a with private AS numbers to have digital certificates, there MUST be a
mechanism in place in the confederation that allows establishment of mechanism in place in the confederation that allows the establishment
a local, customized view of the RPKI, augmenting the global RPKI of a local, customized view of the RPKI, augmenting the Global RPKI
repository data as needed. Since this mechanism (for augmenting and repository data as needed. Since this mechanism (for augmenting and
maintaining a local image of RPKI data) operates locally within an AS maintaining a local image of RPKI data) operates locally within an AS
or AS confederation, it need not be standard based. However, a or AS confederation, it need not be standard based. However, a
standard-based mechanism can be used (see [I-D.ietf-sidr-slurm]). standard-based mechanism can be used (see [SLURM]). Recall that in
Recall that in order to prevent exposure of the internals of AS order to prevent exposure of the internals of AS confederations, a
confederations, a BGPsec speaker exporting to a non-member removes BGPsec speaker exporting to a non-member removes all
all intra-confederation Secure_Path Segments and Signatures (see intra-confederation Secure_Path Segments and Signatures (see
Section 4.3). Section 4.3).
7.6. Robustness Considerations for Accessing RPKI Data 7.6. Robustness Considerations for Accessing RPKI Data
The deployment structure, technologies and best practices concerning The deployment structure, technologies, and best practices concerning
global RPKI data to reach routers (via local RPKI caches) are Global RPKI data to reach routers (via local RPKI caches) are
described in [RFC6810] [I-D.ietf-sidr-rpki-rtr-rfc6810-bis] described in [RFC6810], [RFC8210], [RFC8181], [RFC7115], [RFC8207],
[I-D.ietf-sidr-publication] [RFC7115] [I-D.ietf-sidr-bgpsec-ops] and [RFC8182]. For example, Serial-Number-based incremental update
[I-D.ietf-sidr-delta-protocol]. For example, serial-number based mechanisms are used for efficient transfer of just the data records
incremental update mechanisms are used for efficient transfer of just that have changed since the last update [RFC6810] [RFC8210]. The
the data records that have changed since last update [RFC6810] update notification file is used by Relying Parties (RPs) to discover
[I-D.ietf-sidr-rpki-rtr-rfc6810-bis]. Update notification file is whether any changes exist between the state of the Global RPKI
used by relying parties (RPs) to discover whether any changes exist repository and the RP's cache [RFC8182]. The notification describes
between the state of the global RPKI repository and the RP's cache the location of (1) the files containing the snapshot and
[I-D.ietf-sidr-delta-protocol]. The notification describes the (2) incremental deltas, which can be used by the RP to synchronize
location of the files containing the snapshot and incremental deltas with the repository. Making use of these technologies and best
which can be used by the RP to synchronize with the repository. practices results in enabling robustness, efficiency, and better
Making use of these technologies and best practices results in security for the BGPsec routers and RPKI caches in terms of the flow
enabling robustness, efficiency, and better security for the BGPsec of RPKI data from repositories to RPKI caches to routers. With these
routers and RPKI caches in terms of the flow of RPKI data from mechanisms, it is believed that an attacker wouldn't be able to
repositories to RPKI caches to routers. With these mechanisms, it is meaningfully correlate RPKI data flows with BGPsec RP (or router)
believed that an attacker wouldn't be able to meaningfully correlate actions, thus avoiding attacks that may attempt to determine the set
RPKI data flows with BGPsec RP (or router) actions, thus avoiding of ASes interacting with an RP via the interactions between the RP
attacks that may attempt to determine the set of ASes interacting and RPKI servers.
with an RP via the interactions between the RP and RPKI servers.
7.7. Graceful Restart 7.7. Graceful Restart
During Graceful Restart (GR), restarting and receiving BGPsec During Graceful Restart (GR), restarting and receiving BGPsec
speakers MUST follow the procedures specified in [RFC4724] for speakers MUST follow the procedures specified in [RFC4724] for
restarting and receiving BGP speakers, respectively. In particular, restarting and receiving BGP speakers, respectively. In particular,
the behavior of retaining the forwarding state for the routes in the the behavior of retaining the forwarding state for the routes in the
Loc-RIB [RFC4271] and marking them as stale as well as not Loc-RIB [RFC4271] and marking them as stale, as well as not
differentiating between stale and other information during forwarding differentiating between stale routing information and other
will be the same as specified in [RFC4724]. information during forwarding, will be the same as the behavior
specified in [RFC4724].
7.8. Robustness of Secret Random Number in ECDSA 7.8. Robustness of Secret Random Number in ECDSA
The Elliptic Curve Digital Signature Algorithm (ECDSA) with curve The Elliptic Curve Digital Signature Algorithm (ECDSA) with curve
P-256 is used for signing updates in BGPsec P-256 is used for signing UPDATE messages in BGPsec [RFC8208]. For
[I-D.ietf-sidr-bgpsec-algs]. For ECDSA, it is stated in Section 6.3 ECDSA, it is stated in Section 6.3 of [FIPS186-4] that a new secret
of [FIPS186-4] that a new secret random number "k" shall be generated random number "k" shall be generated prior to the generation of each
prior to the generation of each digital signature. A high entropy digital signature. A high-entropy random bit generator (RBG) must be
random bit generator (RBG) must be used for generating "k", and any used for generating "k", and any potential bias in the "k" generation
potential bias in the "k" generation algorithm must be mitigated (see algorithm must be mitigated (see the methods described in [FIPS186-4]
methods described in [FIPS186-4] [SP800-90A]). and [SP800-90A]).
7.9. Incremental/Partial Deployment Considerations 7.9. Incremental/Partial Deployment Considerations
How will migration from BGP to BGPsec look like? What are the What will migration from BGP to BGPsec look like? What are the
benefits for the first adopters? Initially small groups of benefits for the first adopters? Initially, small groups of
contiguous ASes would be doing BGPsec. There would be possibly one contiguous ASes would be doing BGPsec. There would possibly be one
or more such groups in different geographic regions of the global or more such groups in different geographic regions of the global
Internet. Only the routes originated within each group and Internet. Only the routes originated within each group and
propagated within its borders would get the benefits of cryptographic propagated within its borders would get the benefits of cryptographic
AS path protection. As BGPsec adoption grows, each group grows in AS path protection. As BGPsec adoption grows, each group grows in
size and eventually they join together to form even larger BGPsec size, and eventually they join together to form even larger
capable groups of contiguous ASes. The benefit for early adopters BGPsec-capable groups of contiguous ASes. The benefit for early
starts with AS path security within the contiguous-AS regions spanned adopters starts with AS path security within the regions of
by their respective groups. Over time they would see those contiguous ASes spanned by their respective groups. Over time, they
contiguous-AS regions grow much larger. would see those regions of contiguous ASes grow much larger.
During partial deployment, if an AS in the path doesn't support During partial deployment, if an AS in the path doesn't support
BGPsec, then BGP goes back to traditional mode, i.e. BGPsec updates BGPsec, then BGP goes back to traditional mode, i.e., BGPsec UPDATE
are converted to unsigned updates before forwarding to that AS (see messages are converted to unsigned UPDATE messages before forwarding
Section 4.4). At this point, the assurance that the update to that AS (see Section 4.4). At this point, the assurance that the
propagated via the sequence of ASes listed is lost. In other words, UPDATE message propagated via the sequence of ASes listed is lost.
for the BGPsec routers residing in the ASes starting from the origin In other words, for the BGPsec routers residing in the ASes starting
AS to the AS before the one not supporting BGPsec, the assurance can from the origin AS to the AS before the one not supporting BGPsec,
be still provided, but not beyond that (for the updates in the assurance can still be provided, but not beyond that (for the
consideration). UPDATE messages in consideration).
8. Security Considerations 8. Security Considerations
For a discussion of the BGPsec threat model and related security For a discussion of the BGPsec threat model and related security
considerations, please see RFC 7132 [RFC7132]. considerations, please see RFC 7132 [RFC7132].
8.1. Security Guarantees 8.1. Security Guarantees
When used in conjunction with Origin Validation (see RFC 6483 When used in conjunction with origin validation (see RFC 6483
[RFC6483] and RFC 6811 [RFC6811]), a BGPsec speaker who receives a [RFC6483] and RFC 6811 [RFC6811]), a BGPsec speaker who receives a
valid BGPsec update message, containing a route advertisement for a valid BGPsec UPDATE message containing a route advertisement for a
given prefix, is provided with the following security guarantees: given prefix is provided with the following security guarantees:
o The origin AS number corresponds to an autonomous system that has o The origin AS number corresponds to an AS that has been
been authorized, in the RPKI, by the IP address space holder to authorized, in the RPKI, by the IP address space holder to
originate route advertisements for the given prefix. originate route advertisements for the given prefix.
o For each AS in the path, a BGPsec speaker authorized by the holder o For each AS in the path, a BGPsec speaker authorized by the holder
of the AS number intentionally chose (in accordance with local of the AS number intentionally chose (in accordance with local
policy) to propagate the route advertisement to the subsequent AS policy) to propagate the route advertisement to the subsequent AS
in the path. in the path.
That is, the recipient of a valid BGPsec update message is assured That is, the recipient of a valid BGPsec UPDATE message is assured
that the update propagated via the sequence of ASes listed in the that the UPDATE message propagated via the sequence of ASes listed in
Secure_Path portion of the BGPsec_Path attribute. (It should be the Secure_Path portion of the BGPsec_PATH attribute. (It should be
noted that BGPsec does not offer any guarantee that the data packets noted that BGPsec does not offer any guarantee that the data packets
would flow along the indicated path; it only guarantees that the BGP would flow along the indicated path; it only guarantees that the BGP
update conveying the path indeed propagated along the indicated UPDATE message conveying the path indeed propagated along the
path.) Furthermore, the recipient is assured that this path indicated path.) Furthermore, the recipient is assured that this
terminates in an autonomous system that has been authorized by the IP path terminates in an AS that has been authorized by the IP address
address space holder as a legitimate destination for traffic to the space holder as a legitimate destination for traffic to the given
given prefix. prefix.
Note that although BGPsec provides a mechanism for an AS to validate Note that although BGPsec provides a mechanism for an AS to validate
that a received update message has certain security properties, the that a received UPDATE message has certain security properties, the
use of such a mechanism to influence route selection is completely a use of such a mechanism to influence route selection is completely a
matter of local policy. Therefore, a BGPsec speaker can make no matter of local policy. Therefore, a BGPsec speaker can make no
assumptions about the validity of a route received from an external assumptions about the validity of a route received from an external
(eBGP) BGPsec peer. That is, a compliant BGPsec peer may (depending (eBGP) BGPsec peer. That is, a compliant BGPsec peer may (depending
on the local policy of the peer) send update messages that fail the on the local policy of the peer) send UPDATE messages that fail the
validity test in Section 5. Thus, a BGPsec speaker MUST completely validity test in Section 5. Thus, a BGPsec speaker MUST completely
validate all BGPsec update messages received from external peers. validate all BGPsec UPDATE messages received from external peers.
(Validation of update messages received from internal peers is a (Validation of UPDATE messages received from internal peers is also a
matter of local policy, see Section 5.) matter of local policy; see Section 5.)
8.2. On the Removal of BGPsec Signatures 8.2. On the Removal of BGPsec Signatures
There may be cases where a BGPsec speaker deems 'Valid' (as per the There may be cases where a BGPsec speaker deems 'Valid' (as per the
validation algorithm in Section 5.2) a BGPsec update message that validation algorithm in Section 5.2) a BGPsec UPDATE message that
contains both a 'Valid' and a 'Not Valid' Signature_Block. That is, contains both a 'Valid' and a 'Not Valid' Signature_Block. That is,
the update message contains two sets of signatures corresponding to the UPDATE message contains two sets of signatures corresponding to
two algorithm suites, and one set of signatures verifies correctly two algorithm suites, and one set of signatures verifies correctly
and the other set of signatures fails to verify. In this case, the and the other set of signatures fails to verify. In this case, the
protocol specifies that a BGPsec speaker choosing to propagate the protocol specifies that a BGPsec speaker choosing to propagate the
route advertisement in such an update message MUST add its signature route advertisement in such an UPDATE message MUST add its signature
to each of the Signature_Blocks (see Section 4.2). Thus the BGPsec to each of the Signature_Blocks (see Section 4.2). Thus, the BGPsec
speaker creates a signature using both algorithm suites and creates a speaker creates a signature using both algorithm suites and creates a
new update message that contains both the 'Valid' and the 'Not Valid' new UPDATE message that contains both the 'Valid' and the 'Not Valid'
set of signatures (from its own vantage point). set of signatures (from its own vantage point).
To understand the reason for such a design decision, consider the To understand the reason for such a design decision, consider the
case where the BGPsec speaker receives an update message with both a case where the BGPsec speaker receives an UPDATE message with both a
set of algorithm A signatures which are 'Valid' and a set of set of algorithm A signatures that are 'Valid' and a set of algorithm
algorithm B signatures which are 'Not Valid'. In such a case it is B signatures that are 'Not Valid'. In such a case, it is possible
possible (perhaps even likely, depending on the state of the (perhaps even likely, depending on the state of the algorithm
algorithm transition) that some of the BGPsec speaker's peers (or transition) that some of the BGPsec speaker's peers (or other
other entities further 'downstream' in the BGP topology) do not entities further downstream in the BGP topology) do not support
support algorithm A. Therefore, if the BGPsec speaker were to remove algorithm A. Therefore, if the BGPsec speaker were to remove the
the 'Not Valid' set of signatures corresponding to algorithm B, such 'Not Valid' set of signatures corresponding to algorithm B, such
entities would treat the message as though it were unsigned. By entities would treat the message as though it were unsigned. By
including the 'Not Valid' set of signatures when propagating a route including the 'Not Valid' set of signatures when propagating a route
advertisement, the BGPsec speaker ensures that 'downstream' entities advertisement, the BGPsec speaker ensures that downstream entities
have as much information as possible to make an informed opinion have as much information as possible to make an informed opinion
about the validation status of a BGPsec update. about the validation status of a BGPsec UPDATE message.
Note also that during a period of partial BGPsec deployment, a Note also that during a period of partial BGPsec deployment, a
'downstream' entity might reasonably treat unsigned messages downstream entity might reasonably treat unsigned messages
differently from BGPsec updates that contain a single set of 'Not differently from BGPsec UPDATE messages that contain a single set of
Valid' signatures. That is, by removing the set of 'Not Valid' 'Not Valid' signatures. That is, by removing the set of 'Not Valid'
signatures the BGPsec speaker might actually cause a downstream signatures, the BGPsec speaker might actually cause a downstream
entity to 'upgrade' the status of a route advertisement from 'Not entity to 'upgrade' the status of a route advertisement from
Valid' to unsigned. Finally, note that in the above scenario, the 'Not Valid' to unsigned. Finally, note that in the above scenario,
BGPsec speaker might have deemed algorithm A signatures 'Valid' only the BGPsec speaker might have deemed algorithm A signatures 'Valid'
because of some issue with RPKI state local to its AS (for example, only because of some issue with the RPKI state local to its AS (for
its AS might not yet have obtained a CRL indicating that a key used example, its AS might not yet have obtained a Certificate Revocation
to verify an algorithm A signature belongs to a newly revoked List (CRL) indicating that a key used to verify an algorithm A
certificate). In such a case, it is highly desirable for a signature belongs to a newly revoked certificate). In such a case,
downstream entity to treat the update as 'Not Valid' (due to the it is highly desirable for a downstream entity to treat the UPDATE
revocation) and not as 'unsigned' (which would happen if the 'Not message as 'Not Valid' (due to the revocation) and not as 'unsigned'
Valid' Signature_Blocks were removed enroute). (which would happen if the 'Not Valid' Signature_Blocks were removed
en route).
A similar argument applies to the case where a BGPsec speaker (for A similar argument applies to the case where a BGPsec speaker (for
some reason such as lack of viable alternatives) selects as its best some reason, such as a lack of viable alternatives) selects as its
path (to a given prefix) a route obtained via a 'Not Valid' BGPsec best path (to a given prefix) a route obtained via a 'Not Valid'
update message. In such a case, the BGPsec speaker should propagate BGPsec UPDATE message. In such a case, the BGPsec speaker should
a signed BGPsec update message, adding its signature to the 'Not propagate a signed BGPsec UPDATE message, adding its signature to the
Valid' signatures that already exist. Again, this is to ensure that 'Not Valid' signatures that already exist. Again, this is to ensure
'downstream' entities are able to make an informed decision and not that downstream entities are able to make an informed decision and
erroneously treat the route as unsigned. It should also be noted not erroneously treat the route as unsigned. It should also be noted
that due to possible differences in RPKI data observed at different that due to possible differences in RPKI data observed at different
vantage points in the network, a BGPsec update deemed 'Not Valid' at vantage points in the network, a BGPsec UPDATE message deemed 'Not
an upstream BGPsec speaker may be deemed 'Valid' by another BGP Valid' at an upstream BGPsec speaker may be deemed 'Valid' by another
speaker downstream. BGP speaker downstream.
Indeed, when a BGPsec speaker signs an outgoing update message, it is Indeed, when a BGPsec speaker signs an outgoing UPDATE message, it is
not attesting to a belief that all signatures prior to its are valid. not attesting to a belief that all signatures prior to its own
Instead it is merely asserting that: signature are valid. Instead, it is merely asserting that:
o The BGPsec speaker received the given route advertisement with the o The BGPsec speaker received the given route advertisement with the
indicated prefix, AFI, SAFI, and Secure_Path; and indicated prefix, AFI, SAFI, and Secure_Path, and
o The BGPsec speaker chose to propagate an advertisement for this o The BGPsec speaker chose to propagate an advertisement for this
route to the peer (implicitly) indicated by the 'Target AS route to the peer (implicitly) indicated by the 'Target AS
Number'. Number'.
8.3. Mitigation of Denial of Service Attacks 8.3. Mitigation of Denial-of-Service Attacks
The BGPsec update validation procedure is a potential target for The BGPsec update validation procedure is a potential target for
denial of service attacks against a BGPsec speaker. The mitigation denial-of-service attacks against a BGPsec speaker. The mitigation
of denial of service attacks that are specific to the BGPsec protocol of denial-of-service attacks that are specific to the BGPsec protocol
is considered here. is considered here.
To mitigate the effectiveness of such denial of service attacks, To mitigate the effectiveness of such denial-of-service attacks,
BGPsec speakers should implement an update validation algorithm that BGPsec speakers should implement an update validation algorithm that
performs expensive checks (e.g., signature verification) after performs expensive checks (e.g., signature verification) after
performing less expensive checks (e.g., syntax checks). The performing checks that are less expensive (e.g., syntax checks). The
validation algorithm specified in Section 5.2 was chosen so as to validation algorithm specified in Section 5.2 was chosen so as to
perform checks which are likely to be expensive after checks that are perform checks that are likely to be expensive after checks that are
likely to be inexpensive. However, the relative cost of performing likely to be inexpensive. However, the relative cost of performing
required validation steps may vary between implementations, and thus required validation steps may vary between implementations, and thus
the algorithm specified in Section 5.2 may not provide the best the algorithm specified in Section 5.2 may not provide the best
denial of service protection for all implementations. denial-of-service protection for all implementations.
Additionally, sending update messages with very long AS paths (and Additionally, sending UPDATE messages with very long AS paths (and
hence a large number of signatures) is a potential mechanism to hence a large number of signatures) is a potential mechanism to
conduct denial of service attacks. For this reason, it is important conduct denial-of-service attacks. For this reason, it is important
that an implementation of the validation algorithm stops attempting that an implementation of the validation algorithm stops attempting
to verify signatures as soon as an invalid signature is found. (This to verify signatures as soon as an invalid signature is found. (This
ensures that long sequences of invalid signatures cannot be used for ensures that long sequences of invalid signatures cannot be used for
denial of service attacks.) Furthermore, implementations can denial-of-service attacks.) Furthermore, implementations can
mitigate such attacks by only performing validation on update mitigate such attacks by only performing validation on UPDATE
messages that, if valid, would be selected as the best path. That messages that, if valid, would be selected as the best path. That
is, if an update message contains a route that would lose out in best is, if an UPDATE message contains a route that would lose out in best
path selection for other reasons (e.g., a very long AS path) then it path selection for other reasons (e.g., a very long AS path), then it
is not necessary to determine the BGPsec-validity status of the is not necessary to determine the BGPsec-validity status of the
route. route.
8.4. Additional Security Considerations 8.4. Additional Security Considerations
The mechanism of setting the pCount field to zero is included in this The mechanism of setting the pCount field to 0 is included in this
specification to enable route servers in the control path to specification to enable route servers in the control path to
participate in BGPsec without increasing the length of the AS path. participate in BGPsec without increasing the length of the AS path.
Two other scenarios where pCount=0 is utilized are in the context AS Two other scenarios where pCount=0 is utilized are in the contexts of
confederation (see Section 4.3) and AS migration an AS confederation (see Section 4.3) and of AS migration [RFC8206].
[I-D.ietf-sidr-as-migration]. In these two scenarios, pCount=0 is In these two scenarios, pCount=0 is set and also accepted within the
set and also accepted within the same AS (albeit the AS has two same AS (albeit the AS has two different identities). However,
different identities). However, entities other than route servers, entities other than route servers, confederation ASes, or migrating
confederation ASes or migrating ASes could conceivably use this ASes could conceivably use this mechanism (set the pCount to 0) to
mechanism (set the pCount to zero) to attract traffic (by reducing attract traffic (by reducing the length of the AS path)
the length of the AS path) illegitimately. This risk is largely illegitimately. This risk is largely mitigated if every BGPsec
mitigated if every BGPsec speaker follows the operational guidance in speaker follows the operational guidance in Section 7.2 for
Section 7.2 for configuration for setting pCount=0 and/or accepting configuration for setting pCount=0 and/or accepting pCount=0 from a
pCount=0 from a peer. However, note that a recipient of a BGPsec peer. However, note that a recipient of a BGPsec UPDATE message
update message within which an upstream entity two or more hops away within which an upstream entity two or more hops away has set pCount
has set pCount to zero is unable to verify for themselves whether to 0 is unable to verify for themselves whether pCount was set to 0
pCount was set to zero legitimately. legitimately.
There is a possibility of passing a BGPsec update via tunneling There is a possibility of passing a BGPsec UPDATE message via
between colluding ASes. For example, say, AS-X does not peer with tunneling between colluding ASes. For example, let's say that AS-X
AS-Y, but colludes with AS-Y, signs and sends a BGPsec update to AS-Y does not peer with AS-Y but colludes with AS-Y, and it signs and
by tunneling. AS-Y can then further sign and propagate the BGPsec sends a BGPsec UPDATE message to AS-Y by tunneling. AS-Y can then
update to its peers. It is beyond the scope of the BGPsec protocol further sign and propagate the BGPsec UPDATE message to its peers.
to detect this form of malicious behavior. BGPsec is designed to It is beyond the scope of the BGPsec protocol to detect this form of
protect messages sent within BGP (i.e. within the control plane) - malicious behavior. BGPsec is designed to protect messages sent
not when the control plane in bypassed. within BGP (i.e., within the control plane) -- not when the control
plane is bypassed.
A variant of the collusion by tunneling mentioned above can happen in A variant of the collusion by tunneling mentioned above can happen in
the context of AS confederations. When a BGPsec router (outside of a the context of AS confederations. When a BGPsec router (outside of a
confederation) is forwarding an update to a Member-AS in the confederation) is forwarding an UPDATE message to a Member-AS in the
confederation, it signs the update to the public AS number of the confederation, it signs the UPDATE message to the public AS number of
confederation and not to the member's AS number (see Section 4.3). the confederation and not to the member's AS number (see
The Member-AS can tunnel the signed update to another Member-AS as Section 4.3). The Member-AS can tunnel the signed UPDATE message to
received (i.e. without adding a signature). The update can then be another Member-AS as received (i.e., without adding a signature).
propagated using BGPsec to other confederation members or to BGPsec The UPDATE message can then be propagated using BGPsec to other
neighbors outside of the confederation. This kind of operation is confederation members or to BGPsec neighbors outside of the
possible, but no grave security or reachability compromise is feared confederation. This kind of operation is possible, but no grave
for the following reasons: (1) The confederation members belong to security or reachability compromise is feared for the following
one organization and strong internal trust is expected; and (2) reasons:
Recall that the signatures that are internal to the confederation
MUST be removed prior to forwarding the update to an outside BGPsec o The confederation members belong to one organization, and strong
router (see Section 4.3). internal trust is expected.
o Recall that the signatures that are internal to the confederation
MUST be removed prior to forwarding the UPDATE message to an
outside BGPsec router (see Section 4.3).
BGPsec does not provide protection against attacks at the transport BGPsec does not provide protection against attacks at the transport
layer. As with any BGP session, an adversary on the path between a layer. As with any BGP session, an adversary on the path between a
BGPsec speaker and its peer is able to perform attacks such as BGPsec speaker and its peer is able to perform attacks such as
modifying valid BGPsec updates to cause them to fail validation, modifying valid BGPsec UPDATE messages to cause them to fail
injecting (unsigned) BGP update messages without BGPsec_Path validation, injecting (unsigned) BGP UPDATE messages without
attributes, injecting BGPsec update messages with BGPsec_Path BGPsec_PATH attributes, injecting BGPsec UPDATE messages with
attributes that fail validation, or causing the peer to tear-down the BGPsec_PATH attributes that fail validation, or causing the peer to
BGP session. The use of BGPsec does nothing to increase the power of tear down the BGP session. The use of BGPsec does nothing to
an on-path adversary -- in particular, even an on-path adversary increase the power of an on-path adversary -- in particular, even an
cannot cause a BGPsec speaker to believe a BGPsec-invalid route is on-path adversary cannot cause a BGPsec speaker to believe that a
valid. However, as with any BGP session, BGPsec sessions SHOULD be BGPsec-invalid route is valid. However, as with any BGP session,
protected by appropriate transport security mechanisms (see the BGPsec sessions SHOULD be protected by appropriate transport security
Security Considerations section in [RFC4271]). mechanisms (see the Security Considerations section in [RFC4271]).
There is a possibility of replay attacks which are defined as There is a possibility of replay attacks, defined as follows. In the
follows. In the context of BGPsec, a replay attack occurs when a context of BGPsec, a replay attack occurs when a malicious BGPsec
malicious BGPsec speaker in the AS path suppresses a prefix speaker in the AS path suppresses a prefix withdrawal (implicit or
withdrawal (implicit or explicit). Further, a replay attack is said explicit). Further, a replay attack is said to occur also when a
to occur also when a malicious BGPsec speaker replays a previously malicious BGPsec speaker replays a previously received BGPsec
received BGPsec announcement for a prefix that has since been announcement for a prefix that has since been withdrawn. The
withdrawn. The mitigation strategy for replay attacks involves mitigation strategy for replay attacks involves router certificate
router certificate rollover; please see rollover; please see [ROLLOVER] for details.
[I-D.ietf-sidrops-bgpsec-rollover] for details.
9. IANA Considerations 9. IANA Considerations
IANA is requested to register a new BGP capability from Section 2.1 IANA has registered a new BGP capability described in Section 2.1 in
in the BGP Capabilities Code registry's "IETF Review" range. The the "Capability Codes" registry's "IETF Review" range [RFC8126]. The
description for the new capability is "BGPsec Capability". The description for the new capability is "BGPsec Capability". This
reference for the new capability is this document (i.e. the RFC that document is the reference for the new capability.
replaces draft-ietf-sidr-bgpsec-protocol).
IANA is also requested to register a new path attribute from IANA has also registered a new path attribute described in Section 3
Section 3 in the BGP Path Attributes registry. The code for this new in the "BGP Path Attributes" registry. The code for this new
attribute is "BGPsec_Path". The reference for the new attribute is attribute is "BGPsec_PATH". This document is the reference for the
this document (i.e. the RFC that replaces draft-ietf-sidr-bgpsec- new attribute.
protocol).
IANA is requested to define the "BGPsec Capability" registry in the IANA has defined the "BGPsec Capability" registry in the "Resource
Resource Public Key Infrastructure (RPKI) group. The registry is as Public Key Infrastructure (RPKI)" group. The registry is as shown in
shown in Figure 10 with values assigned from Section 2.1: Figure 10, with values assigned from Section 2.1:
+------+------------------------------------+------------+ +------+------------------------------------+------------+
| Bits | Field | Reference | | Bits | Field | Reference |
+------+------------------------------------+------------+ +------+------------------------------------+------------+
| 0-3 | Version | [This RFC] | | 0-3 | Version | [RFC8205] |
| | Value = 0x0 | | | | Value = 0x0 | |
+------+------------------------------------+------------+ +------+------------------------------------+------------+
| 4 | Direction | [This RFC] | | 4 | Direction | [RFC8205] |
| |(Both possible values 0 and 1 are | | | |(Both possible values 0 and 1 are | |
| | fully specified by this RFC) | | | | fully specified by this RFC) | |
+------+------------------------------------+------------+ +------+------------------------------------+------------+
| 5-7 | Unassigned | [This RFC] | | 5-7 | Unassigned | [RFC8205] |
| | Value = 000 (in binary) | | | | Value = 000 (in binary) | |
+------+------------------------------------+------------+ +------+------------------------------------+------------+
Figure 10: IANA registry for BGPsec Capability. Figure 10: IANA Registry for BGPsec Capability
The Direction bit (4th bit) has value either 0 or 1, and both values The Direction bit (fourth bit) has a value of either 0 or 1, and both
are fully specified by this document (i.e. the RFC that replaces values are fully specified by this document. Future Version values
draft-ietf-sidr-bgpsec-protocol). Future Version values and future and future values of the Unassigned bits are assigned using the
values of the Unassigned bits are assigned using the "Standards "Standards Action" registration procedures defined in RFC 8126
Action" registration procedures defined in RFC 5226 [RFC5226]. [RFC8126].
IANA is requested to define the "BGPsec_Path Flags" registry in the IANA has defined the "BGPsec_PATH Flags" registry in the "Resource
RPKI group. The registry is as shown in Figure 11 with one value Public Key Infrastructure (RPKI)" group. The registry is as shown in
assigned from Section 3.1: Figure 11, with one value assigned from Section 3.1:
+------+-------------------------------------------+------------+ +------+-------------------------------------------+------------+
| Flag | Description | Reference | | Flag | Description | Reference |
+------+-------------------------------------------+------------+ +------+-------------------------------------------+------------+
| 0 | Confed_Segment | [This RFC] | | 0 | Confed_Segment | [RFC8205] |
| | Bit value = 1 means Flag set | | | | Bit value = 1 means Flag set | |
| | (indicates Confed_Segment) | | | | (indicates Confed_Segment) | |
| | Bit value = 0 is default | | | | Bit value = 0 is default | |
+------+-------------------------------------------+------------+ +------+-------------------------------------------+------------+
| 1-7 | Unassigned | [This RFC] | | 1-7 | Unassigned | [RFC8205] |
| | Value: All 7 bits set to zero | | | | Value: All 7 bits set to zero | |
+------+-------------------------------------------+------------+ +------+-------------------------------------------+------------+
Figure 11: IANA registry for BGPsec_Path Flags field. Figure 11: IANA Registry for BGPsec_PATH Flags Field
Future values of the Unassigned bits are assigned using the Future values of the Unassigned bits are assigned using the
"Standards Action" registration procedures defined in RFC 5226 "Standards Action" registration procedures defined in RFC 8126
[RFC5226]. [RFC8126].
10. Contributors
10.1. Authors
Rob Austein
Dragon Research Labs
sra@hactrn.net
Steven Bellovin
Columbia University
smb@cs.columbia.edu
Randy Bush
Internet Initiative Japan
randy@psg.com
Russ Housley
Vigil Security
housley@vigilsec.com
Matt Lepinski
New College of Florida
mlepinski@ncf.edu
Stephen Kent
BBN Technologies
kent@bbn.com
Warren Kumari
Google
warren@kumari.net
Doug Montgomery
USA National Institute of Standards and Technology
dougm@nist.gov
Kotikalapudi Sriram
USA National Institute of Standards and Technology
kotikalapudi.sriram@nist.gov
Samuel Weiler
W3C/MIT
weiler@csail.mit.edu
10.2. Acknowledgements
The authors would like to thank Michael Baer, Oliver Borchert, David
Mandelberg, Mehmet Adalier, Sean Turner, John Scudder, Wes George,
Jeff Haas, Keyur Patel, Alvaro Retana, Nevil Brownlee, Matthias
Waehlisch, Sandy Murphy, Chris Morrow, Tim Polk, Russ Mundy, Wes
Hardaker, Sharon Goldberg, Ed Kern, Doug Maughan, Pradosh Mohapatra,
Mark Reynolds, Heather Schiller, Jason Schiller, Ruediger Volk, and
David Ward for their review, comments, and suggestions during the
course of this work. Thanks are also due to many IESG reviewers
whose comments greatly helped improve the clarity, accuracy, and
presentation in the document.
11. References
11.1. Normative References
[I-D.ietf-sidr-bgpsec-algs] 10. References
Turner, S. and O. Borchert, "BGPsec Algorithms, Key
Formats, & Signature Formats", draft-ietf-sidr-bgpsec-
algs-18 (work in progress), April 2017.
[I-D.ietf-sidr-bgpsec-pki-profiles] 10.1. Normative References
Reynolds, M., Turner, S., and S. Kent, "A Profile for
BGPsec Router Certificates, Certificate Revocation Lists,
and Certification Requests", draft-ietf-sidr-bgpsec-pki-
profiles-21 (work in progress), January 2017.
[IANA-AF] "Address Family Numbers", [IANA-AF] IANA, "Address Family Numbers",
<http://www.iana.org/assignments/address-family-numbers/ <https://www.iana.org/assignments/address-family-numbers>.
address-family-numbers.xhtml>.
[RFC2119] Bradner, S., "Key words for use in RFCs to Indicate [RFC2119] Bradner, S., "Key words for use in RFCs to Indicate
Requirement Levels", BCP 14, RFC 2119, Requirement Levels", BCP 14, RFC 2119,
DOI 10.17487/RFC2119, March 1997, DOI 10.17487/RFC2119, March 1997,
<http://www.rfc-editor.org/info/rfc2119>. <https://www.rfc-editor.org/info/rfc2119>.
[RFC4271] Rekhter, Y., Ed., Li, T., Ed., and S. Hares, Ed., "A [RFC4271] Rekhter, Y., Ed., Li, T., Ed., and S. Hares, Ed., "A
Border Gateway Protocol 4 (BGP-4)", RFC 4271, Border Gateway Protocol 4 (BGP-4)", RFC 4271,
DOI 10.17487/RFC4271, January 2006, DOI 10.17487/RFC4271, January 2006,
<http://www.rfc-editor.org/info/rfc4271>. <https://www.rfc-editor.org/info/rfc4271>.
[RFC4724] Sangli, S., Chen, E., Fernando, R., Scudder, J., and Y. [RFC4724] Sangli, S., Chen, E., Fernando, R., Scudder, J., and Y.
Rekhter, "Graceful Restart Mechanism for BGP", RFC 4724, Rekhter, "Graceful Restart Mechanism for BGP", RFC 4724,
DOI 10.17487/RFC4724, January 2007, DOI 10.17487/RFC4724, January 2007,
<http://www.rfc-editor.org/info/rfc4724>. <https://www.rfc-editor.org/info/rfc4724>.
[RFC4760] Bates, T., Chandra, R., Katz, D., and Y. Rekhter, [RFC4760] Bates, T., Chandra, R., Katz, D., and Y. Rekhter,
"Multiprotocol Extensions for BGP-4", RFC 4760, "Multiprotocol Extensions for BGP-4", RFC 4760,
DOI 10.17487/RFC4760, January 2007, DOI 10.17487/RFC4760, January 2007,
<http://www.rfc-editor.org/info/rfc4760>. <https://www.rfc-editor.org/info/rfc4760>.
[RFC5065] Traina, P., McPherson, D., and J. Scudder, "Autonomous [RFC5065] Traina, P., McPherson, D., and J. Scudder, "Autonomous
System Confederations for BGP", RFC 5065, System Confederations for BGP", RFC 5065,
DOI 10.17487/RFC5065, August 2007, DOI 10.17487/RFC5065, August 2007,
<http://www.rfc-editor.org/info/rfc5065>. <https://www.rfc-editor.org/info/rfc5065>.
[RFC5226] Narten, T. and H. Alvestrand, "Guidelines for Writing an
IANA Considerations Section in RFCs", BCP 26, RFC 5226,
DOI 10.17487/RFC5226, May 2008,
<http://www.rfc-editor.org/info/rfc5226>.
[RFC5492] Scudder, J. and R. Chandra, "Capabilities Advertisement [RFC5492] Scudder, J. and R. Chandra, "Capabilities Advertisement
with BGP-4", RFC 5492, DOI 10.17487/RFC5492, February with BGP-4", RFC 5492, DOI 10.17487/RFC5492, February
2009, <http://www.rfc-editor.org/info/rfc5492>. 2009, <https://www.rfc-editor.org/info/rfc5492>.
[RFC6482] Lepinski, M., Kent, S., and D. Kong, "A Profile for Route [RFC6482] Lepinski, M., Kent, S., and D. Kong, "A Profile for Route
Origin Authorizations (ROAs)", RFC 6482, Origin Authorizations (ROAs)", RFC 6482,
DOI 10.17487/RFC6482, February 2012, DOI 10.17487/RFC6482, February 2012,
<http://www.rfc-editor.org/info/rfc6482>. <https://www.rfc-editor.org/info/rfc6482>.
[RFC6487] Huston, G., Michaelson, G., and R. Loomans, "A Profile for [RFC6487] Huston, G., Michaelson, G., and R. Loomans, "A Profile for
X.509 PKIX Resource Certificates", RFC 6487, X.509 PKIX Resource Certificates", RFC 6487,
DOI 10.17487/RFC6487, February 2012, DOI 10.17487/RFC6487, February 2012,
<http://www.rfc-editor.org/info/rfc6487>. <https://www.rfc-editor.org/info/rfc6487>.
[RFC6793] Vohra, Q. and E. Chen, "BGP Support for Four-Octet [RFC6793] Vohra, Q. and E. Chen, "BGP Support for Four-Octet
Autonomous System (AS) Number Space", RFC 6793, Autonomous System (AS) Number Space", RFC 6793,
DOI 10.17487/RFC6793, December 2012, DOI 10.17487/RFC6793, December 2012,
<http://www.rfc-editor.org/info/rfc6793>. <https://www.rfc-editor.org/info/rfc6793>.
[RFC7606] Chen, E., Ed., Scudder, J., Ed., Mohapatra, P., and K. [RFC7606] Chen, E., Ed., Scudder, J., Ed., Mohapatra, P., and K.
Patel, "Revised Error Handling for BGP UPDATE Messages", Patel, "Revised Error Handling for BGP UPDATE Messages",
RFC 7606, DOI 10.17487/RFC7606, August 2015, RFC 7606, DOI 10.17487/RFC7606, August 2015,
<http://www.rfc-editor.org/info/rfc7606>. <https://www.rfc-editor.org/info/rfc7606>.
11.2. Informative References [RFC8126] Cotton, M., Leiba, B., and T. Narten, "Guidelines for
Writing an IANA Considerations Section in RFCs", BCP 26,
RFC 8126, DOI 10.17487/RFC8126, June 2017,
<https://www.rfc-editor.org/info/rfc8126>.
[Borchert] [RFC8174] Leiba, B., "Ambiguity of Uppercase vs Lowercase in RFC
Borchert, O. and M. Baer, "Modification request: draft- 2119 Key Words", BCP 14, RFC 8174, DOI 10.17487/RFC8174,
ietf-sidr-bgpsec-protocol-14", IETF SIDR WG Mailing List May 2017, <https://www.rfc-editor.org/info/rfc8174>.
message , February 10, 2016,
[RFC8208] Turner, S. and O. Borchert, "BGPsec Algorithms, Key
Formats, and Signature Formats", RFC 8208,
DOI 10.17487/RFC8208, September 2017,
<https://www.rfc-editor.org/info/rfc8208>.
[RFC8209] Reynolds, M., Turner, S., and S. Kent, "A Profile for
BGPsec Router Certificates, Certificate Revocation Lists,
and Certification Requests", RFC 8209,
DOI 10.17487/RFC8209, September 2017,
<https://www.rfc-editor.org/info/rfc8209>.
10.2. Informative References
[Borchert] Borchert, O. and M. Baer, "Subject: Modification request:
draft-ietf-sidr-bgpsec-protocol-14", message to the IETF
SIDR WG Mailing List, 10 February 2016,
<https://mailarchive.ietf.org/arch/msg/ <https://mailarchive.ietf.org/arch/msg/
sidr/8B_e4CNxQCUKeZ_AUzsdnn2f5Mu>. sidr/8B_e4CNxQCUKeZ_AUzsdnn2f5Mu>.
[FIPS186-4] [FIPS186-4]
"FIPS Standards Publication 186-4: Digital Signature National Institute of Standards and Technology, "Digital
Standard", July 2013, Signature Standard (DSS)", NIST FIPS Publication
186-4, DOI 10.6028/NIST.FIPS.186-4, July 2013,
<http://nvlpubs.nist.gov/nistpubs/FIPS/ <http://nvlpubs.nist.gov/nistpubs/FIPS/
NIST.FIPS.186-4.pdf>. NIST.FIPS.186-4.pdf>.
[I-D.ietf-sidr-as-migration]
George, W. and S. Murphy, "BGPSec Considerations for AS
Migration", draft-ietf-sidr-as-migration-06 (work in
progress), December 2016.
[I-D.ietf-sidr-bgpsec-ops]
Bush, R., "BGPsec Operational Considerations", draft-ietf-
sidr-bgpsec-ops-16 (work in progress), January 2017.
[I-D.ietf-sidr-delta-protocol]
Bruijnzeels, T., Muravskiy, O., Weber, B., and R. Austein,
"RPKI Repository Delta Protocol (RRDP)", draft-ietf-sidr-
delta-protocol-08 (work in progress), March 2017.
[I-D.ietf-sidr-publication]
Weiler, S., Sonalker, A., and R. Austein, "A Publication
Protocol for the Resource Public Key Infrastructure
(RPKI)", draft-ietf-sidr-publication-12 (work in
progress), March 2017.
[I-D.ietf-sidr-rpki-rtr-rfc6810-bis]
Bush, R. and R. Austein, "The Resource Public Key
Infrastructure (RPKI) to Router Protocol, Version 1",
draft-ietf-sidr-rpki-rtr-rfc6810-bis-09 (work in
progress), February 2017.
[I-D.ietf-sidr-slurm]
Mandelberg, D., Ma, D., and T. Bruijnzeels, "Simplified
Local internet nUmber Resource Management with the RPKI",
draft-ietf-sidr-slurm-04 (work in progress), March 2017.
[I-D.ietf-sidrops-bgpsec-rollover]
Weis, B., Gagliano, R., and K. Patel, "BGPsec Router
Certificate Rollover", draft-ietf-sidrops-bgpsec-
rollover-00 (work in progress), March 2017.
[RFC6472] Kumari, W. and K. Sriram, "Recommendation for Not Using [RFC6472] Kumari, W. and K. Sriram, "Recommendation for Not Using
AS_SET and AS_CONFED_SET in BGP", BCP 172, RFC 6472, AS_SET and AS_CONFED_SET in BGP", BCP 172, RFC 6472,
DOI 10.17487/RFC6472, December 2011, DOI 10.17487/RFC6472, December 2011,
<http://www.rfc-editor.org/info/rfc6472>. <https://www.rfc-editor.org/info/rfc6472>.
[RFC6480] Lepinski, M. and S. Kent, "An Infrastructure to Support [RFC6480] Lepinski, M. and S. Kent, "An Infrastructure to Support
Secure Internet Routing", RFC 6480, DOI 10.17487/RFC6480, Secure Internet Routing", RFC 6480, DOI 10.17487/RFC6480,
February 2012, <http://www.rfc-editor.org/info/rfc6480>. February 2012, <https://www.rfc-editor.org/info/rfc6480>.
[RFC6483] Huston, G. and G. Michaelson, "Validation of Route [RFC6483] Huston, G. and G. Michaelson, "Validation of Route
Origination Using the Resource Certificate Public Key Origination Using the Resource Certificate Public Key
Infrastructure (PKI) and Route Origin Authorizations Infrastructure (PKI) and Route Origin Authorizations
(ROAs)", RFC 6483, DOI 10.17487/RFC6483, February 2012, (ROAs)", RFC 6483, DOI 10.17487/RFC6483, February 2012,
<http://www.rfc-editor.org/info/rfc6483>. <https://www.rfc-editor.org/info/rfc6483>.
[RFC6810] Bush, R. and R. Austein, "The Resource Public Key [RFC6810] Bush, R. and R. Austein, "The Resource Public Key
Infrastructure (RPKI) to Router Protocol", RFC 6810, Infrastructure (RPKI) to Router Protocol", RFC 6810,
DOI 10.17487/RFC6810, January 2013, DOI 10.17487/RFC6810, January 2013,
<http://www.rfc-editor.org/info/rfc6810>. <https://www.rfc-editor.org/info/rfc6810>.
[RFC6811] Mohapatra, P., Scudder, J., Ward, D., Bush, R., and R. [RFC6811] Mohapatra, P., Scudder, J., Ward, D., Bush, R., and R.
Austein, "BGP Prefix Origin Validation", RFC 6811, Austein, "BGP Prefix Origin Validation", RFC 6811,
DOI 10.17487/RFC6811, January 2013, DOI 10.17487/RFC6811, January 2013,
<http://www.rfc-editor.org/info/rfc6811>. <https://www.rfc-editor.org/info/rfc6811>.
[RFC7093] Turner, S., Kent, S., and J. Manger, "Additional Methods [RFC7093] Turner, S., Kent, S., and J. Manger, "Additional Methods
for Generating Key Identifiers Values", RFC 7093, for Generating Key Identifiers Values", RFC 7093,
DOI 10.17487/RFC7093, December 2013, DOI 10.17487/RFC7093, December 2013,
<http://www.rfc-editor.org/info/rfc7093>. <https://www.rfc-editor.org/info/rfc7093>.
[RFC7115] Bush, R., "Origin Validation Operation Based on the [RFC7115] Bush, R., "Origin Validation Operation Based on the
Resource Public Key Infrastructure (RPKI)", BCP 185, Resource Public Key Infrastructure (RPKI)", BCP 185,
RFC 7115, DOI 10.17487/RFC7115, January 2014, RFC 7115, DOI 10.17487/RFC7115, January 2014,
<http://www.rfc-editor.org/info/rfc7115>. <https://www.rfc-editor.org/info/rfc7115>.
[RFC7132] Kent, S. and A. Chi, "Threat Model for BGP Path Security", [RFC7132] Kent, S. and A. Chi, "Threat Model for BGP Path Security",
RFC 7132, DOI 10.17487/RFC7132, February 2014, RFC 7132, DOI 10.17487/RFC7132, February 2014,
<http://www.rfc-editor.org/info/rfc7132>. <https://www.rfc-editor.org/info/rfc7132>.
[RFC8181] Weiler, S., Sonalker, A., and R. Austein, "A Publication
Protocol for the Resource Public Key Infrastructure
(RPKI)", July 2017,
<https://www.rfc-editor.org/info/rfc8181>.
[RFC8182] Bruijnzeels, T., Muravskiy, O., Weber, B., and R. Austein,
"The RPKI Repository Delta Protocol (RRDP)", RFC 8182,
DOI 10.17487/RFC8182, July 2017,
<https://www.rfc-editor.org/info/rfc8182>.
[RFC8206] George, W. and S. Murphy, "BGPsec Considerations for
Autonomous System (AS) Migration", RFC 8206,
DOI 10.17487/RFC8206, September 2017,
<https://www.rfc-editor.org/info/rfc8206>.
[RFC8207] Bush, R., "BGPsec Operational Considerations", BCP 211,
RFC 8207, DOI 10.17487/RFC8207, September 2017,
<https://www.rfc-editor.org/info/rfc8207>.
[RFC8210] Bush, R. and R. Austein, "The Resource Public Key
Infrastructure (RPKI) to Router Protocol, Version 1",
RFC 8210, DOI 10.17487/RFC8210, September 2017,
<https://www.rfc-editor.org/info/rfc8210>.
[ROLLOVER] Weis, B., Gagliano, R., and K. Patel, "BGPsec Router
Certificate Rollover", Work in Progress,
draft-ietf-sidrops-bgpsec-rollover-01, August 2017.
[SLURM] Mandelberg, D., Ma, D., and T. Bruijnzeels, "Simplified
Local internet nUmber Resource Management with the RPKI",
Work in Progress, draft-ietf-sidr-slurm-04, March 2017.
[SP800-90A] [SP800-90A]
"NIST 800-90A: Deterministic Random Bit Generator National Institute of Standards and Technology,
Validation System", October 2015, "Recommendation for Random Number Generation Using
<http://csrc.nist.gov/groups/STM/cavp/documents/drbg/ Deterministic Random Bit Generators", NIST SP 800-90A
DRBGVS.pdf>. Rev 1, DOI 10.6028/NIST.SP.800-90Ar1, June 2015,
<http://nvlpubs.nist.gov/nistpubs/SpecialPublications/
NIST.SP.800-90Ar1.pdf>.
Acknowledgements
The authors would like to thank Michael Baer, Oliver Borchert, David
Mandelberg, Mehmet Adalier, Sean Turner, Wes George, Jeff Haas,
Alvaro Retana, Nevil Brownlee, Matthias Waehlisch, Tim Polk, Russ
Mundy, Wes Hardaker, Sharon Goldberg, Ed Kern, Doug Maughan, Pradosh
Mohapatra, Mark Reynolds, Heather Schiller, Jason Schiller, Ruediger
Volk, and David Ward for their review, comments, and suggestions
during the course of this work. Thanks are also due to many IESG
reviewers whose comments greatly helped improve the clarity,
accuracy, and presentation in the document.
The authors particularly wish to acknowledge Oliver Borchert and
Michael Baer for their review and suggestions [Borchert] concerning
the sequence of octets to be hashed (Figures 8 and 9 in Sections 4.2
and 5.2, respectively). This was an important contribution based on
their implementation experience.
Contributors
The following people have made significant contributions to this
document and should be considered co-authors:
Rob Austein
Dragon Research Labs
Email: sra@hactrn.net
Steven Bellovin
Columbia University
Email: smb@cs.columbia.edu
Russ Housley
Vigil Security
Email: housley@vigilsec.com
Stephen Kent
BBN Technologies
Email: kent@alum.mit.edu
Warren Kumari
Google
Email: warren@kumari.net
Doug Montgomery
USA National Institute of Standards and Technology
Email: dougm@nist.gov
Chris Morrow
Google, Inc.
Email: morrowc@google.com
Sandy Murphy
SPARTA, Inc., a Parsons Company
Email: sandy@tislabs.com
Keyur Patel
Arrcus
Email: keyur@arrcus.com
John Scudder
Juniper Networks
Email: jgs@juniper.net
Samuel Weiler
W3C/MIT
Email: weiler@csail.mit.edu
Authors' Addresses Authors' Addresses
Matthew Lepinski (editor) Matthew Lepinski (editor)
NCF New College of Florida
5800 Bay Shore Road 5800 Bay Shore Road
Sarasota FL 34243 Sarasota, FL 34243
USA United States of America
Email: mlepinski@ncf.edu Email: mlepinski@ncf.edu
Kotikalapudi Sriram (editor) Kotikalapudi Sriram (editor)
NIST USA National Institute of Standards and Technology
100 Bureau Drive 100 Bureau Drive
Gaithersburg MD 20899 Gaithersburg, MD 20899
USA United States of America
Email: kotikalapudi.sriram@nist.gov Email: kotikalapudi.sriram@nist.gov
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