draft-ietf-sidr-bgpsec-protocol-21.txt   draft-ietf-sidr-bgpsec-protocol-22.txt 
Network Working Group M. Lepinski, Ed. Network Working Group M. Lepinski, Ed.
Internet-Draft NCF Internet-Draft NCF
Intended status: Standards Track K. Sriram, Ed. Intended status: Standards Track K. Sriram, Ed.
Expires: June 26, 2017 NIST Expires: July 20, 2017 NIST
December 23, 2016 January 16, 2017
BGPsec Protocol Specification BGPsec Protocol Specification
draft-ietf-sidr-bgpsec-protocol-21 draft-ietf-sidr-bgpsec-protocol-22
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 autonomous system that
propagates the update message. The digital signatures provide propagates the update message. The digital signatures provide
confidence that every AS on the path of ASes listed in the update confidence that every AS on the path of ASes listed in the update
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Internet-Drafts are working documents of the Internet Engineering Internet-Drafts are working documents of the Internet Engineering
Task Force (IETF). Note that other groups may also distribute Task Force (IETF). Note that other groups may also distribute
working documents as Internet-Drafts. The list of current Internet- working documents as Internet-Drafts. The list of current Internet-
Drafts is at http://datatracker.ietf.org/drafts/current/. Drafts is at http://datatracker.ietf.org/drafts/current/.
Internet-Drafts are draft documents valid for a maximum of six months Internet-Drafts are draft documents valid for a maximum of six months
and may be updated, replaced, or obsoleted by other documents at any and may be updated, replaced, or obsoleted by other documents at any
time. It is inappropriate to use Internet-Drafts as reference time. It is inappropriate to use Internet-Drafts as reference
material or to cite them other than as "work in progress." material or to cite them other than as "work in progress."
This Internet-Draft will expire on June 26, 2017. This Internet-Draft will expire on July 20, 2017.
Copyright Notice Copyright Notice
Copyright (c) 2016 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.
This document is subject to BCP 78 and the IETF Trust's Legal This document is subject to BCP 78 and the IETF Trust's Legal
Provisions Relating to IETF Documents Provisions Relating to IETF Documents
(http://trustee.ietf.org/license-info) in effect on the date of (http://trustee.ietf.org/license-info) in effect on the date of
publication of this document. Please review these documents publication of this document. Please review these documents
carefully, as they describe your rights and restrictions with respect carefully, as they describe your rights and restrictions with respect
to this document. Code Components extracted from this document must to this document. Code Components extracted from this document must
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the Trust Legal Provisions and are provided without warranty as the Trust Legal Provisions and are provided without warranty as
skipping to change at page 2, line 23 skipping to change at page 2, line 23
2. BGPsec Negotiation . . . . . . . . . . . . . . . . . . . . . 3 2. BGPsec Negotiation . . . . . . . . . . . . . . . . . . . . . 3
2.1. The BGPsec Capability . . . . . . . . . . . . . . . . . . 3 2.1. The BGPsec Capability . . . . . . . . . . . . . . . . . . 3
2.2. Negotiating BGPsec Support . . . . . . . . . . . . . . . 4 2.2. Negotiating BGPsec Support . . . . . . . . . . . . . . . 4
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 . . . . . . . . . 13 4.2. Constructing the BGPsec_Path Attribute . . . . . . . . . 13
4.3. Processing Instructions for Confederation Members . . . . 18 4.3. Processing Instructions for Confederation Members . . . . 18
4.4. Reconstructing the AS_PATH Attribute . . . . . . . . . . 20 4.4. Reconstructing the AS_PATH Attribute . . . . . . . . . . 19
5. Processing a Received BGPsec Update . . . . . . . . . . . . . 22 5. Processing a Received BGPsec Update . . . . . . . . . . . . . 21
5.1. Overview of BGPsec Validation . . . . . . . . . . . . . . 23 5.1. Overview of BGPsec Validation . . . . . . . . . . . . . . 22
5.2. Validation Algorithm . . . . . . . . . . . . . . . . . . 24 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. Extensibility Considerations . . . . . . . . . . . . . . 28 6.2. Considerations for the SKI Size . . . . . . . . . . . . . 28
6.3. Extensibility Considerations . . . . . . . . . . . . . . 28
7. Operations and Management Considerations . . . . . . . . . . 29 7. Operations and Management Considerations . . . . . . . . . . 29
8. Security Considerations . . . . . . . . . . . . . . . . . . . 31 8. Security Considerations . . . . . . . . . . . . . . . . . . . 33
8.1. Security Guarantees . . . . . . . . . . . . . . . . . . . 31 8.1. Security Guarantees . . . . . . . . . . . . . . . . . . . 33
8.2. On the Removal of BGPsec Signatures . . . . . . . . . . . 32 8.2. On the Removal of BGPsec Signatures . . . . . . . . . . . 34
8.3. Mitigation of Denial of Service Attacks . . . . . . . . . 33 8.3. Mitigation of Denial of Service Attacks . . . . . . . . . 35
8.4. Additional Security Considerations . . . . . . . . . . . 34 8.4. Additional Security Considerations . . . . . . . . . . . 36
9. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 36 9. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 37
10. Contributors . . . . . . . . . . . . . . . . . . . . . . . . 37 10. Contributors . . . . . . . . . . . . . . . . . . . . . . . . 39
10.1. Authors . . . . . . . . . . . . . . . . . . . . . . . . 37 10.1. Authors . . . . . . . . . . . . . . . . . . . . . . . . 39
10.2. Acknowledgements . . . . . . . . . . . . . . . . . . . . 38 10.2. Acknowledgements . . . . . . . . . . . . . . . . . . . . 40
11. References . . . . . . . . . . . . . . . . . . . . . . . . . 38 11. References . . . . . . . . . . . . . . . . . . . . . . . . . 40
11.1. Normative References . . . . . . . . . . . . . . . . . . 38 11.1. Normative References . . . . . . . . . . . . . . . . . . 40
11.2. Informative References . . . . . . . . . . . . . . . . . 40 11.2. Informative References . . . . . . . . . . . . . . . . . 42
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 41 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 has cryptographic assurance that the advertised route has the
following property: Every AS on the path of ASes listed in the update following property: Every AS on the path of ASes listed in the update
message has explicitly authorized the advertisement of the route to message has explicitly authorized the advertisement of the route to
the subsequent AS in the path. the subsequent AS in the path.
skipping to change at page 3, line 45 skipping to change at page 3, line 46
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: TBD
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 three 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 |
+---------------------------------------+ +---------------------------------------+
| | | |
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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 three bits of the first octet are unassigned and for
future use. These bits are set to zero by the sender of the future use. These bits are set to zero by the sender of the
capability and ignored by the receiver of the capability. capability and 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 [RFC4760]. BGPsec for use with other AFI values 1 and 2 respectively [IANA-AF]. BGPsec for use with other
address families may be specified in future documents. 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
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for four-byte AS numbers. Therefore, any BGP speaker that announces for four-byte AS numbers. Therefore, any BGP speaker that announces
the BGPsec capability, MUST also announce the capability for four- the BGPsec capability, MUST also announce the capability for four-
byte AS support [RFC6793]. If a BGP speaker sends the BGPsec byte AS support [RFC6793]. If a BGP speaker sends the BGPsec
capability but not the four-byte AS support capability then BGPsec capability but not the four-byte AS support capability then BGPsec
has not been successfully negotiated, and update messages containing has not been successfully negotiated, and update messages containing
the BGPsec_Path attribute MUST NOT be sent within such a session. the BGPsec_Path attribute MUST NOT be sent within such a session.
Note that BGPsec update messages can be quite large, therefore any Note that BGPsec update messages can be quite large, therefore any
BGPsec speaker announcing the capability to receive BGPsec messages BGPsec speaker announcing the capability to receive BGPsec messages
SHOULD also announce support for the capability to receive BGP SHOULD also announce support for the capability to receive BGP
extended messages [I-D.ietf-idr-bgp-extended-messages]. extended messages [I-D.ietf-idr-bgp-extended-messages]. Please see
related operational guidance in Section 7.
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
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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 high-
level diagram in Figure 2 provides an overview of the structure of level diagram in Figure 2 provides an overview of the structure of
the BGPsec_Path attribute. the BGPsec_Path attribute.
+---------------------------------------------------------+ +---------------------------------------------------------+
| +-----------------+ | | +-----------------+ |
| | Secure Path | | | | Secure Path | |
| +-----------------+ | | +-----------------+ |
| | AS X | |
| | pCount X | | | | pCount X | |
| | Flags X | | | | Flags X | |
| | AS Y | | | | AS X | |
| | pCount Y | | | | pCount Y | |
| | Flags Y | | | | Flags Y | |
| | AS Y | |
| | ... | | | | ... | |
| +-----------------+ | | +-----------------+ |
| | | |
| +-----------------+ +-----------------+ | | +-----------------+ +-----------------+ |
| | Sig Block 1 | | Sig Block 2 | | | | Sig Block 1 | | Sig Block 2 | |
| +-----------------+ +-----------------+ | | +-----------------+ +-----------------+ |
| | Alg Suite 1 | | Alg Suite 2 | | | | Alg Suite 1 | | Alg Suite 2 | |
| | SKI X1 | | SKI X1 | | | | SKI X1 | | SKI X2 | |
| | Signature X1 | | Signature X1 | | | | Signature X1 | | Signature X2 | |
| | SKI Y1 | | SKI Y1 | | | | SKI Y1 | | SKI Y2 | |
| | Signature Y1 | | Signature Y1 | | | | 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.
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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
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 most
common case, the BGPsec_Path attribute will contain only a single common case, the BGPsec_Path attribute will contain only a single
Signature_Block. However, in order to enable a transition from an Signature_Block. However, in order to enable a transition from an
old algorithm suite to a new algorithm suite (without a flag day), it old algorithm suite to a new algorithm suite (without a flag day), it
will be necessary to include two Signature_Blocks (one for the old will be necessary to include two Signature_Blocks (one for the old
algorithm suite and one for the new algorithm suite) during the algorithm suite and one for the new algorithm suite) during the
transition period. (See Section 6.1 for more discussion of algorithm transition period. (See Section 6.1 for more discussion of algorithm
transitions.) The format of the Signature_Blocks is described below transitions.) The format of the Signature_Blocks is described below
in Section 3.2. in Section 3.2.
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six octets long. Note that this means the Secure_Path Length is two six octets long. Note that this means the Secure_Path Length is two
greater than six times the number Secure_Path Segments (i.e., the greater than six times the number Secure_Path Segments (i.e., the
number 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 Autonomous System in the path to the originating AS of the
prefix specified in the update message. (Note: Repeated Autonomous prefix specified in the update message. (Note: Repeated Autonomous
Systems are compressed out using the pCount field as discussed Systems are compressed out using the pCount field as discussed
below). below).
+----------------------------+ +------------------------------------------------------+
| pCount (1 octet) | | pCount (1 octet) |
+----------------------------+ +------------------------------------------------------+
| Flags (1 octet) | | 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 autonomous system number that the signature covers. This field
enables a BGPsec speaker to mimic the semantics of prepending enables a BGPsec speaker to mimic the semantics of prepending
multiple copies of their AS to the AS_PATH without requiring the multiple copies of their AS to the AS_PATH without requiring the
speaker to generate multiple signatures. Note that Section 9.1.2.2 speaker to generate multiple signatures. Note that Section 9.1.2.2
("Breaking Ties") in [RFC4271] mentions "number of AS numbers" in the ("Breaking Ties") in [RFC4271] mentions "number of AS numbers" in the
AS_PATH attribute that is used in the route selection process. This AS_PATH attribute that is used in the route selection process. This
metric (number of AS numbers) is the same as the AS path length metric (number of AS numbers) is the same as the AS path length
obtained in BGPsec by summing the pCount values in the BGPsec_Path obtained in BGPsec by summing the pCount values in the BGPsec_Path
attribute. The pCount field is also useful in managing route servers attribute. The pCount field is also useful in managing route servers
(see Section 4.2) and AS Number migrations, see (see Section 4.2), AS confederations (see Section 4.3), and AS Number
[I-D.ietf-sidr-as-migration] for details. migrations (see [I-D.ietf-sidr-as-migration] for details).
The left most (i.e. the most significant) bit of the Flags field in The left most (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 one 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 Autonomous System confederation [RFC5065]. (That is, a
sequence of consecutive the Confed_Segment flags are set in a BGPsec sequence of consecutive the Confed_Segment flags are set in a BGPsec
update message whenever, in a non-BGPsec update message, an AS_PATH update message whenever, in a non-BGPsec update message, an AS_PATH
segment of type AS_CONFED_SEQUENCE occurs.) In all other cases the segment of type AS_CONFED_SEQUENCE occurs.) In all other cases the
Confed_Segment flag is set to zero. Confed_Segment flag is set to zero.
The remaining seven bits of the Flags are unassigned and MUST be set The remaining seven bits of the Flags are unassigned and MUST be set
to zero by the sender, and ignored by the receiver. Note, however, to zero 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 eight 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 four-byte AS numbers. Currently-
assigned two-byte AS numbers are converted into four-byte AS numbers assigned two-byte AS numbers are converted into four-byte AS numbers
by setting the two high-order octets of the four-octet field to zero by setting the two high-order octets of the four-octet field to zero
[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 Figure 6 and Figure 7.
+---------------------------------------------+ +---------------------------------------------+
skipping to change at page 10, line 47 skipping to change at page 10, line 47
+---------------------------------------------+ +---------------------------------------------+
| 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 [I-D.ietf-sidr-bgpsec-pki-profiles] that is used to certificate [RFC6487] that is used to verify the signature (see
verify the signature (see Section 5 for details on validity of BGPsec Section 5 for details on validity of BGPsec update messages). The
update messages). SKI field has a fixed 20 octets size. See Section 6.2 for
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 in Figure 7 contains a digital signature that protects
the prefix and the BGPsec_Path attribute (see Section 4 and Section 5 the prefix and the BGPsec_Path attribute (see Section 4 and Section 5
for details on signature generation and validation, respectively). for details on signature generation and validation, respectively).
4. BGPsec Update Messages 4. BGPsec Update Messages
skipping to change at page 11, line 37 skipping to change at page 11, line 37
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 to multiple BGP peers, it MUST generate a separate BGPsec
update message for each unique peer AS to whom the update message is update message for each unique peer AS to whom the update message is
sent. 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 [RFC4760] attribute
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 Resource PKI end-entity certificate whose AS number
resource extension includes the BGPsec speaker's AS number resource extension includes the BGPsec speaker's AS number
[I-D.ietf-sidr-bgpsec-pki-profiles]. Note also that new signatures [I-D.ietf-sidr-bgpsec-pki-profiles]. Note also that new signatures
are only added to a BGPsec update message when a BGPsec speaker is are only added to a BGPsec update message when a BGPsec speaker is
generating an update message to send to an external peer (i.e., when generating an update message to send to an external peer (i.e., when
the AS number of the peer is not equal to the BGPsec speaker's own AS the AS number of the peer is not equal to the BGPsec speaker's own AS
number). Therefore, a BGPsec speaker who only sends BGPsec update number).
messages to peers within its own AS does not need to possess any
private signature keys.
The Resource PKI enables the legitimate holder of IP address The Resource PKI enables the legitimate holder of IP address
prefix(es) to issue a signed object, called a Route Origination prefix(es) to issue a signed object, called a Route Origination
Authorization (ROA), that authorizes a given AS to originate routes Authorization (ROA), that authorizes a given AS to originate routes
to a given set of prefixes (see RFC 6482 [RFC6482]). It is expected to a given set of prefixes (see RFC 6482 [RFC6482]). It is expected
that most relying parties will utilize BGPsec in tandem with origin that most relying parties will utilize BGPsec in tandem with origin
validation (see RFC 6483 [RFC6483] and RFC 6811 [RFC6811]). validation (see RFC 6483 [RFC6483] and RFC 6811 [RFC6811]).
Therefore, it is RECOMMENDED that a BGPsec speaker only originate a Therefore, it is RECOMMENDED that a BGPsec speaker only originate a
BGPsec update advertising a route for a given prefix if there exists BGPsec update advertising a route for a given prefix if there exists
a valid ROA authorizing the BGPsec speaker's AS to originate routes a valid ROA authorizing the BGPsec speaker's AS to originate routes
skipping to change at page 13, line 22 skipping to change at page 13, line 20
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 which 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 (non-
BGPsec) update message. It should be noted that BCP 172 [RFC6472] BGPsec) update message. It should be noted that BCP 172 [RFC6472]
recommends against the use of AS_SET and AS_CONFED_SET in the AS_PATH recommends against the use of AS_SET and AS_CONFED_SET in the AS_PATH
of BGP updates. of BGP updates.
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
internal (iBGP) peer is quite simple. When originating a new route iBGP peer is quite simple. When originating a new route
advertisement and sending it to an internal peer, the BGPsec speaker advertisement and sending it to a BGPsec-capable iBGP peer, the
omits the BGPsec_Path attribute. When a BGPsec speaker chooses to BGPsec speaker omits the BGPsec_Path attribute. When originating a
new route advertisement and sending it to a non-BGPsec iBGP peer, the
BGPsec speaker includes an empty AS_PATH attribute in the update
message. (An empty AS_PATH attribute is one whose length field
contains the value zero [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 BGPsec. In the case when an iBGP peer doesn't support BGPsec, then a
the BGPsec update is reconstructed to a BGP update with AS_PATH and BGP update with AS_PATH is reconstructed from the BGPsec update and
then forwarded (see Section 4.4). In particular, when forwarding to then forwarded (see Section 4.4). In particular, when forwarding to
a BGPsec capable iBGP peer, the BGPsec_Path attribute SHOULD NOT be a BGPsec-capable iBGP (or eBGP) peer, the BGPsec_Path attribute
removed even in the case where the BGPsec update message has not been SHOULD NOT be removed even in the case where the BGPsec update
successfully validated. (See Section 5 for more information on message has not been successfully validated. (See Section 5 for more
validation, and Section 8 for the security ramifications of removing information on validation, and Section 8 for the security
BGPsec signatures.) ramifications of removing BGPsec signatures.)
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
skipping to change at page 14, line 43 skipping to change at page 14, line 45
A route server that participates in the BGP control plane, but does A route server that participates in the BGP control plane, but does
not act as a transit AS in the data plane, may choose to set pCount not act as a transit AS in the data plane, may choose to set pCount
to 0. This option enables the route server to participate in BGPsec to 0. This option enables the route server to participate in BGPsec
and obtain the associated security guarantees without increasing the and obtain the associated security guarantees without increasing the
length of the AS path. (Note that BGPsec speakers compute the length length of the AS path. (Note that BGPsec speakers compute the length
of the AS path by summing the pCount values in the BGPsec_Path of the AS path by summing the pCount values in the BGPsec_Path
attribute, see Section 5.) However, when a route server sets the attribute, see Section 5.) However, when a route server sets the
pCount value to 0, it still inserts its AS number into 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
[I-D.ietf-sidr-as-migration] for a discussion of setting pCount to 0 [I-D.ietf-sidr-as-migration] for a discussion of setting pCount to 0
to facilitate AS Number Migration.) BGPsec speakers SHOULD drop to facilitate AS Number Migration. Also see Section 4.3 for the use
incoming update messages with pCount set to zero in cases where the of pCount=0 in the context of an AS confederation. See Section 7 for
BGPsec speaker does not expect its peer to set pCount to zero. (That operational guidance for configuring a BGPsec router for setting
is, pCount is only to be set to zero in cases such as route servers pCount=0 and/or accepting pCount=0 from a peer.
or AS Number Migration where the BGPsec speaker's peer expects pCount
to be set to zero.)
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
skipping to change at page 15, line 25 skipping to change at page 15, line 26
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 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 which 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
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 [I-D.ietf-sidr-bgpsec-pki-profiles]. This Subject Key Identifier
will be used by recipients of the route advertisement to identify the will be used by recipients of the route advertisement to identify the
proper certificate to use in verifying the signature. proper certificate to use in 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
skipping to change at page 16, line 24 skipping to change at page 16, line 24
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 to the next AS (i.e. (N+1)th AS) in the chain of ASes that form
the AS path. the AS path.
o In order to construct the digital signature for Signature Segment o In order to construct the digital signature for Signature Segment
N (the signature segment being produced by the current AS), first N (the Signature Segment being produced by the current AS), first
construct the sequence of octets to be hashed as shown in construct the sequence of octets to be hashed as shown in
Figure 8. (Note: This sequence of octets includes all the data Figure 8. This sequence of octets includes all the data that the
that the Nth AS attests to by adding its digital signature in the Nth AS attests to by adding its digital signature in the update
update which is being forwarded to a BGPsec speaker in the (N+1)th which is being forwarded to a BGPsec speaker in the (N+1)th AS.
AS.) (For the design rationale for choosing the specific 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 | |
skipping to change at page 18, line 17 skipping to change at page 18, line 17
4.3. Processing Instructions for Confederation Members 4.3. Processing Instructions for Confederation Members
Members of autonomous system confederations [RFC5065] MUST Members of autonomous system confederations [RFC5065] MUST
additionally follow the instructions in this section for processing additionally follow the 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 from a peer that is external to the confederation and chooses to
propagate the update within the confederation, then it first adds a propagate the update within the confederation, then it first adds a
signature signed to its own member AS (i.e. the Target AS number is signature signed to its own Member-AS (i.e. the Target AS number is
the BGPsec speaker's confederation-member AS number). In this the BGPsec speaker's Member-AS number). In this internally modified
internally modified update, the newly added Secure_Path Segment update, the newly added Secure_Path Segment contains the public AS
contains the public AS number of the confederation, the Segment's number (i.e. Confederation Identifier), the Segment's pCount value
pCount value is set to 0, and Confed_Segment flag is set to one. is set to 0, and Confed_Segment flag is set to one. Setting pCount=0
Setting pCount = 0 in this case helps ensure that the AS path length in this case helps ensure that the AS path length is not
is not unnecessarily incremented. The newly added signature is unnecessarily incremented. The newly added signature is generated
generated using a private key corresponding to the public AS number using a private key corresponding to the public AS number of the
of the confederation. The BGPsec speaker propagates the update confederation. The BGPsec speaker propagates the modified update to
modified in this manner to its peers within the confederation. its peers within the confederation.
The reason for the internal modification (i.e. adding a Secure_Path
Segment with pCount = 0) described above is to ensure that the
sequence of (signer AS number, Target AS number) pairs associated
with consecutive signatures in the update are contiguous within the
confederation. The signer AS number is the AS number that is found
in the Secure_Path Segment. By contiguous here we mean that the
Target AS number of each signature in the sequence equals the signer
AS number of the next signature. Without the modification, this
chain would be broken at the boundary of the confederation.
Any modifications mentioned below in the context of propagation of Any BGPsec_Path modifications mentioned below in the context of
the update within the confederation are in addition to the propagation of the update within the confederation are in addition to
modification described above (with pCount = 0). the modification described above (with pCount=0).
When a confederation member sends a BGPsec update message to a peer When a BGPsec speaker sends a BGPsec update message to a peer that
that is a member of the same Member-AS, the confederation member belongs within its own Member-AS, the confederation member SHALL NOT
SHALL NOT modify the BGPsec_Path attribute. (Note that the only modify the BGPsec_Path attribute. When a BGPsec speaker sends a
exception to this is the internal modification described above.) BGPsec update message to a peer that is within the same confederation
When a confederation member sends a BGPsec update message to a peer but in a different Member-AS, the BGPsec speaker puts its Member-AS
that is a member of the same confederation but is a different Member- number in the AS Number field of the Secure_Path Segment that it adds
AS, the confederation member puts its (private) Member-AS Number (as to the BGPsec update message. Additionally, in this case, the
opposed to the public AS Confederation Identifier) in the AS Number Member-AS that generates the Secure_Path Segment sets the
field of the Secure_Path Segment that it adds to the BGPsec update Confed_Segment flag to one. Further, the signature is generated with
message. Additionally, in this case, the confederation member that a private key corresponding to the BGPsec speaker's Member-AS Number.
generates the Secure_Path Segment sets the Confed_Segment flag to (Note: In this document, intra-Member-AS peering is regarded as iBGP
one. Further, the signature is generated with a private key and inter-Member-AS peering is regarded as eBGP. The latter is also
corresponding to the (private) Member-AS Number. 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. If a by other members of the confederation is optional. Note that if a
confederation chooses not to have its members verify signatures added confederation chooses not to verify digital signatures within the
by other confederation members, then when sending a BGPsec update confederation, then BGPsec is able to provide no assurances about the
message to a peer that is a member of the same confederation, the integrity of the Member-AS Numbers placed in Secure_Path Segments
confederation members MAY set the Signature field within the where the Confed_Segment flag is set to one.
Signature Segment that it generates to be zero (in lieu of
calculating the correct digital signature as described in
Section 4.2). Note that if a confederation chooses not to verify
digital signatures within the confederation, then BGPsec is able to
provide no assurances about the integrity of the (private) Member-AS
Numbers placed in Secure_Path Segments where the Confed_Segment flag
is set to one.
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 one. Stop this process once a
Secure_Path Segment is reached which has its Confed_Segment flag Secure_Path Segment is reached which has its Confed_Segment flag
set to zero. Keep a count of the number of segments removed in set to zero. Keep a count of the number of segments removed in
this fashion. this 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 that 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 federation, when a confederation member runs the members. In such a confederation, when a BGPsec speaker runs the
algorithm in Section 5.2, the confederation member, during the algorithm in Section 5.2, the BGPsec speaker, during the process of
process of error checking, first checks whether the Confed_Segment Signature verifications, first checks whether the Confed_Segment flag
flag in the corresponding Secure_Path Segment is set to one. If the in a Secure_Path Segment is set to one. If the flag is set to one,
Confed_Segment flag is set to one in the corresponding Secure_Path the BGPsec speaker skips the verification for the corresponding
Segment, the confederation member does not perform any further checks Signature, and immediately moves on to the next Secure_Path Segment.
on the Signature Segment and immediately moves on to the next
Signature Segment (and checks its corresponding Secure_Path Segment).
Note that as specified in Section 5.2, it is an error when a BGPsec Note that as specified in Section 5.2, it is an error when a BGPsec
speaker receives from a peer, who is not in the same AS speaker receives from a peer, who is not in the same AS
confederation, a BGPsec update containing a Confed_Segment flag set confederation, a BGPsec update containing a Confed_Segment flag set
to one. 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
skipping to change at page 20, line 30 skipping to change at page 20, line 11
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 to a peer,
a BGPsec speaker MUST perform the basic integrity checks listed in a BGPsec speaker MUST perform the basic integrity checks listed in
Section 5.2 to ensure that the received BGPsec update is properly Section 5.2 to ensure that the received BGPsec update is properly
formed. 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 an empty 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 one, 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 empty 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.)
skipping to change at page 21, line 18 skipping to change at page 20, line 47
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_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 zero, then look at the most-
recently added segment in the AS_PATH. recently added segment in the AS_PATH.
* In the case where the AS_PATH is empty 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.)
skipping to change at page 22, line 5 skipping to change at page 21, line 30
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
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
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
is equivalent to an empty AS_PATH [RFC4271].
5. Processing a Received BGPsec Update 5. Processing a Received BGPsec Update
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.
skipping to change at page 22, line 32 skipping to change at page 22, line 16
MAY temporarily defer validation of incoming BGPsec update messages. MAY temporarily defer validation of incoming BGPsec update messages.
The treatment of such BGPsec update messages, whose validation has The treatment of such BGPsec update messages, whose validation has
been deferred, is a matter of local policy. However, an been deferred, is a matter of local policy. However, an
implementation SHOULD ensure that deferment of validation and status implementation SHOULD ensure that deferment of validation and status
of deferred messages is visible to the operator. 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 RPKI state has changed
(e.g., from an RPKI validating cache via the RPKI-to-Router protocol (e.g., from an RPKI validating cache via the RPKI-to-Router protocol
[I-D.ietf-sidr-rpki-rtr-rfc6810-bis]), the BGPsec speaker MUST re-run [I-D.ietf-sidr-rpki-rtr-rfc6810-bis]), the BGPsec speaker MUST re-run
validation on all affected update messages stored in its Adj-RIB-In. validation on all affected update messages stored in its Adj-RIB-In
For example, when a given RPKI certificate ceases to be valid (e.g., [RFC4271]. For example, when a given RPKI certificate ceases to be
it expires or is revoked), all update messages containing a signature valid (e.g., it expires or is revoked), all update messages
whose SKI matches the SKI in the given certificate must be re- containing a signature whose SKI matches the SKI in the given
assessed to determine if they are still valid. If this reassessment certificate MUST be re-assessed to determine if they are still valid.
determines that the validity state of an update has changed then, If this reassessment determines that the validity state of an update
depending on local policy, it may be necessary to re-run best path has changed then, depending on local policy, it may be necessary to
selection. re-run 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
skipping to change at page 23, line 43 skipping to change at page 23, line 28
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 needs 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 MAY be conveyed via
iBGP from an ingress edge router to an egress edge router via some iBGP from an ingress edge router to an egress edge router via some
mechanism, according to local policy within an AS. As discussed in mechanism, according to local policy within an AS. As discussed in
Section 4, when a BGPsec speaker chooses to forward a (syntactically Section 4, when a BGPsec speaker chooses to forward a (syntactically
correct) BGPsec update message, it should be forwarded with its correct) BGPsec update message, it SHOULD be forwarded with its
BGPsec_Path attribute intact (regardless of the validation state of BGPsec_Path attribute intact (regardless of the validation state of
the update message). Based entirely on local policy, an egress the update message). Based entirely on local policy, an egress
router receiving a BGPsec update message from within its own AS MAY router receiving a BGPsec update message from within its own AS MAY
choose to perform its own validation. 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. The error checks specified in protocol violation errors are checked. BGPsec_Path attribute MUST be
present when a BGPsec update is received from an external (eBGP)
BGPsec peer and also when such an update is propagated to an internal
(iBGP) BGPsec peer (see Section 4.2). The error checks specified in
Section 6.3 of [RFC4271] are performed, except that for BGPsec Section 6.3 of [RFC4271] are performed, except that for BGPsec
updates the checks on the AS_PATH attribute do not apply and instead updates the checks on the AS_PATH attribute do not apply and instead
the following checks on BGPsec_Path attribute are performed: the following checks on 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 AS number in the most recently added Secure_Path
Segment (i.e. the one corresponding to the peer from which the Segment (i.e. the one corresponding to the eBGP peer from which
update message was received) matches the AS number of that peer the update message was received) matches the AS number of that
(as specified in the BGP OPEN message). peer as specified in the BGP OPEN message. (Note: This check is
performed only at an ingress BGPsec routers where the update 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 an BGPsec peer that is
not a member of the BGPsec speaker's AS confederation, check to not 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 one.
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 one.
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 equal to zero (see Section 4.2 and expected to set pCount=0 (see Section 4.2 and Section 4.3) then
Section 4.3) then check to ensure that the pCount field in the check to ensure that the pCount field in the most-recently added
most-recently added Secure_Path Segment is not equal to zero. Secure_Path Segment is not equal to zero. (Note: See router
configuration guidance related to this in Section 7.)
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
is not present in the AS path (i.e. rule out 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 using the "treat-as-withdraw"
approach as defined in RFC 7606 [RFC7606]. approach as defined in RFC 7606 [RFC7606]. (Note: Since the AS
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
in the Secure_Path, and this check MAY be included in the 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 validation. 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 in the route selection process,
the BGPsec speaker MUST strip the Signature_Block(s), reconstruct the the BGPsec speaker MUST strip the Signature_Block(s), reconstruct the
AS_PATH from the Secure_Path (see Section 4.4), and treat the update AS_PATH from the Secure_Path (see Section 4.4), and treat the update
as if it was received as an unsigned BGP update. as if it was received as an unsigned BGP update.
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 least
recently added segment). Note that there is a one-to-one 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 that is to be validated. Let AS(1), AS(2), ..., AS(K+1) attribute that is to be validated. Let AS(1), AS(2), ..., AS(K+1)
denote the sequence of AS numbers from the origin AS to the denote the sequence of AS numbers from the origin AS to the
validating AS. Let Secure_Path Segment N and Signature Segment N validating AS. Let Secure_Path Segment N and Signature Segment N
in the BGPsec_Path attribute refer to those corresponding to AS(N) in the BGPsec_Path attribute refer to those corresponding to AS(N)
(where N = 1, 2, ..., K). The BGPsec speaker that is processing (where N = 1, 2, ..., K). The BGPsec speaker that is processing
and validating the BGPsec_Path attribute resides in AS(K+1). Let and 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, SKI,
Public Key) triples in which the AS matches the AS number in the Public Key) triples in which the AS matches the AS number in the
corresponding Secure_Path Segment. Of these triples that match corresponding Secure_Path Segment. Of these triples that match
the AS number, check whether there is an SKI that matches the the AS number, check whether there is an SKI that matches the
value in the Subject Key Identifier field of the Signature value in the Subject Key Identifier field of the Signature
segment. If this check finds no such matching SKI value, then Segment. If this check finds no such matching SKI value, then
mark the entire Signature_Block as 'Not Valid' and proceed to the mark the entire Signature_Block as 'Not Valid' and proceed to the
next Signature_Block. 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
skipping to change at page 27, line 5 skipping to change at page 27, line 4
number of the BGPsec speaker validating the update message. Note number of the BGPsec speaker validating the update message. Note
that if a BGPsec speaker uses multiple AS Numbers (e.g., the 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 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 corresponds to the Signature segment that the validator just that 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 Address Family Identifier (AFI),
Subsequent Address Family Identifier (SAFI), and Prefix 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 all of the trailing bits MUST be
set to zero when constructing this sequence. set to zero 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
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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, a mandatory algorithm suites document exists which
specifies a mandatory-to-use 'current' algorithm suite for use by all specifies a mandatory-to-use 'current' algorithm suite for use by all
BGPsec speakers [I-D.ietf-sidr-bgpsec-algs]. 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, the mandatory algorithm suites
document will be updated to specify a transition from the 'current' document will be updated to specify a transition from the 'current'
algorithm suite to a 'new' algorithm suite. During the period of algorithm suite to a 'new' algorithm suite. During the period of
transition (likely a small number of years), all BGPsec update transition, all BGPsec update messages SHOULD simultaneously use both
messages SHOULD simultaneously use both the 'current' algorithm suite the 'current' algorithm suite and the 'new' algorithm suite. (Note
and the 'new' algorithm suite. (Note that Section 3 and Section 4 that Section 3 and Section 4 specify how the BGPsec_Path attribute
specify how the BGPsec_Path attribute can contain signatures, in can contain signatures, in parallel, for two algorithm suites.) Once
parallel, for two algorithm suites.) Once the transition is the transition is complete, use of the old 'current' algorithm will
complete, use of the old 'current' algorithm will be deprecated, use be deprecated, use of the 'new' algorithm will be mandatory, and a
of the 'new' algorithm will be mandatory, and a subsequent 'even subsequent 'even newer' algorithm suite may be specified as
newer' algorithm suite may be specified as recommended to implement. recommended to implement. Once the transition has successfully been
Once the transition has successfully been completed in this manner, completed in this manner, BGPsec speakers SHOULD include only a
BGPsec speakers SHOULD include only a single Signature_Block single Signature_Block (corresponding to the 'new' algorithm).
(corresponding to the 'new' algorithm).
6.2. Extensibility Considerations 6.2. Considerations for the SKI Size
Depending on the method of generating key identifiers [RFC7093], the
size of the SKI in a RPKI router certificate may vary. The SKI field
in the BGPsec_Path attribute has a fixed 20 octets size (see
Figure 7). If the SKI is longer than 20 octets, then use the
leftmost 20 octets of the SKI (excluding the tag and length)
[RFC7093]. If the SKI value is shorter than 20 octets, then pad the
SKI (excluding the tag and length) to the right (least significant
octets) with octets having zero values.
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
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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, which is designed to accommodate the
desired changes to BGPsec. In such a case, the mandatory algorithm desired changes to BGPsec. In such a case, the mandatory algorithm
suites document would be updated to specify algorithm suites suites document would be updated to specify algorithm suites
appropriate for the new version of BGPsec. appropriate 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 which 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 its deployment are highlighted
here. The Best Current Practice concerning operational deployment of here. The Best Current Practices concerning operations and
BGPSec is provided in [I-D.ietf-sidr-bgpsec-ops]. deployment of BGPsec are provided in [I-D.ietf-sidr-bgpsec-ops].
Section 2.2 describes the negotiation required to establish a BGPsec- Section 2.2 describes the negotiation required to establish a BGPsec-
capable peering session. Not only must the BGPsec capability be capable peering session. Not only must the BGPsec capability be
exchanged (and agreed on), but the BGP multiprotocol extension 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 four-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 result
in the exchange of BGP (unsigned) updates. While the BGP chain of in the exchange of BGP (unsigned) updates. It is RECOMMENDED that an
ASes is not broken, the security can be reduced and a contiguous set implementation log the failure to properly negotiate a BGPsec
of BGPsec peers may not exist anymore. It is RECOMMENDED that an session. Also, an implementation MUST have the ability to prevent a
implementation log the failure to properly negotiate a BGPsec session BGP session from being established if configured for only BGPsec use.
if the local BGP speaker is configured for it. Also, an
implementation MUST have ability to prevent a BGP session from being
established if configured for only BGPsec use.
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 with a transparent AS is expected to set pCount=0 in its Secure_Path
Secure_Path Segment while forwarding an update to a peer (see Segment while forwarding an update to a peer (see Section 4.2).
Section 4.2). Clearly, such an IXP SHOULD configure itself to set Clearly, such an IXP MUST configure its BGPsec router to set pCount=0
its own pCount = 0. As stated in Section 4.2, "BGPsec speakers in its Secure_Path Segment. This also means that a BGPsec speaker
SHOULD drop incoming update messages with pCount set to zero in cases MUST be configured so that it permits pCount=0 from an IXP peer. Two
where the BGPsec speaker does not expect its peer to set pCount to other cases where pCount is set to zero are in the context AS
zero." This means that a BGPsec speaker SHOULD be configured so that confederation (see Section 4.2) and AS migration
it permits pCount =0 from an IXP peer and never permits pCount = 0 [I-D.ietf-sidr-as-migration]. In these two cases, pCount=0 is set
from a peer that is not an IXP. and accepted within the same AS (albeit the AS has two different
identities). Note that if a BGPsec speaker does not expect a peer AS
to set its pCount=0, and if an update received from that peer
violates this, then the update MUST be considered to be in error (see
the list of checks in Section 5.2). See Section 8.4 for a discussion
of security considerations concerning pCount=0.
During the validation of a BGPsec update, route processor performance During the validation of a BGPsec update, route processor performance
speedup can be achieved by incorporating the following observations. speedup can be achieved by incorporating the following observations.
An update is deemed 'Valid' if at least one of the Signature_Blocks An update is deemed 'Valid' if at least one of the Signature_Blocks
is marked as 'Valid' (see Section 5.2). Therefore, if an update is marked as 'Valid' (see Section 5.2). Therefore, if an update
contains two Signature_Blocks and the first one verified is found contains two Signature_Blocks and the first one verified is found
'Valid', then the second Signature_Block does not have to be 'Valid', then the second Signature_Block does not have to be
verified. And if the update were chosen for best path, then the verified. And if the update is chosen for best path, then the BGPsec
BGPsec speaker adds its signature (generated with the respective speaker adds its signature (generated with the respective algorithm)
algorithm) to each of the two Signature_Blocks and forwards the to each of the two Signature_Blocks and forwards the update. Also, a
update. Also, a BGPsec update is deemed 'Not Valid' if at least one BGPsec update is deemed 'Not Valid' if at least one signature in each
signature in each of the Signature_Blocks is invalid. This principle of the Signature_Blocks is invalid. This principle can also be used
can also be used for route processor workload savings, i.e. the for route processor workload savings, i.e. the verification for a
verification for a Signature_Block terminates early when the first Signature_Block terminates early when the first invalid signature is
invalid signature is encountered. encountered.
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 from a peer
and later receives a second BGPsec update message from the same peer and later receives a second BGPsec update message from the same peer
for the same prefix with the same Secure_Path and SKIs, the second for the same prefix with the same Secure_Path and SKIs, the second
update will differ from the first update in the signature fields (for update MAY differ from the first update in the signature fields (for
a non-deterministic signature algorithm). For a deterministic a non-deterministic signature algorithm). However, the two sets of
signature algorithm, the signature fields will also be identical signature fields will not differ if the sender caches and reuses the
between the two updates. On the basis of these observations, an previous signature. For a deterministic signature algorithm, the
implementation may incorporate optimizations in update validation signature fields MUST be identical between the two updates. On the
processing. basis of these observations, an implementation MAY incorporate
optimizations in update validation processing.
In Section 2.2, is was stated that a BGPsec speaker SHOULD announce In Section 2.2, is was stated that a BGPsec speaker SHOULD announce
support for the capability to receive BGP extended messages. Lack of support for the capability to receive BGP extended messages
negotiation of this capability is not expected to pose a problem in [I-D.ietf-idr-bgp-extended-messages]. Lack of negotiation of this
the early years of BGPsec deployment. However, as BGPsec is deployed capability is not expected to pose a problem in the early years of
more and more, the BGPsec update messages would grow in size and some BGPsec deployment. However, as BGPsec is deployed more and more, the
messages may be dropped due to their size exceeding the current 4K BGPsec update messages would grow in size and some messages may be
bytes limit. Therefore, it is strongly RECOMMENDED that all BGPsec dropped due to their size exceeding the current 4K bytes limit.
speakers negotiate the extended message capability within a Therefore, it is strongly RECOMMENDED that all BGPsec speakers
reasonable period of time after initial deployment of BGPsec. negotiate the extended message capability within a reasonable period
of time after initial deployment of BGPsec.
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
stub customer cannot become a BGPsec speaker. If a BGPsec speaker in global RPKI cannot support private AS numbers (i.e. BGPsec speakers
the ISP's AS receives an announcement for a prefix from the stub in private ASes cannot be issued router certificates in the global
customer and chooses to propagate it to BGPsec peers, then it MUST RPKI). For interactions between the stub customer and the ISP, the
strip the private AS and re-originate the prefix. In order to do following two scenarios are possible:
this, the prefix MUST have a ROA authorizing the ISP's AS to
originate it.
It is possible that one or more private AS numbers are used in an AS 1. The stub customer sends an unsigned BGP update for a prefix to
the ISP's AS. An edge BGPsec speaker in the ISP's AS may choose
to propagate the prefix to its non-BGPsec and BGPsec peers. If
so, the ISP's edge BGPsec speaker MUST strip the AS_PATH with the
private AS number, and then (a) re-originate the prefix without
any signatures towards its non-BGPsec peer and (b) re-originate
the prefix including its own signature towards its BGPsec peer.
In both cases (i.e. (a) and (b)), the prefix 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
(using a mechanism such as described in [I-D.ietf-sidr-slurm]).
Then there can be a ROA for the prefix originated by the stub AS,
and the eBGP speaker in the stub AS can be a BGPsec speaker
having a router certificate, albeit the ROA and router
certificate are valid only locally. With this arrangement, the
stub AS sends a signed update for the prefix to the ISP's AS. An
edge BGPsec speaker in the ISP's AS validates the update using
RPKI data based the local RPKI view. Further, it may choose to
propagate the prefix to its non-BGPsec and BGPsec peers. If so,
the ISP's edge BGPsec speaker MUST strip the Secure_Path and the
Signature Segment received from the stub AS with the private AS
number, and then (a) re-originate the prefix without any
signatures towards its non-BGPsec peer and (b) re-originate the
prefix including its own signature towards its BGPsec peer. In
both cases (i.e. (a) and (b)), the prefix 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
confederation [RFC5065]. BGPsec protocol requires that when a BGPsec confederation [RFC5065]. BGPsec protocol requires that when a BGPsec
update propagates through a confederation, each member AS that update propagates through a confederation, each Member-AS that
forwards it must sign the update (see Section 4.3). However, the forwards it to a peer Member-AS MUST sign the update (see
global RPKI cannot support private AS numbers. In order for the Section 4.3). However, the global RPKI cannot support private AS
BGPsec speakers in ASes with private AS numbers to have digital numbers. In order for the BGPsec speakers in Member-ASes with
certificates, there must be a mechanism in place in the confederation private AS numbers to have digital certificates, there MUST be a
that allows establishment of a local, customized view of the RPKI, mechanism in place in the confederation that allows establishment of
augmenting the global RPKI repository data as needed. Since this a local, customized view of the RPKI, augmenting the global RPKI
mechanism (for augmenting and maintaining a local image of RPKI data) repository data as needed. Since this mechanism (for augmenting and
operates locally within an AS or AS confederation, it need not be maintaining a local image of RPKI data) operates locally within an AS
standards based. However, a standards based mechanism can be used or AS confederation, it need not be standard based. However, a
and is described in [I-D.ietf-sidr-slurm]. Recall that in order to standard-based mechanism can be used (see [I-D.ietf-sidr-slurm]).
prevent exposure of the internals of AS confederations, a BGPsec Recall that in order to prevent exposure of the internals of AS
speaker exporting to a non-member removes all intra-confederation confederations, a BGPsec speaker exporting to a non-member removes
Secure_Path Segments and Signatures (see Section 4.3). all intra-confederation Secure_Path Segments and Signatures (see
Section 4.3).
The deployment structure, technologies and best practices concerning
global RPKI data to reach routers (via local RPKI caches) are
described in [RFC6810] [I-D.ietf-sidr-rpki-rtr-rfc6810-bis]
[I-D.ietf-sidr-publication] [RFC7115] [I-D.ietf-sidr-bgpsec-ops]
[I-D.ietf-sidr-delta-protocol]. For example, serial-number based
incremental update mechanisms are used for efficient transfer of just
the data records that have changed since last update [RFC6810]
[I-D.ietf-sidr-rpki-rtr-rfc6810-bis]. Update notification file is
used by relying parties (RPs) to discover whether any changes exist
between the state of the global RPKI repository and the RP's cache
[I-D.ietf-sidr-delta-protocol]. The notification describes the
location of the files containing the snapshot and incremental deltas
which can be used by the RP to synchronize with the repository.
Making use of these technologies and best practices results in
enabling robustness, efficiency, and better security for the BGPsec
routers and RPKI caches in terms of the flow of RPKI data from
repositories to RPKI caches to routers. With these mechanisms, it is
believed that an attacker wouldn't be able to meaningfully correlate
RPKI data flows with BGPsec RP (or router) actions, thus avoiding
attacks that may attempt to determine the set of ASes interacting
with an RP via the interactions between the RP and RPKI servers.
During Graceful Restart (GR), restarting and receiving BGPsec
speakers MUST follow the procedures specified in [RFC4724] for
restarting and receiving BGP speakers, respectively. In particular,
the behavior of retaining the forwarding state for the routes in the
Loc-RIB [RFC4271] and marking them as stale as well as not
differentiating between stale and other information during forwarding
will be the same as specified in [RFC4724].
The Elliptic Curve Digital Signature Algorithm (ECDSA) with curve
P-256 is used for signing updates in BGPsec
[I-D.ietf-sidr-bgpsec-algs]. For ECDSA, it is stated in Section 6.3
of [FIPS186-4] that a new secret random number "k" shall be generated
prior to the generation of each digital signature. A high entropy
random bit generator (RBG) must be used for generating "k", and any
potential bias in the "k" generation algorithm must be mitigated (see
methods described in [FIPS186-4] [SP800-90A]).
How will migration from BGP to BGPsec look like? What are the How 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 be possibly 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 BGPsec
capable groups of contiguous ASes. The benefit for early adopters capable groups of contiguous ASes. The benefit for early adopters
skipping to change at page 32, line 17 skipping to change at page 33, line 45
path.) Furthermore, the recipient is assured that this path path.) Furthermore, the recipient is assured that this path
terminates in an autonomous system that has been authorized by the IP terminates in an autonomous system that has been authorized by the IP
address space holder as a legitimate destination for traffic to the address space holder as a legitimate destination for traffic to the
given prefix. given 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
BGPsec peer. That is, a compliant BGPsec peer may (depending on the (eBGP) BGPsec peer. That is, a compliant BGPsec peer may (depending
local policy of the peer) send update messages that fail the validity on the local policy of the peer) send update messages that fail the
test in Section 5. Thus, a BGPsec speaker MUST completely validate validity test in Section 5. Thus, a BGPsec speaker MUST completely
all BGPsec update messages received from external peers. (Validation validate all BGPsec update messages received from external peers.
of update messages received from internal peers is a matter of local (Validation of update messages received from internal peers is a
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 should add its route advertisement in such an update message MUST add its signature
signature to each of the Signature_Blocks (see Section 4.2). Thus to each of the Signature_Blocks (see Section 4.2). Thus the BGPsec
the BGPsec speaker creates a signature using both algorithm suites speaker creates a signature using both algorithm suites and creates a
and creates a new update message that contains both the 'Valid' and new update message that contains both the 'Valid' and the 'Not Valid'
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 which are 'Valid' and a set of
algorithm B signatures which are 'Not Valid'. In such a case it is algorithm B signatures which are 'Not Valid'. In such a case it is
possible (perhaps even likely, depending on the state of the possible (perhaps even likely, depending on the state of the
algorithm transition) that some of the BGPsec speaker's peers (or algorithm transition) that some of the BGPsec speaker's peers (or
other entities further 'downstream' in the BGP topology) do not other entities further 'downstream' in the BGP topology) do not
support algorithm A. Therefore, if the BGPsec speaker were to remove support algorithm A. Therefore, if the BGPsec speaker were to remove
the 'Not Valid' set of signatures corresponding to algorithm B, such the 'Not Valid' set of signatures corresponding to algorithm B, such
skipping to change at page 34, line 37 skipping to change at page 36, line 15
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 zero 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.
However, entities other than route servers could conceivably use this Two other scenarios where pCount=0 is utilized are in the context AS
confederation (see Section 4.2) and AS migration
[I-D.ietf-sidr-as-migration]. In these two scenarios, pCount=0 is
set and also accepted within the same AS (albeit the AS has two
different identities). However, entities other than route servers,
confederation ASes or migrating ASes could conceivably use this
mechanism (set the pCount to zero) to attract traffic (by reducing mechanism (set the pCount to zero) to attract traffic (by reducing
the length of the AS path) illegitimately. This risk is largely the length of the AS path) illegitimately. This risk is largely
mitigated if every BGPsec speaker drops incoming update messages that mitigated if every BGPsec speaker follows the operational guidance in
set pCount to zero but come from a peer that is not a route server. Section 7 for configuration for setting pCount=0 and/or accepting
However, note that a recipient of a BGPsec update message within pCount=0 from a peer. However, note that a recipient of a BGPsec
which an upstream entity two or more hops away has set pCount to zero update message within which an upstream entity two or more hops away
is unable to verify for themselves whether pCount was set to zero has set pCount to zero is unable to verify for themselves whether
legitimately. pCount was set to zero legitimately.
There is a possibility of passing a BGPsec update via tunneling There is a possibility of passing a BGPsec update via tunneling
between colluding ASes. For example, say, AS-X does not peer with between colluding ASes. For example, say, AS-X does not peer with
AS-Y, but colludes with AS-Y, signs and sends a BGPsec update to AS-Y AS-Y, but colludes with AS-Y, signs and sends a BGPsec update to AS-Y
by tunneling. AS-Y can then further sign and propagate the BGPsec by tunneling. AS-Y can then further sign and propagate the BGPsec
update to its peers. It is beyond the scope of the BGPsec protocol update to its peers. It is beyond the scope of the BGPsec protocol
to detect this form of malicious behavior. BGPsec is designed to to detect this form of malicious behavior. BGPsec is designed to
protect messages sent within BGP (i.e. within the control plane) - protect messages sent within BGP (i.e. within the control plane) -
not when the control plane in bypassed. not when the control plane in 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 to a Member-AS in the
confederation, it signs the update to the public AS number of the confederation, it signs the update to the public AS number of the
confederation and not to the member's AS number (see Section 4.3). confederation and not to the member's AS number (see Section 4.3).
The member AS can tunnel the signed update to another member AS as The Member-AS can tunnel the signed update to another Member-AS as
received (i.e. without adding a signature). The update can then be received (i.e. without adding a signature). The update can then be
propagated using BGPsec to other confederation members or to BGPsec propagated using BGPsec to other confederation members or to BGPsec
neighbors outside of the confederation. This kind of operation is neighbors outside of the confederation. This kind of operation is
possible, but no grave security or reachability compromise is feared possible, but no grave security or reachability compromise is feared
for the following reasons: (1) The confederation members belong to for the following reasons: (1) The confederation members belong to
one organization and strong internal trust is expected; and (2) one organization and strong internal trust is expected; and (2)
Recall that the signatures that are internal to the confederation Recall that the signatures that are internal to the confederation
must be removed prior to forwarding the update to an outside BGPsec MUST be removed prior to forwarding the update to an outside BGPsec
router (see Section 4.3). 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 updates to cause them to fail validation,
injecting (unsigned) BGP update messages without BGPsec_Path injecting (unsigned) BGP update messages without BGPsec_Path
attributes, injecting BGPsec update messages with BGPsec_Path attributes, injecting BGPsec update messages with BGPsec_Path
attributes that fail validation, or causing the peer to tear-down the attributes that fail validation, or causing the peer to tear-down the
BGP session. The use of BGPsec does nothing to increase the power of BGP session. The use of BGPsec does nothing to increase the power of
skipping to change at page 38, line 17 skipping to change at page 39, line 50
Doug Montgomery Doug Montgomery
USA National Institute of Standards and Technology USA National Institute of Standards and Technology
dougm@nist.gov dougm@nist.gov
Kotikalapudi Sriram Kotikalapudi Sriram
USA National Institute of Standards and Technology USA National Institute of Standards and Technology
kotikalapudi.sriram@nist.gov kotikalapudi.sriram@nist.gov
Samuel Weiler Samuel Weiler
Parsons W3C/MIT
weiler+ietf@watson.org weiler@csail.mit.edu
10.2. Acknowledgements 10.2. Acknowledgements
The authors would like to thank Michael Baer, Oliver Borchert, David The authors would like to thank Michael Baer, Oliver Borchert, David
Mandelberg, Sean Turner, John Scudder, Wes George, Jeff Haas, Keyur Mandelberg, Mehmet Adalier, Sean Turner, John Scudder, Wes George,
Patel, Alvaro Retana, Nevil Brownlee, Matthias Waehlisch, Sandy Jeff Haas, Keyur Patel, Alvaro Retana, Nevil Brownlee, Matthias
Murphy, Chris Morrow, Tim Polk, Russ Mundy, Wes Hardaker, Sharon Waehlisch, Sandy Murphy, Chris Morrow, Tim Polk, Russ Mundy, Wes
Goldberg, Ed Kern, Doug Maughan, Pradosh Mohapatra, Mark Reynolds, Hardaker, Sharon Goldberg, Ed Kern, Doug Maughan, Pradosh Mohapatra,
Heather Schiller, Jason Schiller, Ruediger Volk, and David Ward for Mark Reynolds, Heather Schiller, Jason Schiller, Ruediger Volk, and
their review, comments, and suggestions during the course of this David Ward for their review, comments, and suggestions during the
work. 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. References
11.1. Normative References 11.1. Normative References
[I-D.ietf-idr-bgp-extended-messages] [I-D.ietf-idr-bgp-extended-messages]
Bush, R., Patel, K., and D. Ward, "Extended Message Bush, R., Patel, K., and D. Ward, "Extended Message
support for BGP", draft-ietf-idr-bgp-extended-messages-14 support for BGP", draft-ietf-idr-bgp-extended-messages-14
(work in progress), December 2016. (work in progress), December 2016.
[I-D.ietf-sidr-bgpsec-algs] [I-D.ietf-sidr-bgpsec-algs]
Turner, S., "BGPsec Algorithms, Key Formats, & Signature Turner, S., "BGPsec Algorithms, Key Formats, & Signature
Formats", draft-ietf-sidr-bgpsec-algs-16 (work in Formats", draft-ietf-sidr-bgpsec-algs-16 (work in
progress), November 2016. progress), November 2016.
[I-D.ietf-sidr-bgpsec-pki-profiles] [I-D.ietf-sidr-bgpsec-pki-profiles]
Reynolds, M., Turner, S., and S. Kent, "A Profile for Reynolds, M., Turner, S., and S. Kent, "A Profile for
BGPsec Router Certificates, Certificate Revocation Lists, BGPsec Router Certificates, Certificate Revocation Lists,
and Certification Requests", draft-ietf-sidr-bgpsec-pki- and Certification Requests", draft-ietf-sidr-bgpsec-pki-
profiles-18 (work in progress), July 2016. profiles-21 (work in progress), January 2017.
[IANA-AF] "Address Family Numbers",
<http://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>. <http://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>. <http://www.rfc-editor.org/info/rfc4271>.
[RFC4724] Sangli, S., Chen, E., Fernando, R., Scudder, J., and Y.
Rekhter, "Graceful Restart Mechanism for BGP", RFC 4724,
DOI 10.17487/RFC4724, January 2007,
<http://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>. <http://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>. <http://www.rfc-editor.org/info/rfc5065>.
skipping to change at page 40, line 7 skipping to change at page 42, line 7
DOI 10.17487/RFC6793, December 2012, DOI 10.17487/RFC6793, December 2012,
<http://www.rfc-editor.org/info/rfc6793>. <http://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>. <http://www.rfc-editor.org/info/rfc7606>.
11.2. Informative References 11.2. Informative References
[Borchert]
Borchert, O. and M. Baer, "Modification request: draft-
ietf-sidr-bgpsec-protocol-14", IETF SIDR WG Mailing List
message , February 10, 2016,
<https://mailarchive.ietf.org/arch/msg/
sidr/8B_e4CNxQCUKeZ_AUzsdnn2f5Mu>.
[FIPS186-4]
"FIPS Standards Publication 186-4: Digital Signature
Standard", July 2013,
<http://nvlpubs.nist.gov/nistpubs/FIPS/
NIST.FIPS.186-4.pdf>.
[I-D.ietf-sidr-as-migration] [I-D.ietf-sidr-as-migration]
George, W. and S. Murphy, "BGPSec Considerations for AS George, W. and S. Murphy, "BGPSec Considerations for AS
Migration", draft-ietf-sidr-as-migration-06 (work in Migration", draft-ietf-sidr-as-migration-06 (work in
progress), December 2016. progress), December 2016.
[I-D.ietf-sidr-bgpsec-ops] [I-D.ietf-sidr-bgpsec-ops]
Bush, R., "BGPsec Operational Considerations", draft-ietf- Bush, R., "BGPsec Operational Considerations", draft-ietf-
sidr-bgpsec-ops-12 (work in progress), December 2016. sidr-bgpsec-ops-16 (work in progress), January 2017.
[I-D.ietf-sidr-bgpsec-rollover] [I-D.ietf-sidr-bgpsec-rollover]
Gagliano, R., Weis, B., and K. Patel, "BGPsec Router Gagliano, R., Weis, B., and K. Patel, "BGPsec Router
Certificate Rollover", draft-ietf-sidr-bgpsec-rollover-06 Certificate Rollover", draft-ietf-sidr-bgpsec-rollover-06
(work in progress), October 2016. (work in progress), October 2016.
[I-D.ietf-sidr-delta-protocol]
Bruijnzeels, T., Muravskiy, O., Weber, B., and R. Austein,
"RPKI Repository Delta Protocol", draft-ietf-sidr-delta-
protocol-05 (work in progress), January 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-10 (work in
progress), January 2017.
[I-D.ietf-sidr-rpki-rtr-rfc6810-bis] [I-D.ietf-sidr-rpki-rtr-rfc6810-bis]
Bush, R. and R. Austein, "The Resource Public Key Bush, R. and R. Austein, "The Resource Public Key
Infrastructure (RPKI) to Router Protocol", draft-ietf- Infrastructure (RPKI) to Router Protocol", draft-ietf-
sidr-rpki-rtr-rfc6810-bis-07 (work in progress), March sidr-rpki-rtr-rfc6810-bis-08 (work in progress), January
2016. 2017.
[I-D.ietf-sidr-slurm] [I-D.ietf-sidr-slurm]
Mandelberg, D. and D. Ma, "Simplified Local internet Mandelberg, D. and D. Ma, "Simplified Local internet
nUmber Resource Management with the RPKI", draft-ietf- nUmber Resource Management with the RPKI", draft-ietf-
sidr-slurm-02 (work in progress), August 2016. sidr-slurm-02 (work in progress), August 2016.
[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>. <http://www.rfc-editor.org/info/rfc6472>.
skipping to change at page 40, line 47 skipping to change at page 43, line 25
[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, <http://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>. <http://www.rfc-editor.org/info/rfc6483>.
[RFC6810] Bush, R. and R. Austein, "The Resource Public Key
Infrastructure (RPKI) to Router Protocol", RFC 6810,
DOI 10.17487/RFC6810, January 2013,
<http://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>. <http://www.rfc-editor.org/info/rfc6811>.
[RFC7093] Turner, S., Kent, S., and J. Manger, "Additional Methods
for Generating Key Identifiers Values", RFC 7093,
DOI 10.17487/RFC7093, December 2013,
<http://www.rfc-editor.org/info/rfc7093>.
[RFC7115] Bush, R., "Origin Validation Operation Based on the
Resource Public Key Infrastructure (RPKI)", BCP 185,
RFC 7115, DOI 10.17487/RFC7115, January 2014,
<http://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>. <http://www.rfc-editor.org/info/rfc7132>.
[SP800-90A]
"NIST 800-90A: Deterministic Random Bit Generator
Validation System", October 2015,
<http://csrc.nist.gov/groups/STM/cavp/documents/drbg/
DRBGVS.pdf>.
Authors' Addresses Authors' Addresses
Matthew Lepinski (editor) Matthew Lepinski (editor)
NCF NCF
5800 Bay Shore Road 5800 Bay Shore Road
Sarasota FL 34243 Sarasota FL 34243
USA USA
Email: mlepinski@ncf.edu Email: mlepinski@ncf.edu
 End of changes. 90 change blocks. 
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