draft-ietf-dtn-bpsec-06.txt   draft-ietf-dtn-bpsec-07.txt 
Delay-Tolerant Networking E. Birrane Delay-Tolerant Networking E. Birrane
Internet-Draft K. McKeever Internet-Draft K. McKeever
Intended status: Standards Track JHU/APL Intended status: Standards Track JHU/APL
Expires: May 3, 2018 October 30, 2017 Expires: January 2, 2019 July 1, 2018
Bundle Protocol Security Specification Bundle Protocol Security Specification
draft-ietf-dtn-bpsec-06 draft-ietf-dtn-bpsec-07
Abstract Abstract
This document defines a security protocol providing end to end data This document defines a security protocol providing end to end data
integrity and confidentiality services for the Bundle Protocol. integrity and confidentiality services for the Bundle Protocol.
Status of This Memo Status of This Memo
This Internet-Draft is submitted in full conformance with the This Internet-Draft is submitted in full conformance with the
provisions of BCP 78 and BCP 79. provisions of BCP 78 and BCP 79.
skipping to change at page 1, line 31 skipping to change at page 1, line 31
Internet-Drafts are working documents of the Internet Engineering Internet-Drafts are working documents of the Internet Engineering
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working documents as Internet-Drafts. The list of current Internet- working documents as Internet-Drafts. The list of current Internet-
Drafts is at https://datatracker.ietf.org/drafts/current/. Drafts is at https://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 May 3, 2018. This Internet-Draft will expire on January 2, 2019.
Copyright Notice Copyright Notice
Copyright (c) 2017 IETF Trust and the persons identified as the Copyright (c) 2018 IETF Trust and the persons identified as the
document authors. All rights reserved. document authors. All rights reserved.
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described in the Simplified BSD License. described in the Simplified BSD License.
Table of Contents Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 3 1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 3
1.1. Supported Security Services . . . . . . . . . . . . . . . 3 1.1. Supported Security Services . . . . . . . . . . . . . . . 3
1.2. Specification Scope . . . . . . . . . . . . . . . . . . . 4 1.2. Specification Scope . . . . . . . . . . . . . . . . . . . 4
1.3. Related Documents . . . . . . . . . . . . . . . . . . . . 5 1.3. Related Documents . . . . . . . . . . . . . . . . . . . . 5
1.4. Terminology . . . . . . . . . . . . . . . . . . . . . . . 5 1.4. Terminology . . . . . . . . . . . . . . . . . . . . . . . 5
2. Design Decisions . . . . . . . . . . . . . . . . . . . . . . 6 2. Design Decisions . . . . . . . . . . . . . . . . . . . . . . 6
2.1. Block-Level Granularity . . . . . . . . . . . . . . . . . 6 2.1. Block-Level Granularity . . . . . . . . . . . . . . . . . 7
2.2. Multiple Security Sources . . . . . . . . . . . . . . . . 7 2.2. Multiple Security Sources . . . . . . . . . . . . . . . . 7
2.3. Mixed Security Policy . . . . . . . . . . . . . . . . . . 7 2.3. Mixed Security Policy . . . . . . . . . . . . . . . . . . 8
2.4. User-Selected Cipher Suites . . . . . . . . . . . . . . . 8 2.4. User-Selected Cipher Suites . . . . . . . . . . . . . . . 8
2.5. Deterministic Processing . . . . . . . . . . . . . . . . 8 2.5. Deterministic Processing . . . . . . . . . . . . . . . . 8
3. Security Blocks . . . . . . . . . . . . . . . . . . . . . . . 8 3. Security Blocks . . . . . . . . . . . . . . . . . . . . . . . 9
3.1. Block Definitions . . . . . . . . . . . . . . . . . . . . 8 3.1. Block Definitions . . . . . . . . . . . . . . . . . . . . 9
3.2. Uniqueness . . . . . . . . . . . . . . . . . . . . . . . 9 3.2. Uniqueness . . . . . . . . . . . . . . . . . . . . . . . 9
3.3. Target Multiplicity . . . . . . . . . . . . . . . . . . . 9 3.3. Target Multiplicity . . . . . . . . . . . . . . . . . . . 10
3.4. Target Identification . . . . . . . . . . . . . . . . . . 10 3.4. Target Identification . . . . . . . . . . . . . . . . . . 11
3.5. Block Representation . . . . . . . . . . . . . . . . . . 10 3.5. Block Representation . . . . . . . . . . . . . . . . . . 11
3.6. Abstract Security Block . . . . . . . . . . . . . . . . . 11 3.6. Abstract Security Block . . . . . . . . . . . . . . . . . 11
3.7. Block Integrity Block . . . . . . . . . . . . . . . . . . 14 3.7. Block Integrity Block . . . . . . . . . . . . . . . . . . 14
3.8. Block Confidentiality Block . . . . . . . . . . . . . . . 15 3.8. Block Confidentiality Block . . . . . . . . . . . . . . . 15
3.9. Block Interactions . . . . . . . . . . . . . . . . . . . 16 3.9. Block Interactions . . . . . . . . . . . . . . . . . . . 16
3.10. Cipher Suite Parameter and Result Identification . . . . 17 3.10. Cipher Suite Parameter and Result Identification . . . . 18
3.11. BSP Block Example . . . . . . . . . . . . . . . . . . . . 18 3.11. BSP Block Examples . . . . . . . . . . . . . . . . . . . 18
4. Canonical Forms . . . . . . . . . . . . . . . . . . . . . . . 19 3.11.1. Example 1: Constructing a Bundle with Security . . . 18
5. Security Processing . . . . . . . . . . . . . . . . . . . . . 20 3.11.2. Example 2: Adding More Security At A New Node . . . 19
5.1. Bundles Received from Other Nodes . . . . . . . . . . . . 20 4. Canonical Forms . . . . . . . . . . . . . . . . . . . . . . . 21
5.1.1. Receiving BCB Blocks . . . . . . . . . . . . . . . . 20 5. Security Processing . . . . . . . . . . . . . . . . . . . . . 22
5.1.2. Receiving BIB Blocks . . . . . . . . . . . . . . . . 21 5.1. Bundles Received from Other Nodes . . . . . . . . . . . . 22
5.2. Bundle Fragmentation and Reassembly . . . . . . . . . . . 22 5.1.1. Receiving BCBs . . . . . . . . . . . . . . . . . . . 22
6. Key Management . . . . . . . . . . . . . . . . . . . . . . . 22 5.1.2. Receiving BIBs . . . . . . . . . . . . . . . . . . . 23
7. Security Policy Considerations . . . . . . . . . . . . . . . 23 5.2. Bundle Fragmentation and Reassembly . . . . . . . . . . . 24
8. Security Considerations . . . . . . . . . . . . . . . . . . . 24 6. Key Management . . . . . . . . . . . . . . . . . . . . . . . 24
8.1. Attacker Capabilities and Objectives . . . . . . . . . . 24 7. Security Policy Considerations . . . . . . . . . . . . . . . 24
8.2. Attacker Behaviors and BPSec Mitigations . . . . . . . . 25 8. Security Considerations . . . . . . . . . . . . . . . . . . . 26
8.2.1. Eavesdropping Attacks . . . . . . . . . . . . . . . . 25 8.1. Attacker Capabilities and Objectives . . . . . . . . . . 26
8.2.2. Modification Attacks . . . . . . . . . . . . . . . . 26 8.2. Attacker Behaviors and BPSec Mitigations . . . . . . . . 27
8.2.3. Topology Attacks . . . . . . . . . . . . . . . . . . 27 8.2.1. Eavesdropping Attacks . . . . . . . . . . . . . . . . 27
8.2.4. Message Injection . . . . . . . . . . . . . . . . . . 28 8.2.2. Modification Attacks . . . . . . . . . . . . . . . . 28
9. Cipher Suite Authorship Considerations . . . . . . . . . . . 28 8.2.3. Topology Attacks . . . . . . . . . . . . . . . . . . 29
10. Defining Other Security Blocks . . . . . . . . . . . . . . . 29 8.2.4. Message Injection . . . . . . . . . . . . . . . . . . 29
11. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 30 9. Cipher Suite Authorship Considerations . . . . . . . . . . . 30
11.1. Bundle Block Types . . . . . . . . . . . . . . . . . . . 30 10. Defining Other Security Blocks . . . . . . . . . . . . . . . 31
12. References . . . . . . . . . . . . . . . . . . . . . . . . . 30 11. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 32
12.1. Normative References . . . . . . . . . . . . . . . . . . 31 11.1. Bundle Block Types . . . . . . . . . . . . . . . . . . . 32
12.2. Informative References . . . . . . . . . . . . . . . . . 31 12. References . . . . . . . . . . . . . . . . . . . . . . . . . 33
Appendix A. Acknowledgements . . . . . . . . . . . . . . . . . . 31 12.1. Normative References . . . . . . . . . . . . . . . . . . 33
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 31 12.2. Informative References . . . . . . . . . . . . . . . . . 33
Appendix A. Acknowledgements . . . . . . . . . . . . . . . . . . 34
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 34
1. Introduction 1. Introduction
This document defines security features for the Bundle Protocol (BP) This document defines security features for the Bundle Protocol (BP)
[BPBIS] and is intended for use in Delay Tolerant Networks (DTNs) to [I-D.ietf-dtn-bpbis] and is intended for use in Delay Tolerant
provide end-to-end security services. Networks (DTNs) to provide end-to-end security services.
The Bundle Protocol specification [BPBIS] defines DTN as referring to The Bundle Protocol specification [I-D.ietf-dtn-bpbis] defines DTN as
"a networking architecture providing communications in and/or through referring to "a networking architecture providing communications in
highly stressed environments" where "BP may be viewed as sitting at and/or through highly stressed environments" where "BP may be viewed
the application layer of some number of constituent networks, forming as sitting at the application layer of some number of constituent
a store-carry-forward overlay network". The term "stressed" networks, forming a store-carry-forward overlay network". The term
environment refers to multiple challenging conditions including "stressed" environment refers to multiple challenging conditions
intermittent connectivity, large and/or variable delays, asymmetric including intermittent connectivity, large and/or variable delays,
data rates, and high bit error rates. asymmetric data rates, and high bit error rates.
The BP might be deployed such that portions of the network cannot be The BP might be deployed such that portions of the network cannot be
trusted, posing the usual security challenges related to trusted, posing the usual security challenges related to
confidentiality and integrity. However, the stressed nature of the confidentiality and integrity. However, the stressed nature of the
BP operating environment imposes unique conditions where usual BP operating environment imposes unique conditions where usual
transport security mechanisms may not be sufficient. For example, transport security mechanisms may not be sufficient. For example,
the store-carry-forward nature of the network may require protecting the store-carry-forward nature of the network may require protecting
data at rest, preventing unauthorized consumption of critical data at rest, preventing unauthorized consumption of critical
resources such as storage space, and operating without regular resources such as storage space, and operating without regular
contact with a centralized security oracle (such as a certificate contact with a centralized security oracle (such as a certificate
authority). authority).
An end-to-end security service is needed that operates in all of the An end-to-end security service is needed that operates in all of the
environments where the BP operates. environments where the BP operates.
1.1. Supported Security Services 1.1. Supported Security Services
BPSec provides end-to-end integrity and confidentiality services for BPSec provides end-to-end integrity and confidentiality services for
BP bundles. BP bundles, as defined in this section.
Integrity services ensure that protected data within a bundle are not Integrity services ensure that target data within a bundle are not
changed from the time they are provided to the network to the time changed from the time they are provided to the network to the time
they are delivered at their destination. Data changes may be caused they are delivered at their destination. Data changes may be caused
by processing errors, environmental conditions, or intentional by processing errors, environmental conditions, or intentional
manipulation. manipulation. In the context of BPSec, integrity services apply to
plain-text in the bundle.
Confidentiality services ensure that protected data is unintelligible Confidentiality services ensure that target data is unintelligible to
to nodes in the DTN, except for authorized nodes possessing special nodes in the DTN, except for authorized nodes possessing special
information. Confidentiality, in this context, applies to the information. This generally means producing cipher-text from plain-
contents of protected data and does not extend to hiding the fact text and generating authentication information for that cipher-text.
that protected data exist in the bundle. Confidentiality, in this context, applies to the contents of target
data and does not extend to hiding the fact that confidentiality
exists in the bundle.
NOTE: Hop-by-hop authentication is NOT a supported security service NOTE: Hop-by-hop authentication is NOT a supported security service
in this specification, for three reasons. in this specification, for three reasons.
1. The term "hop-by-hop" is ambiguous in a BP overlay, as nodes that 1. The term "hop-by-hop" is ambiguous in a BP overlay, as nodes that
are adjacent in the overlay may not be adjacent in physical are adjacent in the overlay may not be adjacent in physical
connectivity. This condition is difficult or impossible to connectivity. This condition is difficult or impossible to
detect and therefore hop-by-hop authentication is difficult or detect and therefore hop-by-hop authentication is difficult or
impossible to enforce. impossible to enforce.
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as BP extension blocks, and the rules for adding, removing, and as BP extension blocks, and the rules for adding, removing, and
processing these blocks at various points during the bundle's processing these blocks at various points during the bundle's
traversal of the DTN. traversal of the DTN.
BPSec applies only to those nodes that implement it, known as BPSec applies only to those nodes that implement it, known as
"security-aware" nodes. There might be other nodes in the DTN that "security-aware" nodes. There might be other nodes in the DTN that
do not implement BPSec. While all nodes in a BP overlay can exchange do not implement BPSec. While all nodes in a BP overlay can exchange
bundles, BPSec security operations can only happen at BPSec security- bundles, BPSec security operations can only happen at BPSec security-
aware nodes. aware nodes.
This specification does not address individual cipher suite BPSec addresses only the security of data traveling over the DTN, not
implementations. Different networking conditions and operational the underlying DTN itself. Furthermore, while the BPSec protocol can
provide security-at-rest in a store-carry-forward network, it does
not address threats which share computing resources with the DTN and/
or BPSec software implementations. These threats may be malicious
software or compromised libraries which intend to intercept data or
recover cryptographic material. Here, it is the responsibility of
the BPSec implementer to ensure that any cryptographic material,
including shared secret or private keys, is protected against access
within both memory and storage devices.
This specification addresses neither the fitness of externally-
defined cryptographic methods nor the security of their
implementation. Different networking conditions and operational
considerations require varying strengths of security mechanism such considerations require varying strengths of security mechanism such
that mandating a cipher suite in this specification may result in too that mandating a cipher suite in this specification may result in too
much security for some networks and too little security in others. much security for some networks and too little security in others.
It is expected that separate documents will be standardized to define It is expected that separate documents will be standardized to define
cipher suites compatible with BPSec, to include operational cipher cipher suites compatible with BPSec, to include operational cipher
suites and interoperability cipher suites. suites and interoperability cipher suites.
This specification does not address the implementation of security This specification does not address the implementation of security
policy and does not provide a security policy for the BPSec. Similar policy and does not provide a security policy for the BPSec. Similar
to cipher suites, security policies are based on the nature and to cipher suites, security policies are based on the nature and
capabilities of individual networks and network operational concepts. capabilities of individual networks and network operational concepts.
This specification does provide policy considerations when building a This specification does provide policy considerations when building a
security policy. security policy.
This specification does not address how to combine the BPSec security With the exception of the Bundle Protocol, this specification does
blocks with other protocols, other BP extension blocks, or other best not address how to combine the BPSec security blocks with other
practices to achieve security in any particular network protocols, other BP extension blocks, or other best practices to
implementation. achieve security in any particular network implementation.
1.3. Related Documents 1.3. Related Documents
This document is best read and understood within the context of the This document is best read and understood within the context of the
following other DTN documents: following other DTN documents:
"Delay-Tolerant Networking Architecture" [RFC4838] defines the "Delay-Tolerant Networking Architecture" [RFC4838] defines the
architecture for DTNs and identifies certain security assumptions architecture for DTNs and identifies certain security assumptions
made by existing Internet protocols that are not valid in a DTN. made by existing Internet protocols that are not valid in a DTN.
The Bundle Protocol [BPBIS] defines the format and processing of The Bundle Protocol [I-D.ietf-dtn-bpbis] defines the format and
bundles, defines the extension block format used to represent BPSec processing of bundles, defines the extension block format used to
security blocks, and defines the canonicalization algorithms used by represent BPSec security blocks, and defines the canonicalization
this specification. algorithms used by this specification.
The Bundle Security Protocol [RFC6257] and Streamlined Bundle The Bundle Security Protocol [RFC6257] and Streamlined Bundle
Security Protocol [SBSP] documents introduced the concepts of using Security Protocol [I-D.birrane-dtn-sbsp] documents introduced the
BP extension blocks for security services in a DTN. The BPSec is a concepts of using BP extension blocks for security services in a DTN.
continuation and refinement of these documents. The BPSec is a continuation and refinement of these documents.
1.4. Terminology 1.4. Terminology
The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT", The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
"SHOULD", "SHOULD NOT", "RECOMMENDED", "NOT RECOMMENDED", "MAY", and "SHOULD", "SHOULD NOT", "RECOMMENDED", "NOT RECOMMENDED", "MAY", and
"OPTIONAL" in this document are to be interpreted as described in "OPTIONAL" in this document are to be interpreted as described in
[RFC2119]. [RFC2119].
This section defines terminology either unique to the BPSec or This section defines terminology either unique to the BPSec or
otherwise necessary for understanding the concepts defined in this otherwise necessary for understanding the concepts defined in this
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blocks within a bundle to have different security services applied to blocks within a bundle to have different security services applied to
them. them.
Blocks within a bundle represent different types of information. The Blocks within a bundle represent different types of information. The
primary block contains identification and routing information. The primary block contains identification and routing information. The
payload block carries application data. Extension blocks carry a payload block carries application data. Extension blocks carry a
variety of data that may augment or annotate the payload, or variety of data that may augment or annotate the payload, or
otherwise provide information necessary for the proper processing of otherwise provide information necessary for the proper processing of
a bundle along a path. Therefore, applying a single level and type a bundle along a path. Therefore, applying a single level and type
of security across an entire bundle fails to recognize that blocks in of security across an entire bundle fails to recognize that blocks in
a bundle may represent different types of information with different a bundle represent different types of information with different
security needs. security needs.
For example, a payload block might be encrypted to protect its For example, a payload block might be encrypted to protect its
contents and an extension block containing summary information contents and an extension block containing summary information
related to the payload might be integrity signed but unencrypted to related to the payload might be integrity signed but unencrypted to
provide waypoints access to payload-related data without providing provide waypoints access to payload-related data without providing
access to the payload. access to the payload.
2.2. Multiple Security Sources 2.2. Multiple Security Sources
A bundle MAY have multiple security blocks and these blocks MAY have A bundle can have multiple security blocks and these blocks can have
different security sources. different security sources. BPSec implementations MUST NOT assume
that all blocks in a bundle have the same security operations and/or
security sources.
The Bundle Protocol allows extension blocks to be added to a bundle The Bundle Protocol allows extension blocks to be added to a bundle
at any time during its existence in the DTN. When a waypoint adds a at any time during its existence in the DTN. When a waypoint adds a
new extension block to a bundle, that extension block may have new extension block to a bundle, that extension block MAY have
security services applied to it by that waypoint. Similarly, a security services applied to it by that waypoint. Similarly, a
waypoint may add a security service to an existing extension block, waypoint MAY add a security service to an existing extension block,
consistent with its security policy. For example, a node consistent with its security policy.
representing a boundary between a trusted part of the network and an
untrusted part of the network may wish to apply payload encryption
for bundles leaving the trusted portion of the network.
When a waypoint adds a security service to the bundle, the waypoint When a waypoint adds a security service to the bundle, the waypoint
is the security source for that service. The security block(s) which is the security source for that service. The security block(s) which
represent that service in the bundle may need to record this security represent that service in the bundle may need to record this security
source as the bundle destination might need this information for source as the bundle destination might need this information for
processing. For example, a destination node might interpret policy processing. For example, a destination node might interpret policy
as it related to security blocks as a function of the security source as it related to security blocks as a function of the security source
for that block. for that block.
For example, a bundle source may choose to apply an integrity service
to its plain-text payload. Later a waypoint node, representing a
gateway to an insecure portion of the DTN, may receive the bundle and
choose to apply a confidentiality service. In this case, the
integrity security source is the bundle source and the
confidentiality security source is the waypoint node.
2.3. Mixed Security Policy 2.3. Mixed Security Policy
The security policy enforced by nodes in the DTN MAY differ. The security policy enforced by nodes in the DTN may differ.
Some waypoints may not be security aware and will not be able to Some waypoints might not be security aware and will not be able to
process security blocks. Therefore, security blocks must have their process security blocks. Therefore, security blocks must have their
processing flags set such that the block will be treated processing flags set such that the block will be treated
appropriately by non-security-aware waypoints appropriately by non-security-aware waypoints.
Some waypoints will have security policies that require evaluating Some waypoints will have security policies that require evaluating
security services even if they are not the bundle destination or the security services even if they are not the bundle destination or the
final intended destination of the service. For example, a waypoint final intended destination of the service. For example, a waypoint
may choose to verify an integrity service even though the waypoint is could choose to verify an integrity service even though the waypoint
not the bundle destination and the integrity service will be needed is not the bundle destination and the integrity service will be
by other node along the bundle's path. needed by other nodes along the bundle's path.
Some waypoints will determine, through policy, that they are the Some waypoints will determine, through policy, that they are the
intended recipient of the security service and terminate the security intended recipient of the security service and terminate the security
service in the bundle. For example, a gateway node may determine service in the bundle. For example, a gateway node could determine
that, even though it is not the destination of the bundle, it should that, even though it is not the destination of the bundle, it should
verify and remove a particular integrity service or attempt to verify and remove a particular integrity service or attempt to
decrypt a confidentiality service, before forwarding the bundle along decrypt a confidentiality service, before forwarding the bundle along
its path. its path.
Some waypoints may understand security blocks but refuse to process Some waypoints could understand security blocks but refuse to process
them unless they are the bundle destination. them unless they are the bundle destination.
2.4. User-Selected Cipher Suites 2.4. User-Selected Cipher Suites
The security services defined in this specification rely on a variety The security services defined in this specification rely on a variety
of cipher suites providing integrity signatures, cipher-text, and of cipher suites providing integrity signatures, cipher-text, and
other information necessary to populate security blocks. Users MAY other information necessary to populate security blocks. Users may
select different cipher suites to implement security services. For select different cipher suites to implement security services. For
example, some users might prefer a SHA2 hash function for integrity example, some users might prefer a SHA2 hash function for integrity
whereas other users may prefer a SHA3 hash function instead. The whereas other users might prefer a SHA3 hash function instead. The
security services defined in this specification must provide a security services defined in this specification must provide a
mechanism for identifying what cipher suite has been used to populate mechanism for identifying what cipher suite has been used to populate
a security block. a security block.
2.5. Deterministic Processing 2.5. Deterministic Processing
Whenever a node determines that it must process more than one Whenever a node determines that it must process more than one
security block in a received bundle (either because the policy at a security block in a received bundle (either because the policy at a
waypoint states that it should process security blocks or because the waypoint states that it should process security blocks or because the
node is the bundle destination) the order in which security blocks node is the bundle destination) the order in which security blocks
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of security services, even when doing so results in a loss of of security services, even when doing so results in a loss of
flexibility. flexibility.
3. Security Blocks 3. Security Blocks
3.1. Block Definitions 3.1. Block Definitions
This specification defines two types of security block: the Block This specification defines two types of security block: the Block
Integrity Block (BIB) and the Block Confidentiality Block (BCB). Integrity Block (BIB) and the Block Confidentiality Block (BCB).
The BIB is used to ensure the integrity of its security target(s). The BIB is used to ensure the integrity of its plain-text security
The integrity information in the BIB MAY be verified by any node target(s). The integrity information in the BIB MAY be verified
in between the BIB security source and the bundle destination. by any node along the bundle path from the BIB security source to
Security-aware waypoints may add or remove BIBs from bundles in the bundle destination. Security-aware waypoints add or remove
accordance with their security policy. BIBs from bundles in accordance with their security policy. BIBs
are never used to sign the cipher-text provided by a BCB.
The BCB indicates that the security target(s) have been encrypted The BCB indicates that the security target(s) have been encrypted
at the BCB security source in order to protect its content while at the BCB security source in order to protect their content while
in transit. The BCB may be decrypted by security-aware nodes in in transit. The BCB is decrypted by security-aware nodes in the
the network, up to and including the bundle destination, as a network, up to and including the bundle destination, as a matter
matter of security policy. of security policy. BCBs additionally provide authentication
mechanisms for the cipher-text they generate.
3.2. Uniqueness 3.2. Uniqueness
Security operations in a bundle MUST be unique - the same security Security operations in a bundle MUST be unique; the same security
service MUST NOT be applied to a security target more than once in a service MUST NOT be applied to a security target more than once in a
bundle. Since a security operation is represented as a security bundle. Since a security operation is represented as a security
block, this limits what security blocks may be added to a bundle: if block, this limits what security blocks may be added to a bundle: if
adding a security block to a bundle would cause some other security adding a security block to a bundle would cause some other security
block to no longer represent a unique security operation then the new block to no longer represent a unique security operation then the new
block MUST NOT be added. block MUST NOT be added. It is important to note that any cipher-
text integrity mechanism supplied by the BCB is considered part of
the confidentiality service and, therefore, unique from the plain-
text integrity service provided by the BIB.
If multiple security blocks representing the same security operation If multiple security blocks representing the same security operation
were allowed in a bundle at the same time, there would exist were allowed in a bundle at the same time, there would exist
ambiguity regarding block processing order and the property of ambiguity regarding block processing order and the property of
deterministic processing blocks would be lost. deterministic processing blocks would be lost.
Using the notation OP(service,target), several examples illustrate Using the notation OP(service,target), several examples illustrate
this uniqueness requirement. this uniqueness requirement.
o Signing the payload twice: The two operations OP(integrity, o Signing the payload twice: The two operations OP(integrity,
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both be present in the bundle at the same time. both be present in the bundle at the same time.
o Different Services on same block: The two operations o Different Services on same block: The two operations
OP(integrity,payload) and OP(confidentiality, payload) are not OP(integrity,payload) and OP(confidentiality, payload) are not
inherently redundant and may both be present in the bundle at the inherently redundant and may both be present in the bundle at the
same time, pursuant to other processing rules in this same time, pursuant to other processing rules in this
specification. specification.
3.3. Target Multiplicity 3.3. Target Multiplicity
Under special circumstances, a single security block may represent Under special circumstances, a single security block MAY represent
multiple security operations as a way of reducing the overall number multiple security operations as a way of reducing the overall number
of security blocks present in a bundle. In these circumstances, of security blocks present in a bundle. In these circumstances,
reducing the number of security blocks in the bundle reduces the reducing the number of security blocks in the bundle reduces the
amount of redundant information in the bundle. amount of redundant information in the bundle.
A set of security operations may be represented by a single security A set of security operations can be represented by a single security
block if and only if the following conditions are true. block when all of the following conditions are true.
o The security operations apply the same security service. For o The security operations apply the same security service. For
example, they are all integrity operations or all confidentiality example, they are all integrity operations or all confidentiality
operations. operations.
o The cipher suite parameters and key information for the security o The cipher suite parameters and key information for the security
operations are identical. operations are identical.
o The security source for the security operations is the same. o The security source for the security operations is the same.
Meaning the set of operations are being added/removed by the same Meaning the set of operations are being added/removed by the same
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different (e.g., the security targets) are represented individually. different (e.g., the security targets) are represented individually.
When the security block is processed all security operations When the security block is processed all security operations
represented by the security block MUST be applied/evaluated at that represented by the security block MUST be applied/evaluated at that
time. time.
3.4. Target Identification 3.4. Target Identification
A security target is a block in the bundle to which a security A security target is a block in the bundle to which a security
service applies. This target must be uniquely and unambiguously service applies. This target must be uniquely and unambiguously
identifiable when processing a security block. The definition of the identifiable when processing a security block. The definition of the
extension block header from [BPBIS] provides a "Block Number" field extension block header from [I-D.ietf-dtn-bpbis] provides a "Block
suitable for this purpose. Therefore, a security target in a Number" field suitable for this purpose. Therefore, a security
security block MUST be represented as the Block Number of the target target in a security block MUST be represented as the Block Number of
block. the target block.
3.5. Block Representation 3.5. Block Representation
Each security block uses the Canonical Bundle Block Format as defined Each security block uses the Canonical Bundle Block Format as defined
in [BPBIS]. That is, each security block is comprised of the in [I-D.ietf-dtn-bpbis]. That is, each security block is comprised
following elements: of the following elements:
o Block Type Code o Block Type Code
o Block Number o Block Number
o Block Processing Control Flags o Block Processing Control Flags
o CRC Type and CRC Field (if present) o CRC Type and CRC Field (if present)
o Block Data Length o Block Data Length
o Block Type Specific Data Fields o Block Type Specific Data Fields
Security-specific information for a security block is captured in the Security-specific information for a security block is captured in the
"Block Type Specific Data Fields". "Block Type Specific Data Fields".
3.6. Abstract Security Block 3.6. Abstract Security Block
The structure of the security-specific portions of a security block The structure of the security-specific portions of a security block
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Parameters Present Flag. Parameters Present Flag.
In this field, a value of 1 indicates that the associated In this field, a value of 1 indicates that the associated
security block field MUST be included in the security block. A security block field MUST be included in the security block. A
value of 0 indicates that the associated security block field value of 0 indicates that the associated security block field
MUST NOT be in the security block. MUST NOT be in the security block.
Security Source (Optional Field): Security Source (Optional Field):
This field identifies the Endpoint that inserted the security This field identifies the Endpoint that inserted the security
block in the bundle. If the security source field is not block in the bundle. If the security source field is not
present then the source MAY be inferred from other information, present then the source MUST be inferred from other
such as the bundle source or the previous hop, as defined by information, such as the bundle source, previous hop, or other
security policy. This field SHALL be represented by a CBOR values defined by security policy. This field SHALL be
array in accordance with [BPBIS] rules for representing represented by a CBOR array in accordance with
Endpoint Identifiers (EIDs).
[I-D.ietf-dtn-bpbis] rules for representing Endpoint
Identifiers (EIDs).
Cipher Suite Parameters (Optional Field): Cipher Suite Parameters (Optional Field):
This field captures one or more cipher suite parameters that This field captures one or more cipher suite parameters that
should be provided to security-aware nodes when processing the should be provided to security-aware nodes when processing the
security service described by this security block. This field security service described by this security block. This field
SHALL be represented by a CBOR array. Each entry in this array SHALL be represented by a CBOR array. Each entry in this array
is a single cipher suite parameter. A single cipher suite is a single cipher suite parameter. A single cipher suite
parameter SHALL also be represented as a CBOR array comprising parameter SHALL also be represented as a CBOR array comprising
a 2-tuple of the id and value of the parameter, as follows. a 2-tuple of the id and value of the parameter, as follows.
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reference a security block defined in this specification (e.g., a reference a security block defined in this specification (e.g., a
BIB or a BCB). BIB or a BCB).
o The Cipher Suite Id MUST be documented as an end-to-end o The Cipher Suite Id MUST be documented as an end-to-end
authentication-cipher suite or as an end-to-end error-detection- authentication-cipher suite or as an end-to-end error-detection-
cipher suite. cipher suite.
o An EID-reference to the security source MAY be present. If this o An EID-reference to the security source MAY be present. If this
field is not present, then the security source of the block SHOULD field is not present, then the security source of the block SHOULD
be inferred according to security policy and MAY default to the be inferred according to security policy and MAY default to the
bundle source. The security source may also be specified as part bundle source. The security source MAY be specified as part of
of key information described in Section 3.10. key information described in Section 3.10.
Notes: Notes:
o It is RECOMMENDED that cipher suite designers carefully consider o It is RECOMMENDED that cipher suite designers carefully consider
the effect of setting flags that either discard the block or the effect of setting flags that either discard the block or
delete the bundle in the event that this block cannot be delete the bundle in the event that this block cannot be
processed. processed.
o Since OP(integrity, target) is allowed only once in a bundle per o Since OP(integrity, target) is allowed only once in a bundle per
target, it is RECOMMENDED that users wishing to support multiple target, it is RECOMMENDED that users wishing to support multiple
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The Block Processing Control flags value can be set to whatever The Block Processing Control flags value can be set to whatever
values are required by local policy, except that this block MUST values are required by local policy, except that this block MUST
have the "replicate in every fragment" flag set if the target of have the "replicate in every fragment" flag set if the target of
the BCB is the Payload Block. Having that BCB in each fragment the BCB is the Payload Block. Having that BCB in each fragment
indicates to a receiving node that the payload portion of each indicates to a receiving node that the payload portion of each
fragment represents cipher-text. fragment represents cipher-text.
The Block Type Specific Data Fields follow the structure of the The Block Type Specific Data Fields follow the structure of the
ASB. ASB.
A security target listed in the Security Targets field MAY A security target listed in the Security Targets field can
reference the payload block, a non-security extension block, or a reference the payload block, a non-security extension block, or a
BIB block. A BCB MUST NOT include another BCB as a security BIB. A BCB MUST NOT include another BCB as a security target. A
target. A BCB MUST NOT target the primary block. BCB MUST NOT target the primary block.
The Cipher Suite Id MUST be documented as a confidentiality cipher The Cipher Suite Id MUST be documented as a confidentiality cipher
suite. suite that supports authenticated encryption with associated data
(AEAD).
Any additional bytes generated from applying the cipher suite to a Additional information created by a cipher suite (such as
security target (such as additional authenticated text) MAY be additional authenticated data) can be placed either in a security
placed in an appropriate security result (e.g., an Integrity Check result field or in the generated cipher-text. The determination
Value) in accordance with cipher suite and security policy. of where to place these data is a function of the cipher suite
used.
An EID-reference to the security source MAY be present. If this An EID-reference to the security source MAY be present. If this
field is not present, then the security source of the block SHOULD field is not present, then the security source of the block SHOULD
be inferred according to security policy and MAY default to the be inferred according to security policy and MAY default to the
bundle source. The security source may also be specified as part bundle source. The security source MAY be specified as part of
of key information described in Section 3.10. key information described in Section 3.10.
The BCB modifies the contents of its security target(s). When a BCB The BCB modifies the contents of its security target(s). When a BCB
is applied, the security target body data are encrypted "in-place". is applied, the security target body data are encrypted "in-place".
Following encryption, the security target Block Type Specific Data Following encryption, the security target Block Type Specific Data
Fields contains cipher-text, not plain-text. Other block fields field contains cipher-text, not plain-text. Other block fields
remain unmodified, with the exception of the Block Data Length field, remain unmodified, with the exception of the Block Data Length field,
which may be changed if the BCB is allowed to change the length of which MUST be updated to reflect the new length of the Block Type
the block (see below). Specific Data field.
Fragmentation, reassembly, and custody transfer are adversely
affected by a change in size of the payload block due to ambiguity
about what byte range of the block is actually in any particular
fragment. Therefore, when the security target of a BCB is the bundle
payload, the BCB MUST NOT alter the size of the payload block body
data. This "in-place" encryption allows fragmentation, reassembly,
and custody transfer to operate without knowledge of whether or not
encryption has occurred.
If a BCB cannot alter the size of the security target (e.g., the
security target is the payload block or block length modifications
are disallowed by policy) then differences in the size of the cipher-
text and plain-text must be handled in the following way. If the
cipher-text is shorter in length than the plain-text, padding MUST be
used in accordance with the cipher suite policy. If the cipher-text
is larger than the plain-text, overflow bytes MUST be placed in
overflow parameters in the Security Result field.
Notes: Notes:
o It is RECOMMENDED that cipher suite designers carefully consider o It is RECOMMENDED that cipher suite designers carefully consider
the effect of setting flags that either discard the block or the effect of setting flags that either discard the block or
delete the bundle in the event that this block cannot be delete the bundle in the event that this block cannot be
processed. processed.
o The BCB block processing control flags MAY be set independently o The BCB block processing control flags can be set independently
from the processing control flags of the security target(s). The from the processing control flags of the security target(s). The
setting of such flags SHOULD be an implementation/policy decision setting of such flags SHOULD be an implementation/policy decision
for the encrypting node. for the encrypting node.
o A BCB MAY include information as part of additional authenticated
data to address parts of the target block that are not converted
to cipher-text.
3.9. Block Interactions 3.9. Block Interactions
The security block types defined in this specification are designed The security block types defined in this specification are designed
to be as independent as possible. However, there are some cases to be as independent as possible. However, there are some cases
where security blocks may share a security target creating processing where security blocks may share a security target creating processing
dependencies. dependencies.
If confidentiality is being applied to a target that already has If a security target of a BCB is also a security target of a BIB, an
integrity applied to it, then an undesirable condition occurs where a undesirable condition occurs where a security aware waypoint would be
security aware waypoint would be unable to check the integrity result unable to validate the BIB because one of its security target's
of a block because the block contents have been encrypted after the contents have been encrypted by a BCB. To address this situation the
integrity signature was generated. To address this concern, the following processing rules MUST be followed.
following processing rules must be followed.
o If confidentiality is to be applied to a target, it MUST also be o When adding a BCB to a bundle, if some (or all) of the security
applied to any integrity operation already defined for that targets of the BCB also match all of the security targets of an
target. This means that if a BCB is added to encrypt a block, existing BIB, then the existing BIB MUST also be encrypted. This
another BCB MUST also be added to encrypt a BIB also targeting can be accomplished by either adding a new BCB that targets the
that block. existing BIB, or by adding the BIB to the list of security targets
for the BCB. Deciding which way to represent this situation is a
matter of security policy.
o An integrity operation MUST NOT be applied to a security target if o When adding a BCB to a bundle, if some (or all) of the security
a BCB in the bundle shares the same security target. This targets of the BCB match some (but not all) of the security
prevents ambiguity in the order of evaluation when receiving a BIB targets of a BIB, then a new BIB MUST be created and all entries
and a BCB for a given security target. relating to those BCB security targets MUST be moved from the
original BIB to the newly created BIB. The newly created BIB MUST
then be encrypted. This can be accomplished by either adding a
new BCB that targets the new BIB, or by adding the new BIB to the
list of security targets for the BCB. Deciding which way to
represent this situation is a matter of security policy.
o An integrity value MUST NOT be evaluated if the BIB providing the o A BIB MUST NOT be added for a security target that is already the
integrity value is the security target of an existing BCB block in security target of a BCB. In this instance, the BCB is already
the bundle. In such a case, the BIB data contains cipher-text as providing authentication and integrity of the security target and
it has been encrypted. the BIB would be redundant, insecure, and cause ambiguity in block
processing order.
o An integrity value MUST NOT be evaluated if the security target of o A BIB integrity value MUST NOT be evaluated if the BIB is the
the BIB is also the security target of a BCB in the bundle. In security target of an existing BCB. In this case, the BIB data is
such a case, the security target data contains cipher-text as it encrypted.
has been encrypted.
o A BIB integrity value MUST NOT be evaluated if the security target
of the BIB is also the security target of a BCB. In such a case,
the security target data contains cipher-text as it has been
encrypted.
o As mentioned in Section 3.7, a BIB MUST NOT have a BCB as its o As mentioned in Section 3.7, a BIB MUST NOT have a BCB as its
security target. BCBs may embed integrity results as part of security target.
security results.
These restrictions on block interactions impose a necessary ordering These restrictions on block interactions impose a necessary ordering
when applying security operations within a bundle. Specifically, for when applying security operations within a bundle. Specifically, for
a given security target, BIBs MUST be added before BCBs. This a given security target, BIBs MUST be added before BCBs. This
ordering MUST be preserved in cases where the current BPA is adding ordering MUST be preserved in cases where the current BPA is adding
all of the security blocks for the bundle or whether the BPA is a all of the security blocks for the bundle or whether the BPA is a
waypoint adding new security blocks to a bundle that already contains waypoint adding new security blocks to a bundle that already contains
security blocks. security blocks.
NOTE: Since any cipher suite used with a BCB MUST be an AEAD cipher
suite, it is inefficient and possible insecure for a single security
source to add both a BIB and a BCB for the same security target. In
cases where a security source wishes to calculate both a plain-text
integrity mechanism and encrypt a security target, a BCB with a
cipher suite that generates such signatures as additional security
results SHOULD be used instead.
3.10. Cipher Suite Parameter and Result Identification 3.10. Cipher Suite Parameter and Result Identification
Cipher suite parameters and security results each represent multiple Cipher suite parameters and security results each represent multiple
distinct pieces of information in a security block. Each piece of distinct pieces of information in a security block. Each piece of
information is assigned an identifier and a CBOR encoding. information is assigned an identifier and a CBOR encoding.
Identifiers MUST be unique for a given cipher suite but do not need Identifiers MUST be unique for a given cipher suite but do not need
to be unique across all cipher suites. Therefore, parameter ids and to be unique across all cipher suites. Therefore, parameter ids and
security result ids are specified in the context of a cipher suite security result ids are specified in the context of a cipher suite
definition. definition.
Individual BPSec cipher suites SHOULD use existing registries of Individual BPSec cipher suites SHOULD use existing registries of
identifiers and CBOR encodings, such as those defined in [COSE], identifiers and CBOR encodings, such as those defined in [RFC8152],
whenever possible. Cipher suites MAY define their own identifiers whenever possible. Cipher suites SHOULD define their own identifiers
and CBOR encodings when necessary. and CBOR encodings when necessary.
A cipher suite MAY include multiple instances of the same identifier A cipher suite can include multiple instances of the same identifier
for a parameter or result in a security block. Parameters and for a parameter or result in a security block. Parameters and
results are represented using CBOR, and any identification of a new results are represented using CBOR, and any identification of a new
parameter or result must include how the value will be represented parameter or result must include how the value will be represented
using the CBOR specification. Ids themselves are always represented using the CBOR specification. Ids themselves are always represented
as a CBOR unsigned integer. as a CBOR unsigned integer.
3.11. BSP Block Example 3.11. BSP Block Examples
An example of BPSec blocks applied to a bundle is illustrated in
Figure 3. In this figure the first column represents blocks within a
bundle and the second column represents the Block Number for the
block, using the terminology B1...Bn for the purpose of illustration.
Block in Bundle ID This section provides two examples of BPSec blocks applied to a
+===================================+====+ bundle. In the first example, a single node adds several security
| Primary Block | B1 | operations to a bundle. In the second example, a waypoint node
+-----------------------------------+----+ received the bundle created in the first example and adds additional
| BIB | B2 | security operations. In both examples, the first column represents
| OP(integrity, target=B1) | | blocks within a bundle and the second column represents the Block
+-----------------------------------+----+ Number for the block, using the terminology B1...Bn for the purpose
| BCB | B3 | of illustration.
| OP(confidentiality, target=B4) | |
+-----------------------------------+----+
| Extension Block | B4 |
+-----------------------------------+----+
| BIB | B5 |
| OP(integrity, target=B6) | |
+-----------------------------------+----+
| Extension Block | B6 |
+-----------------------------------+----+
| BCB | B7 |
| OP(confidentiality,targets=B8,B9) | |
+-----------------------------------+----+
| BIB (encrypted by B7) | B8 |
| OP(integrity, target=B9) | |
+-----------------------------------+----|
| Payload Block | B9 |
+-----------------------------------+----+
Figure 3: Sample Use of BPSec Blocks 3.11.1. Example 1: Constructing a Bundle with Security
In this example a bundle has four non-security-related blocks: the In this example a bundle has four non-security-related blocks: the
primary block (B1), two extension blocks (B4,B6), and a payload block primary block (B1), two extension blocks (B4,B5), and a payload block
(B9). The following security applications are applied to this (B6). The bundle source wishes to provide an integrity signature of
bundle. the plain-text associated with the primary block, one of the
extension blocks, and the payload. The resultant bundle is
illustrated in Figure 3 and the security actions are described below.
o An integrity signature applied to the canonicalized primary block. Block in Bundle ID
This is accomplished by a single BIB (B2). +======================================+====+
| Primary Block | B1 |
+--------------------------------------+----+
| BIB | B2 |
| OP(integrity, targets=B1, B5, B6) | |
+--------------------------------------+----+
| BCB | B3 |
| OP(confidentiality, target=B4) | |
+--------------------------------------+----+
| Extension Block (encrypted) | B4 |
+--------------------------------------+----+
| Extension Block | B5 |
+--------------------------------------+----+
| Payload Block | B6 |
+--------------------------------------+----+
Figure 3: Security at Bundle Creation
The following security actions were applied to this bundle at its
time of creation.
o An integrity signature applied to the canonicalized primary block
(B1), the second extension block (B5) and the payload block (B6).
This is accomplished by a single BIB (B2) with multiple targets.
A single BIB is used in this case because all three targets share
a security source and policy has them share the same cipher suite,
key, and cipher suite parameters. Had this not been the case,
multiple BIBs could have been added instead.
o Confidentiality for the first extension block (B4). This is o Confidentiality for the first extension block (B4). This is
accomplished by a BCB block (B3). accomplished by a BCB (B3). Once applied, the contents of
extension block B4 are encrypted. The BCB MUST hold an
authentication signature for the cipher-text either in the cipher-
text that now populated the first extension block or as a security
result in the BCB itself, depending on which cipher suite is used
to form the BCB. A plain-text integrity signature may also exist
as a security result in the BCB if one is provided by the selected
confidentiality cipher suite.
o Integrity for the second extension block (B6). This is 3.11.2. Example 2: Adding More Security At A New Node
accomplished by a BIB block (B5). NOTE: If the extension block B6
contains a representation of the serialized bundle (such as a hash
over all blocks in the bundle at the time of its last
transmission) then the BIB block is also providing an
authentication service.
o An integrity signature on the payload (B10). This is accomplished Consider that the bundle as it is illustrated in Figure 3 is now
by a BIB block (B8). received by a waypoint node that wishes to encrypt the first
extension block and the bundle payload. The waypoint security policy
is to allow existing BIBs for these blocks to persist, as they may be
required as part of the security policy at the bundle destination.
o Confidentiality for the payload block and it's integrity The resultant bundle is illustrated in Figure 4 and the security
signature. This is accomplished by a BCB block, B7, encrypting B8 actions are described below. Note that block IDs provided here are
and B9. In this case, the security source, key parameters, and ordered solely for the purpose of this example and not meant to
service are identical, so a single security block MAY be used for impose an ordering for block creation. The ordering of blocks added
this purpose, rather than requiring two BCBs one to encrypt B8 and to a bundle MUST always be in compliance with [I-D.ietf-dtn-bpbis].
one to encrypt B9.
Block in Bundle ID
+======================================+====+
| Primary Block | B1 |
+--------------------------------------+----+
| BIB | B2 |
| OP(integrity, targets=B1) | |
+--------------------------------------+----+
| BIB (encrypted) | B7 |
| OP(integrity, targets=B5, B6) | |
+--------------------------------------+----+
| BCB | B8 |
| OP(confidentiality, target=B4,B6,B7) | |
+--------------------------------------+----+
| BCB | B3 |
| OP(confidentiality, target=B4) | |
+--------------------------------------+----+
| Extension Block (encrypted) | B4 |
+--------------------------------------+----+
| Extension Block (encrypted) | B5 |
+--------------------------------------+----+
| Payload Block (encrypted) | B6 |
+--------------------------------------+----+
Figure 4: Security At Bundle Forwarding
The following security actions were applied to this bundle prior to
its forwarding from the waypoint node.
o Since the waypoint node wishes to encrypt blocks B5 and B6, it
MUST also encrypt the BIBs providing plain-text integrity over
those blocks. However, BIB B2 could not be encrypted in its
entirety because it also held a signature for the primary block
(B1). Therefore, a new BIB (B7) is created and security results
associated with B5 and B6 are moved out of BIB B2 and into BIB B7.
o Now that there is no longer confusion of which plain-text
integrity signatures must be encrypted, a BCB is added to the
bundle with the security targets being the second extension block
(B5) and the payload (B6) as well as the newly created BIB holding
their plain-text integrity signatures (B7). A single new BCB is
used in this case because all three targets share a security
source and policy has them share the same cipher suite, key, and
cipher suite parameters. Had this not been the case, multiple
BCBs could have been added instead.
4. Canonical Forms 4. Canonical Forms
Security services require consistency and determinism in how Security services require consistency and determinism in how
information is presented to cipher suites at the security source and information is presented to cipher suites at the security source and
at a receiving node. For example, integrity services require that at a receiving node. For example, integrity services require that
the same target information (e.g., the same bits in the same order) the same target information (e.g., the same bits in the same order)
is provided to the cipher suite when generating an original signature is provided to the cipher suite when generating an original signature
and when generating a comparison signature. Canonicalization and when generating a comparison signature. Canonicalization
algorithms are used to construct a stable, end-to-end bit algorithms are used to construct a stable, end-to-end bit
representation of a target block. representation of a target block.
Canonical forms are not transmitted, they are used to generate input Canonical forms are not transmitted, they are used to generate input
to a cipher suite for security processing at a security-aware node. to a cipher suite for security processing at a security-aware node.
The canonicalization of the primary block is as specified in [BPBIS]. The canonicalization of the primary block is as specified in
[I-D.ietf-dtn-bpbis].
All non-primary blocks share the same block structure and are All non-primary blocks share the same block structure and are
canonicalized as specified in [BPBIS] with the following exception. canonicalized as specified in [I-D.ietf-dtn-bpbis] with the following
exceptions.
o If the service being applied is a confidentiality service, then o If the service being applied is a confidentiality service, then
the Block Type Code, Block Number, Block Processing Control Flags, the Block Type Code, Block Number, Block Processing Control Flags,
CRC Type and CRC Field (if present), and Block Data Length fields CRC Type and CRC Field (if present), and Block Data Length fields
MUST NOT be included in the canonicalization. Confidentiality MUST NOT be included in the canonicalization. Confidentiality
services are used solely to convert the Block Type Specific Data services are used solely to convert the Block Type Specific Data
Fields from plain-text to cipher-text. Fields from plain-text to cipher-text.
o Reserved flags MUST NOT be included in any canonicalization as it o Reserved flags MUST NOT be included in any canonicalization as it
is not known if those flags will change in transit. is not known if those flags will change in transit.
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5. Security Processing 5. Security Processing
This section describes the security aspects of bundle processing. This section describes the security aspects of bundle processing.
5.1. Bundles Received from Other Nodes 5.1. Bundles Received from Other Nodes
Security blocks must be processed in a specific order when received Security blocks must be processed in a specific order when received
by a security-aware node. The processing order is as follows. by a security-aware node. The processing order is as follows.
o All BCB blocks in the bundle MUST be evaluated prior to evaluating o When BIBs and BCBs share a security target, BCBs MUST be evaluated
any BIBs in the bundle. When BIBs and BCBs share a security first and BIBs second.
target, BCBs MUST be evaluated first and BIBs second.
5.1.1. Receiving BCB Blocks 5.1.1. Receiving BCBs
If a received bundle contains a BCB, the receiving node must If a received bundle contains a BCB, the receiving node MUST
determine whether it has the responsibility of decrypting the BCB determine whether it has the responsibility of decrypting the BCB
security target and removing the BCB prior to delivering data to an security target and removing the BCB prior to delivering data to an
application at the node or forwarding the bundle. application at the node or forwarding the bundle.
If the receiving node is the destination of the bundle, the node MUST If the receiving node is the destination of the bundle, the node MUST
decrypt any BCBs remaining in the bundle. If the receiving node is decrypt any BCBs remaining in the bundle. If the receiving node is
not the destination of the bundle, the node MAY decrypt the BCB if not the destination of the bundle, the node MUST decrypt the BCB if
directed to do so as a matter of security policy. directed to do so as a matter of security policy.
If the security policy of a security-aware node specifies that a If the security policy of a security-aware node specifies that a
bundle should have applied confidentiality to a specific security bundle should have applied confidentiality to a specific security
target and no such BCB is present in the bundle, then the node MUST target and no such BCB is present in the bundle, then the node MUST
process this security target in accordance with the security policy. process this security target in accordance with the security policy.
This MAY involve removing the security target from the bundle. If This may involve removing the security target from the bundle. If
the removed security target is the payload block, the bundle MAY be the removed security target is the payload block, the bundle MUST be
discarded. discarded.
If an encrypted payload block cannot be decrypted (i.e., the If an encrypted payload block cannot be decrypted (i.e., the cipher-
decryption key cannot be deduced or decryption fails), then the text cannot be authenticated), then the bundle MUST be discarded and
bundle MUST be discarded and processed no further. If an encrypted processed no further. If an encrypted security target other than the
security target other than the payload block cannot be decrypted then payload block cannot be decrypted then the associated security target
the associated security target and all security blocks associated and all security blocks associated with that target MUST be discarded
with that target MUST be discarded and processed no further. In both and processed no further. In both cases, requested status reports
cases, requested status reports (see [BPBIS]) MAY be generated to (see [I-D.ietf-dtn-bpbis]) MAY be generated to reflect bundle or
reflect bundle or block deletion. block deletion.
When a BCB is decrypted, the recovered plain-text MUST replace the When a BCB is decrypted, the recovered plain-text MUST replace the
cipher-text in the security target Block Type Specific Data Fields. cipher-text in the security target Block Type Specific Data Fields.
If the Block Data Length field was modified at the time of encryption If the Block Data Length field was modified at the time of encryption
it MUST be updated to reflect the decrypted block length. it MUST be updated to reflect the decrypted block length.
If a BCB contains multiple security targets, all security targets If a BCB contains multiple security targets, all security targets
MUST be processed when the BCB is processed. Errors and other MUST be processed when the BCB is processed. Errors and other
processing steps SHALL be made as if each security target had been processing steps SHALL be made as if each security target had been
represented by an individual BCB with a single security target. represented by an individual BCB with a single security target.
5.1.2. Receiving BIB Blocks 5.1.2. Receiving BIBs
If a received bundle contains a BIB, the receiving node MUST If a received bundle contains a BIB, the receiving node MUST
determine whether it has the final responsibility of verifying the determine whether it has the final responsibility of verifying the
BIB security target and removing it prior to delivering data to an BIB security target and removing it prior to delivering data to an
application at the node or forwarding the bundle. If a BIB check application at the node or forwarding the bundle. If a BIB check
fails, the security target has failed to authenticate and the fails, the security target has failed to authenticate and the
security target SHALL be processed according to the security policy. security target SHALL be processed according to the security policy.
A bundle status report indicating the failure MAY be generated. A bundle status report indicating the failure MAY be generated.
Otherwise, if the BIB verifies, the security target is ready to be Otherwise, if the BIB verifies, the security target is ready to be
processed for delivery. processed for delivery.
skipping to change at page 21, line 50 skipping to change at page 23, line 31
operations mandated by this specification, when both a BIB and a BCB operations mandated by this specification, when both a BIB and a BCB
share a security target, it means that the security target must have share a security target, it means that the security target must have
been encrypted after it was integrity signed and, therefore, the BIB been encrypted after it was integrity signed and, therefore, the BIB
cannot be verified until the security target has been decrypted by cannot be verified until the security target has been decrypted by
processing the BCB. processing the BCB.
If the security policy of a security-aware node specifies that a If the security policy of a security-aware node specifies that a
bundle should have applied integrity to a specific security target bundle should have applied integrity to a specific security target
and no such BIB is present in the bundle, then the node MUST process and no such BIB is present in the bundle, then the node MUST process
this security target in accordance with the security policy. This this security target in accordance with the security policy. This
MAY involve removing the security target from the bundle. If the may involve removing the security target from the bundle. If the
removed security target is the payload or primary block, the bundle removed security target is the payload or primary block, the bundle
MAY be discarded. This action may occur at any node that has the MAY be discarded. This action can occur at any node that has the
ability to verify an integrity signature, not just the bundle ability to verify an integrity signature, not just the bundle
destination. destination.
If a receiving node does not have the final responsibility of If a receiving node does not have the final responsibility of
verifying the BIB it MAY still attempt to verify the BIB to prevent verifying the BIB it MAY attempt to verify the BIB to prevent the
the needless forwarding of corrupt data. If the check fails, the needless forwarding of corrupt data. If the check fails, the node
node SHALL process the security target in accordance to local SHALL process the security target in accordance to local security
security policy. It is RECOMMENDED that if a payload integrity check policy. It is RECOMMENDED that if a payload integrity check fails at
fails at a waypoint that it is processed in the same way as if the a waypoint that it is processed in the same way as if the check fails
check fails at the destination. If the check passes, the node MUST at the destination. If the check passes, the node MUST NOT remove
NOT remove the BIB prior to forwarding. the BIB prior to forwarding.
If a BIB contains multiple security targets, all security targets If a BIB contains multiple security targets, all security targets
MUST be processed if the BIB is processed by the Node. Errors and MUST be processed if the BIB is processed by the Node. Errors and
other processing steps SHALL be made as if each security target had other processing steps SHALL be made as if each security target had
been represented by an individual BIB with a single security target. been represented by an individual BIB with a single security target.
5.2. Bundle Fragmentation and Reassembly 5.2. Bundle Fragmentation and Reassembly
If it is necessary for a node to fragment a bundle payload, and If it is necessary for a node to fragment a bundle payload, and
security services have been applied to that bundle, the fragmentation security services have been applied to that bundle, the fragmentation
rules described in [BPBIS] MUST be followed. As defined there and rules described in [I-D.ietf-dtn-bpbis] MUST be followed. As defined
summarized here for completeness, only the payload block may be there and summarized here for completeness, only the payload block
fragmented; security blocks, like all extension blocks, can never be can be fragmented; security blocks, like all extension blocks, can
fragmented. never be fragmented.
Due to the complexity of payload block fragmentation, including the Due to the complexity of payload block fragmentation, including the
possibility of fragmenting payload block fragments, integrity and possibility of fragmenting payload block fragments, integrity and
confidentiality operations are not to be applied to a bundle confidentiality operations are not to be applied to a bundle
representing a fragment. Specifically, a BCB or BIB MUST NOT be representing a fragment. Specifically, a BCB or BIB MUST NOT be
added to a bundle if the "Bundle is a Fragment" flag is set in the added to a bundle if the "Bundle is a Fragment" flag is set in the
Bundle Processing Control Flags field. Bundle Processing Control Flags field.
Security processing in the presence of payload block fragmentation Security processing in the presence of payload block fragmentation
MAY be handled by other mechanisms outside of the BPSec protocol or may be handled by other mechanisms outside of the BPSec protocol or
by applying BPSec blocks in coordination with an encapsulation by applying BPSec blocks in coordination with an encapsulation
mechanism. mechanism.
6. Key Management 6. Key Management
There exist a myriad of ways to establish, communicate, and otherwise There exist a myriad of ways to establish, communicate, and otherwise
manage key information in a DTN. Certain DTN deployments might manage key information in a DTN. Certain DTN deployments might
follow established protocols for key management whereas other DTN follow established protocols for key management whereas other DTN
deployments might require new and novel approaches. BPSec assumes deployments might require new and novel approaches. BPSec assumes
that key management is handled as a separate part of network that key management is handled as a separate part of network
skipping to change at page 23, line 38 skipping to change at page 25, line 21
associated BPSec blocks, replace the security operation, or some associated BPSec blocks, replace the security operation, or some
other action. other action.
o It is recommended that security operations only be applied to the o It is recommended that security operations only be applied to the
blocks that absolutely need them. If a BPA were to apply security blocks that absolutely need them. If a BPA were to apply security
operations such as integrity or confidentiality to every block in operations such as integrity or confidentiality to every block in
the bundle, regardless of need, there could be downstream errors the bundle, regardless of need, there could be downstream errors
processing blocks whose contents must be inspected or changed at processing blocks whose contents must be inspected or changed at
every hop along the path. every hop along the path.
o It is recommended that BCBs be allowed to alter the size of
extension blocks and the payload block. However, care must be
taken to ensure that changing the size of the payload block while
the bundle is in transit do not negatively affect bundle
processing (e.g., calculating storage needs, scheduling
transmission times, caching block byte offsets).
o Adding a BIB to a security target that has already been encrypted o Adding a BIB to a security target that has already been encrypted
by a BCB is not allowed. If this condition is likely to be by a BCB is not allowed. If this condition is likely to be
encountered, there are (at least) three possible policies that encountered, there are (at least) three possible policies that
could handle this situation. could handle this situation.
1. At the time of encryption, an integrity signature may be 1. At the time of encryption, a plain-text integrity signature
generated and added to the BCB for the security target as may be generated and added to the BCB for the security target
additional information in the security result field. as additional information in the security result field.
2. The encrypted block may be replicated as a new block and 2. The encrypted block may be replicated as a new block and
integrity signed. integrity signed.
3. An encapsulation scheme may be applied to encapsulate the 3. An encapsulation scheme may be applied to encapsulate the
security target (or the entire bundle) such that the security target (or the entire bundle) such that the
encapsulating structure is, itself, no longer the security encapsulating structure is, itself, no longer the security
target of a BCB and may therefore be the security target of a target of a BCB and may therefore be the security target of a
BIB. BIB.
o It is recommended that security policy address whether cipher
suites whose cipher-text is larger (or smaller) than the initial
plain-text are permitted and, if so, for what types of blocks.
Changing the size of a block may cause processing difficulties for
networks that calculate block offsets into bundles or predict
transmission times or storage availability as a function of bundle
size. In other cases, changing the size of a payload as part of
encryption has no significant impact.
8. Security Considerations 8. Security Considerations
Given the nature of DTN applications, it is expected that bundles may Given the nature of DTN applications, it is expected that bundles may
traverse a variety of environments and devices which each pose unique traverse a variety of environments and devices which each pose unique
security risks and requirements on the implementation of security security risks and requirements on the implementation of security
within BPSec. For these reasons, it is important to introduce key within BPSec. For these reasons, it is important to introduce key
threat models and describe the roles and responsibilities of the threat models and describe the roles and responsibilities of the
BPSec protocol in protecting the confidentiality and integrity of the BPSec protocol in protecting the confidentiality and integrity of the
data against those threats. This section provides additional data against those threats. This section provides additional
discussion on security threats that BPSec will face and describes how discussion on security threats that BPSec will face and describes how
BPSec security mechanisms operate to mitigate these threats. BPSec security mechanisms operate to mitigate these threats.
It should be noted that BPSEC addresses only the security of data
traveling over the DTN, not the underlying DTN itself. Additionally,
BPSec addresses neither the fitness of externally-defined
cryptographic methods nor the security of their implementation. It
is the responsibility of the BPSec implementer that appropriate
algorithms and methods are chosen. Furthermore, the BPSec protocol
does not address threats which share computing resources with the DTN
and/or BPSec software implementations. These threats may be
malicious software or compromised libraries which intend to intercept
data or recover cryptographic material. Here, it is the
responsibility of the BPSec implementer to ensure that any
cryptographic material, including shared secret or private keys, is
protected against access within both memory and storage devices.
The threat model described here is assumed to have a set of The threat model described here is assumed to have a set of
capabilities identical to those described by the Internet Threat capabilities identical to those described by the Internet Threat
Model in [RFC3552], but the BPSec threat model is scoped to Model in [RFC3552], but the BPSec threat model is scoped to
illustrate threats specific to BPSec operating within DTN illustrate threats specific to BPSec operating within DTN
environments and therefore focuses on man-in-the-middle (MITM) environments and therefore focuses on man-in-the-middle (MITM)
attackers. attackers. In doing so, it is assumed that the DTN (or significant
portions of the DTN) are completely under the control of an attacker.
8.1. Attacker Capabilities and Objectives 8.1. Attacker Capabilities and Objectives
BPSec was designed to protect against MITM threats which may have BPSec was designed to protect against MITM threats which may have
access to a bundle during transit from its source, Alice, to its access to a bundle during transit from its source, Alice, to its
destination, Bob. A MITM node, Mallory, is a non-cooperative node destination, Bob. A MITM node, Mallory, is a non-cooperative node
operating on the DTN between Alice and Bob that has the ability to operating on the DTN between Alice and Bob that has the ability to
receive bundles, examine bundles, modify bundles, forward bundles, receive bundles, examine bundles, modify bundles, forward bundles,
and generate bundles at will in order to compromise the and generate bundles at will in order to compromise the
confidentiality or integrity of data within the DTN. For the confidentiality or integrity of data within the DTN. For the
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for years and the cipher suite used for a BCB provides inadequate for years and the cipher suite used for a BCB provides inadequate
protection, Mallory may be able to recover the protected data either protection, Mallory may be able to recover the protected data either
before that bundle reaches its intended destination or before the before that bundle reaches its intended destination or before the
information in the bundle is no longer considered sensitive. information in the bundle is no longer considered sensitive.
8.2.2. Modification Attacks 8.2.2. Modification Attacks
As a node participating in the DTN between Alice and Bob, Mallory As a node participating in the DTN between Alice and Bob, Mallory
will also be able to modify the received bundle, including non-BPSec will also be able to modify the received bundle, including non-BPSec
data such as the primary block, payload blocks, or block processing data such as the primary block, payload blocks, or block processing
control flags as defined in [BPBIS]. Mallory will be able to control flags as defined in [I-D.ietf-dtn-bpbis]. Mallory will be
undertake activities which include modification of data within the able to undertake activities which include modification of data
blocks, replacement of blocks, addition of blocks, or removal of within the blocks, replacement of blocks, addition of blocks, or
blocks. Within BPSec, both the BIB and BCB provide integrity removal of blocks. Within BPSec, both the BIB and BCB provide
protection mechanisms to detect or prevent data manipulation attempts integrity protection mechanisms to detect or prevent data
by Mallory. manipulation attempts by Mallory.
The BIB provides that protection to another block which is its The BIB provides that protection to another block which is its
security target. The cryptographic mechanisms used to generate the security target. The cryptographic mechanisms used to generate the
BIB should be strong against collision attacks and Mallory should not BIB should be strong against collision attacks and Mallory should not
have access to the cryptographic material used by the originating have access to the cryptographic material used by the originating
node to generate the BIB (e.g., K_A). If both of these conditions node to generate the BIB (e.g., K_A). If both of these conditions
are true, Mallory will be unable to modify the security target or the are true, Mallory will be unable to modify the security target or the
BIB and lead Bob to validate the security target as originating from BIB and lead Bob to validate the security target as originating from
Alice. Alice.
Since BPSec security operations are implemented by placing blocks in Since BPSec security operations are implemented by placing blocks in
a bundle, there is no in-band mechanism for detecting or correcting a bundle, there is no in-band mechanism for detecting or correcting
certain cases where Mallory removes blocks from a bundle. If Mallory certain cases where Mallory removes blocks from a bundle. If Mallory
removes a BCB block, but keeps the security target, the security removes a BCB, but keeps the security target, the security target
target remains encrypted and there is a possibility that there may no remains encrypted and there is a possibility that there may no longer
longer be sufficient information to decrypt the block at its be sufficient information to decrypt the block at its destination.
destination. If Mallory removes both a BCB (or BIB) and its security If Mallory removes both a BCB (or BIB) and its security target there
target there is no evidence left in the bundle of the security is no evidence left in the bundle of the security operation.
operation. Similarly, if Mallory removes the BIB but not the Similarly, if Mallory removes the BIB but not the security target
security target there is no evidence left in the bundle of the there is no evidence left in the bundle of the security operation.
security operation. In each of these cases, the implementation of In each of these cases, the implementation of BPSec must be combined
BPSec must be combined with policy configuration at endpoints in the with policy configuration at endpoints in the network which describe
network which describe the expected and required security operations the expected and required security operations that must be applied on
that must be applied on transmission and are expected to be present transmission and are expected to be present on receipt. This or
on receipt. This or other similar out-of-band information is other similar out-of-band information is required to correct for
required to correct for removal of security information in the removal of security information in the bundle.
bundle.
A limitation of the BIB may exist within the implementation of BIB A limitation of the BIB may exist within the implementation of BIB
validation at the destination node. If Mallory is a legitimate node validation at the destination node. If Mallory is a legitimate node
within the DTN, the BIB generated by Alice with K_A can be replaced within the DTN, the BIB generated by Alice with K_A can be replaced
with a new BIB generated with K_M and forwarded to Bob. If Bob is with a new BIB generated with K_M and forwarded to Bob. If Bob is
only validating that the BIB was generated by a legitimate user, Bob only validating that the BIB was generated by a legitimate user, Bob
will acknowledge the message as originating from Mallory instead of will acknowledge the message as originating from Mallory instead of
Alice. In order to provide verifiable integrity checks, both a BIB Alice. In order to provide verifiable integrity checks, both a BIB
and BCB should be used and the BCB should require an IND-CCA2 and BCB should be used and the BCB should require an IND-CCA2
encryption scheme. Such an encryption scheme will guard against encryption scheme. Such an encryption scheme will guard against
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network. Upon receiving and processing a bundle that must be routed network. Upon receiving and processing a bundle that must be routed
elsewhere in the network, Mallory has three options as to how to elsewhere in the network, Mallory has three options as to how to
proceed: not forward the bundle, forward the bundle as intended, or proceed: not forward the bundle, forward the bundle as intended, or
forward the bundle to one or more specific nodes within the network. forward the bundle to one or more specific nodes within the network.
Attacks that involve re-routing the packets throughout the network Attacks that involve re-routing the packets throughout the network
are essentially a special case of the modification attacks described are essentially a special case of the modification attacks described
in this section where the attacker is modifying fields within the in this section where the attacker is modifying fields within the
primary block of the bundle. Given that BPSec cannot encrypt the primary block of the bundle. Given that BPSec cannot encrypt the
contents of the primary block, alternate methods must be used to contents of the primary block, alternate methods must be used to
prevent this situation. These methods MAY include requiring BIBs for prevent this situation. These methods may include requiring BIBs for
primary blocks, using encapsulation, or otherwise strategically primary blocks, using encapsulation, or otherwise strategically
manipulating primary block data. The specifics of any such manipulating primary block data. The specifics of any such
mitigation technique are specific to the implementation of the mitigation technique are specific to the implementation of the
deploying network and outside of the scope of this document. deploying network and outside of the scope of this document.
Furthermore, routing rules and policies may be useful in enforcing Furthermore, routing rules and policies may be useful in enforcing
particular traffic flows to prevent topology attacks. While these particular traffic flows to prevent topology attacks. While these
rules and policies may utilize some features provided by BPSec, their rules and policies may utilize some features provided by BPSec, their
definition is beyond the scope of this specification. definition is beyond the scope of this specification.
skipping to change at page 29, line 22 skipping to change at page 30, line 49
information SHOULD be considered for inclusion in these information SHOULD be considered for inclusion in these
specifications. specifications.
o Cipher Suite Parameters. Cipher suites MUST define their o Cipher Suite Parameters. Cipher suites MUST define their
parameter ids, the data types of those parameters, and their CBOR parameter ids, the data types of those parameters, and their CBOR
encoding. encoding.
o Security Results. Cipher suites MUST define their security result o Security Results. Cipher suites MUST define their security result
ids, the data types of those results, and their CBOR encoding. ids, the data types of those results, and their CBOR encoding.
o New Canonicalizations. Cipher suites MAY define new o New Canonicalizations. Cipher suites may define new
canonicalization algorithms as necessary. canonicalization algorithms as necessary.
o Cipher-Text Size. Cipher suites MUST state whether they generate
cipher-text (to include any included authentication information)
that is of a different size than the input plain-text.
If a cipher suite does not wish to alter the size of the plain-
text, it should consider the following.
* Place overflow bytes, authentication signatures, and any
additional authenticated data in security result fields rather
than in the cipher-text itself.
* Pad the cipher-text in cases where the cipher-text is smaller
than the plain-text.
o If a BCB cannot alter the size of the security target then
differences in the size of the cipher-text and plain-text MUST be
handled in the following way. If the cipher-text is shorter in
length than the plain-text, padding MUST be used in accordance
with the cipher suite policy. If the cipher-text is larger than
the plain-text, overflow bytes MUST be placed in overflow
parameters in the Security Result field. Any additional
authentication information can be treated either as overflow
cipher-text or represented separately in the BCB in a security
result field, in accordance with cipher suite documentation and
security policy.
10. Defining Other Security Blocks 10. Defining Other Security Blocks
Other security blocks (OSBs) may be defined and used in addition to Other security blocks (OSBs) may be defined and used in addition to
the security blocks identified in this specification. Both the usage the security blocks identified in this specification. Both the usage
of BIB, BCB, and any future OSBs MAY co-exist within a bundle and MAY of BIB, BCB, and any future OSBs can co-exist within a bundle and can
be considered in conformance with BPSec if each of the following be considered in conformance with BPSec if each of the following
requirements are met by any future identified security blocks. requirements are met by any future identified security blocks.
o Other security blocks (OSBs) MUST NOT reuse any enumerations o Other security blocks (OSBs) MUST NOT reuse any enumerations
identified in this specification, to include the block type codes identified in this specification, to include the block type codes
for BIB and BCB. for BIB and BCB.
o An OSB definition MUST state whether it can be the target of a BIB o An OSB definition MUST state whether it can be the target of a BIB
or a BCB. The definition MUST also state whether the OSB can or a BCB. The definition MUST also state whether the OSB can
target a BIB or a BCB. target a BIB or a BCB.
o An OSB definition MUST provide a deterministic processing order in o An OSB definition MUST provide a deterministic processing order in
the event that a bundle is received containing BIBs, BCBs, and the event that a bundle is received containing BIBs, BCBs, and
OSBs. This processing order MUST NOT alter the BIB and BCB OSBs. This processing order MUST NOT alter the BIB and BCB
processing orders identified in this specification. processing orders identified in this specification.
o An OSB definition MUST provide a canonicalization algorithm if the o An OSB definition MUST provide a canonicalization algorithm if the
default non-primary-block canonicalization algorithm cannot be default non-primary-block canonicalization algorithm cannot be
used to generate a deterministic input for a cipher suite. This used to generate a deterministic input for a cipher suite. This
requirement MAY be waived if the OSB is defined so as to never be requirement can be waived if the OSB is defined so as to never be
the security target of a BIB or a BCB. the security target of a BIB or a BCB.
o An OSB definition MAY NOT require any behavior of a BPSEC-BPA that o An OSB definition MUST NOT require any behavior of a BPSEC-BPA
is in conflict with the behavior identified in this specification. that is in conflict with the behavior identified in this
In particular, the security processing requirements imposed by specification. In particular, the security processing
this specification must be consistent across all BPSEC-BPAs in a requirements imposed by this specification must be consistent
network. across all BPSEC-BPAs in a network.
o The behavior of an OSB when dealing with fragmentation must be o The behavior of an OSB when dealing with fragmentation must be
specified and MUST NOT lead to ambiguous processing states. In specified and MUST NOT lead to ambiguous processing states. In
particular, an OSB definition should address how to receive and particular, an OSB definition should address how to receive and
process an OSB in a bundle fragment that may or may not also process an OSB in a bundle fragment that may or may not also
contain its security target. An OSB definition should also contain its security target. An OSB definition should also
address whether an OSB may be added to a bundle marked as a address whether an OSB may be added to a bundle marked as a
fragment. fragment.
Additionally, policy considerations for the management, monitoring, Additionally, policy considerations for the management, monitoring,
skipping to change at page 30, line 35 skipping to change at page 32, line 41
identification of such blocks shall not, alone, require maintenance identification of such blocks shall not, alone, require maintenance
of this specification. of this specification.
11. IANA Considerations 11. IANA Considerations
A registry of cipher suite identifiers will be required. A registry of cipher suite identifiers will be required.
11.1. Bundle Block Types 11.1. Bundle Block Types
This specification allocates two block types from the existing This specification allocates two block types from the existing
"Bundle Block Types" registry defined in [RFC6255] . "Bundle Block Types" registry defined in [RFC6255].
Additional Entries for the Bundle Block-Type Codes Registry: Additional Entries for the Bundle Block-Type Codes Registry:
+-------+-----------------------------+---------------+ +-------+-----------------------------+---------------+
| Value | Description | Reference | | Value | Description | Reference |
+-------+-----------------------------+---------------+ +-------+-----------------------------+---------------+
| TBD | Block Integrity Block | This document | | TBD | Block Integrity Block | This document |
| TBD | Block Confidentiality Block | This document | | TBD | Block Confidentiality Block | This document |
+-------+-----------------------------+---------------+ +-------+-----------------------------+---------------+
skipping to change at page 31, line 4 skipping to change at page 33, line 6
+-------+-----------------------------+---------------+ +-------+-----------------------------+---------------+
| Value | Description | Reference | | Value | Description | Reference |
+-------+-----------------------------+---------------+ +-------+-----------------------------+---------------+
| TBD | Block Integrity Block | This document | | TBD | Block Integrity Block | This document |
| TBD | Block Confidentiality Block | This document | | TBD | Block Confidentiality Block | This document |
+-------+-----------------------------+---------------+ +-------+-----------------------------+---------------+
Table 1 Table 1
12. References 12. References
12.1. Normative References 12.1. Normative References
[BPBIS] Burleigh, S., Fall, K., and E. Birrane, "Bundle Protocol", [I-D.ietf-dtn-bpbis]
draft-ietf-dtn-bpbis-06 (work in progress), July 2016. Burleigh, S., Fall, K., and E. Birrane, "Bundle Protocol
Version 7", draft-ietf-dtn-bpbis-11 (work in progress),
May 2018.
[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, March 1997. Requirement Levels", BCP 14, RFC 2119,
DOI 10.17487/RFC2119, March 1997,
<https://www.rfc-editor.org/info/rfc2119>.
[RFC3552] Rescorla, E. and B. Korver, "Guidelines for Writing RFC [RFC3552] Rescorla, E. and B. Korver, "Guidelines for Writing RFC
Text on Security Considerations", BCP 72, RFC 3552, Text on Security Considerations", BCP 72, RFC 3552,
DOI 10.17487/RFC3552, July 2003, DOI 10.17487/RFC3552, July 2003,
<https://www.rfc-editor.org/info/rfc3552>. <https://www.rfc-editor.org/info/rfc3552>.
[RFC6255] Blanchet, M., "Delay-Tolerant Networking Bundle Protocol [RFC6255] Blanchet, M., "Delay-Tolerant Networking Bundle Protocol
IANA Registries", RFC 6255, May 2011. IANA Registries", RFC 6255, DOI 10.17487/RFC6255, May
2011, <https://www.rfc-editor.org/info/rfc6255>.
12.2. Informative References 12.2. Informative References
[COSE] Schaad, J., "CBOR Object Signing and Encryption (COSE)", [I-D.birrane-dtn-sbsp]
draft-ietf-cose-msg-24 (work in progress), November 2016. Birrane, E., Pierce-Mayer, J., and D. Iannicca,
"Streamlined Bundle Security Protocol Specification",
draft-birrane-dtn-sbsp-01 (work in progress), October
2015.
[RFC4838] Cerf, V., Burleigh, S., Hooke, A., Torgerson, L., Durst, [RFC4838] Cerf, V., Burleigh, S., Hooke, A., Torgerson, L., Durst,
R., Scott, K., Fall, K., and H. Weiss, "Delay-Tolerant R., Scott, K., Fall, K., and H. Weiss, "Delay-Tolerant
Networking Architecture", RFC 4838, April 2007. Networking Architecture", RFC 4838, DOI 10.17487/RFC4838,
April 2007, <https://www.rfc-editor.org/info/rfc4838>.
[RFC6257] Symington, S., Farrell, S., Weiss, H., and P. Lovell, [RFC6257] Symington, S., Farrell, S., Weiss, H., and P. Lovell,
"Bundle Security Protocol Specification", RFC 6257, May "Bundle Security Protocol Specification", RFC 6257,
2011. DOI 10.17487/RFC6257, May 2011,
<https://www.rfc-editor.org/info/rfc6257>.
[SBSP] Birrane, E., "Streamlined Bundle Security Protocol", [RFC8152] Schaad, J., "CBOR Object Signing and Encryption (COSE)",
draft-birrane-dtn-sbsp-01 (work in progress), October RFC 8152, DOI 10.17487/RFC8152, July 2017,
2015. <https://www.rfc-editor.org/info/rfc8152>.
Appendix A. Acknowledgements Appendix A. Acknowledgements
The following participants contributed technical material, use cases, The following participants contributed technical material, use cases,
and useful thoughts on the overall approach to this security and useful thoughts on the overall approach to this security
specification: Scott Burleigh of the Jet Propulsion Laboratory, Amy specification: Scott Burleigh of the Jet Propulsion Laboratory, Amy
Alford and Angela Hennessy of the Laboratory for Telecommunications Alford and Angela Hennessy of the Laboratory for Telecommunications
Sciences, and Angela Dalton and Cherita Corbett of the Johns Hopkins Sciences, and Angela Dalton and Cherita Corbett of the Johns Hopkins
University Applied Physics Laboratory. University Applied Physics Laboratory.
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