draft-ietf-dtn-bpsec-01.txt   draft-ietf-dtn-bpsec-02.txt 
Delay-Tolerant Networking E. Birrane Delay-Tolerant Networking E. Birrane
Internet-Draft JHU/APL Internet-Draft K. McKeever
Intended status: Experimental J. Mayer Intended status: Experimental JHU/APL
Expires: September 20, 2016 INSYEN AG Expires: January 7, 2017 July 6, 2016
D. Iannicca
NASA GRC
March 19, 2016
Bundle Protocol Security Specification Bundle Protocol Security Specification
draft-ietf-dtn-bpsec-01 draft-ietf-dtn-bpsec-02
Abstract Abstract
This document defines a security protocol providing data integrity This document defines a security protocol providing end to end data
and confidentiality services for the Bundle Protocol. Capabilities integrity and confidentiality services for the Bundle Protocol.
are provided to protect blocks in a bundle along a single path
through a network.
Status of This Memo Status of This Memo
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provisions of BCP 78 and BCP 79. provisions of BCP 78 and BCP 79.
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This Internet-Draft will expire on September 20, 2016. This Internet-Draft will expire on January 7, 2017.
Copyright Notice Copyright Notice
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Table of Contents Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 3 1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 3
1.1. Related Documents . . . . . . . . . . . . . . . . . . . . 3 1.1. Motivation . . . . . . . . . . . . . . . . . . . . . . . 3
1.2. Terminology . . . . . . . . . . . . . . . . . . . . . . . 4 1.2. Supported Security Services . . . . . . . . . . . . . . . 3
2. Key Properties . . . . . . . . . . . . . . . . . . . . . . . 6 1.3. Specification Scope . . . . . . . . . . . . . . . . . . . 4
2.1. Block-Level Granularity . . . . . . . . . . . . . . . . . 6 1.4. Related Documents . . . . . . . . . . . . . . . . . . . . 5
2.2. Multiple Security Sources . . . . . . . . . . . . . . . . 6 1.5. Terminology . . . . . . . . . . . . . . . . . . . . . . . 5
2.3. Mixed Security Policy . . . . . . . . . . . . . . . . . . 7 2. Key Properties . . . . . . . . . . . . . . . . . . . . . . . 7
2.1. Block-Level Granularity . . . . . . . . . . . . . . . . . 7
2.2. Multiple Security Sources . . . . . . . . . . . . . . . . 7
2.3. Mixed Security Policy . . . . . . . . . . . . . . . . . . 8
2.4. User-Selected Ciphersuites . . . . . . . . . . . . . . . 8 2.4. User-Selected Ciphersuites . . . . . . . . . . . . . . . 8
2.5. Deterministic Processing . . . . . . . . . . . . . . . . 8 2.5. Deterministic Processing . . . . . . . . . . . . . . . . 9
3. Security Block Definitions . . . . . . . . . . . . . . . . . 8 3. Security Block Definitions . . . . . . . . . . . . . . . . . 9
3.1. Block Identification . . . . . . . . . . . . . . . . . . 9 3.1. Block Identification . . . . . . . . . . . . . . . . . . 10
3.2. Block Representation . . . . . . . . . . . . . . . . . . 9 3.2. Block Representation . . . . . . . . . . . . . . . . . . 10
3.2.1. CMS Block Type-Specific Data Fields . . . . . . . . . 10 3.3. Block Integrity Block . . . . . . . . . . . . . . . . . . 13
3.2.2. BIB and BCB Block Type-Specific Data Fields . . . . . 10 3.4. Block Confidentiality Block . . . . . . . . . . . . . . . 14
3.3. Block Ordering . . . . . . . . . . . . . . . . . . . . . 11 3.5. Block Interactions . . . . . . . . . . . . . . . . . . . 16
3.4. Block Integrity Block . . . . . . . . . . . . . . . . . . 12 3.6. Multi-Target Block Definitions . . . . . . . . . . . . . 17
3.5. Block Confidentiality Block . . . . . . . . . . . . . . . 13 3.7. Parameters and Result Fields . . . . . . . . . . . . . . 17
3.6. Cryptographic Message Syntax Block . . . . . . . . . . . 15 3.8. BSP Block Example . . . . . . . . . . . . . . . . . . . . 18
3.7. Block Interactions . . . . . . . . . . . . . . . . . . . 16 4. Canonical Forms . . . . . . . . . . . . . . . . . . . . . . . 20
3.8. Parameters and Result Fields . . . . . . . . . . . . . . 17 4.1. Technical Notes . . . . . . . . . . . . . . . . . . . . . 20
3.9. BSP Block Example . . . . . . . . . . . . . . . . . . . . 19 4.2. Primary Block Canonicalization . . . . . . . . . . . . . 21
4. Security Processing . . . . . . . . . . . . . . . . . . . . . 22 4.3. Non-Primary-Block Canonicalization . . . . . . . . . . . 22
4.1. Canonical Forms . . . . . . . . . . . . . . . . . . . . . 22 5. Security Processing . . . . . . . . . . . . . . . . . . . . . 22
4.1.1. Block Canonicalization . . . . . . . . . . . . . . . 22 5.1. Bundles Received from Other Nodes . . . . . . . . . . . . 23
4.1.2. Considerations . . . . . . . . . . . . . . . . . . . 25 5.1.1. Receiving BCB Blocks . . . . . . . . . . . . . . . . 23
4.2. Endpoint ID Confidentiality . . . . . . . . . . . . . . . 25 5.1.2. Receiving BIB Blocks . . . . . . . . . . . . . . . . 23
4.3. Bundles Received from Other Nodes . . . . . . . . . . . . 26 5.2. Bundle Fragmentation and Reassembly . . . . . . . . . . . 24
4.3.1. Receiving BCB Blocks . . . . . . . . . . . . . . . . 26 6. Key Management . . . . . . . . . . . . . . . . . . . . . . . 25
4.3.2. Receiving BIB Blocks . . . . . . . . . . . . . . . . 26 7. Policy Considerations . . . . . . . . . . . . . . . . . . . . 25
4.4. Receiving CMSB Blocks . . . . . . . . . . . . . . . . . . 27 8. Security Considerations . . . . . . . . . . . . . . . . . . . 26
4.5. Bundle Fragmentation and Reassembly . . . . . . . . . . . 27 8.1. Attacker Capabilities and Objectives . . . . . . . . . . 27
4.6. Reactive Fragmentation . . . . . . . . . . . . . . . . . 28 8.2. Attacker Behaviors and BPSec Mitigations . . . . . . . . 28
5. Key Management . . . . . . . . . . . . . . . . . . . . . . . 28 8.2.1. Eavesdropping Attacks . . . . . . . . . . . . . . . . 28
6. Policy Considerations . . . . . . . . . . . . . . . . . . . . 28 8.2.2. Modification Attacks . . . . . . . . . . . . . . . . 28
7. Security Considerations . . . . . . . . . . . . . . . . . . . 29 8.2.3. Topology Attacks . . . . . . . . . . . . . . . . . . 29
8. Conformance . . . . . . . . . . . . . . . . . . . . . . . . . 29 8.2.4. Message Injection . . . . . . . . . . . . . . . . . . 30
9. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 30 9. Ciphersuite Authorship Considerations . . . . . . . . . . . . 30
9.1. Bundle Block Types . . . . . . . . . . . . . . . . . . . 30 10. Conformance . . . . . . . . . . . . . . . . . . . . . . . . . 31
9.2. Cipher Suite Flags . . . . . . . . . . . . . . . . . . . 30 11. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 31
9.3. Parameters and Results . . . . . . . . . . . . . . . . . 31 11.1. Bundle Block Types . . . . . . . . . . . . . . . . . . . 31
10. References . . . . . . . . . . . . . . . . . . . . . . . . . 31 11.2. Cipher Suite Flags . . . . . . . . . . . . . . . . . . . 31
10.1. Normative References . . . . . . . . . . . . . . . . . . 31 11.3. Parameters and Results . . . . . . . . . . . . . . . . . 32
10.2. Informative References . . . . . . . . . . . . . . . . . 32 12. References . . . . . . . . . . . . . . . . . . . . . . . . . 33
12.1. Normative References . . . . . . . . . . . . . . . . . . 33
Appendix A. Acknowledgements . . . . . . . . . . . . . . . . . . 32 12.2. Informative References . . . . . . . . . . . . . . . . . 33
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 32 Appendix A. Acknowledgements . . . . . . . . . . . . . . . . . . 34
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 34
1. Introduction 1. Introduction
This document defines security features for the Bundle Protocol This document defines security features for the Bundle Protocol
[BPBIS] intended for use in delay-tolerant networks, in order to [BPBIS] intended for use in delay-tolerant networks, in order to
provide Delay-Tolerant Networking (DTN) security services. provide Delay-Tolerant Networking (DTN) security services.
1.1. Motivation
The Bundle Protocol is used in DTNs that overlay multiple networks, The Bundle Protocol is used in DTNs that overlay multiple networks,
some of which may be challenged by limitations such as intermittent some of which may be challenged by limitations such as intermittent
and possibly unpredictable loss of connectivity, long or variable and possibly unpredictable loss of connectivity, long or variable
delay, asymmetric data rates, and high error rates. The purpose of delay, asymmetric data rates, and high error rates. The purpose of
the Bundle Protocol is to support interoperability across such the Bundle Protocol is to support interoperability across such
stressed networks. stressed networks.
The stressed environment of the underlying networks over which the The stressed environment of the underlying networks over which the
Bundle Protocol operates makes it important for the DTN to be Bundle Protocol operates makes it important for the DTN to be
protected from unauthorized use, and this stressed environment poses protected from unauthorized use, and this stressed environment poses
unique challenges for the mechanisms needed to secure the Bundle unique challenges for the mechanisms needed to secure the Bundle
Protocol. Furthermore, DTNs may be deployed in environments where a Protocol. Furthermore, DTNs may be deployed in environments where a
portion of the network might become compromised, posing the usual portion of the network might become compromised, posing the usual
security challenges related to confidentiality, integrity, and security challenges related to confidentiality and integrity.
availability.
1.2. Supported Security Services
This specification supports end-to-end integrity and confidentiality
services associated with BP bundles.
Integrity services ensure data within a bundle are not changed. Data
changes may be caused by processing errors, environmental conditions,
or intentional manipulation. An integrity service is one that
provides sufficient confidence to a data receiver that data has not
changed since its value was last asserted.
Confidentiality services ensure that the values of some data within a
bundle can only be determined by authorized receivers of the data.
When a bundle traverses a DTN, many nodes in the network other than
the destination node MAY see the contents of a bundle. A
confidentiality service allows a destination node to generate data
values from otherwise encrypted contents of a bundle.
NOTE: Hop-by-hop authentication is NOT a supported security service
in this specification, for three reasons.
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
connectivity. This condition is difficult or impossible to
predict in the overlay and therefore makes the concept of hop-by-
hop authentication difficult or impossible to enforce at the
overlay.
2. Networks in which BPSec may be deployed may have a mixture of
security-aware and not-security-aware nodes. Hop-by-hop
authentication cannot be deployed in a network if adjacent nodes
in the network have different security capabilities.
3. Hop-by-hop authentication can be viewed as a special case of data
integrity. As such, it is possible to develop policy that
provides a version of authentication using the integrity
mechanisms defined in this specification.
1.3. Specification Scope
This document describes the Bundle Protocol Security Specification This document describes the Bundle Protocol Security Specification
(BPSec), which provides security services for blocks within a bundle (BPSec), which provides security services for blocks within a bundle.
from the bundle source to the bundle destination. Specifically, This includes the data specification for individual BP extension
BPSec provides integrity and confidentiality for bundles along a path blocks and the processing instructions for those blocks.
through a DTN.
BPSec applies, by definition, only to those nodes that implement it, BPSec applies, by definition, only to those nodes that implement it,
known as "security-aware" nodes. There MAY be other nodes in the DTN known as "security-aware" nodes. There MAY be other nodes in the DTN
that do not implement BPSec. All nodes can interoperate with the that do not implement BPSec. All nodes can interoperate with the
exception that BPSec security operations can only happen at BPSec exception that BPSec security operations can only happen at BPSec
security-aware nodes. security-aware nodes.
1.1. Related Documents This specification does not address individual cipher suite
implementations. The definition and enumeration of cipher suites
should be undertaken in separate specification documents.
This specification does not address the implementation of security
policy and does not provide a security policy for the BPSec.
Security policies are typically based on the nature and capabilities
of individual networks and network operational concepts. However,
this specification does recommend policy considerations when building
a security policy.
This specification does not address how to combine the BPSec security
blocks with other protocols, other BP extension blocks, or other best
practices to achieve security in any particular network
implementation.
1.4. 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 delay-tolerant networks, but does not discuss architecture for delay-tolerant networks, but does not discuss
security at any length. security at any length.
The DTN Bundle Protocol [BPBIS] defines the format and processing of The DTN Bundle Protocol [BPBIS] defines the format and processing of
the blocks used to implement the Bundle Protocol, excluding the the blocks used to implement the Bundle Protocol, excluding the
security-specific blocks defined here. security-specific blocks defined here.
The Bundle Security Protocol [RFC6257] and Streamlind Bundle Security The Bundle Security Protocol [RFC6257] and Streamlind Bundle Security
Protocol [SBSP] introduce the concepts of security blocks for Protocol [SBSP] introduce the concepts of security blocks for
security services. BPSec is based off of these documents. security services. BPSec is based off of these documents.
1.2. Terminology 1.5. 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].
We introduce the following terminology for purposes of clarity. This section defines those terms whose definition is important to the
understanding of concepts within this specification.
o Source - the bundle node from which a bundle originates. o Source - the bundle node from which a bundle originates.
o Destination - the bundle node to which a bundle is ultimately o Destination - the bundle node to which a bundle is ultimately
destined. destined.
o Forwarder - the bundle node that forwarded the bundle on its most o Forwarder - the bundle node that forwarded the bundle on its most
recent hop. recent hop.
o Intermediate Receiver, Waypoint, or "Next Hop" - the neighboring o Intermediate Receiver, Waypoint, or "Next Hop" - the neighboring
bundle node to which a forwarder forwards a bundle. bundle node to which a forwarder forwards a bundle.
o Path - the ordered sequence of nodes through which a bundle passes o Path - the ordered sequence of nodes through which a bundle passes
on its way from source to destination. The path is not on its way from source to destination. The path is not
necessarily known by the bundle, or any bundle-aware nodes. necessarily known by the bundle, or any bundle-aware nodes.
Figure 1 below is adapted from [BPBIS] and shows four bundle nodes The application of these terms applied to a sample network topology
(denoted BN1, BN2, BN3, and BN4) that reside above some transport is shown in Figure 1. This figure shows four bundle nodes (BN1, BN2,
layer(s). Three distinct transport and network protocols (denoted BN3, BN4) residing above some transport layer(s). Three distinct
T1/N1, T2/N2, and T3/N3) are also shown. transport and network protocols (T1/N1, T2/N2, and T3/N3) are also
shown.
+---------v-| +->>>>>>>>>>v-+ +->>>>>>>>>>v-+ +-^---------+ +---------v-| +->>>>>>>>>>v-+ +->>>>>>>>>>v-+ +-^---------+
| BN1 v | | ^ BN2 v | | ^ BN3 v | | ^ BN4 | | BN1 v | | ^ BN2 v | | ^ BN3 v | | ^ BN4 |
+---------v-+ +-^---------v-+ +-^---------v-+ +-^---------+ +---------v-+ +-^---------v-+ +-^---------v-+ +-^---------+
| T1 v | + ^ T1/T2 v | + ^ T2/T3 v | | ^ T3 | | T1 v | + ^ T1/T2 v | + ^ T2/T3 v | | ^ T3 |
+---------v-+ +-^---------v-+ +-^---------v + +-^---------+ +---------v-+ +-^---------v-+ +-^---------v + +-^---------+
| N1 v | | ^ N1/N2 v | | ^ N2/N3 v | | ^ N3 | | N1 v | | ^ N1/N2 v | | ^ N2/N3 v | | ^ N3 |
+---------v-+ +-^---------v + +-^---------v-+ +-^---------+ +---------v-+ +-^---------v + +-^---------v-+ +-^---------+
| >>>>>>>>^ >>>>>>>>>>^ >>>>>>>>^ | | >>>>>>>>^ >>>>>>>>>>^ >>>>>>>>^ |
+-----------+ +------------+ +-------------+ +-----------+ +-----------+ +------------+ +-------------+ +-----------+
| | | | | | | |
|<-- An Internet --->| |<--- An Internet --->| |<-- An Internet --->| |<--- An Internet --->|
| | | | | | | |
Figure 1: Bundle Nodes Sitting at the Application Layer of the Figure 1: Bundle Nodes Sitting Above the Transport Layer.
Internet Model
BN1 originates a bundle that it forwards to BN2. BN2 forwards the Consider the case where BN1 originates a bundle that it forwards to
bundle to BN3, and BN3 forwards the bundle to BN4. BN1 is the source BN2. BN2 forwards the bundle to BN3, and BN3 forwards the bundle to
of the bundle and BN4 is the destination of the bundle. BN1 is the BN4. BN1 is the source of the bundle and BN4 is the destination of
first forwarder, and BN2 is the first intermediate receiver; BN2 then the bundle. BN1 is the first forwarder, and BN2 is the first
becomes the forwarder, and BN3 the intermediate receiver; BN3 then intermediate receiver; BN2 then becomes the forwarder, and BN3 the
becomes the last forwarder, and BN4 the last intermediate receiver, intermediate receiver; BN3 then becomes the last forwarder, and BN4
as well as the destination. the last intermediate receiver, as well as the destination.
If node BN2 originates a bundle (for example, a bundle status report If node BN2 originates a bundle (for example, a bundle status report
or a custodial signal), which is then forwarded on to BN3, and then or a custodial signal), which is then forwarded on to BN3, and then
to BN4, then BN2 is the source of the bundle (as well as being the to BN4, then BN2 is the source of the bundle (as well as being the
first forwarder of the bundle) and BN4 is the destination of the first forwarder of the bundle) and BN4 is the destination of the
bundle (as well as being the final intermediate receiver). bundle (as well as being the final intermediate receiver).
We introduce the following security-specific DTN terminology. The following security-specific terminology is also defined to
clarify security operations in this specifiation.
o Security-Service - the security features supported by this o Security-Service - the security features supported by this
specification: authentication, integrity, and confidentiality. specification: integrity and confidentiality.
o Security-Source - a bundle node that adds a security block to a o Security-Source - a bundle node that adds a security block to a
bundle. bundle.
o Security-Target - the portion of a bundle (e.g., the primary o Security-Target - the block within a bundle that receives a
block, payload block, extension block, or entire bundle) that security-service as part of a security-operation.
receives a security-service as part of a security-operation.
o Security Block - a single instance of a BPSec extension block in a o Security Block - a BPSec extension block in a bundle.
bundle.
o Security-Operation - the application of a security-service to a o Security-Operation - the application of a security-service to a
specific security-target, notated as OP(security-service, security-target, notated as OP(security-service, security-target).
security-target). For example, OP(authentication, bundle) or For example, OP(confidentiality, payload). Every security-
OP(confidentiality, payload). Every security-operation in a operation in a bundle MUST be unique, meaning that a security-
bundle MUST be unique, meaning that a security-service can only be service can only be applied to a security-target once in a bundle.
applied to a security-target once in a bundle. A security- A security operation is implemented by a security block.
operation MAY be implemented by one or more security blocks.
2. Key Properties 2. Key Properties
The application of security services in a DTN is a complex endeavor The application of security services in a DTN is a complex endeavor
that must consider physical properties of the network, policies at that must consider physical properties of the network, policies at
each node, and various application security requirements. Rather each node, and various application security requirements. Rather
than enumerate all potential security implementations in all than enumerate all potential security implementations in all
potential DTN topologies, this specification defines a set of key potential DTN topologies, this specification defines a set of key
properties of a security system. The security primitives outlined in properties of a security system. The security primitives outlined in
this document MUST enable the realization of these properties in a this document MUST enable the realization of these properties in a
skipping to change at page 6, line 43 skipping to change at page 7, line 41
Security services within this specification MUST provide block level Security services within this specification MUST provide block level
granularity where applicable such that different blocks within a granularity where applicable such that different blocks within a
bundle may have different security services applied to them. bundle may have different security services applied to them.
For example, within a bundle, a payload might be encrypted to protect For example, within a bundle, a payload might be encrypted to protect
its contents, whereas an extension block containing summary its contents, whereas an extension block containing summary
information related to the payload might be integrity signed but information related to the payload might be integrity signed but
otherwise unencrypted to provide certain nodes access to payload- otherwise unencrypted to provide certain nodes access to payload-
related data without providing access to the payload. related data without providing access to the payload.
Each security block in a bundle will be associated with a specific
security-operation.
2.2. Multiple Security Sources 2.2. Multiple Security Sources
A bundle MAY have multiple security blocks and these blocks MAY have
different 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 node at any time during its existence in the DTN. When a waypoint node
adds a new extension block to a bundle, that extension block may have adds a 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 node may add a security service to an existing extension waypoint node may add a security service to an existing extension
block, consistent with its security policy. For example, a node block, consistent with its security policy. For example, a node
representing a boundary between a trusted part of the network and an representing a boundary between a trusted part of the network and an
untrusted part of the network may wish to apply payload encryption untrusted part of the network may wish to apply payload encryption
for bundles leaving the trusted portion of the network. for bundles leaving the trusted portion of the network.
In each case, a node other than the bundle originator may be adding a In each case, a node other than the bundle originator may add a
security service to the bundle and, as such, the source for the security service to the bundle and, as such, the source for the
security service will be different than the source of the bundle security service will be different than the source of the bundle
itself. Security services MUST track their orginating node so as to itself. Security services MUST track their orginating node so as to
properly apply policy and key selection associated with processing properly apply policy and key selection associated with processing
the security service at the bundle destination. the security service at the bundle destination.
Referring to Figure 1, if the bundle that originates at BN1 is given Referring to Figure 1, if the bundle that originates at BN1 is given
security blocks by BN1, then BN1 is the security-source for those security blocks by BN1, then BN1 is the security-source for those
blocks as well as being the source of the bundle. If the bundle that blocks as well as being the source of the bundle. If the bundle that
originates at BN1 is then given a security block by BN2, then BN2 is originates at BN1 is then given a security block by BN2, then BN2 is
the security-source for that block even though BN1 remains the bundle the security-source for that block even though BN1 remains the bundle
source. source.
A bundle MAY have multiple security blocks and these blocks MAY have
different security-sources. Each security block in a bundle will be
associated with a specific security-operation. All security blocks
comprising a security-operation MUST have the same security-source.
As required in [BPBIS], forwarding nodes MUST transmit blocks in a
bundle in the same order in which they were received. This
requirement applies to all DTN nodes, not just ones that implement
security processing. Blocks in a bundle MAY be added or deleted
according to the applicable specification, but those blocks that are
both received and transmitted MUST be transmitted in the same order
that they were received.
2.3. Mixed Security Policy 2.3. Mixed Security Policy
Different nodes in a DTN may have different security-related Different nodes in a DTN may have different security-related
capabilities. Some nodes may not be security-aware and will not capabilities. Some nodes may not be security-aware and will not
understand any security-related extension blocks. Other nodes may understand any security-related extension blocks. Other nodes may
have security policies that require evaluation of security services have security policies that require evaluation of security services
at places other than the bundle destination (such as verifying at places other than the bundle destination (such as verifying
integrity signatures at certain waypoint nodes). Other nodes may integrity signatures at certain waypoint nodes). Other nodes may
ignore any security processing if they are not the destination of the ignore any security processing if they are not the destination of the
bundle. The security services described in this specification must bundle. The security services described in this specification must
allow each of these scenarios. allow each of these scenarios.
Extension blocks representing security services MUST have their block Extension blocks representing security services MUST have their block
processing flags set such that the block (and bundle, where processing flags set such that the block will be treated
applicable) will be treated appropriately by non-security-aware appropriately by non-security-aware nodes.
nodes.
Extension blocks providing integrity services within a bundle MUST Extension blocks providing integrity services within a bundle MUST
support options to allow waypoint nodes to evaluate these signatures support options to allow waypoint nodes to evaluate these signatures
if such nodes have the proper configuraton to do so. if such nodes have the proper configuraton to do so.
2.4. User-Selected Ciphersuites 2.4. User-Selected Ciphersuites
The security services defined in this specification rely on a a The security services defined in this specification rely on a variety
variety of ciphersuites providing integrity signatures, ciphertext, of cipher suites providing integrity signatures, ciphertext, and
and other information necessary to populate security blocks. Users other information necessary to populate security blocks. Users may
may wish to select differing ciphersuites to implement different wish to select different cipher suites to implement different
security services. For example, some users may wish to use a SHA-1 security services. For example, some users may wish to use a SHA-256
based hash for integrity whereas other users may require a SHA-2 hash based hash for integrity whereas other users may require a SHA-384
instead. The security services defined in this specification MUST hash instead. The security services defined in this specification
provide a mechanism for identifying what ciphersuite has been used to MUST provide a mechanism for identifying what cipher suite has been
populate a security block. used to populate a security block.
2.5. Deterministic Processing 2.5. Deterministic Processing
In all cases, the processing order of security services within a In all cases, the processing order of security services within a
bundle must avoid ambiguity when evaluating security at the bundle bundle must avoid ambiguity when evaluating security at the bundle
destination. This specification MUST provide determinism in the destination. This specification MUST provide determinism in the
application and evaluation of security services, even when doing so application and evaluation of security services, even when doing so
results in a loss of flexibility. results in a loss of flexibility.
3. Security Block Definitions 3. Security Block Definitions
There are three types of security blocks that MAY be included in a There are two types of security blocks that may be included in a
bundle. These are the Block Integrity Block (BIB), the Block bundle. These are the Block Integrity Block (BIB) and the Block
Confidentiality Block (BCB), and the Cryptographic Messaging Syntax Confidentiality Block (BCB).
Block (CMSB).
The BIB is used to ensure the integrity of its security-target. The BIB is used to ensure the integrity of its security-target(s).
The integrity information in the BIB MAY (when possible) be The integrity information in the BIB MAY (when possible) be
verified by any node in between the BIB security-source and the verified by any node in between the BIB security-source and the
bundle destination. BIBs MAY be added to, and removed from, bundle destination. BIBs MAY be added to, and removed from,
bundles as a matter of security policy. bundles as a matter of security policy.
The BCB indicates that the security-target has been encrypted, in The BCB indicates that the security-target(s) has been encrypted,
whole or in part, at the BCB security-source in order to protect in whole or in part, at the BCB security-source in order to
its content while in transit. The BCB may be decrypted by protect its content while in transit. The BCB may be decrypted by
appropriate nodes in the network, up to and including the bundle appropriate nodes in the network, up to and including the bundle
destination, as a matter of security policy. destination, as a matter of security policy.
The CMSB contains a Cryptographic Message Syntax (CMS) payload
used to describe a security service applied to another extension
block. NOTE: Applications may choose to simply place CMS text as
the payload to the bundle. In such cases, security is considered
to be implemented at the application layer and CMSBs are not
required in that case.
Certain cipher suites may allow or require multiple instances of a
block to appear in the bundle. For example, an integrity cipher
suite may require two security blocks, one before the payload block
and one after. Despite the presence of two security blocks, they
both comprise the same security-operation - OP(integirty, target) in
this example.
A security-operation MUST NOT be applied more than once in a bundle. A security-operation MUST NOT be applied more than once in a bundle.
For example, the two security-operations: OP(integrity, payload) and For example, the two security-operations: OP(integrity, payload) and
OP(integrity, payload) are considered redundant and MUST NOT appear OP(integrity, payload) are considered redundant and MUST NOT appear
together in a bundle. However, the two security operations together in a bundle. However, the two security operations
OP(integrity, payload) and OP(integrity, extension_block_1) MAY both OP(integrity, payload) and OP(integrity, extension_block_1) MAY both
be present in the bundle. Also, the two security operations be present in the bundle. Also, the two security operations
OP(integrity, extension_block_1) and OP(integrity, extension_block_2) OP(integrity, extension_block_1) and OP(integrity, extension_block_2)
are unique and may both appear in the same bundle. are unique and may both appear in the same bundle.
Many of the fields in these block definitions use the Self-Delimiting If the same security-service is to be applied to multiple security-
Numeric Value (SDNV) type whose format and encoding is as defined in targets, and cipher suite parameters for each security service are
[BPBIS]. identical, then the set of security-operations can be represented as
a single security-block with multiple security-targets. In such a
case, all security-operations represented in the security-block MUST
be applied/evaluated together.
3.1. Block Identification 3.1. Block Identification
This specification requires that every target block of a security This specification requires that every target block of a security
operation be uniquely identifiable. The definition of the extension operation be uniquely identifiable. The definition of the extension
block header from [BPBIS] provides such a mechanism in the "block block header from [BPBIS] provides such a mechanism in the "Block
number", which provides a unique identifier for a block within a Number" field, which provides a unique identifier for a block within
bundle. Within this specification, a target block will be identified a bundle. Within this specification, a security-target will be
by its unique block number. identified by its unique Block Number.
3.2. Block Representation 3.2. 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 [BPBIS]. That is, each security block is comprised of the
following elements: 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
o Block Data Length o Block Data Length
o Block Type Specific Data Fields o Block Type Specific Data Fields
3.2.1. CMS Block Type-Specific Data Fields The structure of the BIB and BCB Block Type Specific Data fields are
identifcal and illustrated in Figure 2. In this figure, field names
The contents of the CMS block is a single field of CMS data whose prefaced with an '*' are optional and their inclusion in the block is
length is specified by the BLock Data Length parameter. indicated by the Cipher Suite Flags field.
3.2.2. BIB and BCB Block Type-Specific Data Fields
The structure of the BIB and BCB type-specific data fields are
identifcal and given in Figure 2. Although the diagram hints at a
fixed-format layout, this is purely for the purpose of exposition.
Except for the "type" field, all fields are variable in length.
Fields annotated with an '*' are optional, with their inclusion in
the block indicated by the cipher suite flags field.
+---------------------------+-------------------------+ +=================================================
| Security Target (SDNV) | Cipher suite ID (SDNV) | | Field Name | Field Data Type |
+---------------------------+-------------------------+ +=================================================
| Cipher suite Flags (SDNV) | *Source EID (Compound) | | # Security Targets | Unsigned Integer |
+---------------------------+-------------------------+ +---------------------+--------------------------+
| *Parameters (Compound) | *Sec. Result (Compound) | | Security Targets | Array (Unsigned Integer) |
+---------------------------+-------------------------+ +---------------------+--------------------------+
| Cipher Suite ID | Unsigned Integer |
+---------------------+--------------------------+
| Cipher Suite Flags | Unsigned Integer |
+---------------------+--------------------------+
| Security Source | URI - OPTIONAL |
+---------------------+--------------------------+
| Cipher Parameters | Byte Array - OPTIONAL |
+---------------------+--------------------------+
| Security Result | Byte Array |
+---------------------+--------------------------+
Figure 2: BIB and BCB Block Structure Figure 2: BIB and BCB Block Structure
The BIB and BCB type-specific data fields consist of the following Where the block fields are identified as follows.
fields, some of which are optional.
o Security-Target (SDNV) - Uniquely identifies the target of the o # Security Targets - The number of security targets for this
associated security-operation. This MUST be the block number of a security block. This value MUST be at least 1.
block in the bundle.
o Cipher suite ID (SDNV) - Identifies the ciphersuite used to o Security-Targets - This array contains the unique identifier of
implement the security service reprsented by this block. the blocks targetted by this security operation. Each security-
target MUST represent a block present in the bundle. A security-
target MUST NOT be repeated in this array.
o Cipher suite flags (SDNV) - Identifies which optional security o Cipher suite ID - Identifies the cipher suite used to implement
block fields are present in the block. The structure of the the security service represented by this block and applied to each
cipher suite flags field is shown in Figure 3. The presence of an security-target.
o Cipher suite flags - Identifies which optional security block
fields are present in the block. The structure of the Cipher
Suite Flags field is shown in Figure 3. The presence of an
optional field is indicated by setting the value of the optional field is indicated by setting the value of the
corresponding flag to one. A value of zero indicates the corresponding flag to one. A value of zero indicates the
corresponding optional field is not present. The BPSEC cipher corresponding optional field is not present. The BPSEC Cipher
suite flags are defined as follows. Suite Flags are defined as follows.
* bits 6-3 are reserved for future use. Bit Bit Bit Bit Bit Bit Bit Bit
7 6 5 4 3 2 1 0
+-----------------------------------+-----+-----+
| reserved | src |parm |
+-----------------------------------+-----+-----+
MSB LSB
* src - bit 2 indicates whether the security source EID is Figure 3: Cipher Suite Flags
present in the block. This identifief the EID that inserted
the security service in the bundle. If the security source is
not present then the souce of the block MAY be taken to be the
bundle source, the previous hop, or some other EID as defined
by security policy.
* parm - bit 1 indicates whether or not the cipher suite Where:
parameters fields are present in the block.
* res - bit 0 indicates whether or not the security result fields * bits 7-2 are reserved for future use.
are present in the block.
Bit Bit Bit Bit Bit Bit Bit * src - bit 1 indicates whether the Security Source EID is
6 5 4 3 2 1 0 present in the block.
+-----+-----+-----+-----+-----+-----+-----+
| reserved | src |parm | res |
+-----+-----+-----+-----+-----+-----+-----+
Figure 3: Cipher suite flags * parm - bit 0 indicates whether or not the Cipher Suite
Parameters field is present in the block.
o (OPTIONAL) Parameters - compound field of the following two items. o (OPTIONAL) Security Source (URI) - This identifies the EID that
inserted the security service in the bundle. If the security
source is not present then the souce of the block MAY be taken to
be the bundle source, the previous hop, or some other EID as
defined by security policy.
* Length (SDNV) - specifies the length of the next field, which o (OPTIONAL) Parameters (Byte Array) - Compound field of the
captures the parameters data. following two items.
* Data - A byte array encoding one or more cipher suite * Length (Unsigned Integer) - specifies the length of the next
parameters, with each parameter represented as a Type-Length- field, which captures the parameters data.
Value (TLV) triplet. In this triplet, the type and length are
represented as SDNVs and the value is a byte array holding the * Data (Byte Array) - A byte array encoding one or more cipher
parmeter. See Section 3.8 for a list of parameter types that suite parameters, with each parameter represented as a Type-
MUST be supported by BPSEC implementations. BPSEC cipher suite Length-Value (TLV) triplet, defined as follows.
+ Type (Byte) - The parameter type.
+ Length (Unsigned Integer) - The length of the parameter.
+ Value (Byte Array) - The parameter value.
See Section 3.7 for a list of parameter types that MUST be
supported by BPSEC implementations. BPSEC cipher suite
specifications MAY define their own parameters to be specifications MAY define their own parameters to be
represented in this byte array. represented in this byte array.
o (OPTIONAL) Security Result - compound field of the next two items. o Security Result (Byte Array) - Compound field of the next two
items.
* Length (SDNV) - specifies the length of the next field, which
is the security-result data.
* Data - A byte array containing the results of the appropriate * Length (Unsigned Integer) - specifies the length of the next
cipher suite specific calculation (e.g., a signature, Message field, which is the security-result data.
Authentication Code (MAC), or cipher-text block key).
3.3. Block Ordering * Data (Byte Array) - A byte array encoding a security result for
each security-target covered by the security-block, with each
entry represented as a TLV and optionally prepended with
information on which security-target is referenced by the
result, as follows.
A security-operation may be implemented in a bundle using either one + Target (Optional Unsigned Integer) - If the security-block
or two security blocks. For example, the operation OP(integrity, has multiple security-targets, the target field is the Block
block) MAY be accomplished by a single BIB block in the bundle, or it Number of the security-target to which this result field
MAY be accomplished by two BIB blocks in the bundle. To avoid applies. If the security-block only has a single security-
confusion, we use the following terminology to identify the block or target, this field is omitted.
blocks comprising a security-operation.
The terms "First" and "Last" are used ONLY when describing multiple + Type (Unsigned Integer)(Byte) - The type of security result
security blocks comprising a single security-operation. A "First" field.
block refers to the security block that is closest to the primary
block in the canonical form of the bundle. A "Last" block refers to
the security block that is furthest from the primary block in the
canonical form of the bundle.
If a single security block implements the security-operation, then it + Length (Unsigned Integer) - The length of the result field.
is referred to as a "Lone" block. For example, when a bundle
authentication cipher suite requires a single BIB block we refer to
it as a Lone BAB. When a bundle authentication cipher suite requires
two BIB blocks we refer to them as the First BIB and the Last BIB.
This specification and individual cipher suites impose restrictions + Value (Byte Array) - The results of the appropriate cipher
on what optional fields must and must not appear in First blocks, suite specific calculation (e.g., a signature, Message
Last blocks, and Lone blocks. Authentication Code (MAC), or cipher-text block key).
3.4. Block Integrity Block 3.3. Block Integrity Block
A BIB is an ASB with the following additional restrictions: A BIB is an ASB with the following characteristics:
The block-type code value MUST be 0x02. The Block Type Code value MUST be 0x02.
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. Cipher suite designers values are required by local policy. Cipher suite designers
should carefully consider the effect of setting flags that either should carefully consider the effect of setting flags that either
discard the block or delete the bundle in the event that this discard the block or delete the bundle in the event that this
block cannot be processed. block cannot be processed.
The security-target MUST match the BLock Number of a block within A security-target for a BIB MUST NOT reference a security-block
the bundle. The security-target for a BIB MUST NOT reference a defined in this specification (e.g., a BIB or a BCB).
security block defined in this specification (BIB, BCB, or CMSB).
The cipher suite ID MUST be documented as an end-to-end 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.
The cipher suite parameters field MAY be present in either a Lone An EID-reference to the security-source MAY be present. If this
BIB or a First BIB. This field MUST NOT be present in a Last BIB. field is not present, then the security-source of the block SHOULD
be inferred according to security policy and MAY default to the
An EID-reference to the security-source MAY be present in either a bundle source. The security-source may also be specified as part
Lone BIB or a First BIB. This field MUST NOT be present in a Last of key-information described in Section 3.7.
BIB.
The security-result captures the result of applying the cipher The security-result captures the result of applying the cipher
suite calculation (e.g., the MAC or signature) to the relevant suite calculation (e.g., the MAC or signature) to the relevant
parts of the security-target, as specified in the cipher suite parts of the security-target, as specified in the cipher suite
definition. This field MUST be present in either a Lone BIB or a definition. This field MUST be present.
Last BIB. This field MUST NOT be present in a First BIB.
The cipher suite MAY process less than the entire security-target. The cipher suite MAY process less than the entire security-target.
If the cipher suite processes less than the complete, original If the cipher suite processes less than the complete, original
security-target, the cipher suite parameters MUST specify which security-target, the cipher suite parameters MUST specify which
bytes of the security-target are protected. bytes of the security-target are protected.
Notes: Notes:
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
integrity signatures for the same target define a multi-signature integrity signatures for the same target define a multi-signature
cipher suite, capturing multiple security results in cipher suite cipher suite.
parameters.
o For some cipher suites, (e.g., those using asymmetric keying to o For some cipher suites, (e.g., those using asymmetric keying to
produce signatures or those using symmetric keying with a group produce signatures or those using symmetric keying with a group
key), the security information MAY be checked at any hop on the key), the security information MAY be checked at any hop on the
way to the destination that has access to the required keying way to the destination that has access to the required keying
information, in accordance with Section 3.7. information, in accordance with Section 3.5.
o The use of a generally available key is RECOMMENDED if custodial o The use of a generally available key is RECOMMENDED if custodial
transfer is employed and all nodes SHOULD verify the bundle before transfer is employed and all nodes SHOULD verify the bundle before
accepting custody. accepting custody.
3.5. Block Confidentiality Block 3.4. Block Confidentiality Block
A BCB is an ASB with the following additional restrictions: A BCB is an ASB with the following characteristics:
The block-type code value MUST be 0x03. The Block Type Code value MUST be 0x03.
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 a Lone BCB or values are required by local policy, except that this block MUST
First BCB MUST have the "replicate in every fragment" flag set. have the "replicate in every fragment" flag set if the target of
This indicates to a receiving node that the payload portion in the BCB is the Payload Block. Having that BCB in each fragment
each fragment represents cipher-text. This flag SHOULD NOT be set indicates to a receiving node that the payload portion of each
otherwise. Cipher suite designers should carefully consider the fragment represents cipher-text. Cipher suite designers should
effect of setting flags that either discard the block or delete carefully consider the effect of setting flags that either discard
the bundle in the event that this block cannot be processed. the block or delete the bundle in the event that this block cannot
be processed.
The security-target MUST match the BLock Number of a block within A security-target for a BCB MAY reference the payload block, a
the bundle. The security-target for a BCB MAY reference the non-security extension block, or a BIB block. A security-target
payload block, a non-security extension block, or a BIB block. in a BCB MUST NOT be another BCB.
The cipher suite ID MUST be documented as a confidentiality cipher The cipher suite ID MUST be documented as a confidentiality cipher
suite. suite.
Key-information, if available, MUST appear only in a Lone BCB or a
First BCB.
Any additional bytes generated as a result of encryption and/or Any additional bytes generated as a result of encryption and/or
authentication processing of the security-target SHOULD be placed authentication processing of the security-target SHOULD be placed
in an "integrity check value" field (see Section 3.8) in the in an "integrity check value" field (see Section 3.7) or other
security-result of the Lone BCB or Last BCB. such appropriate area in the security-result of the BCB.
The cipher suite parameters field MAY be present in either a Lone
BCB or a First BCB. This field MUST NOT be present in a Last BCB.
An EID-reference to the security-source MAY be present in either a An EID-reference to the security-source MAY be present. If this
Lone BCB or a First BCB. This field MUST NOT be present in a Last field is not present, then the security-source of the block SHOULD
BCB. The security-source can also be specified as part of key- be inferred according to security policy and MAY default to the
information described in Section 3.8. bundle source. The security-source may also be specified as part
of key-information described in Section 3.7.
The security-result MAY be present in either a Lone BCB or a Last The security-result MUST be present in the BCB. This compound
BCB. This field MUST NOT be present in a First BCB. This field normally contains fields such as an encrypted bundle
compound field normally contains fields such as an encrypted encryption key and/or authentication tag.
bundle encryption key and/or authentication tag.
The BCB is the only security block that modifies the contents of its The BCB modifies the contents of its security-target. When a BCB is
security-target. When a BCB is applied, the security-target body applied, the security-target body data are encrypted "in-place".
data are encrypted "in-place". Following encryption, the security- Following encryption, the security-target body data contains cipher-
target body data contains cipher-text, not plain-text. Other text, not plain-text. Other security-target block fields (such as
security-target block fields (such as type, processing control flags, type, processing control flags, and length) remain unmodified.
and length) remain unmodified.
Fragmentation, reassembly, and custody transfer are adversely Fragmentation, reassembly, and custody transfer are adversely
affected by a change in size of the payload due to ambiguity about affected by a change in size of the payload due to ambiguity about
what byte range of the block is actually in any particular fragment. what byte range of the block is actually in any particular fragment.
Therefore, when the security-target of a BCB is the bundle payload, 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. the BCB MUST NOT alter the size of the payload block body data.
Cipher suites SHOULD place any block expansion, such as Cipher suites SHOULD place any block expansion, such as
authentication tags (integrity check values) and any padding authentication tags (integrity check values) and any padding
generated by a block-mode cipher, into an integrity check value item generated by a block-mode cipher, into an integrity check value item
in the security-result field (see Section 3.8) of the BCB. This "in- in the security-result field (see Section 3.7) of the BCB. This "in-
place" encryption allows fragmentation, reassembly, and custody place" encryption allows fragmentation, reassembly, and custody
transfer to operate without knowledge of whether or not encryption transfer to operate without knowledge of whether or not encryption
has occurred. has occurred.
Notes: Notes:
o The cipher suite MAY process less than the entire original o The cipher suite MAY process less than the entire original
security-target body data. If the cipher suite processes less security-target body data. If the cipher suite processes less
than the complete, original security-target body data, the BCB for than the complete, original security-target body data, the BCB for
that security-target MUST specify, as part of the cipher suite that security-target MUST specify, as part of the cipher suite
skipping to change at page 15, line 18 skipping to change at page 16, line 11
o The BCB's "discard" flag may be set independently from its o The BCB's "discard" flag may be set independently from its
security-target's "discard" flag. Whether or not the BCB's security-target's "discard" flag. Whether or not the BCB's
"discard" flag is set is an implementation/policy decision for the "discard" flag is set is an implementation/policy decision for the
encrypting node. (The "discard" flag is more properly called the encrypting node. (The "discard" flag is more properly called the
"Discard if block cannot be processed" flag.) "Discard if block cannot be processed" flag.)
o A BCB MAY include information as part of additional authenticated o A BCB MAY include information as part of additional authenticated
data to address parts of the target block, such as EID references, data to address parts of the target block, such as EID references,
that are not converted to cipher-text. that are not converted to cipher-text.
3.6. Cryptographic Message Syntax Block 3.5. Block Interactions
A CMSB is an ASB with the following additional restrictions:
The block-type code value MUST be 0x04.
The content of the block must contain valid CMS data, as defined
in [RFC5652] , and encoded in X.690 BER or DER encoding.
The block processing control flags value can be set to whatever
values are required by local policy. This flag SHOULD NOT be set
otherwise. Cipher suite designers should carefully consider the
effect of setting flags that either discard the block or delete
the bundle in the event that this block cannot be processed.
The security-target MUST uniquely identify a block within the
bundle. The reserved block type 0x01 specifies the singleton
payload block.
The security operation(s) will be performed on the security-target
block's data and the resulting CMS content will be stored within
the CMSB block's security-result field. The security-target
block's data will then be removed.
A CMSB block MAY include multiple CMS security operations within a
single block to allow for multiple nested operations to be
performed on a bundle block. Multiple CMSB blocks MAY be included
in a bundle as long as the security-target for each is unique.
Key-information, if available, MUST appear within the CMS content
contained in the security-result field.
A CMSB block is created with its corresponding security-target field
pointing to a unique bundle block. The CMS security operations are
performed upon the security-target's data field and the resulting
encoded CMS content is stored within the CMS security-result field of
the CMSB's payload. The security-target block's data MAY be left
intact, replaced with alternate data, or completely erased based on
the specification of the utilized CMS ciphersuite definition and
applicable policy.
Multiple CMS operations may be nested within a single CMSB block to
allow more than one security operation to be performed upon a
security-target.
CMS Operations can be considered to have BPSec parallels: CMSB
Enveloped-Data content type SHALL be considered as equivalent to a
BPSec BCB block, and a CMSB Signed-Data type SHALL be considered as
equivalent to a BPSec BIB block.
3.7. 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 confidentiality is being applied to a target that already has
integrity applied to it, then an undesirable condition occurs where a integrity applied to it, then an undesirable condition occurs where a
security-aware intermediate node would be unable to check the security-aware intermediate node would be unable to check the
integrity result of a block because the block contents have been integrity result of a block because the block contents have been
encrypted after the integrity signature was generated. To address encrypted after the integrity signature was generated. To address
this concern, the following processing rules MUST be followed. this concern, the following processing rules MUST be followed.
o If confidentiality is to be applied to a target, it MUST also be o If confidentiality is to be applied to a target, it MUST also be
applied to every integrity operation already defined for that applied to any integrity operation already defined for that
target. This means that if a BCB is added to encrypt a block, target. This means that if a BCB is added to encrypt a block,
another BCB MUST also be added to encrypt a BIB also targeting another BCB MUST also be added to encrypt a BIB also targeting
that block. that block.
o An integrity operation MUST NOT be applied to a security-target if o An integrity operation MUST NOT be applied to a security-target if
a BCB in the bundle shares the same security-target. This a BCB in the bundle shares the same security-target. This
prevents ambiguity in the order of evaluation when receiving a BIB prevents ambiguity in the order of evaluation when receiving a BIB
and a BCB for a given security-target. and a BCB for a given security-target.
o An integrity value MUST NOT be evaluated if the BIB providing the o An integrity value MUST NOT be evaluated if the BIB providing the
integrity value is the security target of an existing BCB block in integrity value is the security target of an existing BCB block in
the bundle. In such a case, the BIB data contains cipher-text as the bundle. In such a case, the BIB data contains cipher-text as
it has been encrypted. it has been encrypted.
o An integrity value MUST NOT be evaluated if the security-target of o An integrity value MUST NOT be evaluated if the security-target of
the BIB is also the security-target of a BCB in the bundle. In the BIB is also the security-target of a BCB in the bundle. In
such a case, the security-target data contains cipher-text as it such a case, the security-target data contains cipher-text as it
has been encrypted. has been encrypted.
o As mentioned in Section 3.5, a BIB MUST NOT have a BCB as its o As mentioned in Section 3.3, a BIB MUST NOT have a BCB as its
security target. BCBs may embed integrity results as part of security target. BCBs may embed integrity results as part of
cipher suite parameters. cipher suite parameters.
o As mentioned in Section 4.4, CMS operations are considered to have
operational parallels. When a CMSB is used, these parallels MUST
be considered for block interactions (e.g., a Signed-Data
structure MUST NOT be evaluated if the security-target of the
operation is also the security-target of a BCB)
o If a single bundle is going to contain a CMSB as well as other
security blocks, the CMS operations MUST be performed and the CMSB
MUST be created before any other security operation is applied.
Additionally, since the CMSB block may contain either integrity or
confidentiality information in its encapsulated CMS, there is no way
to evaluate conflicts when a BIB/BCB and a CMSB have the same
security target. To address this concern, the following processing
rules MUST be followed.
o If an extension block is the target of a BIB or a BCB, then the
extension block MUST NOT also be the target of a CMSB, and vice-
versa.
o Generally, a CMSB MUST be processed before any BIB or BCB blocks
are processed.
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.
3.8. Parameters and Result Fields 3.6. Multi-Target Block Definitions
A security-block MAY target multiple security-targets if and only if
all cipher suite parameters, security source, and key information are
common for each security operation. The following processing
directives apply for these multi-target blocks.
o If a security-block has more than one security-target, then each
type identifier in the security result TLV MUST be interpretted as
a tuple with the first entry being the security-target for which
the security result applies and the second entry being the type
value enumeration of the security result value.
o If the security-block has a single security-target, the type field
of every entry in the security result array MUST simply be the
type field and MUST NOT be a tuple as described above.
3.7. Parameters and Result Fields
Various cipher suites include several items in the cipher suite Various cipher suites include several items in the cipher suite
parameters and/or security-result fields. Which items MAY appear is parameters and/or security-result fields. Which items MAY appear is
defined by the particular cipher suite description. A cipher suite defined by the particular cipher suite description. A cipher suite
MAY support several instances of the same type within a single block. MAY support several instances of the same type within a single block.
Each item is represented as a type-length-value. Type is a single Each item is represented as a type-length-value. Type is a single
byte indicating the item. Length is the count of data bytes to byte indicating the item. Length is the count of data bytes to
follow, and is an SDNV-encoded integer. Value is the data content of follow, and is an Unsigned Integer. Value is the data content of the
the item. item.
Item types, name, and descriptions are defined as follows. Item types, name, and descriptions are defined as follows.
Cipher suite parameters and result fields. Cipher suite parameters and result fields.
+-------+----------------+------------------------------------------+ +-------+----------------+-----------------------------+------------+
| Type | Name | Description | | Type | Name | Description | Field |
+-------+----------------+------------------------------------------+ +-------+----------------+-----------------------------+------------+
| 0 | Reserved | | | 0 | Reserved | | |
+-------+----------------+------------------------------------------+ +-------+----------------+-----------------------------+------------+
| 1 | Initialization | A random value, typically eight to | | 1 | Initialization | A random value, typically | Cipher |
| | Vector (IV) | sixteen bytes. | | | Vector (IV) | eight to sixteen bytes. | Suite |
+-------+----------------+------------------------------------------+ | | | | Parameters |
| 2 | Reserved | | +-------+----------------+-----------------------------+------------+
+-------+----------------+------------------------------------------+ | 2 | Reserved | | |
| 3 | Key | Material encoded or protected by the key | +-------+----------------+-----------------------------+------------+
| | Information | management system and used to transport | | 3 | Key | Material encoded or | Cipher |
| | | an ephemeral key protected by a long- | | | Information | protected by the key | Suite |
| | | term key. | | | | management system and used | Parameters |
+-------+----------------+------------------------------------------+ | | | to transport an ephemeral | |
| 4 | Content Range | Pair of SDNV values (offset,length) | | | | key protected by a long- | |
| | | specifying the range of payload bytes to | | | | term key. | |
| | | which an operation applies. The offset | +-------+----------------+-----------------------------+------------+
| | | MUST be the offset within the original | | 4 | Content Range | Pair of Unsigned Integers | Cipher |
| | | bundle, even if the current bundle is a | | | | (offset,length) specifying | Suite |
| | | fragment. | | | | the range of payload bytes | Parameters |
+-------+----------------+------------------------------------------+ | | | to which an operation | |
| 5 | Integrity | Result of BAB or BIB digest or other | | | | applies. The offset MUST be | |
| | Signatures | signing operation. | | | | the offset within the | |
+-------+----------------+------------------------------------------+ | | | original bundle, even if | |
| 6 | Unassigned | | | | | the current bundle is a | |
+-------+----------------+------------------------------------------+ | | | fragment. | |
| 7 | Salt | An IV-like value used by certain | +-------+----------------+-----------------------------+------------+
| | | confidentiality suites. | | 5 | Integrity | Result of BAB or BIB digest | Security |
+-------+----------------+------------------------------------------+ | | Signatures | or other signing operation. | Results |
| 8 | BCB Integrity | Output from certain confidentiality | +-------+----------------+-----------------------------+------------+
| | Check Value | cipher suite operations to be used at | | 6 | Unassigned | | |
| | (ICV) / | the destination to verify that the | +-------+----------------+-----------------------------+------------+
| | Authentication | protected data has not been modified. | | 7 | Salt | An IV-like value used by | Cipher |
| | Tag | This value MAY contain padding if | | | | certain confidentiality | Suite |
| | | required by the cipher suite. | | | | suites. | Parameters |
+-------+----------------+------------------------------------------+ +-------+----------------+-----------------------------+------------+
| 9-255 | Reserved | | | 8 | BCB Integrity | Output from certain | Security |
+-------+----------------+------------------------------------------+ | | Check Value | confidentiality cipher | Results |
| | (ICV) / | suite operations to be used | |
| | Authentication | at the destination to | |
| | Tag | verify that the protected | |
| | | data has not been modified. | |
| | | This value MAY contain | |
| | | padding if required by the | |
| | | cipher suite. | |
+-------+----------------+-----------------------------+------------+
| 9-255 | Reserved | | |
+-------+----------------+-----------------------------+------------+
Table 1 Table 1
3.9. BSP Block Example 3.8. BSP Block Example
An example of BPSec blocks applied to a bundle is illustrated in An example of BPSec blocks applied to a bundle is illustrated in
Figure 4. In this figure the first column represents blocks within a Figure 4. In this figure the first column represents blocks within a
bundle and the second column represents a unique identifier for each bundle and the second column represents a unique identifier for each
block, suitable for use as the security-target of a BPSec security- block, suitable for use as the security-target of a BPSec security-
block. Since the mechanism and format of a security-target is not block. Since the mechanism and format of a security-target is not
specified in this document, the terminology B1...Bn is used to specified in this document, the terminology B1...Bn is used to
identify blocks in the bundle for the purposes of illustration. identify blocks in the bundle for the purposes of illustration.
Block in Bundle ID Block in Bundle ID
+=================================+====+ +===================================+====+
| Primary Block | B1 | | Primary Block | B1 |
+---------------------------------+----+ +-----------------------------------+----+
| Lone BIB | B2 | | BIB | B2 |
| OP(integrity, target=B1) | | | OP(integrity, target=B1) | |
+---------------------------------+----+ +-----------------------------------+----+
| Lone BCB | B3 | | BCB | B3 |
| OP(confidentiality, target=B4) | | | OP(confidentiality, target=B4) | |
+---------------------------------+----+ +-----------------------------------+----+
| Extension Block | B4 | | Extension Block | B4 |
+---------------------------------+----+ +-----------------------------------+----+
| Lone BIB | B5 | | BIB | B5 |
| OP(integrity, target=B6) | | | OP(integrity, target=B6) | |
+---------------------------------+----+ +-----------------------------------+----+
| Extension Block | B6 | | Extension Block | B6 |
+---------------------------------+----+ +-----------------------------------+----+
| Lone BCB | B7 | | BCB | B7 |
| OP(confidentiality, target=B8) | | | OP(confidentiality,target=B8,B9) | |
+---------------------------------+----+ +-----------------------------------+----+
| Lone BIB (encrypted by B7) | B8 | | BIB (encrypted by B7) | B8 |
| OP(integrity, target=B10) | | | OP(integrity, target=B9) | |
+---------------------------------+----| +-----------------------------------+----|
| Lone BCB | B9 | | Payload Block | B9 |
| OP(confidentiality, target=B10) | | +-----------------------------------+----+
+---------------------------------+----+
| Payload Block |B10 |
+---------------------------------+----+
Figure 4: Sample Use of BSP Blocks Figure 4: Sample Use of BSP Blocks
In this example a bundle has five non-security-related blocks: the In this example a bundle has four non-security-related blocks: the
primary block (B1), three extension blocks (B4,B6,B9), and a payload primary block (B1), three extension blocks (B4,B6), and a payload
block (B11). The following security applications are applied to this block (B9). The following security applications are applied to this
bundle. bundle.
o An integrity signature applied to the canonicalized primary block. o An integrity signature applied to the canonicalized primary block.
This is accomplished by a single BIB (B2). This is accomplished by a single BIB (B2).
o Confidentiality for the first extension block (B4). This is o Confidentiality for the first extension block (B4). This is
accomplished by a single BCB block (B3). accomplished by a BCB block (B3).
o Integrity for the second extension block (B6). This is o Integrity for the second extension block (B6). This is
accomplished by a single BIB block (B5). NOTE: If the extension accomplished by a BIB block (B5). NOTE: If the extension block B6
block B6 contains a representation of the serialized bundle (such contains a representation of the serialized bundle (such as a hash
as a hash over all blocks in the bundle at the time of its last over all blocks in the bundle at the time of its last
transmission) then the BIB block is also providing an transmission) then the BIB block is also providing an
authentication service from the prior BPSEC-BPA to this BPSEC-BPA. authentication service from the prior BPSEC-BPA to this BPSEC-BPA.
o An integrity signature on the payload (B10). This is accomplished o An integrity signature on the payload (B10). This is accomplished
by a single BIB block (B8). by a BIB block (B8).
o Confidentiality for the payload block and it's integrity o Confidentiality for the payload block and it's integrity
signature. This is accomplished by two Lone BCB blocks: B7 signature. This is accomplished by a BCB block, B7, encrypting B8
encrypting B8, and B9 encrypting B10. and B9.
Block in Bundle ID
+=========================================+====+
| Primary Block | B1 |
+-----------------------------------------+----+
| First BAB | B2 |
| OP(authentication, Bundle) | |
+-----------------------------------------+----+
| Lone CMSB | B3 |
| security-target=0x01 | |
| security-result= | |
| | |
| Signed-Data { | |
| Digest Algorithm(s), | |
| Enveloped-Data { | |
| Encrypted Data, | |
| Encrypted Encryption Key(s) | |
| }, | |
| Signature(s) and Certificate Chain(s) | |
| } | |
| | |
+-----------------------------------------+----+
| Payload Block | B4 |
| (Empty Data Field) | |
+-----------------------------------------+----+
| Last BAB | B5 |
| OP(authentication, Bundle) | |
+-----------------------------------------+----+
Figure 5: Sample Bundle With CMS Block
In this example a bundle has two non-security-related blocks: the
primary block (B1) and a payload block (B4). This method would allow
for the bundle to carry multiple CMS payloads by utilizing a multiple
CMSB ASBs. The following security applications are applied to this
bundle.
o Authentication over the bundle. This is accomplished by two BAB
blocks: B2 and B5.
o Encrypted and signed CMS content contained within the CMSB block.
The first CMS operation, encryption, is performed on the data
contained within the block the security-target points to, in this
case, the payload block. The resulting encrypted data is then
signed and the final CMS content is stored within the CMSB block's
security-result field. The payload block's data is subsequently
removed now that the original data has been encoded within the
CMSB block.
4. Security Processing
This section describes the security aspects of bundle processing.
4.1. Canonical Forms
In order to verify a signature of a block, the exact same bits, in
the exact same order, MUST be input to the calculation upon
verification as were input upon initial computation of the original
signature value.
Many fields in various blocks are stored as variable-length SDNVs.
These are canonicalized into an "unpacked form" as eight-byte fixed-
width fields in network byte order.
4.1.1. Block Canonicalization
This algorithm protects those parts of a block that SHOULD NOT be
changed in transit.
There are three types of blocks that may undergo block 4. Canonical Forms
canonicalization: the primary block, the payload block, or an
extension block.
4.1.1.1. Primary Block Canonicalization By definition, an integrity service determines whether any aspect of
a block was changed from the moment the security service was applied
at the security source until the point of current evaluation. To
successfully verify the integrity of a block, the data passed to the
verifying cipher suite MUST be the same bits, in the same order, as
those passed to the signature-generating cipher suite at the security
source.
The canonical form of the primary block is shown in Figure 6. However, [BPBIS] does not specify a single on-the-wire encoding of
Essentially, it de-references the dictionary block, adjusts lengths bundles. In cases where a security source generates a different
where necessary, and ignores flags that may change in transit. encoding than that used at a receiving node, care MUST be taken to
ensure that the inputs to cipher suites at the receiving node is a
bitwise match to inputs provided at the security source.
+----------------+----------------+----------------+----------------+ This section provides guidance on how to create a canonical form for
| Version | Processing flags (incl. COS and SRR) | each type of block in a bundle. This form MUST be used when
+----------------+----------------+---------------------------------+ generating inputs to cipher suites for use by BPSec blocks.
| Canonical primary block length |
+----------------+----------------+---------------------------------+
| Destination endpoint ID length |
+----------------+----------------+---------------------------------+
| Destination endpoint ID |
+----------------+----------------+---------------------------------+
| Source endpoint ID length |
+----------------+----------------+----------------+----------------+
| Source endpoint ID |
+----------------+----------------+---------------------------------+
| Report-to endpoint ID length |
+----------------+----------------+----------------+----------------+
| Report-to endpoint ID |
+----------------+----------------+----------------+----------------+
+ Creation Timestamp (2 x SDNV) +
+---------------------------------+---------------------------------+
| Lifetime |
+----------------+----------------+----------------+----------------+
Figure 6: The Canonical Form of the Primary Bundle Block This specification does not define any security operation over the
entire bundle and, therefore, provides no canonical form for a
serialized bundle.
The fields shown in Figure 6 are as follows: 4.1. Technical Notes
o The version value is the single-byte value in the primary block. The following technical considerations hold for all canonicalizations
in this section.
o The processing flags value in the primary block is an SDNV, and o Any numeric fields defined as variable-length MUST be expanded to
includes the class-of-service (COS) and status report request their "unpacked" form. For example, a 32-bit integer value MUST
(SRR) fields. For purposes of canonicalization, the unpacked SDNV be unpacked to a four-byte representation.
is ANDed with mask 0x0000 0000 0007 C1BE to set to zero all
reserved bits and the "bundle is a fragment" bit.
o The canonical primary block length value is a four-byte value o Each block encoding MUST follow the CBOR encodings provided in
containing the length (in bytes) of this structure, in network [BPBISCBOR].
byte order.
o The destination endpoint ID length and value are the length (as a o Canonical forms are not transmitted, they are used to generate
four-byte value in network byte order) and value of the input to a cipher suite for secuity processing at a security-aware
destination endpoint ID from the primary bundle block. The URI is node.
simply copied from the relevant part(s) of the dictionary block
and is not itself canonicalized. Although the dictionary entries
contain "null-terminators", the null-terminators are not included
in the length or the canonicalization.
o The source endpoint ID length and value are handled similarly to o Reserved flags MUST NOT be included in any canonicalization as it
the destination. is not known if those flags will chaneg in transit.
o The report-to endpoint ID length and value are handled similarly o These canonicalization algorithms assume that endpoint IDs
to the destination. themselves are immutable and they are unsuitable for use in
environments where that assumption might be violated.
o The unpacked SDNVs for the creation timestamp and lifetime are o Cipher suites MAY define their own canonicalization algorithms and
copied from the primary block. require the use of those algorithms over the ones provided in this
specification. In the event of conflicting canonicalization
algorithms, cipher suite algorithms take precedence over this
specification.
o Fragment offset and total application data unit length are 4.2. Primary Block Canonicalization
ignored, as is the case for the "bundle is a fragment" bit
mentioned above. If the payload data to be canonicalized is less
than the complete, original bundle payload, the offset and length
are specified in the cipher suite parameters.
4.1.1.2. Payload Block Canonicalization The primary block canonical form is the same as the CBOR encoding of
the block, with certain modifications to account for allowed block
changes as the bundle traverses the DTN. The fields that compromise
the primary block, and any special considerations for their
representation in a canonical form, are as follows.
When canonicalizing the payload block, the block processing control o The Version field is included, without modification.
flags value used for canonicalization is the unpacked SDNV value with
reserved and mutable bits masked to zero. The unpacked value is
ANDed with mask 0x0000 0000 0000 0077 to zero reserved bits and the
"last block" bit. The "last block" bit is ignored because BABs and
other security blocks MAY be added for some parts of the journey but
not others, so the setting of this bit might change from hop to hop.
Payload blocks are canonicalized as-is, with the exception that, in o The Bundle Processing Flags field is used, with modification.
some instances, only a portion of the payload data is to be Certain bundle processing flags MAY change as a bundle transits
protected. In such a case, only those bytes are included in the the DTN without indicating an integrity error. These flags, which
canonical form, and additional cipher suite parameters are required are identified below, MUST NOT be represented in the canonicalized
to specify which part of the payload is protected, as discussed form of the bundle processing flags and, instead, be represented
further below. by the bit 0.
4.1.1.3. Extension Block Canonicalization * Reserved flags.
When canonicalizing an extension block, the block processing control * Bundle is a Fragment flag.
flags value used for canonicalization is the unpacked SDNV value with
reserved and mutable bits masked to zero. The unpacked value is
ANDed with mask 0x0000 0000 0000 0057 to zero reserved bits, the
"last block" flag and the "Block was forwarded without being
processed" bit. The "last block" flag is ignored because BABs and
other security blocks MAY be added for some parts of the journey but
not others, so the setting of this bit might change from hop to hop.
The "Block was forwarded without being processed" flag is ignored o The CRC Type, Destination EID, Source Node ID, Report-To EID,
because the bundle may pass through nodes that do not understand that Creation Timestamp, and Lifetime fields are included, without
extension block and this flag would be set. modification.
Endpoint ID references in blocks are canonicalized using the de- o The fragment ID field MAY change if the bundle is fragmented in
referenced text form in place of the reference pair. The reference transit and, as such, this field MUST NOT be included in the
count is not included, nor is the length of the endpoint ID text. canonicalization.
The EID reference is, therefore, canonicalized as <scheme>:<SSP>, o The CRC field MAY change at each hop - for example, if a bundle
which includes the ":" character. becomes fragmented, each fragment will have a different CRC value
from the original signed primary block. As such, this field MUST
NOT be included in the canonicalization.
Since neither the length of the canonicalized EID text nor a null- 4.3. Non-Primary-Block Canonicalization
terminator is used in EID canonicalization, a separator token MUST be
used to determine when one EID ends and another begins. When
multiple EIDs are canonicalized together, the character "," SHALL be
placed between adjacent instances of EID text.
The block-length is canonicalized as its unpacked SDNV value. If the All non-primary blocks (NPBs) in [BPBIS] share the same block
data to be canonicalized is less than the complete, original block structure and should be canonicalized in the same way.
data, this field contains the size of the data being canonicalized
(the "effective block") rather than the actual size of the block.
4.1.2. Considerations Canonicalization for NPBs is dependent on whether the security
operation being performed is integrity or confidentiality. Integrity
operations consider every field in the block, whereas confidentiality
operations only consider the block-type-specific data. Since
confidentiality is applied to hide information (replacing plaintext
with ciphertext) it provides no benefit to include in the
confidentiality calculation information that MUST remain readable,
such as block fields other than the block-type-specific data.
o The canonical forms for the bundle and various extension blocks is The fields that comprise a NPB, and any special considerations for
not transmitted. It is simply an artifact used as input to their representation in a canonical form, are as follows.
digesting.
o We omit the reserved flags because we cannot determine if they o The Block Type Code field is included, without modification, for
will change in transit. The masks specified above will have to be integrity operations and omitted for confidentiality operations.
revised if additional flags are defined and they need to be
protected.
o All SDNV fields here are canonicalized as eight-byte unpacked o The Block Number field is included, without modification, for
values in network byte order. Length fields are canonicalized as integrity operations and omitted for confidentiality operations.
four-byte values in network byte order. Encoding does not need
optimization since the values are never sent over the network.
o These canonicalization algorithms assume that endpoint IDs o The Block Processing Control Flags field is included, without
themselves are immutable and they are unsuitable for use in modification, for integrity operations and omitted for
environments where that assumption might be violated. confidentiality operations, with the exception of reserved flags
which are treated as 0 in both cases.
o Cipher suites MAY define their own canonicalization algorithms and o The CRC type and CRC fields are included, without modification,
require the use of those algorithms over the ones provided in this for integrity operations and omitted for confidentiality
specification. operations.
4.2. Endpoint ID Confidentiality o The Block Type Specific Data field is included, without
modification, for both integrity and confidentiality operations,
with the exception that in some cases only a portion of the
payload data is to be processed. In such a case, only those bytes
are included in the canonical form and additional cipher suite
parameters are required to specify which part of the field is
included.
Every bundle has a primary block that contains the source and 5. Security Processing
destination endpoint IDs, and possibly other EIDs (in the dictionary
field) that cannot be encrypted. If endpoint ID confidentiality is
required, then bundle-in-bundle encapsulation can solve this problem
in some instances.
Similarly, confidentiality requirements MAY also apply to other parts This section describes the security aspects of bundle processing.
of the primary block (e.g., the current-custodian), and that is
supported in the same manner.
4.3. 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 All BCB blocks in the bundle MUST be evaluated prior to evaluating
any BIBs in the bundle. When BIBs and BCBs share a security- any BIBs in the bundle. When BIBs and BCBs share a security-
target, BCBs MUST be evaluated first and BIBs second. target, BCBs MUST be evaluated first and BIBs second.
4.3.1. Receiving BCB Blocks 5.1.1. Receiving BCB Blocks
If the bundle has a BCB and the receiving node is the destination for If a received bundle contains a BCB, the receiving node MUST
the bundle, the node MUST decrypt the relevant parts of the security- determine whether it has the responsibility of decrypting the BCB
target in accordance with the cipher suite specification. security target and removing the BCB prior to delivering data to an
application at the node or forwarding the bundle.
If the relevant parts of an encrypted payload cannot be decrypted If the receiving node is the destination of the bundle, the node MUST
(i.e., the decryption key cannot be deduced or decryption fails), decrypt any BCBs remaining in the bundle. If the receiving node is
then the bundle MUST be discarded and processed no further; in this not the destination of the bundle, the node MAY decrypt the BCB if
case, a bundle deletion status report (see [BPBIS]) indicating the directed to do so as a matter of security policy.
decryption failure MAY be generated. If any other encrypted
security-target cannot be decrypted then the associated security- If the relevant parts of an encrypted payload block cannot be
target and all security blocks associated with that target MUST be decrypted (i.e., the decryption key cannot be deduced or decryption
discarded and processed no further. fails), then the bundle MUST be discarded and processed no further.
If an encrypted security-target other than the payload block cannot
be decrypted then the associated security-target and all security
blocks associated with that target MUST be discarded and processed no
further. In both cases, requested status reports (see [BPBIS]) MAY
be generated to reflect bundle or 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 body data cipher-text in the security-target body data
4.3.2. Receiving BIB Blocks If a BCB contains multiple security-targets, all security-targets
MUST be processed if the BCB is processed by the Node. The effect of
this is to be the same as if each security-target had been
represented by an individual BCB with a single security-target.
5.1.2. Receiving BIB Blocks
If a received bundle contains a BIB, the receiving node MUST
determine whether it has the responsibility of verifying the BIB
security target and whether to remove the BIB prior to delivering
data to an application at the node or forwarding the bundle.
A BIB MUST NOT be processed if the security-target of the BIB is also A BIB MUST NOT be processed if the security-target of the BIB is also
the security-target of a BCB in the bundle. Given the order of the security-target of a BCB in the bundle. Given the order of
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 apply integrity to a specific security-target and no bundle should have applied integrity to a specific security-target
such BIB is present in the bundle, then the node MUST process this and no such BIB is present in the bundle, then the node MUST process
security-target in accordance with the security policy. This MAY this security-target in accordance with the security policy. This
involve removing the security-target from the bundle. If the removed MAY involve removing the security-target from the bundle. If the
security-target is the payload or primary block, the bundle MAY be removed security-target is the payload or primary block, the bundle
discarded. This action may occur at any node that has the ability to MAY be discarded. This action may occur at any node that has the
verify an integrity signature, not just the bundle destination. ability to verify an integrity signature, not just the bundle
destination.
If the bundle has a BIB and the receiving node is the destination for If the bundle has a BIB and the receiving node is the destination for
the bundle, the node MUST verify the security-target in accordance the bundle, the node MUST verify the security-target in accordance
with the cipher suite specification. If a BIB check fails, the with the cipher suite specification. If a BIB check fails, the
security-target has failed to authenticate and the security-target security-target has failed to authenticate and the security-target
SHALL be processed according to the security policy. A bundle status SHALL be processed according to the security policy. A bundle status
report indicating the failure MAY be generated. Otherwise, if the report indicating the failure MAY be generated. Otherwise, if the
BIB verifies, the security-target is ready to be processed for BIB verifies, the security-target is ready to be processed for
delivery. delivery.
If the bundle has a BIB and the receiving node is not the bundle If the bundle has a BIB and the receiving node is not the bundle
destination, the receiving node MAY attempt to verify the value in destination, the receiving node MAY attempt to verify the value in
the security-result field. If the check fails, the node SHALL the security-result field. If the check fails, the node SHALL
process the security-target in accordance to local security policy. process the security-target in accordance to local security policy.
It is RECOMMENDED that if a payload integrity check fails at a It is RECOMMENDED that if a payload integrity check fails at a
waypoint that it is processed in the same way as if the check fails waypoint that it is processed in the same way as if the check fails
at the destination. at the destination.
4.4. Receiving CMSB Blocks If a BIB contains multiple security-targets, all security-targets
MUST be processed if the BIB is processed by the Node. The effect of
A CMSB MUST NOT be processed if its security target is also the this is to be the same as if each security-target had been
security target of any BIB or BCB in the bundle. represented by an individual BIB with a single security-target.
The security services provided by a CMSB will be considered
successful if all services in the CMSB are validated. If any one
service encapsulated in the CMSB fails to validate, then the CMSB
MUST be considered as having failed to validate and MUST be
dispositioned in accordance with security policy.
4.5. Bundle Fragmentation and Reassembly 5.2. Bundle Fragmentation and Reassembly
If it is necessary for a node to fragment a bundle and security If it is necessary for a node to fragment a bundle and security
services have been applied to that bundle, the fragmentation rules services have been applied to that bundle, the fragmentation rules
described in [BPBIS] MUST be followed. As defined there and repeated described in [BPBIS] MUST be followed. As defined there and repeated
here for completeness, only the payload may be fragmented; security here for completeness, only the payload may be fragmented; security
blocks, like all extension blocks, can never be fragmented. In blocks, like all extension blocks, can never be fragmented.
addition, the following security-specific processing is REQUIRED:
o Due to the complexity of bundle fragmentation, including the
possibility of fragmenting bundle fragments, integrity and
confidentiality operations are not to be applied to a bundle
fragment. Specifically, a BCB or BIB MUST NOT be added to a
bundle fragment, even if the security-target of the security block
is not the payload. When integrity and confidentiality must be
applied to a fragment, we RECOMMEND that encapsulation be used
instead.
o The authentication security policy requirements for a bundle MUST
be applied individually to all the bundles resulting from a
fragmentation event.
o The decision to fragment a bundle MUST be made prior to adding
authentication to the bundle. The bundle MUST first be fragmented
and authentication applied to each individual fragment.
4.6. Reactive Fragmentation
When a partial bundle has been received, the receiving node SHALL
consult its security policy to determine if it MAY fragment the
bundle, converting the received portion into a bundle fragment for
further forwarding. Whether or not reactive fragmentation is
permitted SHALL depend on the security policy and the cipher suite
used to calculate the BAB authentication information, if required.
Specifically, if the security policy does not require authentication,
then reactive fragmentation MAY be permitted. If the security policy
does require authentication, then reactive fragmentation MUST NOT be
permitted if the partial bundle is not sufficient to allow
authentication.
If reactive fragmentation is allowed, then all BAB blocks must be Due to the complexity of bundle fragmentation, including the
removed from created fragments. possibility of fragmenting bundle fragments, integrity and
confidentiality operations are not to be applied to a bundle
representing a fragment (i.e., a bundle whose "bundle is a Fragment"
flag is set in the Bundle Processing Control Flags field).
Specifically, a BCB or BIB MUST NOT be added to a bundle fragment,
even if the security-target of the security block is not the payload.
When integrity and confidentiality must be applied to a fragment, we
RECOMMEND that encapsulation be used instead.
5. Key Management 6. Key Management
Key management in delay-tolerant networks is recognized as a Key management in delay-tolerant networks is recognized as a
difficult topic and is one that this specification does not attempt difficult topic and is one that this specification does not attempt
to solve. to solve.
6. Policy Considerations 7. Policy Considerations
When implementing BPSec, several policy decisions must be considered. When implementing BPSec, several policy decisions must be considered.
This section describes key policies that affect the generation, This section describes key policies that affect the generation,
forwarding, and receipt of bundles that are secured using this forwarding, and receipt of bundles that are secured using this
specification. specification.
o If a bundle is received that contains more than one security- o If a bundle is received that contains more than one security-
operation, in violation of BPSec, then the BPA must determine how operation, in violation of BPSec, then the BPA must determine how
to handle this bundle. The bundle may be discarded, the block to handle this bundle. The bundle may be discarded, the block
affected by the security-operation may be discarded, or one affected by the security-operation may be discarded, or one
skipping to change at page 29, line 22 skipping to change at page 26, line 5
operation, or some other action. operation, or some 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
payload block, the primary block, and any block-types specifically payload block, the primary block, and any block-types specifically
identified in the security policy. If a BPA were to apply identified in the security policy. If a BPA were to apply
security operations such as integrity or confidentiality to every security operations such as integrity or confidentiality to every
block in the bundle, regardless of the block type, there could be block in the bundle, regardless of the block type, there could be
downstream errors processing blocks whose contents must be downstream errors processing blocks whose contents must be
inspected at every hop in the network path. inspected at every hop in the network path.
7. Security Considerations o Adding a BIB to a security-target that has already been encrypted
by a BCB is not allowed. Therefore, we recommend three methods to
add an integrity signature to an encrypted security-target.
Certain applications of DTN need to both sign and encrypt a message, 1. At the time of encryption, an integrity signature may be
and there are security issues to consider with this. generated and added to the BCB for the security-target as
additional information in the security-result field.
o To provide an assurance that a security-target came from a 2. The encrypted block may be replicated as a new block and
specific source and has not been changed, then it should be signed integrity signed.
with a BIB.
o To ensure that a security-target cannot be inspected during 3. An encapsulation scheme may be applied to encapsulate the
transit, it should be encrypted with a BCB. security-target (or the entire bundle) such that the
encapsulating structure is, itself, no longer the security-
target of a BCB and may therefore be the security-target of a
BIB.
o Adding a BIB to a security-target that has already been encrypted 8. Security Considerations
by a BCB is not allowed. Therefore, we recommend three methods to
add an integrity signature to an encrypted security-target.
First, at the time of encryption, an integrity signature may be
generated and added to the BCB for the security-target as
additional information in the security-result field. Second, the
encrypted block may be replicated as a new block and integrity
signed. Third, an encapsulation scheme may be applied to
encapsulate the security-target (or the entire bundle) such that
the encapsulating structure is, itself, no longer the security-
target of a BCB and may therefore be the security-target of a BIB.
8. Conformance Given the nature of delay-tolerant networking applications, it is
expected that bundles may traverse a variety of environments and
devices which each pose unique security risks and requirements on the
implementation of security within BPSEC. For these reasons, it is
important to introduce key threat models and describe the roles and
responsibilities of the BPSEC protocol in protecting the
confidentiality and integrity of the data against those threats
throughout the DTN. This section provides additional discussion on
security threats that BPSEC will face and describe in additional
detail how 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
capabilities identical to those described by the Internet Threat
Model in [RFC3552], but the BPSEC threat model is scoped to
illustrate threats specific to BPSEC operating within DTN
environments and therefore focuses on man-in-the-middle (MITM)
attackers.
8.1. Attacker Capabilities and Objectives
BPSEC was designed to protect against MITM threats which may have
access to a bundle during transit from its source, Alice, to its
destination, Bob. A MITM node, Mallory, is a non-cooperative node
operating on the DTN between Alice and Bob that has the ability to
receive bundles, examine bundles, modify bundles, forward bundles,
and generate bundles at will in order to compromise the
confidentiality or integrity of data within the DTN. For the
purposes of this section, any MITM node is assumed to effectively be
security-aware even if it does not implement the BPSec protocol.
There are three classes of MITM nodes which are differentiated based
on their access to cryptographic material:
o Unprivileged Node: Mallory has not been provisioned within the
secure environment and only has access to cryptographic material
which has been publicly-shared.
o Legitimate Node: Mallory is within the secure environment and
therefore has access to cryptographic material which has been
provisioned to Mallory (i.e., K_M) as well as material which has
been publicly-shared.
o Privileged Node: Mallory is a privileged node within the secure
environment and therefore has access to cryptographic material
which has been provisioned to Mallory, Alice and/or Bob (i.e.
K_M, K_A, and/or K_B) as well as material which has been publicly-
shared.
If Mallory is operating as a privileged node, this is tantamount to
compromise; BPSec does not provide mechanisms to detect or remove
Mallory from the DTN or BPSec secure environment. It is up to the
BPSec implementer or the underlying cryptographic mechanisms to
provide appropriate capabilities if they are needed. It should also
be noted that if the implementation of BPSec uses a single set of
shared cryptographic material for all nodes, a legitimate node is
equivalent to a privileged node because K_M == K_A == K_B.
A special case of the legitimate node is when Mallory is either Alice
or Bob (i.e., K_M == K_A or K_M == K_B). In this case, Mallory is
able to impersonate traffic as either Alice or Bob, which means that
traffic to and from that node can be decrypted and encrypted,
respectively. Additionally, messages may be signed as originating
from one of the endpoints.
8.2. Attacker Behaviors and BPSec Mitigations
8.2.1. Eavesdropping Attacks
Once Mallory has received a bundle, she is able to examine the
contents of that bundle and attempt to recover any protected data or
cryptographic keying material from the blocks contained within. The
protection mechanism that BPSec provides against this action is the
BCB, which encrypts the contents of its security-target, providing
confidentiality of the data. Of course, it should be assumed that
Mallory is able to attempt offline recovery of encrypted data, so the
cryptographic mechanisms selected to protect the data should provide
a suitable level of protection.
When evaluating the risk of eavesdropping attacks, it is important to
consider the lifetime of bundles on a DTN. Depending on the network,
bundles may persist for days or even years. If a bundle does persist
on the network for years and the cipher suite used for a BCB provides
inadequate protection, Mallory may be able to recover the protected
data before that bundle reaches its intended destination.
8.2.2. Modification Attacks
As a node participating in the DTN between Alice and Bob, Mallory
will also be able to modify the received bundle, including non-BPSec
data such as the primary block, payload blocks, or block processing
control flags as defined in [BPBIS]. Mallory will be able to
undertake activities which include modification of data within the
blocks, replacement of blocks, addition of blocks, or removal of
blocks. Within BPSec, both the BIB and BCB provide integrity
protection mechanisms to detect or prevent data manipulation attempts
by Mallory.
The BIB provides that protection to another block which is its
security-target. The cryptographic mechansims used to generate the
BIB should be strong against collision attacks and Mallory should not
have access to the cryptographic material used by the originating
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
BIB and lead Bob to validate the security-target as originating from
Alice.
Since BPSec security operations are implemented by placing blocks in
a bundle, there is no in-band mechanism for detecting or correcting
certain cases where Mallory removes blocks from a bundle. If Mallory
removes a BCB block, but keeps the security-target, the security-
target remains encrypted and there is a possibility that there may no
longer be sufficient information to decrypt the block at its
destination. If Mallory removes both a BCB (or BIB) and its
security-target there is no evidence left in the bundle of the
security operation. Similarly, if Mallory removes the BIB but not
the security-target there is no evidence left in the bundle of the
security operation. In each of these cases, the implementation of
BPSec MUST be combined with policy configuration at endpoints in the
network which describe the expected and required security operations
that must be applied on transmission and are expected to be present
on receipt. This or other similar out-of-band information is
required to correct for removal of security information in the
bundle.
A limitation of the BIB may exist within the implementation of BIB
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
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
will acknowledge the message as originating from Mallory instead of
Alice. In order to provide verifiable integrity checks, both a BIB
and BCB should be used. Alice creates a BIB with the protected data
block as the security-target and then creates a BCB with both the BIB
and protected data block as its security-targets. In this
configuration, since Mallory is only a legitimate node and does not
have access to Alice's key K_A, Mallory is unable to decrypt the BCB
and replace the BIB.
8.2.3. Topology Attacks
If Mallory is in a MITM position within the DTN, she is able to
influence how any bundles that come to her may pass through the
network. Upon receiving and processing a bundle that must be routed
elsewhere in the network, Mallory has three options as to how to
proceed: not forward the bundle, forward the bundle as intended, or
forward the bundle to one or more specific nodes within the network.
Attacks that involve re-routing the packets throughout the network
are essentially a special case of the modification attacks described
in this section where the attacker is modifying fields within the
primary block of the bundle. Given that BPSec cannot encrypt the
contents of the primary block, alternate methods must be used to
prevent this situation. These methods MAY include requiring BIBs for
primary blocks, using encapsulation, or otherwise strategically
manipulating primary block data. The specifics of any such
mitigation technique are specific to the implementation of the
deploying network and outside of the scope of this document.
Furthermore, routing rules and policies may be useful in enforcing
particular traffic flows to prevent topology attacks. While these
rules and policies may utilize some features provided by BPSec, their
definition is beyond the scope of this specification.
8.2.4. Message Injection
Mallory is also able to generate new bundles and transmit them into
the DTN at will. These bundles may either be copies or slight
modifications of previously-observed bundles (i.e., a replay attack)
or entirely new bundles generated based on the Bundle Protocol,
BPSec, or other bundle-related protocols. With these attacks
Mallory's objectives may vary, but may be targeting either the bundle
protocol or application-layer protocols conveyed by the bundle
protocol.
BPSec relies on cipher suite capabilities to prevent replay or forged
message attacks. A BCB used with appropriate cryptographic
mechanisms (e.g., a counter-based cipher mode) may provide replay
protection under certain circumstances. Alternatively, application
data itself may be augmented to include mechanisms to assert data
uniqueness and then protected with a BIB, a BCB, or both along with
other block data. In such a case, the receiving node would be able
to validate the uniqueness of the data.
9. Ciphersuite Authorship Considerations
Cipher suite developers or implementers should consider the diverse
performance and conditions of networks on which the Bundle Protocol
(and therefore BPSec) will operate. Specifically, the delay and
capacity of delay-tolerant networks can vary substantially. Cipher
suite developers should consider these conditions to better describe
the conditions when those suites will operate or exhibit
vulnerability, and selection of these suites for implementation
should be made with consideration to the reality. There are key
differences that may limit the opportunity to leverage existing
cipher suites and technologies that have been developed for use in
traditional, more reliable networks:
o Data Lifetime: Depending on the application environment, bundles
may persist on the network for extended periods of time, perhaps
even years. Cryptographic algorithms should be selected to ensure
protection of data against attacks for a length of time reasonable
for the application.
o One-Way Traffic: Depending on the application environment, it is
possible that only a one-way connection may exist between two
endpoints, or if a two-way connection does exist, the round-trip
time may be extremely large. This may limit the utility of
session key generation mechanisms, such as Diffie-Hellman, as a
two-way handshake may not be feasible or reliable.
o Opportunistic Access: Depending on the application environment, a
given endpoint may not be guaranteed to be accessible within a
certain amount of time. This may make asymmetric cryptographic
architectures which rely on a key distribution center or other
trust center impractical under certain conditions.
10. Conformance
All implementations are strongly RECOMMENDED to provide some method All implementations are strongly RECOMMENDED to provide some method
of hop-by-hop verification by generating a hash to some canonical of hop-by-hop verification by generating a hash to some canonical
form of the bundle and placing an integrity signature on that form form of the bundle and placing an integrity signature on that form
using a BIB. using a BIB.
9. IANA Considerations 11. IANA Considerations
This protocol has fields that have been registered by IANA. This protocol has fields that have been registered by IANA.
9.1. Bundle Block Types 11.1. Bundle Block Types
This specification allocates three block types from the existing This specification allocates three 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 |
+-------+-----------------------------+---------------+ +-------+-----------------------------+---------------+
| 2 | Block Integrity Block | This document | | 2 | Block Integrity Block | This document |
| 3 | Block Confidentiality Block | This document | | 3 | Block Confidentiality Block | This document |
| 4 | CMS Block | This document |
+-------+-----------------------------+---------------+ +-------+-----------------------------+---------------+
Table 2 Table 2
9.2. Cipher Suite Flags 11.2. Cipher Suite Flags
This protocol has a cipher suite flags field and certain flags are This protocol has a cipher suite flags field and certain flags are
defined. An IANA registry has been set up as follows. defined. An IANA registry has been set up as follows.
The registration policy for this registry is: Specification Required The registration policy for this registry is: Specification Required
The Value range is: Variable Length The Value range is: Variable Length
Cipher Suite Flag Registry: Cipher Suite Flag Registry:
+--------------------------+-------------------------+--------------+ +--------------------------+-------------------------+--------------+
| Bit Position (right to | Description | Reference | | Bit Position (right to | Description | Reference |
| left) | | | | left) | | |
+--------------------------+-------------------------+--------------+ +--------------------------+-------------------------+--------------+
| 0 | Block contains result | This | | 0 | Block contains result | This |
| | | document | | | | document |
| 1 | Block Contains | This | | 1 | Block Contains | This |
| | parameters | document | | | parameters | document |
skipping to change at page 31, line 5 skipping to change at page 32, line 22
| 1 | Block Contains | This | | 1 | Block Contains | This |
| | parameters | document | | | parameters | document |
| 2 | Source EID ref present | This | | 2 | Source EID ref present | This |
| | | document | | | | document |
| >3 | Reserved | This | | >3 | Reserved | This |
| | | document | | | | document |
+--------------------------+-------------------------+--------------+ +--------------------------+-------------------------+--------------+
Table 3 Table 3
9.3. Parameters and Results 11.3. Parameters and Results
This protocol has fields for cipher suite parameters and results. This protocol has fields for cipher suite parameters and results.
The field is a type-length-value triple and a registry is required The field is a type-length-value triple and a registry is required
for the "type" sub-field. The values for "type" apply to both the for the "type" sub-field. The values for "type" apply to both the
cipher suite parameters and the cipher suite results fields. Certain cipher suite parameters and the cipher suite results fields. Certain
values are defined. An IANA registry has been set up as follows. values are defined. An IANA registry has been set up as follows.
The registration policy for this registry is: Specification Required The registration policy for this registry is: Specification Required
The Value range is: 8-bit unsigned integer. The Value range is: 8-bit unsigned integer.
Cipher Suite Parameters and Results Type Registry: Cipher Suite Parameters and Results Type Registry:
+---------+---------------------------------+---------------+ +---------+-------------------------------------------+-------------+
| Value | Description | Reference | | Value | Description | Reference |
+---------+---------------------------------+---------------+ +---------+-------------------------------------------+-------------+
| 0 | reserved | This document | | 0 | reserved | Section 3.7 |
| 1 | initialization vector (IV) | This document | | 1 | initialization vector (IV) | Section 3.7 |
| 2 | reserved | This document | | 2 | reserved | Section 3.7 |
| 3 | key-information | This document | | 3 | key-information | Section 3.7 |
| 4 | content-range (pair of SDNVs) | This document | | 4 | content-range (pair of Unsigned Integers) | Section 3.7 |
| 5 | integrity signature | This document | | 5 | integrity signature | Section 3.7 |
| 6 | unassigned | This document | | 6 | unassigned | Section 3.7 |
| 7 | salt | This document | | 7 | salt | Section 3.7 |
| 8 | BCB integrity check value (ICV) | This document | | 8 | BCB integrity check value (ICV) | Section 3.7 |
| 9-191 | reserved | This document | | 9-191 | reserved | Section 3.7 |
| 192-250 | private use | This document | | 192-250 | private use | Section 3.7 |
| 251-255 | reserved | This document | | 251-255 | reserved | Section 3.7 |
+---------+---------------------------------+---------------+ +---------+-------------------------------------------+-------------+
Table 4 Table 4
10. References 12. References
10.1. Normative References 12.1. Normative References
[BPBIS] Burleigh, S., Fall, K., and E. Birrane, "Bundle Protocol", [BPBIS] Burleigh, S., Fall, K., and E. Birrane, "Bundle Protocol",
draft-ietf-dtn-bpbis-03 (work in progress), March 2016. draft-ietf-dtn-bpbis-04 (work in progress), July 2016.
[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, March 1997.
[RFC5652] Housley, R., "Cryptographic Message Syntax (CMS)", STD 70, [RFC3552] Rescorla, E. and B. Korver, "Guidelines for Writing RFC
RFC 5652, DOI 10.17487/RFC5652, September 2009, Text on Security Considerations", BCP 72, RFC 3552,
<http://www.rfc-editor.org/info/rfc5652>. DOI 10.17487/RFC3552, July 2003,
<http://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, May 2011.
10.2. Informative References 12.2. Informative References
[BPBISCBOR]
Burleigh, S., "Bundle Protocol CBOR Representation
Specification", draft-burleigh-dtn-rs-cbor-01 (work in
progress), April 2016.
[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, April 2007.
[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, May
2011. 2011.
[SBSP] Birrane, E., "Streamlined Bundle Security Protocol", [SBSP] Birrane, E., "Streamlined Bundle Security Protocol",
skipping to change at page 32, line 42 skipping to change at page 34, line 37
Edward J. Birrane, III Edward J. Birrane, III
The Johns Hopkins University Applied Physics Laboratory The Johns Hopkins University Applied Physics Laboratory
11100 Johns Hopkins Rd. 11100 Johns Hopkins Rd.
Laurel, MD 20723 Laurel, MD 20723
US US
Phone: +1 443 778 7423 Phone: +1 443 778 7423
Email: Edward.Birrane@jhuapl.edu Email: Edward.Birrane@jhuapl.edu
Jeremy Pierce-Mayer Kenneth McKeever
INSYEN AG The Johns Hopkins University Applied Physics Laboratory
Muenchner Str. 20 11100 Johns Hopkins Rd.
Oberpfaffenhofen, Bavaria DE Laurel, MD 20723
Germany
Phone: +49 08153 28 2774
Email: jeremy.mayer@insyen.com
Dennis C. Iannicca
NASA Glenn Research Center
21000 Brookpark Rd.
Brook Park, OH 44135
US US
Phone: +1-216-433-6493 Phone: +1 443 778 2237
Email: dennis.c.iannicca@nasa.gov Email: Ken.McKeever@jhuapl.edu
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