Streamlined Bundle Security Protocol Specification
draft-irtf-dtnrg-sbsp-00
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| Author | Edward J. Birrane | ||
| Last updated | 2014-01-15 (Latest revision 2013-07-14) | ||
| RFC stream | Internet Research Task Force (IRTF) | ||
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draft-irtf-dtnrg-sbsp-00
Delay-Tolerant Networking Research Group E. Birrane
Internet-Draft JHU/APL
Intended status: Experimental July 15, 2013
Expires: January 16, 2014
Streamlined Bundle Security Protocol Specification
draft-irtf-dtnrg-sbsp-00
Abstract
This document defines a streamlined bundle security protocol, which
provides data authentication, integrity, and confidentiality services
for the Bundle Protocol. Capabilities are provided to protect the
bundle payload, and additional data that may be included within the
bundle, along a single path through a network.
Status of This Memo
This Internet-Draft is submitted in full conformance with the
provisions of BCP 78 and BCP 79.
Internet-Drafts are working documents of the Internet Engineering
Task Force (IETF). Note that other groups may also distribute
working documents as Internet-Drafts. The list of current Internet-
Drafts is at http://datatracker.ietf.org/drafts/current/.
Internet-Drafts are draft documents valid for a maximum of six months
and may be updated, replaced, or obsoleted by other documents at any
time. It is inappropriate to use Internet-Drafts as reference
material or to cite them other than as "work in progress."
This Internet-Draft will expire on January 16, 2014.
Copyright Notice
Copyright (c) 2013 IETF Trust and the persons identified as the
document authors. All rights reserved.
This document is subject to BCP 78 and the IETF Trust's Legal
Provisions Relating to IETF Documents
(http://trustee.ietf.org/license-info) in effect on the date of
publication of this document. Please review these documents
carefully, as they describe your rights and restrictions with respect
to this document. Code Components extracted from this document must
include Simplified BSD License text as described in Section 4.e of
the Trust Legal Provisions and are provided without warranty as
described in the Simplified BSD License.
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Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 2
1.1. Related Documents . . . . . . . . . . . . . . . . . . . . 3
1.2. Terminology . . . . . . . . . . . . . . . . . . . . . . . 4
2. Security Block Definitions . . . . . . . . . . . . . . . . . 6
2.1. Abstract Security Block . . . . . . . . . . . . . . . . . 8
2.2. Block Ordering . . . . . . . . . . . . . . . . . . . . . 10
2.3. Bundle Authentication Block . . . . . . . . . . . . . . . 11
2.4. Block Integrity Block . . . . . . . . . . . . . . . . . . 12
2.5. Block Confidentiality Block . . . . . . . . . . . . . . . 13
2.6. Block Interactions . . . . . . . . . . . . . . . . . . . 15
2.7. Parameters and Result Fields . . . . . . . . . . . . . . 16
2.8. BSP Block Example . . . . . . . . . . . . . . . . . . . . 17
3. Security Processing . . . . . . . . . . . . . . . . . . . . . 19
3.1. Canonical Forms . . . . . . . . . . . . . . . . . . . . . 19
3.1.1. Bundle Canonicalization . . . . . . . . . . . . . . . 19
3.1.2. Block Canonicalization . . . . . . . . . . . . . . . 20
3.1.3. Considerations . . . . . . . . . . . . . . . . . . . 22
3.2. Endpoint ID Confidentiality . . . . . . . . . . . . . . . 23
3.3. Bundles Received from Other Nodes . . . . . . . . . . . . 24
3.4. Bundle Fragmentation and Reassembly . . . . . . . . . . . 25
3.5. Reactive Fragmentation . . . . . . . . . . . . . . . . . 26
4. Key Management . . . . . . . . . . . . . . . . . . . . . . . 27
5. Security Considerations . . . . . . . . . . . . . . . . . . . 27
6. Conformance . . . . . . . . . . . . . . . . . . . . . . . . . 27
7. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 27
7.1. Bundle Block Types . . . . . . . . . . . . . . . . . . . 27
7.2. Ciphersuite Flags . . . . . . . . . . . . . . . . . . . . 28
7.3. Parameters and Results . . . . . . . . . . . . . . . . . 28
8. References . . . . . . . . . . . . . . . . . . . . . . . . . 29
8.1. Normative References . . . . . . . . . . . . . . . . . . 29
8.2. Informative References . . . . . . . . . . . . . . . . . 29
Appendix A. Acknowlegements . . . . . . . . . . . . . . . . . . 30
Author's Address . . . . . . . . . . . . . . . . . . . . . . . . 30
1. Introduction
This document defines security features for the Bundle Protocol
[RFC5050] intended for use in delay-tolerant networks, in order to
provide Delay-Tolerant Networking (DTN) security services.
The Bundle Protocol is used in DTNs that overlay multiple networks,
some of which may be challenged by limitations such as intermittent
and possibly unpredictable loss of connectivity, long or variable
delay, asymmetric data rates, and high error rates. The purpose of
the Bundle Protocol is to support interoperability across such
stressed networks. The Bundle Protocol is layered on top of
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underlay-network-specific convergence layers, on top of network-
specific lower layers, to enable an application in one network to
communicate with an application in another network, both of which are
spanned by the DTN.
Security is important for the Bundle Protocol. The stressed
environment of the underlying networks over which the Bundle Protocol
operates makes it important for the DTN to be protected from
unauthorized use, and this stressed environment poses unique
challenges for the mechanisms needed to secure the Bundle Protocol.
Furthermore, DTNs may be deployed in environments where a portion of
the network might become compromised, posing the usual security
challenges related to confidentiality, integrity, and availability.
This document describes the Streamlined Bundle Security Protocol
(SBSP), which provides security services for blocks within a bundle
from the bundle source to the bundle destination. Specifically, the
SBSP provides authentication, integrity, and confidentiality for
bundles along a path through a network.
SBSP applies, by definition, only to those nodes that implement it,
known as "security-aware" nodes. There MAY be other nodes in the DTN
that do not implement SBSP. All nodes can interoperate with the
exception that SBSP security operations can only happen at SBSP
security-aware nodes.
1.1. Related Documents
This document is best read and understood within the context of the
following other DTN documents:
"Delay-Tolerant Networking Architecture" [RFC4838] defines the
architecture for delay-tolerant networks, but does not discuss
security at any length.
The DTN Bundle Protocol [RFC5050] defines the format and processing
of the blocks used to implement the Bundle Protocol, excluding the
security-specific blocks defined here.
The Bundle Security Protocol [RFC6257] introduces the concepts of
security blocks for authentication, confidentiality, and integrity.
The SBSP is based off of this document.
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1.2. Terminology
The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
"SHOULD", "SHOULD NOT", "RECOMMENDED", "NOT RECOMMENDED", "MAY", and
"OPTIONAL" in this document are to be interpreted as described in
[RFC2119].
We introduce the following terminology for purposes of clarity:
o Source - the bundle node from which a bundle originates.
o Destination - the bundle node to which a bundle is ultimately
destined.
o Forwarder - the bundle node that forwarded the bundle on its most
recent hop.
o Intermediate Receiver or "Next Hop" - the neighboring bundle node
to which a forwarder forwards a bundle.
o Path - the ordered sequence of nodes through which a bundle passes
on its way from source to destination. This may or may not be
known by the bundle, or any of the bundle nodes.
Figure 1 below is adapted from [RFC5050] and shows four bundle nodes
(denoted BN1, BN2, BN3, and BN4) that reside above some transport
layer(s). Three distinct transport and network protocols (denoted T1
/N1, T2/N2, and T3/N3) are also shown.
+---------v-| +->>>>>>>>>>v-+ +->>>>>>>>>>v-+ +-^---------+
| BN1 v | | ^ BN2 v | | ^ BN3 v | | ^ BN4 |
+---------v-+ +-^---------v-+ +-^---------v-+ +-^---------+
| T1 v | + ^ T1/T2 v | + ^ T2/T3 v | | ^ T3 |
+---------v-+ +-^---------v-+ +-^---------v + +-^---------+
| N1 v | | ^ N1/N2 v | | ^ N2/N3 v | | ^ N3 |
+---------v-+ +-^---------v + +-^---------v-+ +-^---------+
| >>>>>>>>^ >>>>>>>>>>^ >>>>>>>>^ |
+-----------+ +------------+ +-------------+ +-----------+
| | | |
|<-- An Internet --->| |<--- An Internet --->|
| | | |
Figure 1: Bundle Nodes Sit at the Application Layer of the Internet
Model
BN1 originates a bundle that it forwards to BN2. BN2 forwards the
bundle to BN3, and BN3 forwards the bundle to BN4. BN1 is the source
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of the bundle and BN4 is the destination of the bundle. BN1 is the
first forwarder, and BN2 is the first intermediate receiver; BN2 then
becomes the forwarder, and BN3 the intermediate receiver; BN3 then
becomes the last forwarder, and BN4 the last intermediate receiver,
as well as the destination.
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
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
bundle (as well as being the final intermediate receiver).
We introduce the following security-specific DTN terminology:
o Security-Service - the security features supported by this
specification: authentication, integrity, and confidentiality.
o Security-Source - a bundle node that adds a security block to a
bundle.
o Security-Destination - a bundle node that evaluates a security
block from a bundle. When a security-service is applied hop-by-
hop, the security-destination is the next intermediate receiver.
Otherwise, the security-destination is the same as the bundle
destination.
o Security-Target - the portion of a bundle (e.g., the primary
block, payload block, extension block, or entire bundle) that
receives a security-service as part of a security-operation.
o Security Block - a single instance of a SBSP extension block in a
bundle.
o Security-Operation - the application of a security-service to a
specific security-target, notated as OP(security-service,
security-target). For example, OP(authentication, bundle) or
OP(confidentiality, payload). Every security-operation in a
bundle must be unique, meaning that a security-service can only be
applied to a security-target once in a bundle. A security-
operation may be implemented by one or more security blocks.
Referring to Figure 1 again:
If the bundle that originates at BN1 is given 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 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 source.
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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
and security-destination.
The destination of all security blocks in a bundle MUST be the bundle
destination, with the exception of authentication security blocks,
whose destination is the next hop along the bundle path. In a DTN,
there is typically no guarantee that a bundle will visit a particular
intermediate receiver during its journey, or that a particular series
of intermediate receivers will be visited in a particular order.
Security-destinations different from bundle destinations would place
a tight (and possibly intractable) coupling between security and
routing services in an overlay network. In cases where paths are
both known and unchanging, security tunnels may be constructed
separately from this security protocol specification.
As required in [RFC5050], 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.
If a node is not security-aware, then it forwards the security blocks
in the bundle unchanged unless the bundle's block processing flags
specify otherwise. If a network has some nodes that are not
security-aware, then the block processing flags SHOULD be set such
that security blocks are not discarded at those nodes solely because
they cannot be processed there. Except for this, the non-security-
aware nodes are transparent relay points and are invisible as far as
security processing is concerned.
2. Security Block Definitions
There are three types of security blocks that MAY be included in a
bundle. These are the Bundle Authentication Block (BAB), the Block
Integrity Block (BIB), and the Block Confidentiality Block (BCB).
The BAB is used to ensure the authenticity and integrity of the
bundle along a single hop from forwarder to intermediate receiver.
As such, BABs operate between topologically adjacent nodes.
Security-aware nodes MAY require BABs from a given neighbor in the
network in order to receive and process a received bundle.
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The BIB is used to ensure the authenticity and integrity of its
security-target from the BIB security-source, which creates the
BIB, to the bundle destination, which verifies the BIB
authenticator. The authentication information in the BIB MAY
(when possible) be verified by any node in between the BIB
security-source and the bundle destination.
The BCB indicates that the security-target has been encrypted, in
whole or in part, at the BCB security-source in order to protect
its content while in transit to the bundle destination.
Certain ciphersuites may allow or require multiple instances of a
block to appear in the bundle. For example, an authentication
ciphersuite 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(authentication,bundle) in this example.
A security-operation MAY NOT be applied more than once in a bundle.
For example, the two security-operations: OP(integrity, payload) and
OP(integrity, payload) are redudant and may not appear together in a
bundle. However, the two security operations OP(integrity, payload)
and OP(integrity, extension_block_1) MAY both be present in the
bundle. Also, the two security operations OP(integrity,
extension_block_1) and OP(integrity, extension_block_2) are unique
and may both appear in the same bundle.
Each security block uses the Canonical Bundle Block Format as defined
in [RFC5050]. That is, each security block is comprised of the
following elements:
o Block-type code
o Block processing control flags
o Block EID-reference list (OPTIONAL)
o Block data length
o Block-type-specific data fields
Since the three security blocks have most fields in common, we can
shorten the description of the Block-type-specific data fields of
each security block if we first define an abstract security block
(ASB) and then specify each of the real blocks in terms of the fields
that are present/absent in an ASB. Note that no bundle ever contains
an actual ASB, which is simply a specification artifact.
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2.1. Abstract Security Block
The structure of an Abstract Security Block is 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. Many of the fields below use the
Self-Delimiting Numeric Value (SDNV) type whose format and encoding
is as defined in [RFC5050].
+-----------------------------+----------------------------------+
| Block Type Code (BYTE) | Processing Control Flags (SDNV) |
+-----------------------------+----------------------------------+
| EID Reference Count and List (Compound List) |
+-----------------------------+----------------------------------+
| Block Length (SDNV) | Security Target (Compound) |
+-----------------------------+----------------------------------+
| Ciphersuite ID (SDNV) | Ciphersuite Flags (SDNV) |
+-----------------------------+----------------------------------+
| Params Length (SDNV) | Params Data (Compound) |
+-----------------------------+----------------------------------+
| Result Length (SDNV) | Result Data (Compound) |
+-----------------------------+----------------------------------+
Figure 2: Abstract Security Block Structure
An ASB consists of the following fields, some of which are optional.
o Block-Type Code (Byte) - as described in [RFC5050]. The block-
type codes for security blocks are:
BundleAuthenticationBlock - BAB: 0x02
BlockIntegrityBlock - BIB: 0x03
BlockConfidentialityBlock - BCB: 0x04
o Block Processing Control Flags (SDNV) - as described in [RFC5050].
There are no general constraints on the use of the block
processing control flags, and some specific requirements are
discussed later.
o (OPTIONAL) EID Reference Count and List - as described in
[RFC5050]. Presence of the EID-reference field is indicated by
the setting of the "Block contains an EID-reference field"
(EID_REF) bit of the block processing control flags. If no EID
fields are present, then the composite field itself MUST be
omitted entirely and the EID_REF bit MUST be unset. A count field
of zero is not permitted. The possible EIDs are:
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(OPTIONAL) Security-source - specifies the security-source for
the block. If this is omitted, then the source of the bundle
is assumed to be the security-source unless otherwise indicated
by policy or associated ciphersuite definition. When present,
the Security-Source MUST be the first EID in the list.
(OPTIONAL) Unique Identifier - specifies the bundle-unique
identifier for the block. This is discussed in more detail in
the Security-Target section below.
o Block Length (SDNV) - as described in [RFC5050].
o Block-type-specific data fields as follows:
* Security-Target (Compound) - Uniquely identifies the target of
the associated security-operation. The security-target for any
security block MUST be unambiguous in the context of the bundle
in which it resides.
Currently, [RFC5050] provides no mechanism for uniquely
identifying a block within a bundle. Absent a formal mechanism
for block identification, we RECOMMEND the following algorithm
for uniquely identifying a block within a bundle. Each block
may be given a unique EID in its EID references using the block
type as its scheme and a subscript as its scheme-specific part.
For guaranteed unique block types (such as the payload block)
the associated SSP is set at 0. For block types that are not
guaranteed to be unique, the SSP will be used to uniquely
identify the block.
A security-target may specify this <block type><subscript> and
nodes may first select on block type and then subselect by
subscript when matching the security-target to an actual
extension block.
* Ciphersuite ID (SDNV)
* Ciphersuite flags (SDNV)
* (OPTIONAL) Ciphersuite-Parameters - compound field of the next
two items.
+ Ciphersuite-parameters length (SDNV) - specifies the length
of the next field, which is the ciphersuite-parameters data
field.
+ Ciphersuite-parameters data - parameters to be used with the
ciphersuite in use, e.g., a key identifier or initialization
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vector (IV). See Section 2.7 for a list of potential
parameters and their encoding rules. The particular set of
parameters that is included in this field is defined as part
of a ciphersuite specification.
* (OPTIONAL) Security-Result - compound field of the next two
items.
+ Security-result length (SDNV) - contains the length of the
next field, which is the security-result data field.
+ Security-result data - contains the results of the
appropriate ciphersuite-specific calculation (e.g., a
signature, Message Authentication Code (MAC), or ciphertext
block key).
The structure of the ciphersuite flags field is shown in Figure 3.
In each case, the presence of an optional field is indicated by
setting the value of the corresponding flag to one. A value of zero
indicates the corresponding optional field is missing. Presently,
there are three flags defined for the field; for convenience, these
are shown as they would be extracted from a single-byte SDNV. Future
additions may cause the field to grow to the left so, as with the
flags fields defined in [RFC5050], the description below numbers the
bit positions from the right rather than the standard RFC definition,
which numbers bits from the left.
bits 6-3 are reserved for future use.
src - bit 2 indicates whether the EID-reference field of the ASB
contains the optional reference to the security-source.
parm - bit 1 indicates whether or not the ciphersuite-parameters
length and ciphersuite-parameters data fields are present.
res - bit 0 indicates whether or not the ASB contains the
security-result length and security-result data fields.
Bit Bit Bit Bit Bit Bit Bit
6 5 4 3 2 1 0
+-----+-----+-----+-----+-----+-----+-----+
| reserved | src |parm | res |
+-----+-----+-----+-----+-----+-----+-----+
Figure 3: Ciphersuite Flags
2.2. Block Ordering
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A security-operation may be implemented in a bundle using either one
or two security blocks. For example, the operation
OP(authentication, bundle) MAY be accomplished by a single BAB block
in the bundle, or it MAY be accomplished by two BAB blocks in the
bundle. To avoid confusion, we use the following terminology to
identify the block or blocks comprising a security-operation.
The terms "First" and "Last" are used ONLY when describing multiple
security blocks comprising a single security-operation. A "First"
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
is referred to as a "Lone" block. For example, when a bundle
authentication ciphersuite requires a single BAB block we refer to it
as a Lone BAB. When a bundle authentication ciphersuite requires two
BAB blocks we refer to them as the First BAB and the Last BAB.
This specification and individual ciphersuites impose restrictions on
what optional fields must and must not appear in First blocks, Last
blocks, and Lone blocks.
2.3. Bundle Authentication Block
This section describes typical field values for the BAB, which is
solely used to implement OP(authentication, bundle).
The block-type code field value MUST be 0x02.
The block processing control flags value can be set to whatever
values are required by local policy. Ciphersuite 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 be the entire bundle, which MUST be
represented by a type of 0x00.
The ciphersuite ID MUST be documented as a hop-by-hop
authentication-ciphersuite. When a Lone BAB is used, the
ciphersuite MUST be documented as requiring one instance of the
BAB. When a First BAB and Last BAB are used, the ciphersuite MUST
be documented as requiring two instances of the BAB.
The ciphersuite-parameters field MAY be present, if so specified
in the ciphersuite specification.
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An EID-reference to the security-source MAY be present in either a
First BAB or a Lone BAB. An EID-reference to the security-source
MAY NOT be present in a Last BAB.
The security-result captures the result of applying the
ciphersuite calculation (e.g., the MAC or signature) to the
relevant parts of the bundle, as specified in the ciphersuite
definition. This field MUST be present in either a Lone BAB or a
Last BAB. This field MUST NOT be present in a First BAB.
Notes:
o When multiple BAB blocks are used, the mandatory fields of the
Last BAB must match those of the First BAB.
o The First BAB or Lone BAB, when present, SHOULD immediately follow
the primary block.
o A Last BAB, when present, SHOULD be the last block in the bundle.
o Since OP(authentication, bundle) is allowed only once in a bundle,
it is RECOMMENDED that users wishing to support multiple
authentication signatures define a multi-target ciphersuite,
capturing multiple security results in ciphersuite parameters.
2.4. Block Integrity Block
A BIB is an ASB with the following additional restrictions:
The block-type code value MUST be 0x03.
The block processing control flags value can be set to whatever
values are required by local policy. Ciphersuite 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 payload block.
The reserved type 0x00 specifies the primary block. The security-
target for a BIB MAY NOT reference a security block defined in
this specification (BAB, BIB, or BCB).
The ciphersuite ID MUST be documented as an end-to-end
authentication-ciphersuite or as an end-to-end error-detection-
ciphersuite.
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The ciphersuite-parameters field MAY be present in either a Lone
BIB or a First BIB. This field MAY NOT be present in a Last BIB.
An EID-reference to the security-source MAY be present in either a
Lone BIB or a First BIB. This field MAY NOT be present in a Last
BIB.
The security-result captures the result of applying the
ciphersuite calculation (e.g., the MAC or signature) to the
relevant parts of the security-target, as specified in the
ciphersuite definition. This field MUST be present in either a
Lone BIB or a Last BIB. This field MUST NOT be present in a First
BIB.
The ciphersuite MAY process less than the entire security-target.
If the ciphersuite processes less than the complete, original
security-target, the ciphersuite-parameters MUST specify which
bytes of the security-target are protected.
Notes:
o Since OP(integrity, target) is allowed only once in a bundle per
target, it is RECOMMENDED that users wishing to support multiple
integrity signatures for the same target define a multi-signature
ciphersuite, capturing multiple security results in ciphersuite
parameters.
o For some ciphersuites, (e.g., those using asymmetric keying to
produce signatures or those using symmetric keying with a group
key), the security information MAY be checked at any hop on the
way to the destination that has access to the required keying
information, in accordance with Section 2.6.
o The use of a generally available key is RECOMMENDED if custodial
transfer is employed and all nodes SHOULD verify the bundle before
accepting custody.
2.5. Block Confidentiality Block
A BCB is an ASB with the following additional restrictions:
The block-type code value MUST be 0x04.
The block processing control flags value can be set to whatever
values are required by local policy, except that a Lone BCB or
First BCB MUST have the "replicate in every fragment" flag set.
This flag SHOULD NOT be set otherwise. Ciphersuite designers
should carefully consider the effect of setting flags that either
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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 security-target for a BCB MAY reference the payload
block, a non-security extension block, or a BIB block. The
reserved type 0x01 specifies the payload block.
The ciphersuite ID MUST be documented as a confidentiality
ciphersuite.
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
authentication processing of the security-target SHOULD be placed
in an "integrity check value" field (see Section 2.7) in the
security-result of the Lone BCB or First BCB.
The ciphersuite-parameters field MAY be present in either a Lone
BCB or a First BCB. This field MAY NOT be present in a Last BCB.
An EID-reference to the security-source MAY be present in either a
Lone BCB or a First BCB. This field MAY NOT be present in a Last
BCB. The security-source can also be specified as part of key-
information described in Section 2.7.
The security-result MAY be present in either a Lone BCB or a Last
BCB. This field MAY NOT be present in a First BCB. This compound
field normally contains fields such as an encrypted EK and/or
authentication tag.
The BCB is the only security block that modifies the contents of its
security-target. When a BCB is applied, the security-target body
data are encrypted "in-place". Following encryption, the security-
target body data contains ciphertext, not plaintext. Other security-
target block fields (such as type, processing control flags, and
length) remain unmodified.
Fragmentation, reassembly, and custody transfer are adversely
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.
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.
Ciphersuites SHOULD place any block expansion, such as authentication
tags (integrity check values) and any padding generated by a block-
mode cipher, into an integrity check value item in the security-
result field (see Section 2.7) of the BCB. This "in-place"
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encryption allows fragmentation, reassembly, and custody transfer to
operate without knowledge of whether or not encryption has occurred.
Notes:
o The ciphersuite MAY process less than the entire original
security-target body data. If the ciphersuite processes less than
the complete, original security-target body data, the BCB for that
security-target MUST specify, as part of the ciphersuite-
parameters, which bytes of the body data are protected.
o The BCB's "discard" flag may be set independently from its
security-target's "discard" flag. Whether or not the BCB's
"discard" flag is set is an implementation/policy decision for the
encrypting node. (The "discard" flag is more properly called the
"Discard if block cannot be processed" flag.)
o A BCB MAY include information as part of additional authenticated
data to address parts of the target block, such as EID references,
that are not converted to ciphertext.
At the bundle destination, the processes described above are
reversed.
2.6. Block Interactions
The three security-block types defined in this specification are
designed to be as independent as possible. While correlating
multiple block instances may result in minor space savings due to
shared information, such correlation also has the potential to
increase computational complexity and processing ambiguity. However,
there are some cases where security blocks may share a security-
target creating processing dependencies.
If confidentiality is being applied to a target that already has
integrity applied to it, then an undesireable condition occurs where
a security-aware intermediate node would be unable to check the
integrity result of a block because the block contents have been
encrupted after the integrity signature was generated. To address
this concern, the following processing rules MUST be followed.
o If confidentiality is to be applied to a target, it MUST also be
applied to every integrity operation already defined for that
target. This means that is a BCB is added to encrypt a block,
another BCB MUST also be added to encrypt a BIB also targeting
that block.
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o An integrity value MAY NOT be evaluated if the BIB providing the
integrity value is the security target of an existing BCB block in
the bundle. In such a case, the BIB data contains ciphertext as
it has been encrypted.
o An integrity value MAY NOT be evaluated if the security-target of
the BIB is also the security-target of a BCB in the bundle. In
such a case, the security-target data contains ciphertext as it
has been encrypted.
o As mentioned in Section 2.5, a BIB MAY NOT has a BCB as its
security target. BCBs may embed integrity results as part of
ciphersuite parameters.
2.7. Parameters and Result Fields
Various ciphersuites include several items in the security-parameters
and/or security-result fields. Which items MAY appear is defined by
the particular ciphersuite description. A ciphersuite 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
byte indicating which item this is. Length is the count of data
bytes to follow, and is an SDNV-encoded integer. Value is the data
content of the item.
Item types are
0: Reserved
1: Initialization Vector (IV)
2: Reserved
3: Key-Information
4: Content-Range (offset and length as a pair of SDNVs)
5: Integrity Signature
6: Unassigned
7: Salt
8: BCB Integrity Check Value (ICV), which is also referred to as
the Authentication Tag in this specification.
9 - 255: reserved
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The following descriptions apply to the usage of these items for all
ciphersuites. Additional characteristics are noted in the discussion
for specific suites.
o Initialization Vector (IV): random value, typically eight to
sixteen bytes.
o Key-Information: key material encoded or protected by the key
management system and used to transport an ephemeral key protected
by a long-term key.
o Content-Range: pair of SDNV values (offset then length) specifying
the range of payload bytes to which a particular operation
applies. The offset value MUST be the offset within the original
bundle, which might not be the offset within the current bundle if
the current bundle is already a fragment.
o Integrity Signature: result of BAB or BIB digest or signing
operation.
o Salt: an IV-like value used by certain confidentiality suites.
o BCB integrity check value (ICV): output from certain
confidentiality ciphersuite operations to be used at the
destination to verify that the protected data has not been
modified. This value MAY contain padding if required by the
ciphersuite.
2.8. BSP Block Example
An example of SBSP blocks applied to a bundle is illustrated in
Figure 4. In this figure the first column represents blocks within a
bundle and the second column represents a unique identifier for each
block, suitable for use as the security-target of a SBSP security-
block. Since the mechnism and format of a security-target is not
specified in this document, the terminology B1...Bn is used to
identify blocks in the bundle for the purposes of illustration.
Block in Bundle ID
+=================================+====+
| Primary Block | B1 |
+---------------------------------+----+
| First BAB | B2 |
| OP(authentication, Bundle) | |
+---------------------------------+----+
| Lone BIB | B3 |
| OP(integrity, target=B1) | |
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+---------------------------------+----+
| Lone BCB | B4 |
| OP(confidentiality, target=B5) | |
+---------------------------------+----+
| Extension Block | B5 |
+---------------------------------+----+
| Lone BIB | B6 |
| OP(integrity, target=B7) | |
+---------------------------------+----+
| Extension Block | B7 |
+---------------------------------+----+
| Lone BCB | B8 |
| OP(confidentiality, target=B9) | |
+---------------------------------+----+
| Lone BIB (encrypted by B8) | B9 |
| OP(integrity, target=B11) | |
+---------------------------------+----+
| Lone BCB |B10 |
| OP(confidentiality, target=B11) | |
+---------------------------------+----+
| Payload Block |B11 |
+---------------------------------+----+
| Last BAB |B12 |
| OP(authentication, Bundle) | |
+---------------------------------+----+
Figure 4: Sample Use of BSP Blocks
In this example a bundle has four non-security-related blocks: the
primary block, two extension blocks, and a payload block. The
following security applications are applied to this bundle.
o Authentication over the bundle. This is accomplished by two BAB
blocks: B2 and B12.
o An integrity signature applied to the primary block. This is
accomplished by a single BIB, B3.
o Confidentiality for the first extension block. This is
accomplished by a single BCB block, B4.
o Integrity for the second extension block. This is accomplished by
a single BIB block, B6.
o An integrity signature on the payload. This is accomplished by a
single BIB block, B9.
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o Confidentiality for the payload block and it's integrity
signature. This is accomplished by two Lone BCB blocks: B8
encrypting B9, and B10 encrypting B11.
3. Security Processing
This section describes the security aspects of bundle processing.
3.1. Canonical Forms
In order to verify a signature or MAC on a bundle, 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 or MAC value. Consequently, a node MUST NOT change the
encoding of any URI [RFC3986] in the dictionary field, e.g., changing
the DNS part of some HTTP URL from lower case to upper case. Because
bundles MAY be modified while in transit (either correctly or due to
implementation errors), canonical forms of security-targets MUST be
defined.
3.1.1. Bundle Canonicalization
Bundle canonicalization permits no changes at all to the bundle
between the security-source and the destination, with the exception
of one of the Block Processing Control Flags, as described below. It
is intended for use in BAB ciphersuites. This algorithm conceptually
catenates all blocks in the order presented, but omits all security-
result data fields in security blocks having the bundle as their
security-target. For example, when a BAB ciphersuite specifies this
algorithm, we omit the BAB security-result from the catenation.
Security-result length fields MAY or MAY NOT be included, even though
their corresponding security-result data fields are omitted, as
specified by the ciphersuite.
Notes:
o In the Block Processing Control Flags field, in every block other
than the Primary Block, the flag at bit 5, "Block was forwarded
without being processed" is zeroed out. The Block Processing
Control Flags field, which is an SDNV, is unpacked into a fixed-
width field, and some bits are masked out. The unpacked field is
ANDed with mask 0xFFFF FFFF FFFF FFDF to set to zero the "Block
was forwarded without being processed" bit. If this flag is not
zeroed out, then a bundle passes through a non-security aware
node, this flag will be set. This will then change the message
digest, and a BAB block will fail to verify.
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o In the above, we specify that security-result data is omitted.
This means that no bytes of the security-result data are input.
If the security-result length is included in the catenation, we
assume that the security-result length will be known to the module
that implements the ciphersuite before the security-result is
calculated, and require that this value be in the security-result
length field even though the security-result data itself will be
omitted.
o The 'res' bit of the ciphersuite ID, which indicates whether or
not the security-result length and security-result data field are
present, is part of the canonical form.
o The value of the block data length field, which indicates the
length of the block, is also part of the canonical form. Its
value indicates the length of the entire block when the block
includes the security-result data field.
3.1.2. Block Canonicalization
This algorithm protects those parts of a block that SHOULD NOT be
changed in transit.
Many fields in various blocks are stored as variable-length SDNVs.
These are canonicalized in unpacked form, as eight-byte fixed-width
fields in network byte order. The size of eight bytes is chosen
because implementations MAY handle larger values as invalid, as noted
in [RFC5050].
There are three types of blocks that may undergo block
canonicalization: the primary block, the payload block, or an
extension block.
3.1.2.1. Primary Block Canonicalization
The canonical form of the primary block is shown in Figure 5.
Essentially, it de-references the dictionary block, adjusts lengths
where necessary, and ignores flags that MAY change in transit.
+----------------+----------------+----------------+----------------+
| Version | Processing flags (incl. COS and SRR) |
+----------------+----------------+---------------------------------+
| Canonical primary block length |
+----------------+----------------+---------------------------------+
| Destination endpoint ID length |
+----------------+----------------+---------------------------------+
| Destination endpoint ID |
+----------------+----------------+---------------------------------+
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| Source endpoint ID length |
+----------------+----------------+----------------+----------------+
| Source endpoint ID |
+----------------+----------------+---------------------------------+
| Report-to endpoint ID length |
+----------------+----------------+----------------+----------------+
| Report-to endpoint ID |
+----------------+----------------+----------------+----------------+
+ Creation Timestamp (2 x SDNV) +
+---------------------------------+---------------------------------+
| Lifetime |
+----------------+----------------+----------------+----------------+
Figure 5: The Canonical Form of the Primary Bundle Block
The fields shown in Figure 5 are as follows:
o The version value is the single-byte value in the primary block.
o The processing flags value in the primary block is an SDNV, and
includes the class-of-service (COS) and status report request
(SRR) fields. For purposes of canonicalization, the SDNV is
unpacked into a fixed-width field, and some bits are masked out.
The unpacked field 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
containing the length (in bytes) of this structure, in network
byte order.
o The destination endpoint ID length and value are the length (as a
four-byte value in network byte order) and value of the
destination endpoint ID from the primary bundle block. The URI is
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
the destination.
o The report-to endpoint ID length and value are handled similarly
to the destination.
o The creation timestamp (2 x SDNV) and lifetime (SDNV) are simply
copied from the primary block, with the SDNV values being
represented as eight-byte unpacked values, in network byte order.
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o Fragment offset and total application data unit length are
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 security-parameters.
3.1.2.2. Payload Block Canonicalization
Payload blocks are canonicalized as-is, with the exception that, in
some instances, only a portion of the payload data is to be
protected. In such a case, only those bytes are included in the
canonical form, and additional ciphersuite-parameters are required to
specify which part of the payload is protected, as discussed further
below.
3.1.2.3. Extension Block Canonicalization
When canonicalizing an extension block, the block processing control
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
because the bundle may pass through nodes that do not understand that
extension block and this flag would be set.
Endpoint ID references in blocks are canonicalized using the de-
referenced text form in place of the reference pair. The reference
count is not included, nor is the length of the endpoint ID text.
The EID reference is, therefore, canonicalized as <scheme>:<SSP>,
which includes the ":" character.
The block-length is canonicalized as an eight-byte unpacked value in
network byte order. If the data to be canonicalized is less than the
complete, original block data, this field contains the size of the
data being canonicalized (the "effective block") rather than the
actual size of the block.
3.1.3. Considerations
o The canonical forms for the bundle and various extension blocks is
not transmitted. It is simply an artifact used as input to
digesting.
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o We omit the reserved flags because we cannot determine if they
will change in transit. The masks specified above will have to be
revised if additional flags are defined and they need to be
protected.
o Our URI encoding does not preserve the null-termination convention
from the dictionary field, nor do we canonicalize the scheme and
scheme-specific part (SSP) separately. Instead, the byte array <
scheme name > : < scheme-specific part (SSP)> is used in the
canonicalization.
o Since neither the length of the canonicalized EID text nor a null-
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.
o The URI encoding will cause errors if any node rewrites the
dictionary content (e.g., changing the DNS part of an HTTP URL
from lower case to upper case). This could happen transparently
when a bundle is synched to disk using one set of software and
then read from disk and forwarded by a second set of software.
Because there are no general rules for canonicalizing URIs (or
IRIs), this problem may be an unavoidable source of integrity
failures.
o All SDNV fields here are canonicalized as eight-byte unpacked
values in network byte order. Length fields are canonicalized as
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
themselves are immutable and they are unsuitable for use in
environments where that assumption might be violated.
o Ciphersuites MAY define their own canonicalization algorithms and
require the use of those algorithms over the ones provided in this
specification.
3.2. Endpoint ID Confidentiality
Every bundle MUST contain a primary block that contains the source
and destination endpoint IDs, and possibly other EIDs (in the
dictionary field), and that cannot be encrypted. If endpoint ID
confidentiality is required, then bundle-in-bundle encapsulation can
solve this problem in some instances.
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Similarly, confidentiality requirements MAY also apply to other parts
of the primary block (e.g., the current-custodian), and that is
supported in the same manner.
3.3. Bundles Received from Other Nodes
Security blocks MUST be processed in a specific order when received
by a security-aware node. The processing order is as follows.
o All BAB blocks in the bundle MUST be evaluated prior to evaluating
any other block in the bundle.
o All BCB blocks in the bundle SHOULD be evaluated prior to
evaluating any BIBs in the bundle. When BIBs and BCBs share a
security-target, BCBs MUST be evaluated first and BIBs second.
Nodes implementing this specification SHALL consult their security
policy to determine whether or not a received bundle is required by
policy to include a BAB. If the bundle has no BAB, and one is not
required, then BAB processing on the received bundle is complete, and
the bundle is ready to be further processed for BIB/BCB handling or
delivery or forwarding.
If the bundle is required to have a BAB but does not, then the bundle
MUST be discarded and processed no further. If the BAB security-
source cannot be determined or the security-result value check fails,
the bundle has failed to authenticate, and the bundle MUST be
discarded and processed no further. If the BAB verifies, or if a BAB
is not required, the bundle is ready for further processing as
determined by extension blocks and/or policy.
A BAB received in a bundle MUST be stripped before the bundle is
forwarded. A new BAB MAY be added as required by policy. This MAY
require correcting the "last block" field of the to-be-forwarded
bundle.
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
with the ciphersuite specification. If the security-target fails to
verify, it MUST be processed in accordance with the security policy
of the node.
If the security policy of a security-aware node specifies that a
bundle SHOULD apply integrity to a specific security-target and no
such BIB is present in the bundle, then the node MUST process this
security-target in accordance with the security policy. This MAY
involve removing the security-target from the bundle. If the removed
security-target is the payload or primary block, the bundle MAY be
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discarded. This action MAY occur at any node that has the ability to
verify an integrity signature, not just the bundle destination.
If the bundle has a BCB and the receiving node is the destination for
the bundle, the node MUST decrypt the relevant parts of the security-
target in accordance with the ciphersuite specification.
If the relevant parts of an encrypted payload cannot be decrypted
(i.e., the decryption key cannot be deduced or decryption fails),
then the bundle MUST be discarded and processed no further; in this
case, a bundle deletion status report (see [RFC5050]) indicating the
decryption failure MAY be generated. If any other encrypted
security-target cannot be decrypted then the associated security-
target and all security blocks associated with that target MUST be
discarded and processed no further.
When a BCB is decrypted, the recovered plaintext MUST replace the
ciphertext in the security-target body data
If the bundle has one or more BIBs and the receiving node is the
bundle's destination, the node MUST verify the value in each BIB
security-result field(s) in accordance with the ciphersuite
specification. If a BIB check fails, the security-target has failed
to authenticate and the security-target SHALL be processed according
to the security policy. A bundle status report indicating the
failure MAY be generated. Otherwise, if the BIB verifies, the
security-target is ready to be processed for delivery.
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
the security-result field. If it is able to check and the check
fails, the node SHALL process the security-target in accordance to
local security policy. It is RECOMMENDED that if a payload integrity
check fails that the bundle be discarded and that if an extension
block integrity check fails, the block and all security blocks using
it as their security-target be removed from the bundle.
3.4. Bundle Fragmentation and Reassembly
If it is necessary for a node to fragment a bundle and security
services have been applied to that bundle, the fragmentation rules
described in [RFC5050] MUST be followed. As defined there and
repeated here for completeness, only the payload MAY be fragmented;
security blocks, like all extension blocks, can never be fragmented.
In addition, the following security-specific processing is REQUIRED:
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o The security policy requirements for a bundle MUST be applied
individually to all the bundles resulting from a fragmentation
event.
o If the original bundle contained the security-operation
OP(integrity, payload), then each of the associated BIB blocks
MUST be included in some fragment.
o If the original bundle contained the security-operation
OP(confidentiality, payload), then the "first" BCB block, which
contains key-information, MUST have the "replicate in every
fragment" flag set, and thereby be replicated in every fragment.
This is to ensure that the canonical block-sequence can be
recovered during reassembly. The Last BCB for this security-
operation, if any, MUST be included in some fragment but SHOULD
NOT be sent more than once. They MUST be placed in a fragment in
accordance with the fragmentation rules described in [RFC5050].
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 may 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 Ciphersuites that support applying security-services to less than
the complete, original security-target MUST specify, as part of
the ciphersuite-parameters, which bytes of the security-target are
affected. When verification occurs, only the specified range of
the security-target bytes are used for verification.
o A BAB ciphersuite MAY specified that it only applied to non-
fragmented bundles and not to bundle fragments.
o A ciphersuite MAY be specified to apply to only a portion of a
security-target, regardless of whether the security-target is a
fragment.
o The decision to fragment a bundle MUST be made prior to adding
authentication to the bundle. A bundle with BAB blocks MAY NOT be
fragmented. Instead, the bundle MUST first be fragmented and
authentication applied to each individual fragment.
3.5. Reactive Fragmentation
When a partial bundle has been received, the receiving node SHALL
consult its security policy to determine if it MAY fragment the
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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 ciphersuite
used to calculate the BAB authentication information, if required.
4. Key Management
Key management in delay-tolerant networks is recognized as a
difficult topic and is one that this specification does not attempt
to solve.
5. Security Considerations
Certain applications of DTN need to both sign and encrypt a message,
and there are security issues to consider with this.
If the intent is to provide an assurance that a message did, in fact,
come from a specific source and has not been changed, then it should
be signed first and then encrypted. A signature on an encrypted
message does not establish any relationship between the signer and
the original plaintext message.
On the other hand, if the intent is to reduce the threat of denial-
of-service attacks, then signing the encrypted message is
appropriate. A message that fails the signature check will not be
processed through the computationally intensive decryption pass. A
more extensive discussion of these points is in S/MIME 3.2 Message
Specification [RFC5751], especially in Section 3.6.
If a security-destination were to generate reports in the event that
some security validation step fails, then that might leak information
about the internal structure or policies of the DTN containing the
security-destination. This is sometimes considered bad security
practice, so it SHOULD only be done with care.
6. Conformance
All implementations are strongly RECOMMENDED to provide at least a
BAB ciphersuite. A relay node, for example, might not deal with end-
to-end confidentiality and data integrity, but it SHOULD exclude
unauthorized traffic and perform hop-by-hop bundle verification.
7. IANA Considerations
This protocol has fields that have been registered by IANA.
7.1. Bundle Block Types
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This specification allocates three codepoints from the existing
"Bundle Block Types" registry defined in [RFC6255].
Additional Entries for the Bundle Block-Type Codes Registry:
+--------+-----------------------------+---------------+
| Value | Description | Reference |
+--------+-----------------------------+---------------+
| 2 | Bundle Authentication Block | This document |
| 3 | Block Integrity Block | This document |
| 4 | Block Confidentiality Block | This document |
+--------+-----------------------------+---------------+
Table 1
7.2. Ciphersuite Flags
This protocol has a ciphersuite flags field and certain flags are
defined. An IANA registry has been set up as follows.
The registration policy for this registry is: Specification Required
The Value range is: Variable Length
Ciphersuite Flag Registry:
+------------------------+------------------------+-----------------+
| Bit Position (right to | Description | Reference |
| left) | | |
+------------------------+------------------------+-----------------+
| 0 | Block contains result | This document |
| 1 | Block Contains | This document |
| | parameters | |
| 2 | Source EID ref present | This document |
| >3 | Reserved | This document |
+------------------------+------------------------+-----------------+
Table 2
7.3. Parameters and Results
This protocol has fields for ciphersuite-parameters and results. 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
ciphersuite-parameters and the ciphersuite results fields. Certain
values are defined. An IANA registry has been set up as follows.
The registration policy for this registry is: Specification Required
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The Value range is: 8-bit unsigned integer.
Ciphersuite-Parameters and Results Type Registry:
+---------+---------------------------------+---------------+
| Value | Description | Reference |
+---------+---------------------------------+---------------+
| 0 | reserved | This document |
| 1 | initialization vector (IV) | This document |
| 2 | reserved | This document |
| 3 | key-information | This document |
| 4 | content-range (pair of SDNVs) | This document |
| 5 | integrity signature | This document |
| 6 | unassigned | This document |
| 7 | salt | This document |
| 8 | BCB integrity check value (ICV) | This document |
| 9-191 | reserved | This document |
| 192-250 | private use | This document |
| 251-255 | reserved | This document |
+---------+---------------------------------+---------------+
Table 3
8. References
8.1. Normative References
[RFC2119] Bradner, S., "Key words for use in RFCs to Indicate
Requirement Levels", BCP 14, RFC 2119, March 1997.
[RFC5050] Scott, K. and S. Burleigh, "Bundle Protocol
Specification", RFC 5050, November 2007.
[RFC6255] Blanchet, M., "Delay-Tolerant Networking Bundle Protocol
IANA Registries", RFC 6255, May 2011.
8.2. Informative References
[RFC3986] Berners-Lee, T., Fielding, R., and L. Masinter, "Uniform
Resource Identifier (URI): Generic Syntax", STD 66, RFC
3986, January 2005.
[RFC4838] Cerf, V., Burleigh, S., Hooke, A., Torgerson, L., Durst,
R., Scott, K., Fall, K., and H. Weiss, "Delay-Tolerant
Networking Architecture", RFC 4838, April 2007.
Birrane Expires January 16, 2014 [Page 29]
Internet-Draft SBSP July 2013
[RFC5751] Ramsdell, B. and S. Turner, "Secure/Multipurpose Internet
Mail Extensions (S/MIME) Version 3.2 Message
Specification", RFC 5751, January 2010.
[RFC6257] Symington, S., Farrell, S., Weiss, H., and P. Lovell,
"Bundle Security Protocol Specification", RFC 6257, May
2011.
Appendix A. Acknowlegements
The following participants contributed technical material, use cases,
and useful thoughts on the overall approach to this security
specification: Scott Burleigh of the Jet Propulsion Laboratory, Amy
Alford and Angela Hennessy of the Laboratory for Telecommunications
Sciences, and Angela Dalton and Cherita Corbett of the Johns Hopkins
University Applied Physics Laboratory.
Author's Address
Edward J. Birrane, III
The Johns Hopkins University Applied Physics Laboratory
11100 Johns Hopkins Rd.
Laurel, MD 20723
US
Phone: +1 443 778 7423
Email: Edward.Birrane@jhuapl.edu
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