wdiff draft-ietf-dtn-bpsec-00.txt draft-ietf-dtn-bpsec-01.txt

Delay-Tolerant Networking E. Birrane
Internet-Draft JHU/APL
Intended status: Experimental J. Mayer
Expires: July 1, September 20, 2016 INSYEN AG
D. Iannicca
NASA GRC
December 29, 2015
March 19, 2016

Bundle Protocol Security Specification
draft-ietf-dtn-bpsec-00
draft-ietf-dtn-bpsec-01

Abstract

This document defines a security protocol providing data
authentication, integrity, integrity
and confidentiality services for the Bundle Protocol. Capabilities
are provided to protect blocks in a bundle along a single path
through a network.

Status of This Memo

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provisions of BCP 78 and BCP 79.

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Table of Contents

1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 3
1.1. Related Documents . . . . . . . . . . . . . . . . . . . . 3
1.2. Terminology . . . . . . . . . . . . . . . . . . . . . . . 4
2. Key Properties . . . . . . . . . . . . . . . . . . . . . . . 6
2.1. Block-Level Granularity . . . . . . . . . . . . . . . . . 6
2.2. Multiple Security Sources . . . . . . . . . . . . . . . . 7 6
2.3. Single Security Destinations . . . . . . . . . . . . . . 7
2.4. Mixed Security Policy . . . . . . . . . . . . . . . . . . 8
2.5. 7
2.4. User-Selected Ciphersuites . . . . . . . . . . . . . . . 8
2.6.
2.5. Deterministic Processing . . . . . . . . . . . . . . . . 8
3. Security Block Definitions . . . . . . . . . . . . . . . . . 9 8
3.1. Block Identification . . . . . . . . . . . . . . . . . . 10 9
3.2. Abstract Security Block Representation . . . . . . . . . . . . . . . . . 11
3.3. Block Ordering . 9
3.2.1. CMS Block Type-Specific Data Fields . . . . . . . . . 10
3.2.2. BIB and BCB Block Type-Specific Data Fields . . . . . 10
3.3. Block Ordering . . . . . . 14
3.4. Bundle Authentication Block . . . . . . . . . . . . . . . 15
3.5. 11
3.4. Block Integrity Block . . . . . . . . . . . . . . . . . . 16
3.6. 12
3.5. Block Confidentiality Block . . . . . . . . . . . . . . . 17
3.7. 13
3.6. Cryptographic Message Syntax Block . . . . . . . . . . . 19
3.8. 15
3.7. Block Interactions . . . . . . . . . . . . . . . . . . . 20
3.9. 16
3.8. Parameters and Result Fields . . . . . . . . . . . . . . 22
3.10. 17
3.9. BSP Block Example . . . . . . . . . . . . . . . . . . . . 24 19
4. Security Processing . . . . . . . . . . . . . . . . . . . . . 27 22
4.1. Canonical Forms . . . . . . . . . . . . . . . . . . . . . 27 22
4.1.1. Bundle Canonicalization . . . . . . . . . . . . . . . 27
4.1.2. Block Canonicalization . . . . . . . . . . . . . . . 28
4.1.3. 22
4.1.2. Considerations . . . . . . . . . . . . . . . . . . . 31 25
4.2. Endpoint ID Confidentiality . . . . . . . . . . . . . . . 32 25
4.3. Bundles Received from Other Nodes . . . . . . . . . . . . 32 26
4.3.1. Receiving BAB Blocks . . . . . . . . . . . . . . . . 32
4.3.2. Receiving BCB Blocks . . . . . . . . . . . . . . . . 33
4.3.3. 26
4.3.2. Receiving BIB Blocks . . . . . . . . . . . . . . . . 33 26
4.4. Receiving CMSB Blocks . . . . . . . . . . . . . . . . . . 34 27
4.5. Bundle Fragmentation and Reassembly . . . . . . . . . . . 34 27
4.6. Reactive Fragmentation . . . . . . . . . . . . . . . . . 35 28
5. Key Management . . . . . . . . . . . . . . . . . . . . . . . 35 28
6. Policy Considerations . . . . . . . . . . . . . . . . . . . . 35 28
7. Security Considerations . . . . . . . . . . . . . . . . . . . 36 29
8. Conformance . . . . . . . . . . . . . . . . . . . . . . . . . 37 29
9. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 37 30
9.1. Bundle Block Types . . . . . . . . . . . . . . . . . . . 37 30
9.2. Cipher Suite Flags . . . . . . . . . . . . . . . . . . . 37 30
9.3. Parameters and Results . . . . . . . . . . . . . . . . . 38 31
10. References . . . . . . . . . . . . . . . . . . . . . . . . . 39 31
10.1. Normative References . . . . . . . . . . . . . . . . . . 39 31
10.2. Informative References . . . . . . . . . . . . . . . . . 39 32

Appendix A. Acknowledgements . . . . . . . . . . . . . . . . . . 40 32
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 40 32

1. Introduction

This document defines security features for the Bundle Protocol
[RFC5050]
[BPBIS] 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 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 Bundle Protocol Security Specification
(BPSec), which provides security services for blocks within a bundle
from the bundle source to the bundle destination. Specifically,
BPSec provides authentication, integrity, integrity and confidentiality for bundles along a path
through a DTN.

BPSec 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 BPSec. All nodes can interoperate with the
exception that BPSec security operations can only happen at BPSec
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] [BPBIS] 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] and Streamlind Bundle Security
Protocol [SBSP] introduce the concepts of security blocks for
authentication, confidentiality, and integrity.
security services. BPSec is based off of this document. these documents.

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, Waypoint, 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. The path is not
necessarily known by the bundle, or any bundle-aware nodes.

Figure 1 below is adapted from [RFC5050] [BPBIS] 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 Sitting 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
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 BPSec 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.

2. Key Properties

The application of security services in a DTN is a complex endeavor
that must consider physical properties of the network, policies at
each node, and various application security requirements. Rather
than enumerate all potential security implementations in all
potential DTN topologies, this specification defines a set of key
properties of a security system. The security primitives outlined in
this document MUST enable the realization of these properties in a
DTN deploying the Bundle Protocol.

2.1. Block-Level Granularity

Blocks within a bundle represent different types of information. The
primary block contains identification and routing information. The
payload block carries application data. Extension blocks carry a
variety of data that may augment or annotate the payload, or
otherwise provide information necessary for the proper processing of
a bundle along a path. Therefore, applying a single level and type
of security across an entire bundle fails to recognize that blocks in
a bundle may represent different types of information with different
security needs.

Security services within this specification MUST provide block level
granularity where applicable such that different blocks within a
bundle may have different security services applied to them.

For example, within a bundle, a payload might be encrypted to protect
its contents, whereas an extension block containing summary
information related to the payload might be integrity signed but
otherwise unencrypted to provide certain nodes access to payload-
related data without providing access to the payload.

2.2. Multiple Security Sources

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
adds a new extension block to a bundle, that extension block may have
security services applied to it by that waypoint. Similarly, a
waypoint node may add a security service to an existing extension
block, consistent with its security policy. For example, a node
representing a boundary between a trusted part of the network and an
untrusted part of the network may wish to apply payload encryption
for bundles leaving the trusted portion of the network.

In each case, a node other than the bundle originator may be adding a
security service to the bundle and, as such, the source for the
security service will be different than the source of the bundle
itself. Security services MUST track their orginating node so as to
properly apply policy and key selection associated with processing
the security service at the bundle destination.

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
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.

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. security-source.

As required in [RFC5050], [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. Single Mixed Security Destinations

The destination of all security blocks Policy

Different nodes in a bundle MUST DTN may have different security-related
capabilities. Some nodes may not be the bundle
destination, with the exception security-aware and will not
understand any security-related extension blocks. Other nodes may
have security policies that require evaluation 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.

2.4. Mixed Security Policy

Different nodes in a DTN may have different security-related
capabilities. Some nodes may not be security-aware and will not
understand any security-related extension blocks. Other nodes may
have security policies that require evaluation of security services
at places other than services
at places other than the bundle destination (such as verifying
integrity signatures at certain waypoint nodes). Other nodes may
ignore any security processing if they are not the destination of the
bundle. The security services described in this specification must
allow each of these scenarios.

Extension blocks representing security services MUST have their block
processing flags set such that the block (and bundle, where
applicable) will be treated appropriately by non-security-aware
nodes.

Extension blocks providing integrity and authentication services within a bundle MUST
support options to allow waypoint nodes to evaluate these signatures
if such nodes have the proper configuraton to do so.

2.5.

2.4. User-Selected Ciphersuites

The security services defined in this specification rely on a a
variety of ciphersuites providing integrity signatures, ciphertext,
and other information necessary to populate security blocks. Users
may wish to select differing ciphersuites to implement different
security services. For example, some users may wish to use a SHA-1
based hash for integrity whereas other users may require a SHA-2 hash
instead. The security services defined in this specification MUST
provide a mechanism for identifying what ciphersuite has been used to
populate a security block.

2.6.

2.5. Deterministic Processing

In all cases, the processing order of security services within a
bundle must avoid ambiguity when evaluating security at the bundle
destination. This specification MUST provide determinism in the
application and evaluation of security services, even when doing so
results in a loss of flexibility.

3. Security Block Definitions

There are four three types of security blocks that MAY be included in a
bundle. These are the Bundle Authentication Block (BAB), the Block Integrity Block (BIB), the Block
Confidentiality Block (BCB), and the Cryptographic Messaging Syntax
Block (CMSB).

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 choose to require BABs from a given
neighbor in the network in order to receive and process a received
bundle.

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. security-target.
The authentication integrity information in the BIB MAY (when possible) be
verified by any node in between the BIB security-source and the
bundle destination. BIBs MAY be added to, and removed from,
bundles as a matter of security policy.

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 transit. The BCB may be decrypted by
appropriate nodes in the network, up to and including the bundle destination.
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 authentication 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(authentication,bundle) OP(integirty, target) in
this example.

A security-operation MUST NOT be applied more than once in a bundle.
For example, the two security-operations: OP(integrity, payload) and
OP(integrity, payload) are considered redundant and MUST 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.

Many of the fields in these block definitions use the Self-Delimiting
Numeric Value (SDNV) type whose format and encoding is as defined in
[RFC5050].
[BPBIS].

3.1. Block Identification

This specification requires that every target block of a security
operation be uniquely identifiable. In cases where there can only be
a single instance The definition of a block in the bundle (as is the case with the
primary extension
block and the payload block) then header from [BPBIS] provides such a mechanism in the "block
number", which provides a unique identifier is
simply the for a block type. These blocks are described as "singleton
blocks". It is possible that within a bundle may contain multiple instances
of a block type. In such
bundle. Within this specification, a case, each instance of the target block type
must will be uniquely identifiable and identified
by its unique block number.

3.2. Block Representation

Each security block uses the Canonical Bundle Block Format as defined
in [BPBIS]. That is, each security block type itself is not
sufficient for this identification. These blocks are described as
"non-singleton blocks".

The definition comprised of the extension block header from [RFC5050] does not
provide additional identifying information for a block beyond the
block type.
following elements:

o Block Type Code

o Block Number

o Block Processing Control Flags

o Block Data Length

o Block Type Specific Data Fields

3.2.1. CMS Block Type-Specific Data Fields

The addition contents of an occurrence number to the CMS block is
necessary to identify the block instance in the bundle. This section
describes the use of an Artificial EID (AEID) reference in a block
header to add unique identification for non-singleton blocks.

Figure 7 single field of [RFC5050] illustrates that an EID reference in a block
header CMS data whose
length is specified by the 2-tuple BLock Data Length parameter.

3.2.2. BIB and BCB Block Type-Specific Data Fields

The structure of the reference scheme BIB and the reference
scheme specific part (SSP), each of which BCB type-specific data fields are encoded as SDNVs. The
AEID MUST encode the occurrence number in the reference scheme SDNV
identifcal and MUST set given in Figure 2. Although the reference SSP to 0. A reference SSP value of 0 diagram hints at a
fixed-format layout, this is
an invalid offset purely for an SSP in the bundle dictionary and, therefore, the use purpose of 0 in this field identifies the reference as an AEID.

The occurrence number MAY be any positive value that is not already
present as an occurrence number exposition.
Except for the same block type "type" field, all fields are variable in the
bundle. These numbers length.
Fields annotated with an '*' are independent of relative optional, with their inclusion in
the block position
within indicated by the bundle, cipher suite flags field.

Figure 2: BIB and whether blocks BCB Block Structure

The BIB and BCB type-specific data fields consist of the same type have been
added or removed from following
fields, some of which are optional.

o Security-Target (SDNV) - Uniquely identifies the bundle. Once an AEID has been added to a
block instance, it target of the
associated security-operation. This MUST NOT be changed until all security operations
that target the block instance have been removed from number of a
block in the bundle.

If a node wishes

o Cipher suite ID (SDNV) - Identifies the ciphersuite used to apply a
implement the security service reprsented by this block.

o Cipher suite flags (SDNV) - Identifies which optional security operation to a target
block it
MUST determine whether fields are present in the target block is a singleton block or a
non-singleton block. If The structure of the target block
cipher suite flags field is non-singleton, then shown in Figure 3. The presence of an
optional field is indicated by setting the
node MUST find value of the AEID for
corresponding flag to one. A value of zero indicates the target. If an AEID
corresponding optional field is not present. The BPSEC cipher
suite flags are defined as follows.

* bits 6-3 are reserved for future use.

* src - bit 2 indicates whether the security source EID is
present in the target block header then block. This identifief the node MAY choose to either cancel EID that inserted
the security operation or add an AEID to the block, service in accordance with
security policy.

If a node chooses to add an AEID to a target block header it MUST
perform the following activities.

o The "Block contains an EID reference field" flag MUST be set for bundle. If the target block, if it security source is
not already set.

o The EID reference count for the block MUST be updated to reflect
the addition of present then the AEID.

o The scheme offset souce of the AEID MUST block MAY be a value greater than 0. The
scheme offset MUST NOT taken to be the same as any other AEID of any other
block in the
bundle sharing the same block type.

o The SSP offset of the AEID MUST be source, the value 0. There MUST NOT be
any previous hop, or some other EID in the block header that has a value of 0 for as defined
by security policy.

* parm - bit 1 indicates whether or not the
SSP offset.

If there is no AEID cipher suite
parameters fields are present in a block, and if a node is unable to
add an AEID by following the above process, then block.

* res - bit 0 indicates whether or not the block MUST NOT
have an BPSec security operation applied to it.

It is RECOMMENDED that every block result fields
are present in a bundle other than the primary
and payload blocks be treated as a non-singleton block. However, the
identification

Bit Bit Bit Bit Bit Bit Bit
6 5 4 3 2 1 0
+-----+-----+-----+-----+-----+-----+-----+
| reserved | src |parm | res |
+-----+-----+-----+-----+-----+-----+-----+

Figure 3: Cipher suite flags

o (OPTIONAL) Parameters - compound field of singleton blocks SHOULD be in accordance with the
security policy following two items.

* Length (SDNV) - specifies the length of a node.

3.2. Abstract Security Block

Each security block uses the Canonical Bundle Block Format as defined
in [RFC5050]. That is, next field, which
captures the parameters data.

* Data - A byte array encoding one or more cipher suite
parameters, with each security block parameter represented as a Type-Length-
Value (TLV) triplet. In this triplet, the type and length are
represented as SDNVs and the value is comprised of a byte array holding the
following elements:

o Block Type Code

o Block Processing Control Flags
parmeter. See Section 3.8 for a list of parameter types that
MUST be supported by BPSEC implementations. BPSEC cipher suite
specifications MAY define their own parameters to be
represented in this byte array.

o Block EID Reference List (OPTIONAL)

o Block Data Security Result - compound field of the next two items.

* Length

o Block Type Specific Data Fields

Since (SDNV) - specifies the four security block types have most fields in common, we
can shorten length of the next field, which
is the security-result data.

* Data - A byte array containing the description results of the block type appropriate
cipher suite specific data fields if
we first define an abstract calculation (e.g., a signature, Message
Authentication Code (MAC), or cipher-text block key).

3.3. Block Ordering

A security-operation may be implemented in a bundle using either one
or two security blocks. For example, the operation OP(integrity,
block) MAY be accomplished by a single BIB block (ASB) and then specify
each of in the real bundle, or it
MAY be accomplished by two BIB 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 bundle. To avoid
confusion, we use the following terminology to identify the block or
blocks comprising a specification artifact. security-operation.

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.

+-----------------------------+----------------------------------+
| Block Type Code (BYTE) | Processing Control Flags (SDNV) |
+-----------------------------+----------------------------------+
| EID Reference Count terms "First" and List (Compound List) |
+-----------------------------+----------------------------------+
| Block Length (SDNV) | Security Target (Compound) |
+-----------------------------+----------------------------------+
| Cipher suite ID (SDNV) | Cipher suite 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 "Last" are optional.

o Block-Type Code (Byte) - as described in [RFC5050]. The block-
type codes for used ONLY when describing multiple
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 comprising a single security-operation. A "First"
block refers to the use of security block that is closest to the primary
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 canonical form of the "Block contains an EID reference field"
(EID_REF) bit of bundle. A "Last" block refers to
the security block processing control flags. If no EID
fields are present, then that is furthest from the composite field itself MUST be
omitted entirely and primary block in the EID_REF bit MUST be unset. A count field
canonical form of zero is not permitted. The possible EIDs are:

(OPTIONAL) Security-source - specifies the security-source for the block. bundle.

If this is omitted, then the source of a single security block implements the bundle security-operation, then it
is assumed referred to be the security-source unless otherwise indicated
by policy or associated as a "Lone" block. For example, when a bundle
authentication cipher suite definition. When present,
the security-source MUST be the first EID in the list.

(OPTIONAL) AEID - specifies an identifier that can be used requires a single BIB block we refer to
uniquely identify an instance of
it as a non-singleton block. This
field MUST be present for non-singleton blocks. This field
MUST NOT be present for singleton blocks, such Lone BAB. When a bundle authentication cipher suite requires
two BIB blocks we refer to them as the primary
block First BIB and the payload block. The construction of the AEID is
discussed in Section 3.1.

o Block Length (SDNV) - as described in [RFC5050].

o Block type specific data Last BIB.

This specification and individual cipher suites impose restrictions
on what optional fields as follows:

* Security-Target (Compound) - Uniquely identifies the target of
the associated security-operation.

As discussed must and must not appear in Section 3.1 a singleton block is identified by
its block type First blocks,
Last blocks, and a non-singleton block Lone blocks.

3.4. Block Integrity Block

A BIB is identified by the
combination of its block type and an occurrence number. The
security-target is a compound field that contains ASB with the block
type (as a byte) and occurrence number (as an SDNV). following additional restrictions:

The occurrence number of a singleton block block-type code value MUST be set to 0. 0x02.

The occurrence number of a non-singleton block MUST processing control flags value can be set to whatever
values are required by local policy. Cipher suite designers
should carefully consider the scheme offset effect of the AEID associated with setting flags that either
discard the block being
targeted by or delete the security operation.

* (OPTIONAL) Cipher suite ID (SDNV)

* (OPTIONAL) Cipher suite flags (SDNV)

* (OPTIONAL) Cipher Suite Parameters - compound field of bundle in the next
two items.

+ Cipher suite parameters length (SDNV) - specifies event that this
block cannot be processed.

The security-target MUST match the length BLock Number of a block within
the next field, which is the bundle. The security-target for a BIB MUST NOT reference a
security block defined in this specification (BIB, BCB, or CMSB).

The cipher suite-parameters data
field.

+ Cipher suite parameters data - parameters to ID MUST be used with
the documented as an end-to-end
authentication-cipher suite or as an end-to-end error-detection-
cipher suite.

The cipher suite parameters field MAY be present in use, e.g., either a key identifier Lone
BIB or
initialization vector (IV). See Section 3.9 for a list of
potential parameters and their encoding rules. The
particular set of parameters that is included in this First BIB. This field
is defined as part of MUST NOT be present in a cipher suite specification.

* (OPTIONAL) Security Result - compound field of the next two
items.

+ Security result length (SDNV) - contains the length of the
next field, which is Last BIB.

An EID-reference to the security-source MAY be present in either a
Lone BIB or a First BIB. This field MUST NOT be present in a Last
BIB.

The security-result data field.

+ Security result data - contains captures the results result of applying the
appropriate cipher
suite specific calculation (e.g., a
signature, Message Authentication Code (MAC), the MAC or cipher-text
block key).

The structure signature) to the relevant
parts of the security-target, as specified in the cipher suite flags
definition. This field is shown MUST be present in Figure 3.
In each case, the presence of an optional either a Lone BIB or a
Last BIB. This field is indicated by
setting MUST NOT be present in a First BIB.

The cipher suite MAY process less than the value of entire security-target.
If the corresponding flag to one. A value cipher suite processes less than the complete, original
security-target, the cipher suite parameters MUST specify which
bytes of zero
indicates the corresponding optional field is missing. Presently,
there security-target are three flags defined 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 field; for convenience, these
are shown as they would be extracted from same target define a single-byte SDNV. Future
additions may cause the field to grow multi-signature
cipher suite, capturing multiple security results in cipher suite
parameters.

o For some cipher suites, (e.g., those using asymmetric keying to the left so, as
produce signatures or those using symmetric keying with a group
key), the
flags fields defined in [RFC5050], the description below numbers the
bit positions from the right rather than security information MAY be checked at any hop on the standard RFC definition,
which numbers bits from
way to the left.

bits 6-3 are reserved for future use.

src - bit 2 indicates whether destination that has access to the EID-reference field required keying
information, in accordance with Section 3.7.

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.

3.5. Block Confidentiality Block

A BCB is an ASB
contains with the optional reference following additional restrictions:

The block-type code value MUST be 0x03.

The block processing control flags value can be set to the security-source.

parm - bit 1 indicates whether or not the cipher suite parameters
length and cipher suite parameters data fields whatever
values 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: Cipher Suite Flags

3.3. Block Ordering

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 required by local policy, except that a single BAB block
in the bundle, Lone BCB or it MAY be accomplished by two BAB blocks in the
bundle. To avoid confusion, we use
First BCB MUST have the following terminology "replicate in every fragment" flag set.
This indicates 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 receiving node that is closest to the primary
block payload portion in
each fragment represents cipher-text. This flag SHOULD NOT be set
otherwise. Cipher suite designers should carefully consider the canonical form
effect of setting flags that either discard the bundle. A "Last" block refers to or delete
the security block that is furthest from bundle in the primary event that this block in cannot be processed.

The security-target MUST match the
canonical form BLock Number of the bundle.

If a single security block implements within
the security-operation, then it
is referred to as bundle. The security-target for a "Lone" block. For example, when a bundle
authentication cipher suite requires a single BAB block we refer to
it as a Lone BAB. When a bundle authentication cipher suite requires
two BAB blocks we refer to them as the First BAB and the Last BAB.

This specification and individual cipher suites impose restrictions
on what optional fields must and must not appear in First blocks,
Last blocks, and Lone blocks.

3.4. 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. Cipher suite designers
should carefully consider the effect of setting flags that either
discard BCB MAY reference the block
payload block, a non-security extension 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 <block type><occurrence number> of <0x00><0x00>. BIB block.

The cipher suite ID MUST be documented as a hop-by-hop
authentication confidentiality cipher
suite. When

Key-information, if available, MUST appear only in a Lone BAB is used, the cipher
suite MUST be documented as requiring one instance of the BAB.
When BCB or a
First BAB and Last BAB are used, BCB.

Any additional bytes generated as a result of encryption and/or
authentication processing of the cipher suite MUST security-target SHOULD be
documented as requiring two instances placed
in an "integrity check value" field (see Section 3.8) in the
security-result of the BAB. Lone BCB or Last BCB.

The cipher suite parameters field MAY be present, if so specified
in the cipher suite specification.

An EID-reference to the security-source MAY be present in either a
First BAB Lone
BCB or a Lone BAB. 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
Lone BCB or a First BCB. This field MUST NOT be present in a Last BAB.
BCB. The security-result captures the result of applying the cipher
suite calculation (e.g., the MAC or signature) to the relevant
parts of the bundle, as security-source can also be specified as part of key-
information described in the cipher suite definition.
This field MUST Section 3.8.

The security-result MAY be present in either a Lone BAB BCB or a Last BAB.
BCB. This field MUST NOT be present in a First BAB.

Notes:

o BCB. This
compound field normally contains fields such as an encrypted
bundle encryption key and/or authentication tag.

The BCB is the only security block that modifies the contents of its
security-target. When multiple BAB blocks a BCB is applied, the security-target body
data are used, encrypted "in-place". Following encryption, the mandatory security-
target body data contains cipher-text, not plain-text. 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
Last BAB must match those payload due to ambiguity about
what byte range 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 actually in any particular fragment.
Therefore, when the security-target of a bundle,
it is RECOMMENDED that users wishing to support multiple
authentication signatures define a multi-target cipher suite,
capturing multiple security results in cipher suite parameters.

3.5. Block Integrity Block

A BIB BCB is an ASB with the following additional restrictions:

The block-type code bundle payload,
the BCB MUST NOT alter the size of the payload block body data.
Cipher suites 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 3.8) of the BCB. This "in-
place" encryption allows fragmentation, reassembly, and custody
transfer to operate without knowledge of whether or not encryption
has occurred.

Notes:

o The BCB's "discard" flag may be 0x03. 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 cipher-text.

3.6. Cryptographic Message Syntax Block

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 reserved type 0x00 specifies security operation(s) will be performed on the singleton
primary block. The security-target for a BIB MUST NOT reference a
security block defined in this specification (BAB, BIB, or BCB).

The cipher suite ID MUST
block's data and the resulting CMS content will be documented as an end-to-end
authentication-cipher suite or as an end-to-end error-detection-
cipher suite. stored within
the CMSB block's security-result field. The cipher suite parameters field MAY security-target
block's data will then be present in either a Lone
BIB or removed.

A CMSB block MAY include multiple CMS security operations within a First BIB. This field MUST NOT
single block to allow for multiple nested operations to be present in
performed on a Last BIB.

An EID-reference to the security-source bundle block. Multiple CMSB blocks MAY be present included
in either a
Lone BIB or a First BIB. This field bundle as long as the security-target for each is unique.

Key-information, if available, MUST NOT be present 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 Last
BIB. unique bundle block. The security-result captures CMS security operations are
performed upon the result of applying security-target's data field and the cipher
suite calculation (e.g., resulting
encoded CMS content is stored within the MAC CMS security-result field of
the CMSB's payload. The security-target block's data MAY be left
intact, replaced with alternate data, or signature) to completely erased based on
the relevant
parts specification of the security-target, as specified in the cipher suite
definition. This field MUST utilized CMS ciphersuite definition and
applicable policy.

Multiple CMS operations may be present in either a Lone BIB or nested within a
Last BIB. This field MUST NOT be present in a First BIB.

The cipher suite MAY process less single CMSB block to
allow more than the entire 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
to be as independent as possible. 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 undesirable condition occurs where a
security-aware intermediate node would be unable to check the cipher suite processes less than
integrity result of a block because the complete, original
security-target, block contents have been
encrypted after the cipher suite parameters MUST specify which
bytes of integrity signature was generated. To address
this concern, the security-target are protected.

Notes: following processing rules MUST be followed.

o Since OP(integrity, target) If confidentiality is allowed only once in to be applied to a bundle per target, it is RECOMMENDED that users wishing MUST also be
applied to support multiple every integrity signatures operation already defined for the same target define that
target. This means that if a multi-signature
cipher suite, capturing multiple security results in cipher suite
parameters.

o For some cipher suites, (e.g., those using asymmetric keying BCB is added to
produce signatures or those using symmetric keying with encrypt a group
key), the security information MAY be checked at any hop on the
way block,
another BCB MUST also be added to the destination encrypt a BIB also targeting
that has access block.

o An integrity operation MUST NOT be applied to a security-target if
a BCB in the required keying
information, bundle shares the same security-target. This
prevents ambiguity in accordance with Section 3.8.

o The use the order of evaluation when receiving a generally available key is RECOMMENDED if custodial
transfer is employed BIB
and all nodes SHOULD verify the bundle before
accepting custody.

3.6. Block Confidentiality Block

A a BCB is an ASB with the following additional restrictions:

The block-type code for a given security-target.

o An integrity value MUST NOT be 0x04.

The block processing control flags evaluated if the BIB providing the
integrity value can be set to whatever
values are required by local policy, except that a Lone BCB or
First BCB MUST have is the "replicate security target of an existing BCB block in every fragment" flag set.
This indicates to
the bundle. In such a receiving node that case, the payload portion in
each fragment represents cipher-tex

t. This flag SHOULD BIB data contains cipher-text as
it has been encrypted.

o An integrity value MUST NOT be set otherwise. Cipher suite designers
should carefully consider evaluated if the effect security-target of setting flags that either
discard the block or delete
the bundle in BIB is also the event that this
block cannot be processed.

The security-target MUST uniquely identify of a block within BCB in the bundle. The security-target for In
such a BCB MAY reference case, the payload
block, a non-security extension block, or security-target data contains cipher-text as it
has been encrypted.

o As mentioned in Section 3.5, a BIB block. The
reserved type 0x01 specifies the singleton payload block.

The MUST NOT have a BCB as its
security target. BCBs may embed integrity results as part of
cipher suite ID 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 documented as considered for block interactions (e.g., a confidentiality cipher
suite.

Key-information, if available, Signed-Data
structure MUST appear only in NOT be evaluated if the security-target of the
operation is also the security-target of a Lone BCB or BCB)

o If a
First BCB.

Any additional bytes generated as single bundle is going to contain a result of encryption and/or
authentication processing of CMSB as well as other
security blocks, the security-target SHOULD CMS operations MUST be placed
in an "integrity check value" field (see Section 3.9) in performed and the
security-result of CMSB
MUST be created before any other security operation is applied.

Additionally, since the Lone BCB CMSB block may contain either integrity or Last BCB.

The cipher suite parameters field MAY be present
confidentiality information in either its encapsulated CMS, there is no way
to evaluate conflicts when a Lone
BCB or BIB/BCB and a First BCB. This field CMSB have the same
security target. To address this concern, the following processing
rules MUST NOT be present in a Last BCB.

An EID-reference to followed.

o If an extension block is the security-source MAY be present in either target of a
Lone BCB BIB or a First BCB. This field BCB, then the
extension block MUST NOT be present in a Last
BCB. The security-source can also be specified as part the target of key-
information described in Section 3.9.

The security-result MAY be present in either a Lone BCB 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 Last
BCB. necessary ordering
when applying security operations within a bundle. Specifically, for
a given security-target, BIBs MUST be added before BCBs. This field
ordering MUST NOT be present preserved in a First BCB. This
compound field normally contains fields such as an encrypted
bundle encryption key and/or authentication tag.

The BCB cases where the current BPA is adding
all of the only security block that modifies the contents of its
security-target. When a BCB is applied, blocks for the security-target body
data are encrypted "in-place". Following encryption, bundle or whether the security-
target body data BPA is a
waypoint adding new security blocks to a bundle that already contains cipher-text, not plain-text. Other
security-target block fields (such as type, processing control flags,
and length) remain unmodified.

Fragmentation, reassembly,
security blocks.

3.8. Parameters and custody transfer are adversely
affected by a change Result Fields

Various cipher suites include several items in size of the payload due to ambiguity about
what byte range of the block cipher suite
parameters and/or security-result fields. Which items MAY appear is actually in any particular fragment.
Therefore, when
defined by the security-target particular cipher suite description. A cipher suite
MAY support several instances of the same type within a BCB single block.

Each item is represented as a type-length-value. Type is a single
byte indicating the bundle payload,
the BCB MUST NOT alter item. Length is the size count of the payload block body data.
Cipher suites SHOULD place any block expansion, such as
authentication tags (integrity check values) data bytes to
follow, and any padding
generated by a block-mode cipher, into is an integrity check value item
in SDNV-encoded integer. Value is the security-result field (see Section 3.9) data content of
the BCB. This "in-
place" encryption allows fragmentation, reassembly, item.

Item types, name, and custody
transfer descriptions are defined as follows.

Cipher suite parameters and result fields.

+-------+----------------+------------------------------------------+
| Type | Name | Description |
+-------+----------------+------------------------------------------+
| 0 | Reserved | |
+-------+----------------+------------------------------------------+
| 1 | Initialization | A random value, typically eight to operate without knowledge of whether |
| | Vector (IV) | sixteen bytes. |
+-------+----------------+------------------------------------------+
| 2 | Reserved | |
+-------+----------------+------------------------------------------+
| 3 | Key | Material encoded or not encryption
has occurred.

Notes:

o The cipher suite MAY process less than the entire original
security-target body data. If the cipher suite processes less
than the complete, original security-target body data, protected by the BCB for
that security-target MUST specify, as part key |
| | Information | management system and used to transport |
| | | an ephemeral key protected by a long- |
| | | term key. |
+-------+----------------+------------------------------------------+
| 4 | Content Range | Pair of SDNV values (offset,length) |
| | | specifying the cipher suite
parameters, which bytes range of the body data are protected.

o payload bytes to |
| | | which an operation applies. The BCB's "discard" flag may offset |
| | | MUST 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 offset within the
"Discard original |
| | | bundle, even 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 cipher-text.

3.7. Cryptographic Message Syntax Block

A CMSB current bundle is an ASB with the following additional restrictions:

The block-type code value MUST be 0x05.

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 cipher suite. |
+-------+----------------+------------------------------------------+
| 9-255 | Reserved | |
+-------+----------------+------------------------------------------+

Table 1

3.9. BSP Block Example

An example of BPSec blocks applied to be
performed on a bundle block. Multiple CMSB blocks MAY be included is illustrated in
Figure 4. In this figure the first column represents blocks within a
bundle as long as and the security-target second column represents a unique identifier for each is unique.

Key-information, if available, MUST appear within the CMS content
contained in
block, suitable for use as the security-result field.

A CMSB block is created with its corresponding security-target field
pointing to of a unique bundle BPSec security-
block. The CMS security operations are
performed upon Since the security-target's data field mechanism and the resulting
encoded CMS content format of a security-target is stored within not
specified in this document, the CMS security-result field of terminology B1...Bn is used to
identify blocks in the CMSB's payload. The security-target block's data MAY be left
intact, replaced with alternate data, or completely erased based on bundle for the specification purposes 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 illustration.

Block in Bundle ID
+=================================+====+
| Primary Block | B1 |
+---------------------------------+----+
| Lone BIB | B2 |
| OP(integrity, target=B1) | |
+---------------------------------+----+
| Lone BCB block, and a CMSB Signed-Data type SHALL be considered as
equivalent to a BPSec | B3 |
| OP(confidentiality, target=B4) | |
+---------------------------------+----+
| Extension Block | B4 |
+---------------------------------+----+
| Lone BIB block.

3.8. | B5 |
| OP(integrity, target=B6) | |
+---------------------------------+----+
| Extension Block Interactions

The four security-block types defined in | B6 |
+---------------------------------+----+
| Lone BCB | B7 |
| OP(confidentiality, target=B8) | |
+---------------------------------+----+
| Lone BIB (encrypted by B7) | B8 |
| OP(integrity, target=B10) | |
+---------------------------------+----|
| Lone BCB | B9 |
| OP(confidentiality, target=B10) | |
+---------------------------------+----+
| Payload Block |B10 |
+---------------------------------+----+

Figure 4: Sample Use of BSP Blocks

In this specification are
designed to be as independent as possible. However, there are some
cases where security example a bundle has five non-security-related blocks: the
primary block (B1), three extension blocks may share (B4,B6,B9), and a security-target creating
processing dependencies.

If confidentiality is being payload
block (B11). The following security applications are applied to a target that already has this
bundle.

o An integrity signature applied to it, then an undesirable condition occurs where a
security-aware intermediate node would be unable to check the
integrity result of canonicalized primary block.
This is accomplished by a block because single BIB (B2).

o Confidentiality for the first extension block contents have been
encrypted after the integrity signature was generated. To address
this concern, the following processing rules MUST be followed.

o If confidentiality (B4). This is to be applied to
accomplished by a target, it MUST also be
applied to every integrity operation already defined single BCB block (B3).

o Integrity for that
target. the second extension block (B6). This means that if a BCB is added to encrypt a block,
another BCB MUST also be added to encrypt
accomplished by a single BIB also targeting
that block.

o An integrity operation MUST NOT be applied to block (B5). NOTE: If the extension
block B6 contains a security-target if representation of the serialized bundle (such
as a BCB hash over all blocks in the bundle shares the same security-target. This
prevents ambiguity in at the order time of evaluation when receiving a BIB
and a BCB for a given security-target.

o An integrity value MUST NOT be evaluated if its last
transmission) then the BIB providing the
integrity value block is the security target of also providing an existing BCB block in
the bundle. In such a case,
authentication service from the BIB data contains cipher-text as
it has been encrypted. prior BPSEC-BPA to this BPSEC-BPA.

o An integrity value MUST NOT be evaluated if the security-target of signature on the BIB payload (B10). This is also the security-target of a BCB in the bundle. In
such a case, the security-target data contains cipher-text as it
has been encrypted.

o As mentioned in Section 3.6, accomplished
by a single BIB MUST NOT have a BCB as its
security target. BCBs may embed integrity results as part of
cipher suite parameters. block (B8).

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 Confidentiality 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.

o On reception of a bundle containing a CMSB and other security
blocks, the CMSB must be decoded last.

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 payload block MUST NOT also be the target of a CMSB, and vice-
versa.

o If a bundle it's integrity
signature. This is the target of a BAB block, then the bundle MUST NOT
also be the target of a CMSB, and vice-versa.

o Generally, a CMSB MUST be processed before any BIB or accomplished by two Lone BCB blocks
are processed.

These restrictions on block interactions impose a necessary ordering
when applying security operations within a bundle. Specifically, for
a given security-target, BIBs MUST be added before BCBs, blocks: B7
encrypting B8, and BABs
MUST be added after all other security blocks. This ordering MUST be
preserved B9 encrypting B10.

Block in cases where the current BPA is adding 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 security
blocks.

3.9. Parameters and Result Fields

Various cipher suites include several items in the cipher suite
parameters and/or security-result fields. Which items MAY appear is
defined by the particular cipher suite description. A cipher suite
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 the item. 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, name, and descriptions are defined as follows.

Cipher suite parameters and result fields.

+-------+----------------+------------------------------------------+ Bundle ID
+=========================================+====+
| Type Primary Block | Name B1 | Description
+-----------------------------------------+----+
|
+-------+----------------+------------------------------------------+ First BAB | 0 B2 | Reserved
| OP(authentication, Bundle) |
+-------+----------------+------------------------------------------+ | 1
+-----------------------------------------+----+
| Initialization Lone CMSB | A random value, typically eight to B3 |
| security-target=0x01 | Vector (IV) | sixteen bytes.
|
+-------+----------------+------------------------------------------+ security-result= | 2 | Reserved
| |
+-------+----------------+------------------------------------------+ | 3
| Key Signed-Data { | Material encoded or protected by the key |
| Digest Algorithm(s), | Information | management system and used to transport
| Enveloped-Data { | |
| an ephemeral key protected by a long- Encrypted Data, | |
| Encrypted Encryption Key(s) | term key. |
+-------+----------------+------------------------------------------+
| 4 }, | Content Range | Pair of SDNV values (offset,length)
| Signature(s) and Certificate Chain(s) | |
| specifying the range of payload bytes to } | |
| | which an operation applies. The offset |
+-----------------------------------------+----+
| Payload Block | B4 | MUST be the offset within the original
| (Empty Data Field) | |
+-----------------------------------------+----+
| bundle, even if the current bundle is a Last BAB | B5 |
| OP(authentication, Bundle) | fragment. |
+-------+----------------+------------------------------------------+
| 5 | Integrity | Result of BAB or BIB digest or other |
| | Signatures | signing operation. |
+-------+----------------+------------------------------------------+
| 6 | Unassigned | |
+-------+----------------+------------------------------------------+
| 7 | Salt | An IV-like value used by certain |
| | | confidentiality suites. |
+-------+----------------+------------------------------------------+
| 8 | BCB Integrity | Output from certain confidentiality |
| | Check Value | cipher suite operations to be used at |
| | (ICV) / | the destination to verify that the |
| | Authentication | protected data has not been modified. |
| | Tag | This value MAY contain padding if |
| | | required by the cipher suite. |
+-------+----------------+------------------------------------------+
| 9-255 | Reserved | |
+-------+----------------+------------------------------------------+

Table 1

3.10. BSP Block Example

An example of BPSec 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 BPSec security-
block. Since the mechanism 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 5: Sample Bundle ID
+=================================+====+
| Primary With CMS Block | B1 |
+---------------------------------+----+
| First BAB | B2 |
| OP(authentication, Bundle) | |
+---------------------------------+----+
| Lone BIB | B3 |
| OP(integrity, target=B1) | |
+---------------------------------+----+
| 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 (B1), two extension blocks (B5,B7), and a payload block
(B11). 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 canonicalized 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.

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.

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 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 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.

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. The size of eight bytes is
chosen because implementations MAY handle larger SDNV values as
invalid, as noted in [RFC5050].

4.1.1. Bundle Canonicalization

Bundle canonicalization permits no changes at all to the example a bundle
between has two non-security-related blocks: the security-source
primary block (B1) and the destination, with the exception
of one of the Block Processing Control Flags, as described below. It
is intended for use in BAB cipher suites. a payload block (B4). This algorithm
conceptually catenates all blocks in the order presented, but omits
all security-result data fields in security blocks having method would allow
for the bundle
as their security-target. For example, when to carry multiple CMS payloads by utilizing a BAB cipher suite
specifies this algorithm, we omit the BAB security-result from the
catenation. multiple
CMSB ASBs. The inclusion of security-result length fields is as
determined by the specified cipher suite. A security-result length
field MAY be present even when the corresponding security-result data
fields following security applications are omitted.

Notes:

o In the Block Processing Control Flags field the unpacked SDNV is
ANDed with mask 0xFFFF FFFF FFFF FFDF applied to zero the flag at bit 5
("Block was forwarded without being processed"). If this flag is
not zeroed out, then a bundle passing through a non-security aware
node will set this flag which will change the message digest and
bundle.

o Authentication over the bundle. This is accomplished by two BAB block will fail to verify.
blocks: B2 and B5.

o In Encrypted and signed CMS content contained within the above, we specify that security-result data CMSB block.
The first CMS operation, encryption, is omitted.
This means that no bytes of performed on 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
contained within the cipher suite before block the security-result is
calculated, and require that this value be security-target points to, in this
case, the security-result
length field even though the security-result data itself will be
omitted.

o payload block. The 'res' bit of resulting encrypted data is then
signed and the cipher suite ID, which indicates whether or
not final CMS content is stored within the CMSB block's
security-result length and security-result field. The payload block's data field are
present, is part of the canonical form.

o The value of subsequently
removed now that the block original data length field, which indicates has been encoded within the
length of
CMSB block.

4. Security Processing

This section describes the block, is also part security aspects of the canonical form. Its
value indicates the length bundle processing.

4.1. Canonical Forms

In order to verify a signature of a block, the entire block when exact same bits, in
the block
includes exact same order, MUST be input to the security-result data field.

4.1.2. 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
canonicalization: the primary block, the payload block, or an
extension block.

4.1.2.1.

4.1.1.1. Primary Block Canonicalization

The canonical form of the primary block is shown in Figure 6.
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 |
+----------------+----------------+---------------------------------+
| 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

The fields shown in Figure 6 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 unpacked SDNV
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 unpacked SDNVs for the creation timestamp and lifetime are
copied from the primary block.

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 cipher suite parameters.

4.1.2.2.

4.1.1.2. Payload Block Canonicalization

When canonicalizing the payload 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 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
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 cipher suite parameters are required
to specify which part of the payload is protected, as discussed
further below.

4.1.2.3.

4.1.1.3. 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.

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.

The block-length is canonicalized as its unpacked SDNV value. 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.

4.1.3.

4.1.2. 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.

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 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 they
will change in transit. The masks specified above will have to be
revised if additional flags are no general rules for canonicalizing URIs (or
IRIs), this problem may defined and they need to be an unavoidable source of integrity
failures.
protected.

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 Cipher suites MAY define their own canonicalization algorithms and
require the use of those algorithms over the ones provided in this
specification.

4.2. Endpoint ID Confidentiality

Every bundle has a primary block that contains the source and
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
of the primary block (e.g., the current-custodian), and that is
supported in the same manner.

4.3. 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 MUST 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.

4.3.1. Receiving BAB Blocks

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 is not required to have a BAB 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.
Security policy may provide a means to override this default behavior
and require processing of a BAB if it exists.

If the bundle is required to have a BAB but does not, then the bundle
MUST be discarded and processed no further. If the bundle is
required to have a BAB but the key information for the security-
source cannot be determined or the security-result value check fails,
then the bundle has failed to authenticate, (e.g., the current-custodian), and that is
supported in the bundle same manner.

4.3. Bundles Received from Other Nodes

Security blocks MUST be
discarded and processed no further.

If the bundle is required to have in a BAB, and specific order when received
by a BAB exists, and the
BAB information is verified, then the BAB security-aware node. The processing on the received
bundle order is complete, and as follows.

o All BCB blocks in the bundle is ready to MUST be further processed
for BIB/BCB handling or delivery or forwarding.

A BAB received evaluated prior to evaluating
any BIBs in the bundle. When BIBs and BCBs share a bundle security-
target, BCBs 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.

4.3.2. evaluated first and BIBs second.

4.3.1. Receiving BCB Blocks

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 cipher suite 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]) [BPBIS]) 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 plain-text MUST replace the
cipher-text in the security-target body data

4.3.3.

4.3.2. Receiving BIB Blocks

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
operations mandated by this specification, when both a BIB and a BCB
share a security-target, it means that the security-target MUST have
been encrypted after it was integrity signed and, therefore, the BIB
cannot be verified until the security-target has been decrypted by
processing the BCB.

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
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 BIB and the receiving node is the destination for
the bundle, the node MUST verify the security-target in accordance
with the cipher suite 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 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 at a
waypoint that it is processed in the same way as if the check fails
at the destination.

4.4. Receiving CMSB Blocks

A CMSB MUST NOT be processed if its security target is also the
security target of any BAB, BIB, BIB or BCB in the bundle.

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

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] [BPBIS] 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:

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 A BAB cipher suite MAY specify that it only applies to non-
fragmented bundles and not to bundle fragments.

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.

o If a bundle with a BAB is fragmented by a non-security-aware node,
then the entire bundle must be re-assembled before being processed
to allow for the proper verification of the BAB.

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
removed from created fragments.

5. 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.

6. Policy Considerations

When implementing BPSec, several policy decisions must be considered.
This section describes key policies that affect the generation,
forwarding, and receipt of bundles that are secured using this
specification.

o If a bundle is received that contains more than one security-
operation, in violation of BPSec, then the BPA must determine how
to handle this bundle. The bundle may be discarded, the block
affected by the security-operation may be discarded, or one
security-operation may be favored over another.

o BPAs in the network MUST understand what security-operations they
should apply to bundles. This decision may be based on the source
of the bundle, the destination of the bundle, or some other
information related to the bundle.

o If an intermediate receiver has been configured to add a security-
operation to a bundle, and the received bundle already has the
security-operation applied, then the receiver MUST understand what
to do. The receiver may discard the bundle, discard the security-
target and associated BPSec blocks, replace the security-
operation, or some other action.

o It is recommended that security operations only be applied to the
payload block, the primary block, and any block-types specifically
identified in the security policy. If a BPA were to apply
security operations such as integrity or confidentiality to every
block in the bundle, regardless of the block type, there could be
downstream errors processing blocks whose contents must be
inspected at every hop in the network path.

7. Security Considerations

Certain applications of DTN need to both sign and encrypt a message,
and there are security issues to consider with this.

o To provide an assurance that a security-target came from a
specific source and has not been changed, then it should be signed
with a BIB.

o To ensure that a security-target cannot be inspected during
transit, it should be encrypted with a BCB.

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.
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

All implementations are strongly RECOMMENDED to provide at least a
BAB cipher suite. A relay node, for example, might not deal with
end-to-end confidentiality and data integrity, but it SHOULD exclude
unauthorized traffic and perform some method
of hop-by-hop verification by generating a hash to some canonical
form of the bundle verification. and placing an integrity signature on that form
using a BIB.

9. IANA Considerations

This protocol has fields that have been registered by IANA.

9.1. Bundle Block Types

This specification allocates three block types from the existing
"Bundle Block Types" registry defined in [RFC6255]. [RFC6255] .

Additional Entries for the Bundle Block-Type Codes Registry:

Table 2

9.2. Cipher Suite Flags

This protocol has a cipher suite 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

Cipher Suite Flag Registry:

Table 3

9.3. 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
for the "type" sub-field. The values for "type" apply to both the
cipher suite parameters and the cipher suite results fields. Certain
values are defined. An IANA registry has been set up as follows.

The registration policy for this registry is: Specification Required

The Value range is: 8-bit unsigned integer.

Cipher Suite Parameters and Results Type Registry:

Table 4

10. References

10.1. Normative References

[BPBIS] Burleigh, S., Fall, K., and E. Birrane, "Bundle Protocol",
draft-ietf-dtn-bpbis-03 (work in progress), March 2016.

[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.

[RFC5652] Housley, R., "Cryptographic Message Syntax (CMS)", STD 70,
RFC 5652, DOI 10.17487/RFC5652, September 2009,
<http://www.rfc-editor.org/info/rfc5652>.

[RFC6255] Blanchet, M., "Delay-Tolerant Networking Bundle Protocol
IANA Registries", RFC 6255, May 2011.

10.2. 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.

[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.

[SBSP] Birrane, E., "Streamlined Bundle Security Protocol",
draft-birrane-dtn-sbsp-01 (work in progress), October
2015.

Appendix A. Acknowledgements

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.

Authors' Addresses

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

Jeremy Pierce-Mayer
INSYEN AG
Muenchner Str. 20
Oberpfaffenhofen, Bavaria DE
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

Phone: +1-216-433-6493
Email: dennis.c.iannicca@nasa.gov