Bundle Protocol Security (BPSec) COSE Context

Bundle Protocol Security (BPSec) COSE Context The Johns Hopkins University Applied Physics Laboratory

11100 Johns Hopkins Rd. Laurel MD 20723 United States of America brian.sipos+ietf@gmail.com

Transport Delay-Tolerant Networking COSE DTN PKIX This document defines a security context suitable for using CBOR Object Signing and Encryption (COSE) algorithms within Bundle Protocol Security (BPSec) integrity and confidentiality blocks. A profile for COSE, focused on asymmetric-keyed algorithms, and for PKIX certificates are also defined for BPSec interoperation.

Introduction The Bundle Protocol Security (BPSec) Specification defines structure and encoding for Block Integrity Block (BIB) and Block Confidentiality Block (BCB) types but does not specify any security contexts to be used by either of the security block types. The CBOR Object Signing and Encryption (COSE) specifications and defines a structure, encoding, and algorithms to use for cryptographic signing and encryption. This document describes how to use the algorithms and encodings of COSE within BPSec blocks to apply those algorithms to Bundle security in . A bare minimum of interoperability algorithms and algorithm parameters is specified by this document in . The focus of the recommended algorithms is to allow BPSec to be used in a Public Key Infrastructure (PKI) as described in using a certificate profile defined in . Examples of specific security operations are provided in to aid in implementation support of the interoperability algorithms of . Examples of public key certificates are provided in which are compatible with the profile in and specific corresponding algorithms.

Scope This document describes a profile of COSE which is tailored for use in BPSec and a method of including full COSE messages within BPSec security blocks. This document does not address:

Policies or mechanisms for issuing Public Key Infrastructure Using X.509 (PKIX) certificates; provisioning, deploying, or accessing certificates and private keys; deploying or accessing certificate revocation lists (CRLs); or configuring security parameters on an individual entity or across a network.
Uses of COSE beyond the profile defined in this document.
How those COSE algorithms are intended to be used within a larger security context. Many header parameters used by COSE (e.g., key identifiers) depend on the network environment and security policy related to that environment.

PKIX Environments and CA Policy This specification gives requirements about how to use PKIX certificates issued by a Certificate Authority (CA), but does not define any mechanisms for how those certificates come to be. To support the PKIX uses defined in this document, the CA(s) issuing certificates for BP nodes are aware of the end use of the certificate, have a mechanism for verifying ownership of a Node ID, and are issuing certificates directly for that Node ID. BPSec security verifiers and acceptors authenticate the Node ID of security sources when verifying integrity (see ) using a public key provided by a PKIX certificate (see ) following the certificate profile of .

Use of CDDL This document defines CBOR structure using the Concise Data Definition Language (CDDL) of . The entire CDDL structure can be extracted from the XML version of this document using the XPath expression: '//sourcecode[@type="cddl"]' The following initial fragment defines the top-level rules of this document's CDDL, including the ASB data structure with its parameter/result sockets and rules needed for validating the example CBOR content. start = bpsec-cose-asb / external_aad / primary-block / extension-block / MAC_structure / Sig_structure / Enc_structure / COSE_KeySet The definitions for the rules MAC_structure, Sig_structure, Enc_structure, and COSE_KeySet are taken from COSE . The definition for the rule COSE_CertHash is taken from COSE X.509 . The definitions for the rules eid, primary-block, and extension-block, the sockets $extension-block, and the generic rule extension-block-use are taken from BP . The BPSec specification did not define its extension blocks using CDDL, so a supplementary definition for BPSec is provided in .

Requirements Language 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 BCP 14 when, and only when, they appear in all capitals, as shown here.

BPSec Security Context This document specifies a single security context for use in both BPSec integrity and confidentiality blocks. This is done to save code points allocated to this specification and to simplify the encoding of COSE-in-BPSec; the BPSec block type uniquely defines the acceptable parameters and COSE messages which can be present. The COSE security context SHALL have the Security Context ID specified in . Both types of security block can use the same parameters, defined in , to carry public key-related information and each type of security block allows specific COSE message results, defined in .

COSE context declaration CDDL ; Specialize the ASB for this context $ext-data-asb /= bpsec-cose-asb bpsec-cose-asb = bpsec-context-use< 3, ; Context ID COSE $bpsec-cose-param, $bpsec-cose-result >

Security Scope The scope here refers to the set of information used by the security context to cryptographically bind with the plaintext data being integrity-protected or confidentiality-protected. This information is generically referred to as additional authenticated data (AAD), which is also the term used by COSE to describe the same data. The sources for AAD within the COSE context are described below, controlled by the AAD Scope parameter, and implemented as defined in . The purpose of this parameter is similar to the AAD Scope parameter and Integrity Scope parameter of but expanded to allow including any block in the bundle as AAD.

Primary Block:: The primary block identifies a bundle and, once created, the contents of this block are immutable. Changes to the primary block associated with the security target indicate that the target is no longer in its original bundle. Including the primary block as part of AAD ensures that security target appears in the same bundle that the security source intended.
Canonical Block-Type-Specific Data:: Including the block-type-specific data (BTSD) of a non-target block as part of AAD ensures that that other block's BTSD does not change after the security block is added. This can guarantee that not only has the security target BTSD not changed but the additional blocks' BTSD have not changed.
Canonical Block Metadata:: Including block metadata, which identifies and types a block, as part of AAD ensures that the block presence does not change after the security block is added. This metadata explicitly excludes the CRC type and value fields because the CRC is derived from the BTSD. The metadata of the security block and the target block are also allowed, which binds the security result to that specific target.
Containing Abstract Security Block:: The above sources of AAD allow covering the primary block, target block, and any other block besides the security block which contains the security operation for this COSE context The metadata of the containing security block can be included as described above, using AAD scope key -2 with the flag for metadata, but the BTSD of the security block (as defined in ) is also partially covered by AAD. The Security Targets field can be included indirectly by using AAD scope key -1 with the flag for metadata, which includes the target block number. The Security Context ID is not included directly, but modification of this field will cause processing (verification or acceptance) of the associated security operations to fail. The Security Source field is included as AAD unconditionally, so is protected from modification. The Security Context Flags and Security Context Parameters are not included directly, but the modification of parameters will cause processing of security operations to fail. The Security Results are also not included directly, but these are the COSE messages themselves which are designed to be handled as plaintext.

Because of the above, it is possible for a security source to create a COSE context integrity operation which covers every block of a bundle at the time the BIB is added (excluding CRC Type and value fields). By using a minimal AAD scope it is also possible for an integrity operation to cover only the BTSD of a single target block independently of the block metadata or bundle primary block associated with the target at the time the BIB is added.

Parameters Each COSE context parameter value SHALL consist of the COSE structure indicated by in its decoded (CBOR item) form. Each security block SHALL contain no more than one of each parameter type per target block. COSE Context Parameters

Parameter ID	Parameter Structure	Reference
3	`additional-protected`	of this document
4	`additional-unprotected`	of this document
5	`AAD-scope`	of this document

When a parameter is not present and a default value is defined below, a security verifier or acceptor SHALL use that default value to process the target:

The default additional-protected is '' (an empty byte string).
The default additional-unprotected is '' (an empty byte string).
The default AAD-scope is {0:0b1,-1:0b1,-2:0b1} (a map which indicates the AAD contains the metadata of the primary, target, and security blocks).

Additional Header Maps The two parameters Additional Protected and Additional Unprotected allow de-duplicating header items which are common to all COSE results. Both additional header values contain a CBOR map which is to be merged with each of the result's unprotected headers. Although the additional header items are all treated as unprotected from the perspective of the COSE message, the additional protected map is included within the external_aad (see ). The expected use of additional header map is to contain a certificate (chain) or identifier (see ) which applies to all results in the same security block. Following the same pattern as COSE, when both additional header maps are present in a single security block they SHALL not contain any duplicated labels. Security verifiers and acceptors SHALL treat a pair of additional header maps containing duplicated labels as invalid. No more than one of each Additional Protected and Additional Unprotected parameter SHALL be present in a single security block. Security verifiers and acceptors SHALL treat a security block with multiple instances of either additional header type as invalid. There is no well-defined behavior for a security acceptor to handle multiple Additional Protected parameters. Security sources SHOULD NOT include an additional header parameter which represents an empty map. Security verifiers and acceptors SHALL handle empty header map parameters, specifically the Additional Protected parameter because it is part of the external_aad. Security verifiers and acceptors SHALL treat the aggregate of both additional header maps as being present in the unprotected header map of the highest-layers of the COSE message of each result. For single-layer messages (i.e., COSE_Encrypt0, COSE_MAC0, and COSE_Sign1) the additional headers apply to the message itself (layer 0) and for other messages the additional headers apply to the final recipients. If the same header label is present in a additional header map and a COSE layer's headers the item in the result header SHALL take precedence (i.e., the additional header items are added only if they are not already present in a layer's header). Additional header maps SHALL NOT contain any private key material. The security parameters are all stored in the bundle as plaintext and are visible to any bundle handlers.

Additional Headers CDDL $bpsec-cose-param /= [3, additional-protected] additional-protected = empty_or_serialized_map $bpsec-cose-param /= [4, additional-unprotected] additional-unprotected = empty_or_serialized_map

AAD Scope The AAD Scope parameter controls what data is included in the AAD for both integrity and confidentiality operations. The AAD Scope parameter SHALL be encoded as a CBOR map containing keys referencing bundle blocks (as uint or nint items) and values representing a collection of bit flags (as uint items) as defined below. Non-negative integer AAD Scope keys SHALL be interpreted as block numbers in the bundle containing the AAD Scope parameter. Negative integer AAD Scope keys SHALL be interpreted as special (non-block-number) identifiers according to the IANA registry defined in . That registry contains the following initial values from as well as reserved blocks for experimental and private use. AAD Scope Special Keys

Value	Name	Description
-1	Target block	Include the target block of the security operation associated with the AAD.
-2	Security block	Include the security block containing the security operation associated with the AAD.

AAD Scope values SHALL be interpreted as bit flags according to the IANA registry defined in with initial values defined in . Any AAD Scope value bits SHALL NOT all be set to zero, which would represent the lack of presence in the AAD and serves no purpose. When the map key identifies the primary block (block number zero) the bits SHALL only have AAD-metadata set, as the primary block has no BTSD. When the map key identifies the containing security block the bits SHALL only have AAD-metadata set, as the security block BTSD does not yet exist. When the map key identifies the target block the bits SHALL only have AAD-metadata set, as the target block BTSD is already part of the security operation (integrity or confidentiality). All unassigned bits SHALL be set to zero (which will be elided by CBOR encoding) by security sources. All unassigned bits SHALL be ignored by security verifiers and acceptors. AAD Scope Flags

Bit Position(from LSbit)	Name	Description
0	`AAD-metadata`	If bit is set, indicates that the block metadata is included in the AAD.
1	`AAD-btsd`	If bit is set, indicates that the BTSD is included in the AAD.

A CDDL representation of this definition is included in for reference.

AAD Scope CDDL $bpsec-cose-param /= [5, AAD-scope] AAD-scope = { *AAD-scope-key => AAD-scope-val } ; All uint keys are block numbers AAD-scope-key = uint / ($blk-id-special .within (-1 .. -65536)) $blk-id-special /= -1 ; target block $blk-id-special /= -2 ; security block AAD-scope-val = uint .bits $AAD-scope-flags $AAD-scope-flags /= 0 ; AAD-metadata $AAD-scope-flags /= 1 ; AAD-btsd The default value for this parameter (in ) includes the primary, target, and security block metadata.

Results Although each COSE context result is a COSE message, the types of message allowed depend upon the security block type in which the result is present: only MAC or signature messages are allowed in a BIB and only encryption messages are allowed in a BCB. The code points for Result ID values are identical to the existing COSE message-marking tags in . This avoids the need for value-mapping between code points of the two registries. When embedding COSE messages, the message CBOR structure SHALL be encoded as a byte string used as the result value. This allows a security acceptor to skip over unwanted results without needing to decode the result structure. When embedding COSE messages, the CBOR-tagged form SHALL NOT be used. The Result ID values already provide the same information as the COSE tags (using the same code points). These generic requirements are formalized in the CDDL fragment of .

COSE context results CDDL $bpsec-cose-result /= [16, bstr .cbor COSE_Encrypt0] $bpsec-cose-result /= [17, bstr .cbor COSE_Mac0] $bpsec-cose-result /= [18, bstr .cbor COSE_Sign1] $bpsec-cose-result /= [96, bstr .cbor COSE_Encrypt] $bpsec-cose-result /= [97, bstr .cbor COSE_Mac] $bpsec-cose-result /= [98, bstr .cbor COSE_Sign]

Integrity Messages When used within a Block Integrity Block, the COSE context SHALL allow only the Result IDs from . Each integrity result value SHALL consist of the COSE message indicated by in its non-tagged encoded form. COSE Integrity Results

Result ID	Result Structure	Reference
97	encoded `COSE_Mac`
17	encoded `COSE_Mac0`
98	encoded `COSE_Sign`
18	encoded `COSE_Sign1`

Each integrity result SHALL use the "detached" payload form with null payload value. The integrity result for COSE_Mac and COSE_Mac0 messages are computed by the procedure in . The integrity result for COSE_Sign and COSE_Sign1 messages are computed by the procedure in . The COSE "protected attributes from the application" used for a signature or MAC result SHALL be the encoded data defined in . The COSE payload used for a signature or MAC result SHALL be one of the following: the encoded form of the primary block if the target is the primary block (block number zero), or the BTSD content of the target if the target is not the primary block (block number non-zero).

Confidentiality Messages When used within a Block Confidentiality Block, COSE context SHALL allow only the Result IDs from . Each confidentiality result value SHALL consist of the COSE message indicated by in its non-tagged encoded form. COSE Confidentiality Results

Result ID	Result Structure	Reference
96	encoded `COSE_Encrypt`
16	encoded `COSE_Encrypt0`

Only algorithms which support Authenticated Encryption with Authenticated Data (AEAD) SHALL be usable in the first (content) layer of a confidentiality result. Because COSE encryption with AEAD appends the authentication tag with the ciphertext, the size of the BTSD will grow after an encryption operation. Security verifiers and acceptors SHALL NOT assume that the size of the plaintext is the same as the size of the ciphertext. Each confidentiality result SHALL use the "detached" payload form with null payload value. The confidentiality result for COSE_Encrypt and COSE_Encrypt0 messages are computed by the procedure in . The COSE "protected attributes from the application" used for an encryption result SHALL be the encoded data defined in . The COSE payload used for an encryption result SHALL be the BTSD content of the target. Because confidentiality of the primary block is disallowed by BPSec, there is no logic here for handling a BCB with a target on the primary block.

Key Considerations This specification does not impose any additional key requirements beyond those already specified for each COSE algorithm required in .

Canonicalization Algorithms Generating or processing COSE messages for the COSE context follows the profile defined in with the "protected attributes from the application" (i.e., the external_aad item) generated as defined in .

Generating AAD The AAD contents and encoding defined in this section are used for both integrity and confidentiality messages. The encoding of this AAD is different from AAD of and the front items of IPPT of due to support for AAD covering the ASB security source field and covering an arbitrary number of blocks in the same bundle. If the AAD Scope map contains any key which is a positive integer (block number) referencing a block which does not exist in the current bundle or any key which is a negative integer (special key) not supported by the processing entity the generation of the AAD SHALL be considered failed. When used as the external_aad for COSE operations, the AAD SHALL be encoded in accordance with the core deterministic encoding requirements of . The AAD byte string SHALL consist of an encoded CBOR sequence, generated by concatenating the following byte string parts:

The first part SHALL be the encoded Security Source EID associated with the ASB containing this security operation.
The second part SHALL be the encoded AAD Scope value itself, which is a CBOR map. Because of deterministic encoding, the negative keys will occur after positive keys.
For each entry of the AAD Scope map, in ascending block number order followed by the negative special keys in descending order, the next items SHALL be one or both of the following:
1. If the map value has the AAD-metadata flag set, the next part is block metadata taken from either:
  - If the map key is block number zero, the next part SHALL be the encoded form of the primary block of the containing bundle. This represents the full primary block, including its definite-length array head.
  - Otherwise, next part SHALL be the encoded form of the first three fields of the block (i.e., the block type code, block number, and control flags) identified by the block number in the map key. This part is just the three encoded integer fields concatenated with no framing (array or otherwise).
2. If the map value has the AAD-btsd flag set and the map key is not block number zero, the next part is the encoded BTSD of the block identified by the block number in the map key. This part includes a byte string head.
The last part SHALL be the encoded form of the Additional Protected parameter. This part includes a byte string head. This has a default value of an empty string, defined in .

Be aware that, because of deterministic encoding requirements here, there is no guarantee that AAD parts containing the same CBOR data as the ASB or containing bundle (e.g., the Security Source field), result in the same encoded byte string. When generated by the same entity they are expected to be the same, but an entity verifying or accepting a security operation SHALL treat bundle and block contents as untrusted input and re-encode the AAD parts. A CDDL representation of this data is shown below in .

COSE context AAD CDDL ; Specialized here to contain a specific sequence external_aad /= bstr .cborseq AAD-list AAD-list = [ security-source: eid, AAD-scope, *AAD-block, ; copy of additional-protected (or default empty bstr) additional-protected ] ; each AAD item is a group, not a sub-array AAD-block = ( ? primary-block, ; present for block number zero ? block-metadata, ; present if AAD-metadata flag set ? bstr, ; present if AAD-btsd flag set ) ; Selected fields of a canonical block block-metadata = ( block-type-code: uint, block-number: uint, block-control-flags, )

Payload Data When correlating between BPSec target BTSD and COSE plaintext or payload, any byte string SHALL be handled in its decoded (CBOR item) form. This means any CBOR header or tag in a source encoding are ignored for the purposes of security processing. This also means that if the source byte string was encoded in a non-conforming way, for example in indefinite-length form or with a non-minimum-size length, the security processing always treats it in a deterministically encoded CBOR form.

Processing This section describes block-level requirements for handling COSE security data. All security results generated for BIB or BCB blocks SHALL conform to the COSE profile of with header augmentation as defined in .

Node Authentication This section explains how the certificate profile of is used by a security acceptor to both validate an end-entity certificate and to use that certificate to authenticate the security source for an integrity result. For a confidentiality result, some of the requirements in this section are implicit in an implementation using a private key associated with a certificate used by a result recipient. It is an implementation matter to ensure that a BP agent is configured to generate or receive results associated with valid certificates. A security source MAY prohibit generating a result (either integrity or confidentiality) for an end-entity certificate which is not considered valid according to . Generating a result which is likely to be discarded is wasteful of bundle size and transport resources.

Certificate Identification Because of the standard policy of using separate certificates for transport, signing, and encryption (see ) a single Node ID is likely to be associated with multiple certificates, and any or all of those certificates MAY be present within an "x5bag" in an Additional Protected parameter (see ). When present, a security verifier or acceptor SHALL use an "x5chain" or "x5t" to identify an end-entity certificate to use for result processing. Security verifiers and acceptors SHALL NOT assume that a validated certificate containing a NODE-ID matching a security source is enough to associate a certificate with a COSE message or recipient (see ).

Certificate Validation For each end-entity certificate contained in or identified by by a COSE result, a security verifier or acceptor SHALL perform the certification path validation of up to one of the acceptor's trusted CA certificates. When evaluating a certificate Validity time interval, a security verifier or acceptor SHALL use the Bundle Creation Time of the primary block as the reference instead of the current time. If enabled by local policy, the entity SHALL perform an OCSP check of each certificate providing OCSP authority information in accordance with . If certificate validation fails or if security policy disallows a certificate for any reason, the acceptor SHALL treat the associated security result as failed. Leaving out part of the certification chain can cause the entity to fail to validate a certificate if the left-out certificates are unknown to the entity (see ). For each end-entity certificate contained in or identified by a COSE context result, a security verifier or acceptor SHALL apply security policy to the Key Usage extension (if present) and Extended Key Usage extension (if present) in accordance with and the profile in .

Node ID Authentication If required by security policy, for each end-entity certificate referenced by a COSE context integrity result a security verifier or acceptor SHALL validate the certificate NODE-ID in accordance with using the NODE-ID reference identifier from the Security Source of the containing security block. If the NODE-ID validation result is Failure or if the result is Absent and security policy requires an authenticated Node ID, a security verifier or acceptor SHALL treat the result as failed.

Policy Recommendations A RECOMMENDED security policy is to enable the use of OCSP checking when internet connectivity is present. A RECOMMENDED security policy is that if an Extended Key Usage is present that it needs to contain id-kp-bundleSecurity of to be usable as an end-entity certificate for COSE security results. A RECOMMENDED security policy is to require a validated Node ID (of ) and to ignore any other identifiers in the end-entity certificate. This policy relies on and informs the certificate requirements in and . This policy assumes that a DTN-aware CA (see ) will only issue a certificate for a Node ID when it has verified that the private key holder actually controls the DTN node; this is needed to avoid the threat identified in . This policy requires that a certificate contain a NODE-ID and allows the certificate to also contain network-level identifiers. A tailored policy on a more controlled network could relax the requirement on Node ID validation and/or Extended Key Usage presence.

COSE Profile This section contains requirements which apply to the use of COSE within the BPSec security context defined in this document. Other variations of COSE within BPSec can be used but are not expected to be interoperable or usable by all security verifiers and acceptors.

COSE Messages When generating a BPSec result, security sources SHALL use only COSE labels with a uint value. When processing a BPSec result, security verifiers and acceptors MAY handle COSE labels with with a tstr value. When used in a BPSec result, each COSE message SHALL contain an explicit algorithm identifier in the first (content) layer in accordance with . When available, each COSE message SHALL contain a key identifier in the last layer for all signatures or recipients. See and for specifics about key identifiers. When a key identifier is not available, BPSec verifiers and acceptors SHALL use the Security Source and the Bundle Source to imply which keys can be used for security operations. Using implied keys has an interoperability risk, see for details. A BPSec security operation always occurs within the context of the immutable primary block with its parameters (specifically the Source Node ID) and the security block with its optional Security Source. The algorithms required by this profile support using shared symmetric keys using modern key strengths, with recommended algorithms to support elliptic curve cryptography (ECC) keypairs and RSA keypairs. The focus of this profile is to enable interoperation between security sources and acceptors on an open network, where more explicit COSE parameters make it easier for BPSec acceptors to avoid assumptions and avoid out-of-band parameters. The requirements of this profile still allow the use of potentially not-easily-interoperable algorithms and message/recipient configurations for use by private networks, where message size is more important than explicit COSE parameters.

Interoperability Algorithms The minimum set of COSE algorithms needed for interoperability in non-constrained devices is listed in this section and organized by the type of associated key material. This profile intentionally does not prohibit the use of any other algorithms in specific implementations, devices, or networks and is meant only to provide a starting point for general purpose implementations. It also does not address post-quantum algorithms which have been finalized by NIST but are still undergoing standardization in the IETF (see . The full set of COSE algorithms available is managed at . Each algorithm in this profile is marked as being US CNSS CNSA 1.0 conformant or CNSA 2.0 conformant to aid in further narrowing of network-specific profiles and implementations. All of these algorithms in this profile are approved by US NIST FIPS 140-3 , however FIPS 140 certification involves review of software and hardware design and implementation detail outside the scope of this document. The threshold for minimum security strength to be included in this interoperability minimum is roughly equivalent to CNSA 1.0 and the CCSDS Space Data Link Security rationale green book . The breadth of algorithm variety is intended to cover many different current use cases beyond simple symmetric key security and be compatible with current PKIX mechanisms and strategies.

Hashing Algorithms Implementations conforming to this specification SHALL support the non-keyed hash algorithms in if they will operate with public key certificates. Hash Algorithms

Name	Code	Conformance
SHA-256/64	-15
SHA-256	-16
SHA-512/256	-17
SHA-384	-43	CNSA 1.0 and 2.0
SHA-512	-44	CNSA 2.0

These algorithms are currently used in the COSE_CertHash of "x5t" header parameters, which are expected to be included as unprotected (see ). The truncated algorithms are useful for certificate filtering using shorter thumbprints, so are included here even though they fall below the CNSA 1.0 minimum strength for protecting data.

Symmetric Algorithms Implementations conforming to this specification SHALL support the symmetric keyed algorithms in . The "direct" algorithm is really just a recipient placeholder to allow using a content encryption key (CEK) identifier in a that COSE layer, so has no cryptographic function or effect on security strength. Symmetric Algorithms

BPSec Block	COSE Layer	Name	Code	Conformance
Integrity	0	HMAC 384/384	6	CNSA 1.0 and 2.0
Integrity	0	HMAC 512/512	7	CNSA 2.0
Confidentiality	0	A256GCM	3	CNSA 1.0 and 2.0
Integrity or Confidentiality	1	A256KW	-5	CNSA 1.0 and 2.0
Integrity or Confidentiality	1	direct	-6	N/A
Integrity or Confidentiality	1	direct+HKDF-SHA-512	-11	CNSA 1.0 and 2.0

When generating a BIB result from a symmetric key, implementations SHALL use a COSE_Mac or COSE_Mac0 using the private key directly. When a COSE_Mac or COSE_Mac0 is used with a direct key, the top-layer headers SHALL include a key identifier (see ). The key length used for HMAC algorithms SHALL be equal to the hash function output length. This is consistent with COSE requirements on derived keys for HMAC but more strict to apply to all keys used for HMAC. When generating a BCB result from a symmetric CEK, implementations SHOULD use COSE_Encrypt or COSE_Encrypt0 with direct CEK. Session CEKs SHALL be managed to avoid overuse and the vulnerabilities associated with large amount of ciphertext from the same key. When generating a BCB result from a symmetric key-encryption key (KEK), implementations SHOULD use a COSE_Encrypt message with a recipient containing an indirect (wrapped or derived) CEK. When a COSE_Encrypt is used with an overall KEK, the recipient layer SHALL include a key identifier for the KEK. When a COSE_Encrypt is used with a symmetric KEK and a single recipient, the direct HKDF algorithms (code -10 and -11) are RECOMMENDED over the key wrapped algorithms (code -3 through -5) to reduce message size and the need for symmetric key generation. When processing a COSE_Encrypt with a symmetric KEK, a security verifier or acceptor SHALL process all KDF context data from the recipient headers in accordance with even though the source is not required to provide any of those parameters.

ECC Algorithms Implementations conforming to this specification SHALL support the ECC algorithms in if they will operate with ECC key material using NIST curves. ECC Algorithms

BPSec Block	COSE Layer	Name	Code	Conformance
Integrity	0 or 1	ESP384	-51	CNSA 1.0
Integrity	0 or 1	ESP512	-52
Confidentiality	1	ECDH-ES + HKDF-512	-26	CNSA 1.0
Confidentiality	1	ECDH-SS + HKDF-512	-28	CNSA 1.0
Confidentiality	1	ECDH-ES + A256KW	-31	CNSA 1.0
Confidentiality	1	ECDH-SS + A256KW	-34	CNSA 1.0

When generating a BIB result from an ECC private key, implementations SHALL use a COSE_Sign or COSE_Sign1 using the private key directly. When a COSE_Sign or COSE_Sign1 is used with an ECC private key, the top-layer headers SHALL include a corresponding public key identifier (see ). When generating a BCB result from an ECC public key, implementations SHALL use a COSE_Encrypt message with a recipient containing an indirect (wrapped or derived) CEK. When a COSE_Encrypt is used with an ECC public key, the recipient layer SHALL include a public key identifier (see ). When a COSE_Encrypt is used with an ECC public key, the security source SHALL either generate an ephemeral ECC keypair or choose a unique HKDF "salt" for each security operation. When a COSE_Encrypt is used with an ECC public key and a single recipient, the direct HKDF algorithms (code -25 through -28) are RECOMMENDED over the key wrapped algorithms (code -29 through -34) to reduce message size and the need for symmetric key generation. When processing a COSE_Encrypt with an ECC public key, a security verifier or acceptor SHALL process all KDF context data from the recipient headers in accordance with even though the source is not required to provide any of those parameters. The choice of whether to use ECDH in static-static (SS) or ephemeral-static (EH) mode depends on what security properties are needed for the operation. ECDH-SS can reduce message size and allows key generation to happen outside of the source entity, but also requires the ECC public key to either be known by the recipient(s) and identified by or be fully transmitted by a header parameter (as discussed in ). ECDH-ES can provide forward secrecy by using the ephemeral key only for single messages, but also requires the source to generate a new key when needed.

RSA Algorithms Implementations conforming to this specification SHALL support the RSA algorithms in if they will operate with RSA key material. RSA Algorithms

BPSec Block	COSE Layer	Name	Code	Conformance
Integrity	0 or 1	PS384	-38	CNSA 1.0
Integrity	0 or 1	PS512	-39
Confidentiality	1	RSAES-OAEP w/ SHA-512	-42	CNSA 1.0

When generating a BIB result from an RSA keypair, implementations SHALL use a COSE_Sign or COSE_Sign1 using the private key directly. When a COSE_Sign or COSE_Sign1 is used with an RSA keypair, the top-layer headers SHALL include a public key identifier (see ). When a COSE signature is generated with an RSA keypair, the signature uses a PSS salt in accordance with . When generating a BCB result from an RSA public key, implementations SHALL use a COSE_Encrypt message with a recipient containing a key-wrapped CEK. When a COSE_Encrypt is used with an RSA public key, the recipient layer SHALL include a public key identifier (see ).

Needed Header Parameters The set of COSE header parameters needed for interoperability is listed in this section. The full set of COSE header parameters available is managed at . Implementations conforming to this specification SHALL support the header parameters in . This support means required-to-implement not required-to-use for any particular COSE message. Specific COSE algorithms have their own requirements about which header parameters are mandatory or optional to use in the associated COSE message layer. The phrasing in uses the term "required" where the parameter needs to be understood by all message processors, "optional" where the need for a parameter is determined by the specific end use, and "conditional" for cases where one parameter of several options is needed by this profile. For example, a choice of specific symmetric key identifier or asymmetric key identifier is conditional and chosen by the source. Interoperability Header Parameters

Name	Label	Need
alg	1	Required for COSE
crit	2	Required for COSE
content type	3	Optional for COSE
kid	4	Conditional for this COSE profile
IV	5	Conditional for symmetric encryption algorithms
Partial IV	6	Conditional for symmetric encryption algorithms
kid context	10	Optional for this COSE profile
x5bag	32	Conditional for public key algorithms
x5chain	33	Conditional for public key algorithms
x5t	34	Conditional for public key algorithms
ephemeral key	-1	Required for ECDH-ES algorithms
static key	-2	Conditional for ECDH-SS algorithms
static key id	-3	Conditional for ECDH-SS algorithms
salt	-20	Required for HKDF-using algorithms (direct and ECDH)
x5t-sender	-27	Conditional for ECDH-SS algorithms
x5chain-sender	-29	Conditional for ECDH-SS algorithms

This profile of COSE does not use in-message KDF context information as defined in . The context header parameters for PartyU (code -21 through -23) and PartyV (code -24 through -26) SHALL NOT be present in any COSE message within this security context. A side effect of this is that, to satisfy COSE requirements, the "salt" parameter SHALL always be present in a layer when an HKDF is used by the algorithm for that layer.

Symmetric Keys and Identifiers This section applies when a BIB or BCB uses a shared symmetric key for MAC, encryption, or key-wrap. When using symmetric keyed algorithms, the security source SHALL include a symmetric key identifier as a signature or recipient header. The symmetric key identifier SHALL be either a "kid" of (possibly with "kid context" of ), or an equivalent identifier. This requirement makes the selection of keys by verifiers and acceptors unambiguous. When present, a "kid" parameter is used to uniquely identify a single shared key known to the security source and all expected security verifiers and acceptors. Specific strategies or mechanisms to generate or ensure uniqueness of "kid" values within some domain of use is outside the scope of this profile. Specific users of this profile can define such mechanisms specific to their abilities and needs. When present, a "kid context" parameter SHALL be used as a correlator with a larger scope than an individual "kid" value. The use of a "kid context" allows security verifiers and acceptors to correlate using that larger scope even if they cannot match the sibling "kid" value. For example, a "kid context" can be used to identify a long-lived security association between two entities while an individual "kid" identifies a single shared key agreed within that larger association.

Asymmetric Key Types and Identifiers This section applies when a BIB uses a public key for verification or key-wrap, or when a BCB uses a public key for encryption or key-wrap. When using asymmetric keyed algorithms, the security source SHALL include a public key container or public key identifier as a signature or recipient header. The public key identifier SHALL be either an "x5t" or "x5chain" of , or "kid" (possibly with "kid context"), or an equivalent identifier. When BIB result contains a "x5t" identifier, the security source MAY include an appropriate certificate container ("x5chain" or "x5bag") in a direct COSE header or an additional header security parameter (see ). When a BIB result contains an "x5chain", the security source SHOULD NOT also include an "x5t" because the first certificate in the chain is implicitly the applicable end-entity certificate. For a BIB, if all potential security verifiers and acceptors are known to possess related public key and/or certificate data then the public key or additional header parameters can be omitted. Risks of not including related credential data are described in and . When present, public keys and certificates SHOULD be included as additional header parameters rather than within result COSE messages. This provides size efficiency when multiple security results are present because they will all be from the same security source and likely share the same public key material. Security verifiers and acceptors SHALL still process public keys or certificates present in a result message or recipient as applying to that individual COSE level. Security verifiers and acceptors SHALL aggregate all COSE_Key objects from all parameters within a single BIB or BCB, independent of encoded type or order of parameters. Because each context contains a single set of security parameters which apply to all results in the same context, security verifiers and acceptors SHALL treat all public keys as being related to the security source itself and potentially applying to every result.

Policy Recommendations The RECOMMENDED priority policy for including public key identifiers for BIB results is as follows:

When receivers are not known to possess certificate chains, a full chain is included (as an "x5chain").
When receivers are known to possess root and intermediate CAs, just the end-entity certificate is included (again as an "x5chain").
When receivers are known to possess associated chains including end-entity certificates, a certificate thumbnail (as an "x5t").
Some arbitrary identifier is used to correlate to an end-entity certificate (as a "kid" with an optional "kid context").
The BIB Security Source is used to imply an associated end-entity certificate which identifies that Node ID.

When certificates are used for public key data and the end-entity certificate is not explicitly trusted (i.e. pinned), a security verifier or acceptor SHALL perform the certification path validation of up to one or more trusted CA certificates. Leaving out part of the certification chain can cause a security verifier or acceptor to fail to validate a BIB if the left-out certificates are unknown to the acceptor (see ). The RECOMMENDED priority policy for including public key identifiers for BCB results is as follows:

When receivers are known to possess associated end-entity certificates, a certificate thumbnail (as an "x5t").
Some arbitrary identifier is used to correlate to the private key (as a "kid" with an optional "kid context").

Any end-entity certificate associated with a BIB security source or BCB result recipient SHALL adhere to the profile of .

PKIX Certificate Profile This section contains requirements on certificates used for the COSE context, while contains requirements for how such certificates are transported or identified. The profile here mandates specific data to be present in CA and end-entity certificates but does not mandate any specific key types or signing algorithms to be used. Such details are left to algorithm-specific profiles such as for CNSA 1.0. All end-entity X.509 certificates used for BPSec SHALL conform to , or any updates or successors to that profile. This profile requires Version 3 certificates due to the extensions used by this profile. Security verifiers and acceptors SHALL reject as invalid Version 1 and Version 2 end-entity certificates. Security verifiers and acceptors SHALL accept certificates that contain an empty Subject field or contain a Subject without a Common Name. Security verifiers and acceptors SHALL use the Subject Alternative Name extension for identity information in end-entity certificates. All BPSec end-entity certificates SHALL contain a Basic Constraints extension in accordance with marked as critical. All BPSec end-entity certificates SHALL contain a Subject Alternative Name extension in accordance with marked as critical. A BPSec end-entity certificate SHALL contain a NODE-ID in its Subject Alternative Name extension which authenticates the Node ID of the security source (for integrity) or a security verifier or acceptor (for confidentiality). The identifier type NODE-ID is defined in . All BPSec CA certificates SHOULD contain both a Subject Key Identifier extension in accordance with and an Authority Key Identifier extension in accordance with . All BPSec end-entity certificates SHOULD contain an Authority Key Identifier extension in accordance with . Security verifiers and acceptors SHOULD NOT rely on either a Subject Key Identifier and an Authority Key Identifier being present in any received certificate. Including key identifiers simplifies the work of an entity needing to assemble a certification chain. All BPSec CA certificates SHOULD contain an Extended Key Usage extension in accordance with . When allowed by CA policy, a BPSec end-entity certificate SHALL contain an Extended Key Usage extension in accordance with . When the PKIX Extended Key Usage extension is present, it SHALL contain a key purpose id-kp-bundleSecurity of . The id-kp-bundleSecurity purpose MAY be combined with other purposes in the same certificate. When allowed by CA policy, a BPSec end-entity certificate SHALL contain a Key Usage extension in accordance with marked as critical. The PKIX Key Usage bits which are consistent with COSE security are: digitalSignature, nonRepudiation, keyEncipherment, and keyAgreement. The specific algorithms used by COSE messages in security results determine which of those key uses are exercised. See for discussion of key use policies across multiple certificates. A BPSec end-entity certificate MAY contain an Online Certificate Status Protocol (OCSP) URI within an Authority Information Access extension in accordance with . Security verifiers and acceptors are not expected to have continuous internet connectivity sufficient to perform OCSP verification.

Multiple-Certificate Uses A RECOMMENDED security policy is to limit asymmetric keys (and thus public key certificates) to single uses among the following:

Bundle transport:: With key uses as defined in the convergence layer specification(s). Transports can require additional Extended Key Usage, such as id-kp-serverAuth or id-kp-clientAuth.
Block signing:: With key use digitalSignature and/or nonRepudiation.
Block encryption:: With key use keyEncipherment and/or keyAgreement.

This policy is the same one recommended by for email security and by Section 5.2 of more generally. Effectively this means that a BP node uses separate certificates for transport (e.g., as a TCPCL entity), BIB signing (as a security source), and BCB encryption (as a security acceptor).

Security Considerations This section separates security considerations into threat categories based on guidance of BCP 72 .

Threat: BPSec Block Replay The bundle's primary block contains fields which uniquely identify a bundle: the Source Node ID, Creation Timestamp, and fragment parameters (see ). These same fields are used to correlate Administrative Records with the bundles for which the records were generated. Including the primary block in the AAD Scope for integrity and confidentiality (see ) binds the verification of the secured block to its parent bundle and disallows replay of any block with its BIB or BCB. This profile of COSE limits the encryption algorithms to only AEAD in order to include the context of the encrypted data as AAD. If an agent mistakenly allows the use of non-AEAD encryption when decrypting and verifying a BCB, the possibility of block replay attack is present.

Threat: Untrusted End-Entity Certificate The profile in uses end-entity certificates chained up to a trusted root CA, where each certificate has a specific validity time interval. A security verifier or acceptor needs to assemble an entire certificate chain in order to validate the use of an end-entity certificate. A security source can include a certificate set which does not contain the full chain, possibly excluding intermediate or root CAs. In an environment where security verifiers and acceptors are known to already contain needed root and intermediate CAs there is no need to include those CAs, but this has a risk of a relying node not actually having one of the needed CAs. A security verifier or acceptor needs to use the bundle creation time when assembling a certificate chain and and validating it. Because of this, a security source needs to use the bundle creation time as the specific instant for choosing appropriate certificate(s) based on their validity time interval. The selection of a certificate outside of its validity time period will cause the entire security operation to be unusable.

Threat: Certificate Validation Vulnerabilities Even when a security acceptor is operating properly an attacker can attempt to exploit vulnerabilities within certificate check algorithms or configuration to authenticate using an invalid certificate. An invalid certificate exploit could lead to higher-level security issues and/or denial of service to the Node ID being impersonated. There are many reasons, described in and , why a certificate can fail to validate, including using the certificate outside of its validity time interval, using purposes for which it was not authorized, or using it after it has been revoked by its CA. Validating a certificate is a complex task and can require network connectivity outside of the primary BP convergence layer network path(s) if a mechanism such as OCSP is used by the CA. The configuration and use of particular certificate validation methods are outside of the scope of this document.

Threat: Security Source Impersonation When certificates are referenced by BIB results it is possible that the certificate does not contain a NODE-ID or does contain one but has a mismatch with the actual security source (see ). Having a CA-validated certificate does not alone guarantee the identity of the security source from which the certificate is provided; additional validation procedures in bind the Node ID based on the contents of the certificate.

Threat: Unidentifiable Key The profile in recommends key identifiers when possible and the parameters in section allow encoding public keys where available. If the application using a COSE Integrity or COSE Confidentiality context leaves out key identification data (in a COSE recipient structure), a security verifier or acceptor for those BPSec blocks only has the primary block available to use when verifying or decrypting the target block. This leads to a situation, identified in BPSec Security Considerations, where a signature is verified to be valid but not from the expected Security Source. Because the key identifier headers are unprotected (see ), there is still the possibility that an active attacker removes or alters key identifier(s) in the result. This can cause a security verifier or acceptor to not be able to properly verify a valid signature or not use the correct private key to decrypt valid ciphertext.

Threat: Non-Trusted Public Key The profile in allows the use of PKIX which typically involves end-entity certificates chained up to a trusted root CA. A BIB can reference or contain end-entity certificates not previously known to a security acceptor but the acceptor can still trust the certificate by verifying it up to a trusted CA. In an environment where security verifiers and acceptors are known to already contain needed root and intermediate CAs there is no need to include those CAs in a proper chain within the security parameters, but this has a risk of an acceptor not actually having one of the needed CAs. Because the security parameters are not included as AAD, there is still the possibility that an active attacker removes or alters certification chain data in the parameters. This can cause a security verifier or acceptor to be able to verify a valid signature but not trust the public key used to perform the verification.

Threat: Passive Leak of Key Material It is important that the key requirements of apply only to public keys and PKIX certificates. Including non-public key material in ASB parameters will expose that material in the bundle data and over the bundle convergence layer during transport.

Threat: Algorithm Vulnerabilities Because this use of COSE leaves the specific algorithms chosen for BIB and BCB use up to the applications securing bundle data, it is important to use only COSE algorithms which are marked as "recommended" in the IANA registry . Specifically for the case of vulnerability to a cryptographically relevant quantum computer, algorithms for signing and key encapsulation have been identified in but are not yet available as COSE code points allocated by published standards.

Inherited Security Considerations All of the security considerations of the underlying BPSec apply to this security context. Because this security context uses whole COSE messages and inherits all COSE processing, all of the security considerations of apply to this security context. When public key certificates are used, all of the security considerations of and any other narrowing PKIX profile apply to this security context.

AAD-Covered Block Modification The AAD Scope parameter can be used to refer to any other block within the same bundle (by its unique block number) at the time the associated security operation is added to a bundle. Because of this, if any block within the AAD coverage is modified (by any node along the bundle's forwarding path) in a way which affects the generated AAD value it will cause verification or acceptance of the containing security operation to fail. One reason why such a modification would be made is that the other block has an expected lifetime shorter than the security operation. For example, a Previous Node block () is expected to be removed or replaced at each hop. The AAD Scope parameter SHALL NOT reference any other block with an expected lifetime shorter than the containing security operation. Another reason for a modification is that the other block is designed to be updated along the forwarding path. For example, a Hop Count block () is expected to be modified as the bundle is forwarded by each node. The AAD Scope parameter SHALL NOT reference any other block using the flag AAD-btsd () if that other block is expected to be modified by intermediate nodes during the lifetime of the containing security operation. One reason for a block to be removed is if it has its block processing control flags () have the bit set indicating "Discard block if it can't be processed" and the block type or type-specific data cannot be handled by any node along the forwarding path. The AAD Scope parameter SHALL NOT reference any other block having block processing control flags with the bit set indicating "Discard block if it can't be processed" unless it is known that all possible receiving nodes can process the associated block type during the lifetime of the containing security operation.

IANA Considerations Registration procedures referred to in this section are defined in .

Bundle Protocol Within the "Bundle Protocol" registry group , the following entry has been added to the "BPSec Security Context Identifiers" registry. BPSec Security Context Identifiers

Value	Description	Reference
3	COSE	[This specification]

Within the "Bundle Protocol" registry group , the IANA has created and now maintains a new registry named "BPSec COSE AAD Scope Special Keys". shows the initial values for this registry. The registration policy for this registry is Specification Required. Specifications of new entries need to define how they relate to AAD generation procedure of . The value range is negative 16-bit integer. This value range is combined with the non-negative 64-bit integer block numbers for the AAD Scope key domain (). BPSec COSE AAD Scope Special Keys

Value	Name	Reference
-1	Target block	[This specification]
-2	Security block	[This specification]
-3 to -238	Unassigned
-239 to -240	Reserved for Experimental Use	[This specification]
-241 to -256	Reserved for Private Use	[This specification]
-257 to -65536	Reserved

Within the "Bundle Protocol" registry group , the IANA has created and now maintains a new registry named "BPSec COSE AAD Scope Flags". shows the initial values for this registry. The registration policy for this registry is Specification Required. Specifications of new entries need to define how they relate to AAD generation procedure of . The value range is a bit position within an unsigned 64-bit integer. BPSec COSE AAD Scope Flags

Bit Position(from LSbit)	Name	Reference
0	`AAD-metadata`	[This specification]
1	`AAD-btsd`	[This specification]
2-64	Unassigned

References Normative References Bundle Protocol IANA CBOR Object Signing and Encryption (COSE) IANA Structure of Management Information (SMI) Numbers IANA Informative References Recommendation for Key Management - Part 1: General US National Institute of Standards and Technology Security Requirements for Cryptographic Modules US National Institute of Standards and Technology Space Data Link Security Protocol - Summary of Concept and Rationale Consultative Committee for Space Data Systems Use of Public Standards for Secure Information Sharing US Committee on National Security Systems Use of Public Standards for Secure Information Sharing US Committee on National Security Systems DTN Bundle Protocol Security COSE Security Context The Johns Hopkins University Applied Physics Laboratory Demo Convergence Layer Agent The Johns Hopkins University Applied Physics Laboratory Wireshark repository Wireshark Foundation

Example Security Operations These examples are intended to have the correct structure of COSE security blocks but in some cases use simplified algorithm parameters or smaller key sizes than are required by the actual COSE profile defined in this documents. Each example indicates how it differs from the actual profile if there is a meaningful difference. All of these examples operate within the context of the bundle primary block of with a security target block of . All example figures use the extended diagnostic notation .

Primary block CBOR diagnostic [ 7, / BP version / 0, / flags / 0, / CRC type / [1, "//dst/svc"], / destination / [1, "//src/svc"], / source / [1, "//src/"], / report-to / [ / timestamp: / 813110400000, / creation time: 2025-10-07T00:00:00Z / 0 / seq. no. / ], 1000000 / lifetime / ]

Target block CBOR diagnostic [ 1, / type code: payload / 1, / block num / 0, / flags / 0, / CRC type / <<"hello">> / block-type-specific-data / ] Together these form an original bundle without any security operations present. This bundle is encoded as the following 67 octets in base-16: 9f880700008201692f2f6473742f7376638201692f2f7372632f7376638201662f2f 7372632f821b000000bd51281400001a000f42408501010000466568656c6c6fff All of the block integrity block examples operate within the context of the "frame" block of , and block confidentiality block examples within the frame block of .

Block integrity frame block CBOR diagnostic [ 11, / type code: BIB / 3, / block num / 0, / flags / 0, / CRC type / '' / BTSD to be replaced with ASB / ]

Block confidentiality frame block CBOR diagnostic [ 12, / type code: BCB / 3, / block num / 0, / flags / 0, / CRC type / '' / BTSD to be replaced with ASB / ] All of the examples also operate within a security block containing the AAD Scope parameter with value {0:0b1,-1:0b1} indicating the primary block and target block metadata are included. This results in a consistent AAD-list as shown in , which is encoded as the byte string for COSE external_aad in all of the examples.

Example scope AAD-list CBOR-sequence diagnostic [1, "//src/"], / security source / {0:0b1, -1:0b1}, / AAD-scope / [7, 0, 0, [1, "//dst/svc"], [1, "//src/svc"], [1, "//src/"], [813110400000, 0 ], 1000000], / primary-block / 1, 1, 0, / target block-metadata / '' / additional-protected / The only differences between these examples which use ECC or RSA keypairs and a use of a public key certificate are: the highest-layer parameters would contain an "x5t" (or equivalent, see ) value instead of a "kid" value. This would not be a change to a protected header so, given the same private key, there would be no change to the signature or wrapped-key data. Because each of the COSE_Encrypt examples using key wrap or encapsulation (, , ) use the same CEK within the same AAD, the target ciphertext is also identical. The target block after application of the encryption is shown in .

Encrypted Target block CBOR diagnostic [ 1, / type code: payload / 1, / block num / 0, / flags / 0, / CRC type / h'1fd25f64a2ee886e97ecfde7667371214f5add54a089' / ciphertext / ]

Symmetric Key COSE_Mac0 This is an example of a MAC with recipient having a 384-bit symmetric key (same size of the hash output) identified by a "kid".

Symmetric Key [ { / kty / 1: 4, / symmetric / / kid / 2: 'ExampleMAC', / alg / 3: 6, / HMAC 384 384 / / ops / 4: [9, 10], / MAC create, MAC verify / / k / -1: h'3a5c74e32ab4558a99581ec3a816576812aabe895db04494cda2 5b711d7b5ed4077466e677860648412f1bf8c91d0624' } ] The external_aad is the encoded data from . The payload is the encoded target BTSD from .

MAC_structure CBOR diagnostic [ "MAC0", / context / h'a10105', / protected / h'8201662f2f7372632fa200012001880700008201692f2f6473742f7376638201 692f2f7372632f7376638201662f2f7372632f821b000000bd51281400001a000f42 4001010040', / external_aad / h'6568656c6c6f' / payload / ]

ECC Keypair COSE_Sign1 This is an example of a signature with a recipient having a P-256 curve ECC keypair identified by a "kid". The associated public key is included as a security parameter.

Example Keys [ { / signing private key / / kty / 1: 2, / EC2 / / kid / 2: 'ExampleEC2', / alg / 3: -51, / ESP384 / / ops / 4: [1, 2], / sign, verify / / crv / -1: 2, / P-384 / / x / -2: h'02dfc49747f5d3d219fe6185744729fa1672ef7d11cb57ca0320 c632be06ca3fdcc118e63140ba3ec57ea7b85d419568', / y / -3: h'4526e81bf0d9ea0924f05a3453ad75b92806671511544c993f6b d908a7a4239d476cfdfd74d6c68836488ad1e60b0e7d', / d / -4: h'3494803544d85a84d802400b50f51eea23b72d7d850b53cbf300 6e5be2940d4a2c18d510a412efc7dc7875fbba22cca9' } ] The external_aad is the encoded data from . The payload is the encoded target BTSD from .

Sig_structure CBOR diagnostic [ "Signature1", / context / h'a10126', / protected / h'8201662f2f7372632fa200012001880700008201692f2f6473742f7376638201 692f2f7372632f7376638201662f2f7372632f821b000000bd51281400001a000f42 4001010040', / external_aad / h'6568656c6c6f' / payload / ]

RSA Keypair COSE_Sign1 This is an example of a signature with a recipient having a 3072-bit RSA keypair identified by a "kid". The associated public key is included as a security parameter. This key strength is not supposed to be a secure configuration, only intended to explain the procedure. This signature uses a random salt, so the full signature output is not deterministic.

Example Keys [ { / signing private key / / kty / 1: 3, / RSA / / kid / 2: 'ExampleRSA', / alg / 3: -38, / PS384 / / ops / 4: [1, 2], / sign, verify / / n / -1: h'f47b7c275eff5bf74e9e69d2b50e9a5dc0666147ca2541fce9a2 53d00840e2481378733797a9db641911937aff7cbc579f16484cea2cd3fbe2db3bbb 26b18e2b95b49b9255f378ee62f806227dd0ddeb48456358bfe1cadd861645e89208 c5a5b1da34af0e3f0ad1f82633fb6b21b7ef901bffebf1144ed0d4cfcb51e21b820c fa6c829ca95cd08f3eb779b31569bb5e64c67f9976df92284ecea085a9a25882707a 9ba2af769017983e58b48afde78149453ebdcf1bcad76c30c253deaacc21a4a91bce 2b896776c1c5cfe0aaaae714c0b7e2063542ea81ec27af2746fd402e02e71040e41a a23c79179e20a93c921fb26d13e11f802c2836506d0f0be507997aa07454f8b74a80 7c9342c8697d670fe6b1c2574a18013296cca897c4ddb96215fd30a4c4ee5db5b484 4c9d1e7bd6923ab0feaa30fe79d821fb63ed391b175837d53db1b207bc984b9a377c 7b4fb58738cca4254c3273440830cee84552304e8aaed0c0187b59339b28f213076a f2c77aa46fe37bef31910ada5e44643ac7b1', / e / -2: h'010001', / d / -3: h'5a4dfac0d33317ff5b1879ab793db7455f2ce0e596fd5ff1e901 15a08087b18c413a15d4a007e41d8a71eaa81490a926bd4289d072e6b8102ba25073 1c02b238b95cc4f1d2d1ece45cb41c66a22bafcd0da48726daf2a20c159136e7d527 944f46d73ee084184682e4ca0a287d26e92535c532a4790e8bb6589f0bce2f6f693d 900db994f9fb92a95f01ed077cb667f938ab73f9cc27715bcc357fb4acb20630ad2c 40893b0a6a9be0ab50b7d4bfbd088e85919e61f325a33b0fc2e709c879c33ab7675a 395f45c8e5f08c1a7e1871f6bc12eef424566896eca111e42060ea64ea5ea11f693f 6923525829a0e394434eb0ec1a5586677bcab8a7b8d961b6134236f027d3dd2c0fee 03e46f534d782d73bf4b1b906dae037c4fc6982082b5c1946418780e3a2a14ba5717 ddb98df721e42da8b419a7febc06c3948cd0612e2b3d861077d5622af774d6af4f19 f1d38658174eded20954d45d4c1db848ea3c8805aaf338615ae9e40e3990352c0dfe 84563b67d2e72638806807e8b56edb41', / p / -4: h'fd804ae7f7499d69cd3d1299879e9645b90e829e92c88d759bf2 b3d4ed391b592407c2f1f26dd0f345bbe448b21a2248450652aebaa65a6815919dba 29d66ea2c1d862cab37391190c5e1fb162d7101412588d913fecd0e675785522661a ecbbc50e2678e60485080b472e5f5720854a21eb456e1c26de4102d99cc2e08afa13 d2aa3e7f94d91e2fb43ab400c5e3061c69fcfcf78c7a81cdcc672d0f5630eb08ac90 86a8c957d4f8c9c71dd75a78efe1e1d764d34d7043f0aac9a0d0beaf8921', / q / -5: h'f6e46eff1e17493b92e379a6ae2594970d6ab3ff43bb84fda781 0b5feb89d94008fbf8de9ce8584aa95ad759261ce78fd421c26f5c1eaf482792e6fc 25eeac320a2195db28ab9071182ca4d4d041cfea6d754940248527352337e87e7b44 14d59b916808e977d97676cf97ee04b7f95aa3611f1fb98b7a341563ca42e9af810b 67ecd8989deb96ddde66004efdda610c77cd75b9337b5e1993c6d2b3212c64461d61 334193bad6ebb62ae67325e1157a394c8c7422a3d65ecd0212114d7e9c91', / dP / -6: h'ec2626217f38c17e3d26267c855d1389f2017566b940409f0dd e82edd8eb38f1ca61bc95dd0bb5f9d9bd55c4eebcefb0b93451b3d9c67c33b7dc05b dd5999f48d92175ae748b34e0cba7a7087d15f1317181b2a75b90856e1a823574acf f6a06e563f02cf1c1c6179f41f90df1c126c9cf5d373982da2673136f9adbe38733b d61a31c43876ad6f70383280a0c4e177442bbdcffd28a90ff20ea008ce7f2fc10018 9451859300c02931d7d4c0f48d7d669a758928af209285a4128212d71a261', / dQ / -7: h'a0d29842f294f48d2bd7a56c9fcfb704d626856d67ef8467be6 edebbf2afeea639b3f89ef9d29780bae483967caf235f9b2d0a7c83a331466d10d20 9b9a3c8e3279a4d055f6eb23e19232b93bcbcc1f4d0ac2fb4ea9519bf115bdfc4540 33b1711a91bfd822721ae7b222ab34ebb90602c409d878ad3821cdf3a0b8c9eb045f cea0b6be3ae2ac23170273d58371fc34bddd626332787dafa0a3adf10f430f8787bb 6cf2e8e4e8ca52a1ab3d699fc0e83794395d228a6548398431b05ce570521', / qInv / -8: h'1f1b16da1f590fc9e6b174122d8c78554adee8627c31068ab ccf56f8a73c04fd677567d9fe246b1ff972c9b74e238bf4e04b9cef7e0ba76befea4 3a0e114a0aff45b2cbeff649614281017c1f00be91ba2562453a0a5ee25f6518fcf0 7dddf2da2c645bc337a51b8108dba1aab223893c7fcbabdb5b9c88b618e858eda994 b7c04b1bffe2612f743e857707dccea4f7a93d711f818a8e6420890c2e73eb7f4fcc 3c55c7d83b4d2bbd9bcea0c0668570e9ca7e92e5ca626754180da12a6b85a85' } ] The external_aad is the encoded data from . The payload is the encoded target BTSD from .

Sig_structure CBOR diagnostic [ "Signature1", / context / h'a1013824', / protected / h'8201662f2f7372632fa200012001880700008201692f2f6473742f7376638201 692f2f7372632f7376638201662f2f7372632f821b000000bd51281400001a000f42 4001010040', / external_aad / h'6568656c6c6f' / payload / ]

Abstract Security Block CBOR diagnostic [1], / targets / 3, / security context / 1, / flags: params-present / [1, "//src/"], / security source / [ / parameters / [ 5, / AAD-scope / {0:0b1,-1:0b1} / primary metadata, target metadata / ] ], [ [ / target block #1 / [ / result / 18, / COSE_Sign1 tag / <<[ <<{ / protected / / alg / 1: -38 / PS384 / }>>, { / unprotected / / kid / 4: 'ExampleRSA' }, null, / payload detached / h'93573a924293bc39714337edebd6bc6ea5a3b8e70f765f1f0cbf1e9410 e890117d745858b6d63ec85414b7d9e37d5c83cd44b2ba58bb68b9ea5a9d988cb80c 47b0218f7f4f17427a7707f951703d90505613a5728ac53851cb230fa143fc622661 d0f2042a4d588ca7e2ba1009943258fe0181de637d8a3a7c0659906f6fbbda5c2941 81032831a07fe61aedefd862332417c08b4e8c7af6d5239425a6c93eb0d851ec9994 5ec80d3004eec0d9a129f4f2cc62f29548d429e4a6ea30fe07638e647b2c1b4c06a4 3af25b318f1d368957c76c1b1e3f60e123e7d51e45a3951a6ee9922343c02666cc51 852c95a3dee396f650f2b2af3f0e02d92a1793855397a55087e5b3eb25eb78e9493b 72ae8710069c62e78d3968983a2058c9d1242903bf97d2ffd803a989dcf8a80d514b dc84365258fc30d4a29201e115c589664ed7ca27eddb0a5524902bcae2f1cd77ec24 44971e80596bb1f5b22ef4c53fe493b460d1bb449a95b645b10c1e65e593afea852b 9e6786ea7edd8b230e4a9c59e4468a' / signature / ]>> ] ] ] The final bundle is encoded as the following 510 octets in base-16: 9f880700008201692f2f6473742f7376638201692f2f7372632f7376638201662f2f 7372632f821b000000bd51281400001a000f4240850b0300005901b3810103018201 662f2f7372632f818205a200012001818182125901978444a1013825a1044a457861 6d706c65525341f659018093573a924293bc39714337edebd6bc6ea5a3b8e70f765f 1f0cbf1e9410e890117d745858b6d63ec85414b7d9e37d5c83cd44b2ba58bb68b9ea 5a9d988cb80c47b0218f7f4f17427a7707f951703d90505613a5728ac53851cb230f a143fc622661d0f2042a4d588ca7e2ba1009943258fe0181de637d8a3a7c0659906f 6fbbda5c294181032831a07fe61aedefd862332417c08b4e8c7af6d5239425a6c93e b0d851ec99945ec80d3004eec0d9a129f4f2cc62f29548d429e4a6ea30fe07638e64 7b2c1b4c06a43af25b318f1d368957c76c1b1e3f60e123e7d51e45a3951a6ee99223 43c02666cc51852c95a3dee396f650f2b2af3f0e02d92a1793855397a55087e5b3eb 25eb78e9493b72ae8710069c62e78d3968983a2058c9d1242903bf97d2ffd803a989 dcf8a80d514bdc84365258fc30d4a29201e115c589664ed7ca27eddb0a5524902bca e2f1cd77ec2444971e80596bb1f5b22ef4c53fe493b460d1bb449a95b645b10c1e65 e593afea852b9e6786ea7edd8b230e4a9c59e4468a8501010000466568656c6c6fff

Symmetric CEK COSE_Encrypt0 This is an example of an encryption with an explicit CEK identified by a "kid". The key used is shown in , which includes a Base IV parameter in order to reduce the total size of the COSE message using a Partial IV.

Example Key [ { / kty / 1: 4, / symmetric / / kid / 2: 'ExampleCEK', / alg / 3: 3, / A256GCM / / ops / 4: [3, 4], / encrypt, decrypt / / base IV / 5: h'6f3093eba5d85143c3dc0000', / k / -1: h'13bf9cead057c0aca2c9e52471ca4b19ddfaf4c0784e3f3e8e39 99dbae4ce45c' } ] The external_aad is the encoded data from .

Enc_structure CBOR diagnostic [ "Encrypt0", / context / h'a10103', / protected / h'8201662f2f7372632fa200012001880700008201692f2f6473742f7376638201 692f2f7372632f7376638201662f2f7372632f821b000000bd51281400001a000f42 4001010040' / external_aad / ] The ASB item for this encryption operation is shown in and corresponds with the updated target block (containing the ciphertext) of . This ciphertext is different than the common one in because of the different context string in .

Encrypted Target block CBOR diagnostic [ 1, / type code: payload / 1, / block num / 0, / flags / 0, / CRC type / h'1fd25f64a2ee5c93bb884d529bce14cb24bdeaf8a3f1' / ciphertext / ] The final bundle is encoded as the following 139 octets in base-16: 9f880700008201692f2f6473742f7376638201692f2f7372632f7376638201662f2f 7372632f821b000000bd51281400001a000f4240850c030000583181010301820166 2f2f7372632f818205a20001200181818210578343a10103a2044a4578616d706c65 43454b0642484af68501010000561fd25f64a2ee5c93bb884d529bce14cb24bdeaf8 a3f1ff

Symmetric Key COSE_Encrypt with Key Wrap This is an example of an encryption with a random CEK and an explicit key-encryption key (KEK) identified by a "kid". The keys used are shown in .

Example Keys [ { / kty / 1: 4, / symmetric / / kid / 2: 'ExampleKEK', / alg / 3: -5, / A256KW / / ops / 4: [5, 6], / wrap, unwrap / / k / -1: h'0e8a982b921d1086241798032fedc1f883eab72e4e43bb2d11cf ae38ad7a972e' }, { / wrapped CEK / / kty / 1: 4, / symmetric / / alg / 3: 3, / A256GCM / / k / -1: h'13bf9cead057c0aca2c9e52471ca4b19ddfaf4c0784e3f3e8e39 99dbae4ce45c' } ] The external_aad is the encoded data from .

Enc_structure CBOR diagnostic [ "Encrypt", / context / h'a10103', / protected / h'8201662f2f7372632fa200012001880700008201692f2f6473742f7376638201 692f2f7372632f7376638201662f2f7372632f821b000000bd51281400001a000f42 4001010040' / external_aad / ] The ASB item for this encryption operation is shown in and corresponds with the updated target block (containing the ciphertext) of . The recipient does not have any protected header parameters because AES Key Wrap does not allow any AAD.

Symmetric Key COSE_Encrypt with HKDF This is an example of an encryption with a derived CEK and an explicit key-derivation key (KDK) identified by a "kid". The keys used are shown in , where the second key is the CEK derived from the KDK via a salt value in the recipient header.

Example Keys [ { / kty / 1: 4, / symmetric / / kid / 2: 'ExampleKDK', / alg / 3: -11, / direct+HKDF-SHA-512 / / ops / 4: [7], / derive key / / k / -1: h'0e8a982b921d1086241798032fedc1f883eab72e4e43bb2d11cf ae38ad7a972e' }, { / derived CEK / / kty / 1: 4, / symmetric / / alg / 3: 3, / A256GCM / / k / -1: h'b0f3604f54d3f15e272357d1df75b50ede1475b0cdb17fef0fd1 46b9bbcda3a3' } ] The external_aad is the encoded data from .

Enc_structure CBOR diagnostic [ "Encrypt", / context / h'a10103', / protected / h'8201662f2f7372632fa200012001880700008201692f2f6473742f7376638201 692f2f7372632f7376638201662f2f7372632f821b000000bd51281400001a000f42 4001010040' / external_aad / ] The ASB item for this encryption operation is shown in and corresponds with the updated target block (containing the ciphertext) of . This ciphertext is different than the common one in because of the different derived CEK in .

Encrypted Target block CBOR diagnostic [ 1, / type code: payload / 1, / block num / 0, / flags / 0, / CRC type / h'7443d510ee5ce1280ac6639b2256c98015ebfa8a8eb4' / ciphertext / ] The final bundle is encoded as the following 177 octets in base-16: 9f880700008201692f2f6473742f7376638201692f2f7372632f7376638201662f2f 7372632f821b000000bd51281400001a000f4240850c030000585781010301820166 2f2f7372632f818205a2000120018181821860583b8443a10103a1054c6f3093eba5 d85143c3dc484af6818343a1012aa2044a4578616d706c654b454b33502fa8c8352a ea17faf7407271a5e90eb8408501010000567443d510ee5ce1280ac6639b2256c980 15ebfa8a8eb4ff

ECC Keypair COSE_Encrypt with Key Wrap This is an example of an encryption with an P-256 curve ephemeral sender keypair and a static recipient keypair identified by a "kid". The keys used are shown in .

Example Keys [ { / sender ephemeral private key / / kty / 1: 2, / EC2 / / crv / -1: 2, / P-384 / / x / -2: h'2f88f095c45c96e377e18d717a5e6007ce8f6076ae82009d1637 5e1b9abaa9497a4bde513be6c9b0e7dae96033968c45', / y / -3: h'fd27656fbb97f789d667f40d73b65ab362b22dd23bf492bee72b f3409f68dddf208040a5fcbcbee74545741e2866cb2d', / d / -4: h'c4fff15193b8bceff5e221cc37b919fa8d33581a37c08d3e8520 a658b4040a443f8fb3b54fb4ce882510e76017b66261' }, { / recipient private key / / kty / 1: 2, / EC2 / / kid / 2: 'ExampleEC2', / alg / 3: -31, / ECDH-ES + A256KW / / ops / 4: [7], / derive key / / crv / -1: 2, / P-384 / / x / -2: h'0057ea0e6fdc50ddc1111bd810eae7c0ba24645d44d4712db0c8 354c234b2970b4ac27e78f38250069d128f98e51ceb1', / y / -3: h'4b72c50b27267637c40adcd78bd025e4b654a645d2ba7ba9894c c73b2431d4cdc040d66e8eb2dad731f7dca57108545c', / d / -4: h'7931af7cc3010ae457bcb8be100acdafab8492de633b20384c3e 4de5e5e94899d9d9de25c04d6205ae6bb9385ce16ff7' }, { / wrapped CEK / / kty / 1: 4, / symmetric / / alg / 3: 3, / A256GCM / / k / -1: h'13bf9cead057c0aca2c9e52471ca4b19ddfaf4c0784e3f3e8e39 99dbae4ce45c' } ] The external_aad is the encoded data from .

ECC Keypair COSE_Encrypt with HKDF This is an example of an encryption with an P-256 curve static sender keypair and a static recipient keypair each identified by a "kid". The keys used are shown in , where the third key is the CEK derived from the ECDH secret via a salt value in the recipient header.

Example Keys [ { / kty / 1: 2, / EC2 / / kid / 2: 'SenderEC2', / alg / 3: -28, / ECDH-SS + HKDF-512 / / ops / 4: [7], / derive key / / crv / -1: 2, / P-384 / / x / -2: h'2f88f095c45c96e377e18d717a5e6007ce8f6076ae82009d1637 5e1b9abaa9497a4bde513be6c9b0e7dae96033968c45', / y / -3: h'fd27656fbb97f789d667f40d73b65ab362b22dd23bf492bee72b f3409f68dddf208040a5fcbcbee74545741e2866cb2d', / d / -4: h'c4fff15193b8bceff5e221cc37b919fa8d33581a37c08d3e8520 a658b4040a443f8fb3b54fb4ce882510e76017b66261' }, { / recipient private key / / kty / 1: 2, / EC2 / / kid / 2: 'ExampleEC2', / alg / 3: -28, / ECDH-SS + HKDF-512 / / ops / 4: [7], / derive key / / crv / -1: 2, / P-384 / / x / -2: h'0057ea0e6fdc50ddc1111bd810eae7c0ba24645d44d4712db0c8 354c234b2970b4ac27e78f38250069d128f98e51ceb1', / y / -3: h'4b72c50b27267637c40adcd78bd025e4b654a645d2ba7ba9894c c73b2431d4cdc040d66e8eb2dad731f7dca57108545c', / d / -4: h'7931af7cc3010ae457bcb8be100acdafab8492de633b20384c3e 4de5e5e94899d9d9de25c04d6205ae6bb9385ce16ff7' }, { / derived CEK / / kty / 1: 4, / symmetric / / alg / 3: 3, / A256GCM / / k / -1: h'67bb109aaee51e9616b512d5750139444ca26e6c0eeaa87f3917 de41dd9ad9f6' } ] The external_aad is the encoded data from .

Enc_structure CBOR diagnostic [ "Encrypt", / context / h'a10103', / protected / h'8201662f2f7372632fa200012001880700008201692f2f6473742f7376638201 692f2f7372632f7376638201662f2f7372632f821b000000bd51281400001a000f42 4001010040' / external_aad / ] The ASB item for this encryption operation is shown in and corresponds with the updated target block (containing the ciphertext) of . This ciphertext is different than the common one in because of the different derived CEK in .

Encrypted Target block CBOR diagnostic [ 1, / type code: payload / 1, / block num / 0, / flags / 0, / CRC type / h'925c33206eb8223957ae40693c02d1f6a0cdb71574aa' / ciphertext / ] The final bundle is encoded as the following 189 octets in base-16: 9f880700008201692f2f6473742f7376638201692f2f7372632f7376638201662f2f 7372632f821b000000bd51281400001a000f4240850c030000586381010301820166 2f2f7372632f818205a200012001818182186058478443a10103a1054c6f3093eba5 d85143c3dc484af6818344a101381ba3044a4578616d706c65454332224953656e64 657245433233502fa8c8352aea17faf7407271a5e90eb840850101000056925c3320 6eb8223957ae40693c02d1f6a0cdb71574aaff

RSA Keypair COSE_Encrypt This is an example of an encryption with a recipient having a 1024-bit RSA keypair identified by a "kid". The associated public key is included as a security parameter. This key strength is not supposed to be a secure configuration, only intended to explain the procedure. This padding scheme uses a random salt, so the full Layer 1 ciphertext output is not deterministic.

Example Keys [ { / recipient private key / / kty / 1: 3, / RSA / / kid / 2: 'ExampleRSA', / alg / 3: -42, / RSAES-OAEP w SHA-512 / / ops / 4: [1, 2], / sign, verify / / n / -1: h'c257bd2257000620d6c12e7fb988b891c0fa0f8eab597e2c56f0 ae49da3f24eb9b99f9cc147820bd7f3feffc41cd63aa7a805a454c73d60cee478ac8 e6be050943a134565c5b84aa619ba674f901314e2007bab3740c3b581720bc89d50c 81726722d5c6bbb9966285dd66d4524561aadd0d6e8d7d970530a6c30af202e55e4e 44505ce08ebe5217d2825edfa76397226ef58517abcc2e73873386ef9a0d14306466 f2ed2c61ce6eaca12a026b62db054379e9f6575e802355f53ce3efd44d58dd9f2ba7 385130815eed0e4649547fc38ff469a4f098d22214a6adf72c3f6a3b3ee3545835ea a9a9ab6467b17a62acb3179f31dc534539ffd21981fe5e5ea088ff4f1cdf051d8d97 704101e81d8030e2e4863c1571452f94a9f47ec7339536058c287c376b0a6b5c6226 fdefd716b4438a9f987d50de25a73537d42a54d9d042f8d623f493d1fe0fdea8cd75 0381796cc9af7fdbac6eb7c8b4aa2e3f227d0fbbfbece7fd707e0f739b23a63b5a51 18f553e834facda493e276ec9663ba65bf2b', / e / -2: h'010001', / d / -3: h'132665ced99cce7dc8e643488c5b37b8b662784afa2bce33874e 486ba2e9004b2e762c8d0562aaf33bf3ec6d6d2729d02ad45ffb73ce4c442797541f cf7634f52b3d5a1f67bd658eb6773473fd4a0bf638a61a546ee07a5932a4e3ff299d 05afba104ed964e12390f4c392cb8edf2301c7ae22fbd294218ba03b183bd8638aa3 3d61b52d3428f684e8c0e0f6ba934fd95c440432876d63670de65ac05c6be2813c3b 8014dfd53416bd7054bd3aa0af42a45a01df12253a8cd62908057be4987462758517 12623580de4cea4cefb2fbd154874bf13894d2a09ea9f18a9d6fcf66e8fefbf4029c e635ac1b60b444bab134ec67e397172a1dc79018ccc5713edaa21917cb34486a2a81 c9e45ee21eb9bf465e7f42b4dfe17f17505b07d52bcf5233f215d96479201858e238 b2672c2de6c589107f2877479a39728360a718400b3de94759f4e50049e279677481 dd9151f82be9fef8289e297123e0ef08479010c4cc98096788857009fa41f8670556 03491dea29e74d30925b42cceb004e7a371d', / p / -4: h'e49562b275ab259750b010ade9720f0c1e07c42e73d969b9c28d f2bb6a72a162c24101a9a97091a935ce5202015e9540971734ceb0f4014fecbaf7f0 c4a6eeb6d82b46a69b4e5ed9a1099035e6dbfa3686985f8ae9c6a2f1afd2c1a5b60d 16f4b1d22741bcfb12c103c11a3a68700c93e010906192289774f86400bbd513fad6 42b32fb7b9ddb05d5c48ce9bbcae48239ce41f7630f6ec6ccf9dbeffc84edc2944f7 49b16f445b829a7bc5dce644a377fa88035e0756aeca77c71dcb8f87514f', / q / -5: h'd9a6fee7a8e74201b5afe5188b0498fe4f902b7a4fd18fe64c1d 6344188bb4ac26ccf3ff66f244ab2bb2d87fc94ac9e3e13482799f12585df2b6d556 233c818853071912bc56c2b4c81ef9674e552af7bf8907f9ff9d318dcf7bc04eb086 4a6c618468e3005721c1b9de436f81e9f9ae5d54228eba78af72760997e91d6f9481 a43a5557fce42acf08868b460cfca2f3cdee7f47205f24343bceebb011e4aa80f94c c3a65f04dd5810e783d509f2346488338ec9012a046ad92ea9a10589e565', / dP / -6: h'a8b520fd3a1fb144f7069ba8e02d90b18ed08899086424c637b 3f0bd2699a8476dbbf0f039e09d8157f7094bf59acb69ba9a241d9138e66709000dd 3243158ea96ad8a1d996ec44eb7ae89435f3a687829eaf8495cb580ba04dcf693c9c 3eb777a6ef30e6fde973ee1f879d53613cd14af414a6ed9232075f2864c8c557dc39 ab3ebf08217aa696ade9bd5f1d7d681e3d6fdffc289ed151e5235c92c9bb8a881c52 706baf0b6711bf9ccf4824f69c584dde1d92a631c3531b629bdf1e9e323bd', / dQ / -7: h'a0fa7a9e2cb69e835535fb63e3ae4ada0d4ebc59829fa4a6d8b 503ae61d932900142a554c977768283978bb937d030f272a6bbb9e88551066b75fee 3eebbd9b25276757cfdffcd9298511075efe1de1dcf74328a1d1cce81ec6bc318704 762d4366c108794c0dd1ec3b2387e48c01d0371d3c09b801fb2e41d998ad9c803b6f b0bd4793ad2b88f51012541ed55bda5685d6f8083c2d59b996682ec9f151ce35ef10 46dd0a786998f81313ab85edadd155e07841bf6d874dbf23629100760ae61', / qInv / -8: h'598da6c558bf08c201b845b2dab3ff00a2ee74ce064d86f18 af2f8b721205224526b7d8b9c42f6bc7f34a8c8623dcfc28ff800e28f23cd3018148 57a728b282a121ee6d47d031eef5c14d84d6aadfd2bdf3ef9d10dce7dda11ba466f1 25d67772b945b79baa5092f86f98dcfd1d8fc946fd24851bc3e49033c29d6509a73d 64326d3981b165be7bb2fa15d2696200c786fe1098449ded9207af0391caabf617da 3fd8c777e1ad755bd24855dc6d84933987543f12fba160c3c71de8bff439468' }, { / encapsulated CEK / / kty / 1: 4, / symmetric / / alg / 3: 3, / A256GCM / / k / -1: h'13bf9cead057c0aca2c9e52471ca4b19ddfaf4c0784e3f3e8e39 99dbae4ce45c' } ] The external_aad is the encoded data from .

Abstract Security Block CBOR diagnostic [1], / targets / 3, / security context / 1, / flags: params-present / [1, "//src/"], / security source / [ / parameters / [ 5, / AAD-scope / {0:0b1,-1:0b1} / primary metadata, target metadata / ] ], [ [ / target block #1 / [ / result / 96, / COSE_Encrypt tag / <<[ <<{ / protected / / alg / 1: 3 / A256GCM / }>>, { / unprotected / / iv / 5: h'6f3093eba5d85143c3dc484a' }, null, / payload detached / [ [ / recipient / <<>>, / protected / { / unprotected / / alg / 1: -42, / RSAES-OAEP w SHA-512 / / kid / 4: 'ExampleRSA' }, h'407e01f5fc110dcf186fb9d7b627a45a2cfb230724b55a7b17aba0 e184688c7913278b505d23d9a0087fc02bc3422b8e12d106741ce1e075fa0346352d f5c4a4f7e81c4e2c08003fb1df95f8e1b84b92e06d23b8c23b50e3507635df98841c c5ec190b1095919515886476ba674a0fccad15e367a2b7515be59926abf5be8082ff 68679446c6f95dc05366014d437740e1878396a9e25dfb11000e5f07a45f9e3bebd7 b4a2f7d28313de67d41b9ac11873285140244aa0df61cdfcc02e4b06e1493814d57d 4748c035535caccfdd897066c21efc7f79abfd070297b991fb049a86114138c68f46 47fe9052d8378cff99a7bdbe340041cc272e4d612b62ca4f1892f022164095ff63d6 32d55b66db7e025ec28374083d933f53d8d9750bfba377c8e0afdc3636960e19703e 1b65c1c7684b2543c252f086f37792fd65935f6dc942acfea7cad77ae2777ff3f700 f37dfeb65f3968a4fc7544d2d346e498f8f53737877583387846bae1baaef0aab6dd 5725e617d0d994cc0c8a1a3a6b659f768a' / key-encapsulation / ] ] ]>> ] ] ] The final bundle is encoded as the following 547 octets in base-16: 9f880700008201692f2f6473742f7376638201692f2f7372632f7376638201662f2f 7372632f821b000000bd51281400001a000f4240850c0300005901c8810103018201 662f2f7372632f818205a20001200181818218605901ab8443a10103a1054c6f3093 eba5d85143c3dc484af6818340a2013829044a4578616d706c65525341590180407e 01f5fc110dcf186fb9d7b627a45a2cfb230724b55a7b17aba0e184688c7913278b50 5d23d9a0087fc02bc3422b8e12d106741ce1e075fa0346352df5c4a4f7e81c4e2c08 003fb1df95f8e1b84b92e06d23b8c23b50e3507635df98841cc5ec190b1095919515 886476ba674a0fccad15e367a2b7515be59926abf5be8082ff68679446c6f95dc053 66014d437740e1878396a9e25dfb11000e5f07a45f9e3bebd7b4a2f7d28313de67d4 1b9ac11873285140244aa0df61cdfcc02e4b06e1493814d57d4748c035535caccfdd 897066c21efc7f79abfd070297b991fb049a86114138c68f4647fe9052d8378cff99 a7bdbe340041cc272e4d612b62ca4f1892f022164095ff63d632d55b66db7e025ec2 8374083d933f53d8d9750bfba377c8e0afdc3636960e19703e1b65c1c7684b2543c2 52f086f37792fd65935f6dc942acfea7cad77ae2777ff3f700f37dfeb65f3968a4fc 7544d2d346e498f8f53737877583387846bae1baaef0aab6dd5725e617d0d994cc0c 8a1a3a6b659f768a8501010000561fd25f64a2ee886e97ecfde7667371214f5add54 a089ff

Example Public Key Certificates This section contains example public key certificates corresponding to end-entity private keys and identities used in examples of with structure and extensions conforming to the profile of . All of the example certificates contain a validity time interval extending a short amount around the original bundle creation time of the original bundle.

Root CA Certificate This root CA certificate and private key are included for completeness in testing path validation with a full chain. This root CA does not allow any intermediates purely as an example, while a typical deployed PKI would separate a root CA from intermediate signing CA(s). It also does not include any Certificate Policies, Name Constraints, or Policy Constraints extensions as an operational CA might do to express or control how its subordinates are validated and used. It does, however, include an Extended Key Usage (EKU) value id-kp-bundleSecurity which indicates that this certificate tree is authorized for securing BP data.

CA Certificate Content Version: 3 (0x2) Serial Number: 15:15:ff:a7:40:a4:bd:73:f5:ba Signature Algorithm: ecdsa-with-SHA384 Issuer: CN = Certificate Authority Validity Not Before: Oct 6 00:00:00 2025 GMT Not After : Oct 16 00:00:00 2025 GMT Subject: CN = Certificate Authority Subject Public Key Info: Public Key Algorithm: id-ecPublicKey Public-Key: (384 bit) pub: 04:cc:7b:ba:7b:04:77:e0:f7:97:30:40:a1:83:fd: 0c:8b:44:9f:6f:e2:bd:ab:ec:df:9c:7a:72:e2:2c: b3:55:6a:49:64:89:ca:75:f8:09:f1:1f:73:7e:08: 00:71:c0:e6:1c:06:36:15:68:c2:24:be:ab:29:17: 54:fd:40:c8:75:b8:be:3f:f7:46:0b:50:d4:28:1b: ec:95:d5:34:b4:4a:f4:97:71:5a:09:52:11:e3:59: 28:b2:fb:f4:55:c7:6a ASN1 OID: secp384r1 NIST CURVE: P-384 X509v3 extensions: X509v3 Basic Constraints: critical CA:TRUE, pathlen:0 X509v3 Key Usage: critical Certificate Sign, CRL Sign X509v3 Extended Key Usage: 1.3.6.1.5.5.7.3.35 X509v3 Subject Key Identifier: 1B:77:33:BE:83:75:66:6A:75:86:22:F2:AB:0A:17:60:3F:42:56:03 X509v3 Authority Key Identifier: 1B:77:33:BE:83:75:66:6A:75:86:22:F2:AB:0A:17:60:3F:42:56:03

CA Certificate PEM -----BEGIN CERTIFICATE----- MIIB8DCCAXagAwIBAgIKFRX/p0CkvXP1ujAKBggqhkjOPQQDAzAgMR4wHAYDVQQD DBVDZXJ0aWZpY2F0ZSBBdXRob3JpdHkwHhcNMjUxMDA2MDAwMDAwWhcNMjUxMDE2 MDAwMDAwWjAgMR4wHAYDVQQDDBVDZXJ0aWZpY2F0ZSBBdXRob3JpdHkwdjAQBgcq hkjOPQIBBgUrgQQAIgNiAATMe7p7BHfg95cwQKGD/QyLRJ9v4r2r7N+cenLiLLNV aklkicp1+AnxH3N+CABxwOYcBjYVaMIkvqspF1T9QMh1uL4/90YLUNQoG+yV1TS0 SvSXcVoJUhHjWSiy+/RVx2qjezB5MBIGA1UdEwEB/wQIMAYBAf8CAQAwDgYDVR0P AQH/BAQDAgEGMBMGA1UdJQQMMAoGCCsGAQUFBwMjMB0GA1UdDgQWBBQbdzO+g3Vm anWGIvKrChdgP0JWAzAfBgNVHSMEGDAWgBQbdzO+g3VmanWGIvKrChdgP0JWAzAK BggqhkjOPQQDAwNoADBlAjBQLyBu8JDNdPcOkHpJZuH9BIbshDBEn3H+SNBubiS9 sRgqWp+gphgvVUBlo+na0TACMQCv0zQ7tVQHG7n8i3fw6hLNrk4UrwfXX91tcp3M a9Z6MI8EU1mRAmqkM63oRHeNGS0= -----END CERTIFICATE-----

CA Private Key PEM -----BEGIN EC PRIVATE KEY----- MIGkAgEBBDBj90cnyONTJ3DqsSBdr4Df0zZ951wOLbQgqDPC8zw0wcrrQ5CT6+Ov sA2i87696dWgBwYFK4EEACKhZANiAATMe7p7BHfg95cwQKGD/QyLRJ9v4r2r7N+c enLiLLNVaklkicp1+AnxH3N+CABxwOYcBjYVaMIkvqspF1T9QMh1uL4/90YLUNQo G+yV1TS0SvSXcVoJUhHjWSiy+/RVx2o= -----END EC PRIVATE KEY-----

Signing Source End-Entity Certificate This end-entity certificate corresponds with the private key used for signing in . It contains a SAN authenticating the single security source from that example, an EKU authorizing the identity, and a Key Usage authorizing the signing.

Signing Certificate Content Version: 3 (0x2) Serial Number: 6f:fe:89:dc:b7:6e:d3:72:ea:7a Signature Algorithm: ecdsa-with-SHA384 Issuer: CN = Certificate Authority Validity Not Before: Oct 6 00:00:00 2025 GMT Not After : Oct 16 00:00:00 2025 GMT Subject: CN = src Subject Public Key Info: Public Key Algorithm: id-ecPublicKey Public-Key: (384 bit) pub: 04:02:df:c4:97:47:f5:d3:d2:19:fe:61:85:74:47: 29:fa:16:72:ef:7d:11:cb:57:ca:03:20:c6:32:be: 06:ca:3f:dc:c1:18:e6:31:40:ba:3e:c5:7e:a7:b8: 5d:41:95:68:45:26:e8:1b:f0:d9:ea:09:24:f0:5a: 34:53:ad:75:b9:28:06:67:15:11:54:4c:99:3f:6b: d9:08:a7:a4:23:9d:47:6c:fd:fd:74:d6:c6:88:36: 48:8a:d1:e6:0b:0e:7d ASN1 OID: secp384r1 NIST CURVE: P-384 X509v3 extensions: X509v3 Basic Constraints: critical CA:FALSE X509v3 Subject Alternative Name: critical othername: 1.3.6.1.5.5.7.8.11::dtn://src/ X509v3 Key Usage: critical Digital Signature X509v3 Extended Key Usage: 1.3.6.1.5.5.7.3.35 X509v3 Authority Key Identifier: 1B:77:33:BE:83:75:66:6A:75:86:22:F2:AB:0A:17:60:3F:42:56:03

Signing Certificate PEM -----BEGIN CERTIFICATE----- MIIB4TCCAWegAwIBAgIKb/6J3Ldu03LqejAKBggqhkjOPQQDAzAgMR4wHAYDVQQD DBVDZXJ0aWZpY2F0ZSBBdXRob3JpdHkwHhcNMjUxMDA2MDAwMDAwWhcNMjUxMDE2 MDAwMDAwWjAOMQwwCgYDVQQDDANzcmMwdjAQBgcqhkjOPQIBBgUrgQQAIgNiAAQC 38SXR/XT0hn+YYV0Ryn6FnLvfRHLV8oDIMYyvgbKP9zBGOYxQLo+xX6nuF1BlWhF Jugb8NnqCSTwWjRTrXW5KAZnFRFUTJk/a9kIp6QjnUds/f101saINkiK0eYLDn2j fjB8MAwGA1UdEwEB/wQCMAAwJgYDVR0RAQH/BBwwGqAYBggrBgEFBQcIC6AMFgpk dG46Ly9zcmMvMA4GA1UdDwEB/wQEAwIHgDATBgNVHSUEDDAKBggrBgEFBQcDIzAf BgNVHSMEGDAWgBQbdzO+g3VmanWGIvKrChdgP0JWAzAKBggqhkjOPQQDAwNoADBl AjBHljyxGGWxBmV5pz6Mgkn2k8MH9Am0+4ZGzRcEvMORA9R6371sJ0OYpuy1pPrd rwcCMQDrxYHocIePcAKYQnAAaNbn4pm/GaiTFgoQJWQn1tTMy3CyeocQMB0if57Y w6Xw0+Y= -----END CERTIFICATE-----

Encryption Recipient End-Entity Certificate This end-entity certificate corresponds with the private key used for decrypting . It contains a SAN identifying the single security acceptor from that example, an EKU authorizing the identity, and a Key Usage authorizing the key agreement.

Key-Agreement Certificate Content Version: 3 (0x2) Serial Number: 3f:24:0b:cd:a6:f7:fc:3c:29:de Signature Algorithm: ecdsa-with-SHA384 Issuer: CN = Certificate Authority Validity Not Before: Oct 6 00:00:00 2025 GMT Not After : Oct 16 00:00:00 2025 GMT Subject: CN = dst Subject Public Key Info: Public Key Algorithm: id-ecPublicKey Public-Key: (384 bit) pub: 04:00:57:ea:0e:6f:dc:50:dd:c1:11:1b:d8:10:ea: e7:c0:ba:24:64:5d:44:d4:71:2d:b0:c8:35:4c:23: 4b:29:70:b4:ac:27:e7:8f:38:25:00:69:d1:28:f9: 8e:51:ce:b1:4b:72:c5:0b:27:26:76:37:c4:0a:dc: d7:8b:d0:25:e4:b6:54:a6:45:d2:ba:7b:a9:89:4c: c7:3b:24:31:d4:cd:c0:40:d6:6e:8e:b2:da:d7:31: f7:dc:a5:71:08:54:5c ASN1 OID: secp384r1 NIST CURVE: P-384 X509v3 extensions: X509v3 Basic Constraints: critical CA:FALSE X509v3 Subject Alternative Name: critical othername: 1.3.6.1.5.5.7.8.11::dtn://dst/ X509v3 Key Usage: critical Key Agreement X509v3 Extended Key Usage: 1.3.6.1.5.5.7.3.35 X509v3 Authority Key Identifier: 1B:77:33:BE:83:75:66:6A:75:86:22:F2:AB:0A:17:60:3F:42:56:03

Key-Agreement Certificate PEM -----BEGIN CERTIFICATE----- MIIB4DCCAWegAwIBAgIKPyQLzab3/Dwp3jAKBggqhkjOPQQDAzAgMR4wHAYDVQQD DBVDZXJ0aWZpY2F0ZSBBdXRob3JpdHkwHhcNMjUxMDA2MDAwMDAwWhcNMjUxMDE2 MDAwMDAwWjAOMQwwCgYDVQQDDANkc3QwdjAQBgcqhkjOPQIBBgUrgQQAIgNiAAQA V+oOb9xQ3cERG9gQ6ufAuiRkXUTUcS2wyDVMI0spcLSsJ+ePOCUAadEo+Y5RzrFL csULJyZ2N8QK3NeL0CXktlSmRdK6e6mJTMc7JDHUzcBA1m6OstrXMffcpXEIVFyj fjB8MAwGA1UdEwEB/wQCMAAwJgYDVR0RAQH/BBwwGqAYBggrBgEFBQcIC6AMFgpk dG46Ly9kc3QvMA4GA1UdDwEB/wQEAwIDCDATBgNVHSUEDDAKBggrBgEFBQcDIzAf BgNVHSMEGDAWgBQbdzO+g3VmanWGIvKrChdgP0JWAzAKBggqhkjOPQQDAwNnADBk AjArcmaF95pLvgjxXBYa7mtDhEEgnYVsZytcWFu74yLx/7u/mUEsK0AgOrV+uTTo pqoCMAINw25QZUv9t8r+7lEmAo1em5730riu0Axq1yv0jF0LebLSYP6/fWe0cCwt /zk1CA== -----END CERTIFICATE-----

CDDL Definitions for BPSec The normative definitions of BPSec do not include corresponding CDDL extending the rules defined for BP. The following CDDL provides those definitions as an update to that specification. These definitions include a new socket $ext-data-asb for all possible ASB contents and a generic rule bpsec-context-use which allows a security context to define a single rule for the ASB socket to include all of their parameter and result types together. ; Block Confidentiality Block (BCB) $extension-block /= extension-block-use< 12, bstr .cborseq ext-data-asb > ; Specialization of $ext-data-asb for a security context. ; The ParamPair and ResultPair should be sockets for specializing ; those structures for the individual security context. bpsec-context-use = [ targets: [ + target-block-num ], context-id: ContextId, asb-flags, ? security-source: eid, ? parameters: [ + ParamPair .within asb-id-value-pair ], target-results: [ + [ + ResultPair .within asb-id-value-pair ] ] ] ]]>

Acknowledgments Thanks to Lars Baumgaertner and Lukas Holst at ESA for review and prototyping feedback.

Implementation Status [NOTE to the RFC Editor: please remove this section before publication, as well as the reference to , , , and .] This section records the status of known implementations of the protocol defined by this specification at the time of posting of this Internet-Draft, and is based on a proposal described in . The description of implementations in this section is intended to assist the IETF in its decision processes in progressing drafts to RFCs. Please note that the listing of any individual implementation here does not imply endorsement by the IETF. Furthermore, no effort has been spent to verify the information presented here that was supplied by IETF contributors. This is not intended as, and must not be construed to be, a catalog of available implementations or their features. Readers are advised to note that other implementations can exist. A limited implementation of this COSE Context has been added to the to help with interoperability testing. As of the time of writing a COSE Context dissector has been accepted to the default development branch of the Wireshark project . That dissector integrates the full-featured COSE dissector on top of BPSec, so will scale with any future additions to COSE itself. An example implementation of this COSE Context has been created as a GitHub project and is intended to use as a proof-of-concept and as a source of data for the examples in . This example implementation only handles CBOR encoding/decoding and cryptographic functions, it does not construct actual BIB or BCB and does not integrate with a BP Agent.