Concise Reference Integrity Manifest
draft-ietf-rats-corim-04
| Document | Type | Active Internet-Draft (rats WG) | |
|---|---|---|---|
| Authors | Henk Birkholz , Thomas Fossati , Yogesh Deshpande , Ned Smith , Wei Pan | ||
| Last updated | 2024-03-04 | ||
| Replaces | draft-birkholz-rats-corim | ||
| RFC stream | Internet Engineering Task Force (IETF) | ||
| Intended RFC status | (None) | ||
| Formats | |||
| Additional resources | Mailing list discussion | ||
| Stream | WG state | WG Document | |
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| Consensus boilerplate | Unknown | ||
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draft-ietf-rats-corim-04
Remote ATtestation ProcedureS H. Birkholz
Internet-Draft Fraunhofer SIT
Intended status: Standards Track T. Fossati
Expires: 5 September 2024 Y. Deshpande
arm
N. Smith
Intel
W. Pan
Huawei Technologies
4 March 2024
Concise Reference Integrity Manifest
draft-ietf-rats-corim-04
Abstract
Remote Attestation Procedures (RATS) enable Relying Parties to assess
the trustworthiness of a remote Attester and therefore to decide
whether to engage in secure interactions with it. Evidence about
trustworthiness can be rather complex and it is deemed unrealistic
that every Relying Party is capable of the appraisal of Evidence.
Therefore that burden is typically offloaded to a Verifier. In order
to conduct Evidence appraisal, a Verifier requires not only fresh
Evidence from an Attester, but also trusted Endorsements and
Reference Values from Endorsers and Reference Value Providers, such
as manufacturers, distributors, or device owners. This document
specifies the information elements for representing Endorsements and
Reference Values in CBOR format.
Status of This Memo
This Internet-Draft is submitted in full conformance with the
provisions of BCP 78 and BCP 79.
Internet-Drafts are working documents of the Internet Engineering
Task Force (IETF). Note that other groups may also distribute
working documents as Internet-Drafts. The list of current Internet-
Drafts is at https://datatracker.ietf.org/drafts/current/.
Internet-Drafts are draft documents valid for a maximum of six months
and may be updated, replaced, or obsoleted by other documents at any
time. It is inappropriate to use Internet-Drafts as reference
material or to cite them other than as "work in progress."
This Internet-Draft will expire on 5 September 2024.
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Copyright Notice
Copyright (c) 2024 IETF Trust and the persons identified as the
document authors. All rights reserved.
This document is subject to BCP 78 and the IETF Trust's Legal
Provisions Relating to IETF Documents (https://trustee.ietf.org/
license-info) in effect on the date of publication of this document.
Please review these documents carefully, as they describe your rights
and restrictions with respect to this document. Code Components
extracted from this document must include Revised BSD License text as
described in Section 4.e of the Trust Legal Provisions and are
provided without warranty as described in the Revised BSD License.
Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 5
1.1. Terminology and Requirements Language . . . . . . . . . . 5
1.2. CDDL Typographical Conventions . . . . . . . . . . . . . 5
1.3. Common Types . . . . . . . . . . . . . . . . . . . . . . 6
1.3.1. Non-Empty . . . . . . . . . . . . . . . . . . . . . . 6
1.3.2. Entity . . . . . . . . . . . . . . . . . . . . . . . 6
1.3.3. Validity . . . . . . . . . . . . . . . . . . . . . . 7
1.3.4. UUID . . . . . . . . . . . . . . . . . . . . . . . . 8
1.3.5. UEID . . . . . . . . . . . . . . . . . . . . . . . . 8
1.3.6. OID . . . . . . . . . . . . . . . . . . . . . . . . . 8
1.3.7. Tagged Integer Type . . . . . . . . . . . . . . . . . 8
1.3.8. Digest . . . . . . . . . . . . . . . . . . . . . . . 8
1.3.9. Tagged Bytes Type . . . . . . . . . . . . . . . . . . 9
2. Concise Reference Integrity Manifest (CoRIM) . . . . . . . . 9
2.1. CoRIM Map . . . . . . . . . . . . . . . . . . . . . . . . 10
2.1.1. Identity . . . . . . . . . . . . . . . . . . . . . . 11
2.1.2. Tags . . . . . . . . . . . . . . . . . . . . . . . . 11
2.1.3. Locator Map . . . . . . . . . . . . . . . . . . . . . 11
2.1.4. Profile Types . . . . . . . . . . . . . . . . . . . . 12
2.1.5. Entities . . . . . . . . . . . . . . . . . . . . . . 12
2.2. Signed CoRIM . . . . . . . . . . . . . . . . . . . . . . 13
2.2.1. Protected Header Map . . . . . . . . . . . . . . . . 13
2.2.2. Meta Map . . . . . . . . . . . . . . . . . . . . . . 14
2.2.2.1. Signer Map . . . . . . . . . . . . . . . . . . . 14
2.2.3. Unprotected CoRIM Header Map . . . . . . . . . . . . 15
3. Concise Module Identifier (CoMID) . . . . . . . . . . . . . . 15
3.1. Structure . . . . . . . . . . . . . . . . . . . . . . . . 16
3.1.1. Tag Identity . . . . . . . . . . . . . . . . . . . . 17
3.1.1.1. Tag ID . . . . . . . . . . . . . . . . . . . . . 17
3.1.1.2. Tag Version . . . . . . . . . . . . . . . . . . . 18
3.1.2. Entities . . . . . . . . . . . . . . . . . . . . . . 18
3.1.3. Linked Tag . . . . . . . . . . . . . . . . . . . . . 18
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3.1.4. Triples . . . . . . . . . . . . . . . . . . . . . . . 19
3.1.4.1. Common Types . . . . . . . . . . . . . . . . . . 21
3.1.4.1.1. Environment . . . . . . . . . . . . . . . . . 21
3.1.4.1.2. Class . . . . . . . . . . . . . . . . . . . . 21
3.1.4.1.3. Instance . . . . . . . . . . . . . . . . . . 22
3.1.4.1.4. Group . . . . . . . . . . . . . . . . . . . 23
3.1.4.1.5. Measurements . . . . . . . . . . . . . . . . 23
3.1.4.1.5.1. Measurement Keys . . . . . . . . . . . . 24
3.1.4.1.5.2. Measurement Values . . . . . . . . . . . 24
3.1.4.1.5.3. Version . . . . . . . . . . . . . . . . . 26
3.1.4.1.5.4. Security Version Number . . . . . . . . . 27
3.1.4.1.5.5. Flags . . . . . . . . . . . . . . . . . . 28
3.1.4.1.5.6. Raw Values Types . . . . . . . . . . . . 29
3.1.4.1.5.7. Address Types . . . . . . . . . . . . . . 29
3.1.4.1.6. Crypto Keys . . . . . . . . . . . . . . . . . 30
3.1.4.1.7. Integrity Registers . . . . . . . . . . . . . 31
3.1.4.1.8. Domain Types . . . . . . . . . . . . . . . . 32
3.1.4.2. Reference Values Triple . . . . . . . . . . . . . 32
3.1.4.3. Endorsed Values Triple . . . . . . . . . . . . . 32
3.1.4.4. Device Identity Triple . . . . . . . . . . . . . 33
3.1.4.5. Attestation Keys Triple . . . . . . . . . . . . . 33
3.1.4.6. Domain Dependency Triple . . . . . . . . . . . . 33
3.1.4.7. Domain Membership Triple . . . . . . . . . . . . 34
3.1.4.8. CoMID-CoSWID Linking Triple . . . . . . . . . . . 34
3.1.4.9. Conditional Endorsement Series Triple . . . . . . 34
3.1.4.10. Conditional Endorsement Triple . . . . . . . . . 35
3.1.4.11. Multi-Environment Conditional (MEC) Endorsement
Triple . . . . . . . . . . . . . . . . . . . . . . 36
3.2. Extensibility . . . . . . . . . . . . . . . . . . . . . . 37
3.2.1. Map Extensions . . . . . . . . . . . . . . . . . . . 37
3.2.2. Data Type Extensions . . . . . . . . . . . . . . . . 37
4. CoBOM . . . . . . . . . . . . . . . . . . . . . . . . . . . . 37
4.1. Structure . . . . . . . . . . . . . . . . . . . . . . . . 38
5. CoRIM-based Appraisal of Evidence . . . . . . . . . . . . . . 39
5.1. Verifier Abstraction . . . . . . . . . . . . . . . . . . 39
5.2. Appraisal Context initialisation . . . . . . . . . . . . 40
5.2.1. CoRIM Selection . . . . . . . . . . . . . . . . . . . 40
5.2.2. CoBOM Extraction . . . . . . . . . . . . . . . . . . 41
5.2.3. Tags Identification and Validation . . . . . . . . . 41
5.2.4. Appraisal Context Construction . . . . . . . . . . . 42
5.3. Evidence Collection . . . . . . . . . . . . . . . . . . . 42
5.3.1. Cryptographic validation of Evidence . . . . . . . . 42
5.3.2. The Accepted Claims Set . . . . . . . . . . . . . . . 43
5.3.2.1. Accepted Claims Set Initialization . . . . . . . 44
5.3.2.2. The authorized-by field in Accepted Claims Set . 44
5.4. Accepted Claims Set augmentation using CoMID triples . . 45
5.4.1. Ordering of triple processing . . . . . . . . . . . . 46
5.4.2. Processing Reference Values Triple . . . . . . . . . 46
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5.4.3. Processing Endorsed Value Triple . . . . . . . . . . 46
5.4.4. Processing triples representing Conditional
Endorsements . . . . . . . . . . . . . . . . . . . . 46
5.4.4.1. Processing Conditional Endorsement Triple . . . . 47
5.4.4.2. Processing Multi-Environment Conditional (MEC)
Endorsement Triple . . . . . . . . . . . . . . . . 47
5.4.4.3. Processing Conditional Endorsement Series
Triple . . . . . . . . . . . . . . . . . . . . . . 47
5.4.4.4. Matching a stateful environment against the
Accepted Claims Set . . . . . . . . . . . . . . . . 48
5.4.4.5. Matching a single measurement-values-map
codepoint . . . . . . . . . . . . . . . . . . . . . 49
5.4.4.5.1. Comparison for svn entries . . . . . . . . . 50
5.4.4.5.2. Comparison for digests entries . . . . . . . 50
5.4.4.5.3. Comparison for raw-value entries . . . . . . 51
5.4.4.5.4. Comparison for cryptokeys entries . . . . . . 51
5.4.4.5.5. Comparison for Integrity Registers . . . . . 51
5.4.4.5.6. Handling of new tags . . . . . . . . . . . . 51
5.4.5. Adding CoMID Endorsed Values to the Accepted Claims
Set . . . . . . . . . . . . . . . . . . . . . . . . . 52
5.5. Adding DICE/SPDM Evidence to the Accepted Claims Set . . 52
5.5.1. Transforming SPDM Evidence to a format usable for
matching . . . . . . . . . . . . . . . . . . . . . . 52
5.5.2. Transforming DICE Evidence to a format usable for
matching . . . . . . . . . . . . . . . . . . . . . . 52
6. Implementation Status . . . . . . . . . . . . . . . . . . . . 53
6.1. Veraison . . . . . . . . . . . . . . . . . . . . . . . . 54
7. Security and Privacy Considerations . . . . . . . . . . . . . 54
8. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 54
8.1. New COSE Header Parameters . . . . . . . . . . . . . . . 55
8.2. New CBOR Tags . . . . . . . . . . . . . . . . . . . . . . 55
8.3. New CoRIM Registries . . . . . . . . . . . . . . . . . . 56
8.4. New CoMID Registries . . . . . . . . . . . . . . . . . . 56
8.5. New CoBOM Registries . . . . . . . . . . . . . . . . . . 57
8.6. New Media Types . . . . . . . . . . . . . . . . . . . . . 57
8.6.1. corim-signed+cbor . . . . . . . . . . . . . . . . . . 57
8.6.2. corim-unsigned+cbor . . . . . . . . . . . . . . . . . 58
8.7. CoAP Content-Formats Registration . . . . . . . . . . . . 58
9. References . . . . . . . . . . . . . . . . . . . . . . . . . 58
9.1. Normative References . . . . . . . . . . . . . . . . . . 58
9.2. Informative References . . . . . . . . . . . . . . . . . 61
Appendix A. Full CoRIM CDDL . . . . . . . . . . . . . . . . . . 62
Acknowledgments . . . . . . . . . . . . . . . . . . . . . . . . . 76
Contributors . . . . . . . . . . . . . . . . . . . . . . . . . . 76
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 76
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1. Introduction
In order to conduct Evidence appraisal, a Verifier requires not only
fresh Evidence from an Attester, but also trusted Endorsements (e.g.,
test results or certification data) and Reference Values (e.g., the
version or digest of a firmware component) associated with the
Attester. Such Endorsements and Reference Values are obtained from
the relevant supply chain actors, such as manufacturers,
distributors, or device owners. In a complex supply chain, it is
likely that multiple actors will produce these values at different
points in time. Besides, one supply chain actor will only provide
the subset of characteristics that they know about the Attester.
Attesters vary from one vendor to another, and for a given vendor
from one product to another. Not only Attesters can evolve and
therefore new measurement types need to be expressed, but an Endorser
may also want to provide new security relevant attributes about an
Attester at a future point in time.
This document specifies Concise Reference Integrity Manifests (CoRIM)
a CBOR [STD94] based data model addressing the above challenges by
using an extensible format common to all supply chain actors and
Verifiers. CoRIM enables Verifiers to reconcile a complex and
scattered supply chain into a single homogeneous view.
1.1. Terminology and Requirements Language
This document uses terms and concepts defined by the RATS
architecture. For a complete glossary see Section 4 of [RFC9334].
The terminology from CBOR [STD94], CDDL [RFC8610] and COSE [STD96]
applies; in particular, CBOR diagnostic notation is defined in
Section 8 of [STD94] and Appendix G of [RFC8610].
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 [RFC2119] [RFC8174] when, and only when, they appear in all
capitals, as shown here.
1.2. CDDL Typographical Conventions
The CDDL definitions in this document follow the naming conventions
illustrated in Table 1.
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+========================+===============+==========================+
| Type trait | Example | Typographical convention |
+========================+===============+==========================+
| extensible | int / text / | $NAME-type-choice |
| type choice | ... | |
+------------------------+---------------+--------------------------+
| closed type | int / text | NAME-type-choice |
| choice | | |
+------------------------+---------------+--------------------------+
| group | ( 1 => int // | $$NAME-group-choice |
| choice | 2 => text ) | |
+------------------------+---------------+--------------------------+
| group | ( 1 => int, 2 | NAME-group |
| | => text ) | |
+------------------------+---------------+--------------------------+
| type | int | NAME-type |
+------------------------+---------------+--------------------------+
| tagged type | #6.123(int) | tagged-NAME-type |
+------------------------+---------------+--------------------------+
| map | { 1 => int, 2 | NAME-map |
| | => text } | |
+------------------------+---------------+--------------------------+
| flags | &( a: 1, b: 2 | NAME-flags |
| | ) | |
+------------------------+---------------+--------------------------+
Table 1: Type Traits & Typographical Conventions
1.3. Common Types
The following CDDL types are used in both CoRIM and CoMID.
1.3.1. Non-Empty
The non-empty generic type is used to express that a map with only
optional members MUST at least include one of the members.
non-empty<M> = (M) .and ({ + any => any })
1.3.2. Entity
The entity-map is a generic type describing an organization
responsible for the contents of a manifest. It is instantiated by
supplying two parameters:
* A role-type-choice, i.e., a selection of roles that entities of
the instantiated type can claim
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* An extension-socket, i.e., a CDDL socket that can be used to
extend the attributes associated with entities of the instantiated
type
entity-map<role-type-choice, extension-socket> = {
&(entity-name: 0) => $entity-name-type-choice
? &(reg-id: 1) => uri
&(role: 2) => [ + role-type-choice ]
* extension-socket
}
$entity-name-type-choice /= text
The following describes each member of the entity-map.
* entity-name (index 0): The name of entity which is responsible for
the action(s) as defined by the role. $entity-name-type-choice can
only be text. Other specifications can extend the $entity-name-
type-choice (see Section 8.4).
* reg-id (index 1): A URI associated with the organization that owns
the entity name
* role (index 2): A type choice defining the roles that the entity
is claiming. The role is supplied as a parameter at the time the
entity-map generic is instantiated.
* extension-socket: A CDDL socket used to add new information
structures to the entity-map.
Examples of how the entity-map generic is instantiated can be found
in Section 2.1.5 and Section 3.1.2.
1.3.3. Validity
A validity-map represents the time interval during which the signer
warrants that it will maintain information about the status of the
signed object (e.g., a manifest).
In a validity-map, both ends of the interval are encoded as epoch-
based date/time as per Section 3.4.2 of [STD94].
validity-map = {
? &(not-before: 0) => time
&(not-after: 1) => time
}
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* not-before (index 0): the date on which the signed manifest
validity period begins
* not-after (index 1): the date on which the signed manifest
validity period ends
1.3.4. UUID
Used to tag a byte string as a binary UUID defined in Section 4.1.2.
of [RFC4122].
uuid-type = bytes .size 16
tagged-uuid-type = #6.37(uuid-type)
1.3.5. UEID
Used to tag a byte string as Universal Entity ID Claim (UUID) defined
in Section 4.2.1 of [I-D.ietf-rats-eat].
ueid-type = bytes .size 33
tagged-ueid-type = #6.550(ueid-type)
1.3.6. OID
Used to tag a byte string as the BER encoding [X.690] of an absolute
object identifier [RFC9090].
oid-type = bytes
tagged-oid-type = #6.111(oid-type)
1.3.7. Tagged Integer Type
Used as a class identifier for the environment. It is expected that
the integer value is vendor specific rather than globally meaningful.
Therefore, the sibling vendor field in the class-map MUST be
populated to define the namespace under which the value must be
understood.
tagged-int-type = #6.551(int)
1.3.8. Digest
A digest represents the value of a hashing operation together with
the hash algorithm used. The type of the digest algorithm identifier
can be either int or text. When carried as an integer value, it is
interpreted according to the "Named Information Hash Algorithm
Registry" [IANA.named-information]. When it is carried as text,
there are no requirements with regards to its format. In general,
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the int encoding is RECOMMENDED. The text encoding should only be
used when the digest type conveys reference value measurements that
are matched verbatim with Evidence that uses the same convention -
e.g., Section 4.4.1.5 of [I-D.tschofenig-rats-psa-token]).
digest = [
alg: (int / text),
val: bytes
]
1.3.9. Tagged Bytes Type
An opaque, variable-length byte string. It can be used in different
contexts: as an instance, class or group identifier in an
environment-map; as a raw value measurement in a measurement-values-
map. Its semantics are defined by the context in which it is found,
and by the overarching CoRIM profile. When used as an identifier the
responsible allocator entity SHOULD ensure uniqueness within the
context that it is used.
tagged-bytes = #6.560(bytes)
2. Concise Reference Integrity Manifest (CoRIM)
A CoRIM is a collection of tags and related metadata as described
below.
Tags can be of different types:
* Concise Module ID (CoMID) tags (Section 3) contain metadata and
claims about the hardware and firmware modules.
* Concise Software ID (CoSWID) tags [I-D.ietf-sacm-coswid] describe
software components.
* Concise Bill of Material (CoBOM) tags (Section 4) contain the list
of CoMID and CoSWID tags that the Verifier should consider as
"active" at a certain point in time.
The set of tags is extensible so that future specifications can add
new kinds of information. For example, Concise Trust Anchor Stores
(CoTS) [I-D.ietf-rats-concise-ta-stores] is currently being defined
as a standard CoRIM extension.
Each CoRIM contains a unique identifier to distinguish a CoRIM from
other CoRIMs.
// Tracked at: https://github.com/ietf-rats-wg/draft-ietf-rats-corim/
issues/73
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CoRIM can also carry the following optional metadata:
* A locator, which allows discovery of possibly related RIMs
* A profile identifier, which is used to interpret the information
contained in the enclosed tags. A profile allows the base CoRIM
schema to be customised to fit a specific Attester. For example,
see [I-D.fdb-rats-psa-endorsements].
* A validity period, which indicates the time period for which the
CoRIM contents are valid.
* Information about the supply chain entities responsible for the
contents of the CoRIM and their associated roles.
A CoRIM can be signed (Section 2.2) using COSE Sign1 to provide end-
to-end security to the CoRIM contents. When CoRIM is signed, the
protected header carries further identifying information about the
CoRIM signer. Alternatively, CoRIM can be encoded as a CBOR-tagged
payload (Section 2.1) and transported over a secure channel.
The following CDDL describes the top-level CoRIM.
corim = tagged-concise-rim-type-choice
$concise-rim-type-choice /= tagged-corim-map
$concise-rim-type-choice /= tagged-signed-corim
2.1. CoRIM Map
The CDDL specification for the corim-map is as follows and this rule
and its constraints must be followed when creating or validating a
CoRIM map.
corim-map = {
&(id: 0) => $corim-id-type-choice
&(tags: 1) => [ + $concise-tag-type-choice ]
? &(dependent-rims: 2) => [ + corim-locator-map ]
? &(profile: 3) => $profile-type-choice
? &(rim-validity: 4) => validity-map
? &(entities: 5) => [ + corim-entity-map ]
* $$corim-map-extension
}
The following describes each child item of this map.
* id (index 0): A globally unique identifier to identify a CoRIM.
Described in Section 2.1.1
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* tags (index 1): An array of one or more CoMID or CoSWID tags.
Described in Section 2.1.2
* dependent-rims (index 2): One or more services supplying
additional, possibly dependent, manifests or related files.
Described in Section 2.1.3
* profile (index 3): An optional profile identifier for the tags
contained in this CoRIM. The profile MUST be understood by the
CoRIM processor. Failure to recognize the profile identifier MUST
result in the rejection of the entire CoRIM. If missing, the
profile defaults to DICE. Described in Section 2.1.4
* rim-validity (index 4): Specifies the validity period of the
CoRIM. Described in Section 1.3.3
* entities (index 5): A list of entities involved in a CoRIM life-
cycle. Described in Section 2.1.5
* $$corim-map-extension: This CDDL socket is used to add new
information structures to the corim-map. See Section 8.3.
tagged-corim-map = #6.501(corim-map)
2.1.1. Identity
A CoRIM Identifier uniquely identifies a CoRIM instance. The base
schema allows UUID and text identifiers. Other types of identifiers
could be defined as needed.
$corim-id-type-choice /= tstr
$corim-id-type-choice /= uuid-type
2.1.2. Tags
A $concise-tag-type-choice is a tagged CBOR payload that carries
either a CoMID (Section 3), a CoSWID [I-D.ietf-sacm-coswid], or a
CoBOM Section 4.
$concise-tag-type-choice /= tagged-concise-swid-tag
$concise-tag-type-choice /= tagged-concise-mid-tag
$concise-tag-type-choice /= tagged-concise-bom-tag
2.1.3. Locator Map
The locator map contains pointers to repositories where dependent
manifests, certificates, or other relevant information can be
retrieved by the Verifier.
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corim-locator-map = {
&(href: 0) => uri
? &(thumbprint: 1) => digest
}
The following describes each child element of this type.
* href (index 0): URI identifying the additional resource that can
be fetched
* thumbprint (index 1): expected digest of the resource referenced
by href. See Section 1.3.8.
2.1.4. Profile Types
Profiling is the mechanism that allows the base CoRIM schema to be
customised to fit a specific Attester.
A profile defines which of the optional parts of a CoRIM are
required, which are prohibited, and which extension points are
exercised and how. A profile MUST NOT alter the syntax or semantics
of a standard CoRIM type. A profile MAY constrain the values of a
given CoRIM type to a subset of the values. A profile MAY extend the
set of a given CoRIM type using the defined extension points (see
Section 3.2). Exercised extension points should preserve the intent
of the original semantics.
CoRIM profiles SHOULD be specified in a publicly available document.
A CoRIM profile can use one of the base CoRIM media types defined in
Section 8.6.1 and Section 8.6.2 with the profile parameter set to the
appropriate value. Alternatively, it MAY define and register its own
media type.
A profile identifier is either an OID [RFC9090] or a URL [STD66].
The profile identifier uniquely identifies a documented profile. Any
changes to the profile, even the slightest deviation, is considered a
different profile that MUST have a different identifier.
$profile-type-choice /= uri
$profile-type-choice /= tagged-oid-type
2.1.5. Entities
The CoRIM Entity is an instantiation of the Entity generic
(Section 1.3.2) using a $corim-role-type-choice.
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The only role defined in this specification for a CoRIM Entity is
manifest-creator.
The $$corim-entity-map-extension extension socket is empty in this
specification.
corim-entity-map =
entity-map<$corim-role-type-choice, $$corim-entity-map-extension>
$corim-role-type-choice /= &(manifest-creator: 1)
2.2. Signed CoRIM
signed-corim = #6.18(COSE-Sign1-corim)
Signing a CoRIM follows the procedures defined in CBOR Object Signing
and Encryption [STD96]. A CoRIM tag MUST be wrapped in a COSE_Sign1
structure. The CoRIM MUST be signed by the CoRIM creator.
The following CDDL specification defines a restrictive subset of COSE
header parameters that MUST be used in the protected header alongside
additional information about the CoRIM encoded in a corim-meta-map
(Section 2.2.2).
COSE-Sign1-corim = [
protected: bstr .cbor protected-corim-header-map
unprotected: unprotected-corim-header-map
payload: bstr .cbor tagged-corim-map
signature: bstr
]
The following describes each child element of this type.
* protected: A CBOR Encoded protected header which is protected by
the COSE signature. Contains information as given by Protected
Header Map below.
* unprotected: A COSE header that is not protected by COSE
signature.
* payload: A CBOR encoded tagged CoRIM.
* signature: A COSE signature block which is the signature over the
protected and payload components of the signed CoRIM.
2.2.1. Protected Header Map
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protected-corim-header-map = {
&(alg-id: 1) => int
&(content-type: 3) => "application/corim-unsigned+cbor"
&(issuer-key-id: 4) => bstr
&(corim-meta: 8) => bstr .cbor corim-meta-map
* cose-label => cose-value
}
The following describes each child item of this map.
* alg-id (index 1): An integer that identifies a signature
algorithm.
* content-type (index 3): A string that represents the "MIME Content
type" carried in the CoRIM payload.
* issuer-key-id (index 4): A bit string which is a key identity
pertaining to the CoRIM Issuer.
* corim-meta (index 8): A map that contains metadata associated with
a signed CoRIM. Described in Section 2.2.2.
Additional data can be included in the COSE header map as per
Section 3 of [STD96].
2.2.2. Meta Map
The CoRIM meta map identifies the entity or entities that create and
sign the CoRIM. This ensures the consumer is able to identify
credentials used to authenticate its signer.
corim-meta-map = {
&(signer: 0) => corim-signer-map
? &(signature-validity: 1) => validity-map
}
The following describes each child item of this group.
* signer (index 0): Information about the entity that signs the
CoRIM. Described in Section 2.2.2.1
* signature-validity (index 1): Validity period for the CoRIM.
Described in Section 1.3.3
2.2.2.1. Signer Map
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corim-signer-map = {
&(signer-name: 0) => $entity-name-type-choice
? &(signer-uri: 1) => uri
* $$corim-signer-map-extension
}
* signer-name (index 0): Name of the organization that performs the
signer role
* signer-uri (index 1): A URI identifying the same organization
* $$corim-signer-map-extension: Extension point for future expansion
of the Signer map.
2.2.3. Unprotected CoRIM Header Map
unprotected-corim-header-map = {
* cose-label => cose-value
}
3. Concise Module Identifier (CoMID)
A CoMID tag contains information about hardware, firmware, or module
composition.
Each CoMID has a unique ID that is used to unambigously identify
CoMID instances when cross referencing CoMID tags, for example in
typed link relations, or in a CoBOM tag.
A CoMID defines several types of Claims, using "triples" semantics.
At a high level, a triple is a statement that links a subject to an
object via a predicate. CoMID triples typically encode assertions
made by the CoRIM author about Attesting or Target Environments and
their security features, for example measurements, cryptographic key
material, etc.
The set of triples is extensible. The following triples are
currently defined:
* Reference Values triples: containing Reference Values that are
expected to match Evidence for a given Target Environment
(Section 3.1.4.2).
* Endorsed Values triples: containing "Endorsed Values", i.e.,
features about an Environment that do not appear in Evidence.
Specific examples include testing or certification data pertaining
to a module (Section 3.1.4.3).
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* Device Identity triples: containing cryptographic credentials -
for example, an IDevID - uniquely identifying a device
(Section 3.1.4.4).
* Attestation Key triples: containing cryptographic keys that are
used to verify the integrity protection on the Evidence received
from the Attester (Section 3.1.4.5).
* Domain dependency triples: describing trust relationships between
domains, i.e., collection of related environments and their
measurements (Section 3.1.4.6).
* Domain membership triples: describing topological relationships
between (sub-)modules. For example, in a composite Attester
comprising multiple sub-Attesters (sub-modules), this triple can
be used to define the topological relationship between lead- and
sub- Attester environments (Section 3.1.4.7).
* CoMID-CoSWID linking triples: associating a Target Environment
with existing CoSWID tags (Section 3.1.4.8).
3.1. Structure
The CDDL specification for the concise-mid-tag map is as follows and
this rule and its constraints MUST be followed when creating or
validating a CoMID tag:
concise-mid-tag = {
? &(language: 0) => text
&(tag-identity: 1) => tag-identity-map
? &(entities: 2) => [ + comid-entity-map ]
? &(linked-tags: 3) => [ + linked-tag-map ]
&(triples: 4) => triples-map
* $$concise-mid-tag-extension
}
The following describes each member of the concise-mid-tag map.
* lang (index 0): A textual language tag that conforms with IANA
"Language Subtag Registry" [IANA.language-subtag-registry]. The
context of the specified language applies to all sibling and
descendant textual values, unless a descendant object has defined
a different language tag. Thus, a new context is established when
a descendant object redefines a new language tag. All textual
values within a given context MUST be considered expressed in the
specified language.
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* tag-identity (index 1): A tag-identity-map containing unique
identification information for the CoMID. Described in
Section 3.1.1.
* entities (index 2): Provides information about one or more
organizations responsible for producing the CoMID tag. Described
in Section 3.1.2.
* linked-tags (index 3): A list of one or more linked-tag-map
(described in Section 3.1.3), providing typed relationships
between this and other CoMIDs.
* triples (index 4): One or more triples providing information
specific to the described module, e.g.: reference or endorsed
values, cryptographic material, or structural relationship between
the described module and other modules. Described in
(Section 3.1.4).
3.1.1. Tag Identity
tag-identity-map = {
&(tag-id: 0) => $tag-id-type-choice
? &(tag-version: 1) => tag-version-type
}
The following describes each member of the tag-identity-map.
* tag-id (index 0): A universally unique identifier for the CoMID.
Described in Section 3.1.1.1.
* tag-version (index 1): Optional versioning information for the
tag-id . Described in Section 3.1.1.2.
3.1.1.1. Tag ID
$tag-id-type-choice /= tstr
$tag-id-type-choice /= uuid-type
A Tag ID is either a 16-byte binary string, or a textual identifier,
uniquely referencing the CoMID. The tag identifier MUST be globally
unique. Failure to ensure global uniqueness can create ambiguity in
tag use since the tag-id serves as the global key for matching,
lookups and linking. If represented as a 16-byte binary string, the
identifier MUST be a valid universally unique identifier as defined
by [RFC4122]. There are no strict guidelines on how the identifier
is structured, but examples include a 16-byte GUID (e.g., class 4
UUID) [RFC4122], or a URI [STD66].
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3.1.1.2. Tag Version
tag-version-type = uint .default 0
Tag Version is an integer value that indicates the specific release
revision of the tag. Typically, the initial value of this field is
set to 0 and the value is increased for subsequent tags produced for
the same module release. This value allows a CoMID tag producer to
correct an incorrect tag previously released without indicating a
change to the underlying module the tag represents. For example, the
tag version could be changed to add new metadata, to correct a broken
link, to add a missing reference value, etc. When producing a
revised tag, the new tag-version value MUST be greater than the old
tag-version value.
3.1.2. Entities
comid-entity-map =
entity-map<$comid-role-type-choice, $$comid-entity-map-extension>
The CoMID Entity is an instantiation of the Entity generic
(Section 1.3.2) using a $comid-role-type-choice.
The $$comid-entity-map-extension extension socket is empty in this
specification.
$comid-role-type-choice /= &(tag-creator: 0)
$comid-role-type-choice /= &(creator: 1)
$comid-role-type-choice /= &(maintainer: 2)
The roles defined for a CoMID entity are:
* tag-creator (value 0): creator of the CoMID tag.
* creator (value 1): original maker of the module described by the
CoMID tag.
* maintainer (value 2): an entity making changes to the module
described by the CoMID tag.
3.1.3. Linked Tag
The linked tag map represents a typed relationship between the
embedding CoMID tag (the source) and another CoMID tag (the target).
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linked-tag-map = {
&(linked-tag-id: 0) => $tag-id-type-choice
&(tag-rel: 1) => $tag-rel-type-choice
}
The following describes each member of the tag-identity-map.
* linked-tag-id (index 0): Unique identifier for the target tag.
For the definition see Section 3.1.1.1.
* tag-rel (index 1): the kind of relation linking the source tag to
the target identified by linked-tag-id.
$tag-rel-type-choice /= &(supplements: 0)
$tag-rel-type-choice /= &(replaces: 1)
The relations defined in this specification are:
* supplements (value 0): the source tag provides additional
information about the module described in the target tag.
* replaces (value 1): the source tag corrects erroneous information
contained in the target tag. The information in the target MUST
be disregarded.
3.1.4. Triples
The triples-map contains all the CoMID triples broken down per
category. Not all category need to be present but at least one
category MUST be present and contain at least one entry.
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triples-map = non-empty<{
? &(reference-triples: 0) =>
[ + reference-triple-record ]
? &(endorsed-triples: 1) =>
[ + endorsed-triple-record ]
? &(identity-triples: 2) =>
[ + identity-triple-record ]
? &(attest-key-triples: 3) =>
[ + attest-key-triple-record ]
? &(dependency-triples: 4) =>
[ + domain-dependency-triple-record ]
? &(membership-triples: 5) =>
[ + domain-membership-triple-record ]
? &(coswid-triples: 6) =>
[ + coswid-triple-record ]
? &(conditional-endorsement-series-triples: 8) =>
[ + conditional-endorsement-series-triple-record ]
? &(conditional-endorsement-triples: 9) =>
[ + conditional-endorsement-triple-record ]
? &(mec-endorsement-triples: 10) =>
[ + mec-endorsement-triple-record ]
* $$triples-map-extension
}>
The following describes each member of the triples-map:
* reference-triples (index 0): Triples containing reference values.
Described in Section 3.1.4.2.
* endorsed-triples (index 1): Triples containing endorsed values.
Described in Section 3.1.4.3.
* identity-triples (index 2): Triples containing identity
credentials. Described in Section 3.1.4.4.
* attest-key-triples (index 3): Triples containing verification keys
associated with attesting environments. Described in
Section 3.1.4.5.
* dependency-triples (index 4): Triples describing trust
relationships between domains. Described in Section 3.1.4.6.
* membership-triples (index 5): Triples describing topological
relationships between (sub-)modules. Described in
Section 3.1.4.7.
* coswid-triples (index 6): Triples associating modules with
existing CoSWID tags. Described in Section 3.1.4.8.
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* conditional-endorsement-series-triples (index 8) Triples
describing a series of conditional Endorsements based on the
acceptance of a stateful environment. Described in
Section 3.1.4.9.
* conditional-endorsement-triples (index 9) Triples describing
conditional Endorsement based on the acceptance of a stateful
environment. Described in Section 3.1.4.10.
* mec-endorsement-triple-record (index 10) Triples describing a
series of Endorsement that are applicable based on the acceptance
of a series of stateful environment records. Described in
Section 3.1.4.11.
3.1.4.1. Common Types
3.1.4.1.1. Environment
An environment-map may be used to represent a whole Attester, an
Attesting Environment, or a Target Environment. The exact semantic
depends on the context (triple) in which the environment is used.
An environment is named after a class, instance or group identifier
(or a combination thereof).
environment-map = non-empty<{
? &(class: 0) => class-map
? &(instance: 1) => $instance-id-type-choice
? &(group: 2) => $group-id-type-choice
}>
The following describes each member of the environment-map:
* class (index 0): Contains "class" attributes associated with the
module. Described in Section 3.1.4.1.2.
* instance (index 1): Contains a unique identifier of a module's
instance. See Section 3.1.4.1.3.
* group (index 2): identifier for a group of instances, e.g., if an
anonymization scheme is used.
3.1.4.1.2. Class
The Class name consists of class attributes that distinguish the
class of environment from other classes. The class attributes
include class-id, vendor, model, layer, and index. The CoMID author
determines which attributes are needed.
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class-map = non-empty<{
? &(class-id: 0) => $class-id-type-choice
? &(vendor: 1) => tstr
? &(model: 2) => tstr
? &(layer: 3) => uint
? &(index: 4) => uint
}>
$class-id-type-choice /= tagged-oid-type
$class-id-type-choice /= tagged-uuid-type
$class-id-type-choice /= tagged-int-type
$class-id-type-choice /= tagged-bytes
The following describes each member of the class-map:
* class-id (index 0): Identifies the environment via a well-known
identifier. Typically, class-id is an object identifier (OID)
variable-length opaque byte string (Section 1.3.9) or universally
unique identifier (UUID). Use of this attribute is preferred.
* vendor (index 1): Identifies the entity responsible for choosing
values for the other class attributes that do not already have
naming authority.
* model (index 2): Describes a product, generation, and family. If
populated, vendor MUST also be populated.
* layer (index 3): Is used to capture where in a sequence the
environment exists. For example, the order in which bootstrap
code is executed may have security relevance.
* index (index 4): Is used when there are clones (i.e., multiple
instances) of the same class of environment. Each clone is given
a different index value to disambiguate it from the other clones.
For example, given a chassis with several network interface
controllers (NIC), each NIC can be given a different index value.
3.1.4.1.3. Instance
An instance carries a unique identifier that is reliably bound to a
Target Environment that is an instance of the Attester.
The types defined for an instance identifier are CBOR tagged
expressions of UEID, UUID, variable-length opaque byte string
(Section 1.3.9), or cryptographic key identifier.
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$instance-id-type-choice /= tagged-ueid-type
$instance-id-type-choice /= tagged-uuid-type
$instance-id-type-choice /= $crypto-key-type-choice
$instance-id-type-choice /= tagged-bytes
3.1.4.1.4. Group
A group carries a unique identifier that is reliably bound to a group
of Attesters, for example when a number of Attester are hidden in the
same anonymity set.
The types defined for a group identified are UUID and variable-length
opaque byte string (Section 1.3.9).
$group-id-type-choice /= tagged-uuid-type
$group-id-type-choice /= tagged-bytes
3.1.4.1.5. Measurements
Measurements can be of a variety of things including software,
firmware, configuration files, read-only memory, fuses, IO ring
configuration, partial reconfiguration regions, etc. Measurements
comprise raw values, digests, or status information.
An environment has one or more measurable elements. Each element can
have a dedicated measurement or multiple elements could be combined
into a single measurement. Measurements can have class, instance or
group scope. This is typically determined by the triple's
environment.
Class measurements apply generally to all the Attesters in the given
class. Instance measurements apply to a specific Attester instance.
Environments identified by a class identifier have measurements that
are common to the class. Environments identified by an instance
identifier have measurements that are specific to that instance.
The supply chain entity that is responsible for providing the the
measurements (i.e. Reference Values or Endorsed Values) is by
default the CoRIM signer. If a different entity is authorized to
provide measurement values, the authorized-by statement can be
supplied in the measurement-map.
measurement-map = {
? &(mkey: 0) => $measured-element-type-choice
&(mval: 1) => measurement-values-map
? &(authorized-by: 2) => [ + $crypto-key-type-choice ]
}
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The following describes each member of the measurement-map:
* mkey (index 0): An optional unique identifier of the measured
(sub-)environment. See Section 3.1.4.1.5.1.
* mval (index 1): The measurements associated with the
(sub-)environment. Described in Section 3.1.4.1.5.2.
* authorized-by (index 2): The cryptographic identity of the
individual or organization that is the designated authority for
this measurement. For example, producer of the measurement or a
delegated supplier.
3.1.4.1.5.1. Measurement Keys
The types defined for a measurement identifier are OID, UUID or uint.
$measured-element-type-choice /= tagged-oid-type
$measured-element-type-choice /= tagged-uuid-type
$measured-element-type-choice /= uint
3.1.4.1.5.2. Measurement Values
A measurement-values-map contains measurements associated with a
certain environment. Depending on the context (triple) in which they
are found, elements in a measurement-values-map can represent class
or instance measurements. Note that some of the elements have
instance scope only.
Measurement values may support use cases beyond Verifier appraisal.
Typically, a Relying Party determines if additional processing is
desirable and whether the processing is applied by the Verifier or
the Relying Party.
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measurement-values-map = non-empty<{
? &(version: 0) => version-map
? &(svn: 1) => svn-type-choice
? &(digests: 2) => [ + digest ]
? &(flags: 3) => flags-map
? (
&(raw-value: 4) => $raw-value-type-choice,
? &(raw-value-mask: 5) => raw-value-mask-type
)
? &(mac-addr: 6) => mac-addr-type-choice
? &(ip-addr: 7) => ip-addr-type-choice
? &(serial-number: 8) => text
? &(ueid: 9) => ueid-type
? &(uuid: 10) => uuid-type
? &(name: 11) => text
? &(cryptokeys: 13) => [ + $crypto-key-type-choice ]
? &(integrity-registers: 14) => integrity-registers
* $$measurement-values-map-extension
}>
The following describes each member of the measurement-values-map.
* version (index 0): Typically changes whenever the measured
environment is updated. Described in Section 3.1.4.1.5.3.
* svn (index 1): The security version number typically changes only
when a security relevant change is made to the measured
environment. Described in Section 3.1.4.1.5.4.
* digests (index 2): Contains the digest(s) of the measured
environment together with the respective hash algorithm used in
the process. See Section 1.3.8.
* flags (index 3): Describes security relevant operational modes.
For example, whether the environment is in a debug mode, recovery
mode, not fully configured, not secure, not replay protected or
not integrity protected. The flags field indicates which
operational modes are currently associated with measured
environment. Described in Section 3.1.4.1.5.5.
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* raw-value (index 4): Contains the actual (not hashed) value of the
element. An optional raw-value-mask (index 5) indicates which
bits in the raw-value field are relevant for verification. A mask
of all ones ("1") means all bits in the raw-value field are
relevant. Multiple values could be combined to create a single
raw-value attribute. The vendor determines how to pack multiple
values into a single raw-value structure. The same packing format
is used when collecting Evidence so that Reference Values and
collected values are bit-wise comparable. The vendor determines
the encoding of raw-value and the corresponding raw-value-mask.
* mac-addr (index 6): A EUI-48 or EUI-64 MAC address associated with
the measured environment. Described in Section 3.1.4.1.5.7.
* ip-addr (index 7): An IPv4 or IPv6 address associated with the
measured environment. Described in Section 3.1.4.1.5.7.
* serial-number (index 8): A text string representing the product
serial number.
* ueid (index 9): UEID associated with the measured environment.
See Section 1.3.5.
* uuid (index 10): UUID associated with the measured environment.
See Section 1.3.4.
* name (index 11): a name associated with the measured environment.
* cryptokeys (index 13): identifies cryptographic keys that are
protected by the Target Environment See Section 3.1.4.1.6 for the
supported formats. An Attesting Environment determines that keys
are protected as part of Claims collection. Appraisal verifies
that, for each value in cryptokeys, there is a matching Reference
Value entry. Matching is described in Section 5.4.4.5.4.
* integrity-registers (index 14): A group of one or more named
measurements associated with the environment. Described in
Section 3.1.4.1.7.
3.1.4.1.5.3. Version
A version-map contains details about the versioning of a measured
environment.
version-map = {
&(version: 0) => text
? &(version-scheme: 1) => $version-scheme
}
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The following describes each member of the version-map:
* version (index 0): the version string
* version-scheme (index 1): an optional indicator of the versioning
convention used in the version attribute. Defined in Section 4.1
of [I-D.ietf-sacm-coswid]. The CDDL is copied below for
convenience.
$version-scheme /= &(multipartnumeric: 1)
$version-scheme /= &(multipartnumeric-suffix: 2)
$version-scheme /= &(alphanumeric: 3)
$version-scheme /= &(decimal: 4)
$version-scheme /= &(semver: 16384)
$version-scheme /= int / text
3.1.4.1.5.4. Security Version Number
The following details the security version number (svn) and the
minimum security version number (min-svn) statements. A security
version number is used to track changes to an object (e.g., a secure
enclave, a boot loader executable, a configuration file, etc.) that
are security relevant. Rollback of a security relevant change is
considered to be an attack vector, as such, security version numbers
can't be decremented. If a security relevant flaw is discovered in
the Target Environment and subsequently fiexed, the svn value is
typically incremented.
There may be several revisions to a Target Environment that are in
use at the same time. If there are multiple revisions with different
svn values, the revision with a lower svn value may or may not be in
a security critical condition. The Endorser may provide a minimum
security version number using min-svn to specify the lowest svn value
that is acceptable. svn values that are equal to or greater than min-
svn do not signal a security critical condition. svn values that are
below min-svn are in a security critical condition that is unsafe for
normal use.
The svn-type-choice measurement consists of a tagged-svn or tagged-
min-svn value. The tagged-svn and tagged-min-svn tags are CBOR tags
with the values #6.552 and #6.553 respectively.
svn-type = uint
svn = svn-type
min-svn = svn-type
tagged-svn = #6.552(svn)
tagged-min-svn = #6.553(min-svn)
svn-type-choice = tagged-svn / tagged-min-svn
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3.1.4.1.5.5. Flags
The flags-map measurement describes a number of boolean operational
modes. If a flags-map value is not specified, then the operational
mode is unknown.
flags-map = {
? &(is-configured: 0) => bool
? &(is-secure: 1) => bool
? &(is-recovery: 2) => bool
? &(is-debug: 3) => bool
? &(is-replay-protected: 4) => bool
? &(is-integrity-protected: 5) => bool
? &(is-runtime-meas: 6) => bool
? &(is-immutable: 7) => bool
? &(is-tcb: 8) => bool
? &(is-confidentiality-protected: 9) => bool
* $$flags-map-extension
}
The following describes each member of the flags-map:
* is-configured (index 0): If the flag is true, the measured
environment is fully configured for normal operation.
* is-secure (index 1): If the flag is true, the measured
environment's configurable security settings are fully enabled.
* is-recovery (index 2): If the flag is true, the measured
environment is in recovery mode.
* is-debug (index 3): If the flag is true, the measured environment
is in a debug enabled mode.
* is-replay-protected (index 4): If the flag is true, the measured
environment is protected from replay by a previous image that
differs from the current image.
* is-integrity-protected (index 5): If the flag is true, the
measured environment is protected from unauthorized update.
* is-runtime-meas (index 6): If the flag is true, the measured
environment is measured after being loaded into memory.
* is-immutable (index 7): If the flag is true, the measured
environment is immutable.
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* is-tcb (index 8): If the flag is true, the measured environment is
a trusted computing base.
* is-confidentiality-protected (index 9): If the flag is true, the
measured environment is confidentiality protected. For example,
if the measured environment consists of memory, the sensitive
values in memory are encrypted.
3.1.4.1.5.6. Raw Values Types
Raw value measurements are typically vendor defined values that are
checked by Verifiers for consistency only, since the security
relevance is opaque to Verifiers.
There are two parts to a raw-value-group, a measurement and an
optional mask. The default raw value measurement is of type tagged-
bytes (Section 1.3.9). Additional raw value types can be defined,
but must be CBOR tagged so that parsers can distinguish between the
various semantics of type values.
The mask is applied by the Verifier as part of appraisal. Only the
raw value bits with corresponding TRUE mask bits are compared during
appraisal.
When a new raw value type is defined, the convention for applying the
mask is also defined. Typically, a CoRIM profile is used to define
new raw values and mask semantics.
$raw-value-type-choice /= tagged-bytes
raw-value-mask-type = bytes
3.1.4.1.5.7. Address Types
The types or associating addressing information to a measured
environment are:
ip-addr-type-choice = ip4-addr-type / ip6-addr-type
ip4-addr-type = bytes .size 4
ip6-addr-type = bytes .size 16
mac-addr-type-choice = eui48-addr-type / eui64-addr-type
eui48-addr-type = bytes .size 6
eui64-addr-type = bytes .size 8
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3.1.4.1.6. Crypto Keys
A cryptographic key can be one of the following formats:
* tagged-pkix-base64-key-type: PEM encoded SubjectPublicKeyInfo.
Defined in Section 13 of [RFC7468].
* tagged-pkix-base64-cert-type: PEM encoded X.509 public key
certificate. Defined in Section 5 of [RFC7468].
* tagged-pkix-base64-cert-path-type: X.509 certificate chain created
by the concatenation of as many PEM encoded X.509 certificates as
needed. The certificates MUST be concatenated in order so that
each directly certifies the one preceding.
* tagged-cose-key-type: CBOR encoded COSE_Key or COSE_KeySet.
Defined in Section 7 of [STD96]
A cryptographic key digest can be one of the following formats:
* tagged-thumbprint-type: a digest of a raw public key. The digest
value may be used to find the public key if contained in a lookup
table.
* tagged-cert-thumbprint-type: a digest of a certificate. The
digest value may be used to find the certificate if contained in a
lookup table.
* tagged-cert-path-thumbprint-type: a digest of a certification
path. The digest value may be used to find the certificate path
if contained in a lookup table.
In a split Verifier scenario, a first Verifier may verify the
signature of a cryptographic key then compute a digest of the key
that is forwarded to a second Verifier. The second Verifier
completes the signature verification by performing certificate path
validation, revocation checks, and trust anchor checks.
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$crypto-key-type-choice /= tagged-pkix-base64-key-type
$crypto-key-type-choice /= tagged-pkix-base64-cert-type
$crypto-key-type-choice /= tagged-pkix-base64-cert-path-type
$crypto-key-type-choice /= tagged-cose-key-type
$crypto-key-type-choice /= tagged-thumbprint-type
$crypto-key-type-choice /= tagged-cert-thumbprint-type
$crypto-key-type-choice /= tagged-cert-path-thumbprint-type
tagged-pkix-base64-key-type = #6.554(tstr)
tagged-pkix-base64-cert-type = #6.555(tstr)
tagged-pkix-base64-cert-path-type = #6.556(tstr)
tagged-thumbprint-type = #6.557(digest)
tagged-cose-key-type = #6.558(COSE_KeySet / COSE_Key)
tagged-cert-thumbprint-type = #6.559(digest)
tagged-cert-path-thumbprint-type = #6.561(digest)
3.1.4.1.7. Integrity Registers
An Integrity Registers map groups together one or more measured
"objects". Each measured object has a unique identifier and one or
more associated digests. Identifiers are either unsigned integers or
text strings and their type matters, e.g., unsigned integer 5 is
distinct from the text string "5".
integrity-register-id-type-choice = uint / text
integrity-registers = {
+ integrity-register-id-type-choice => [ + digest ]
}
All the measured objects in an Integrity Registers map are explicitly
named and the order in which they appear in the map is irrelevant.
Any digests associated with a measured object represent an acceptable
state for the object. Therefore, if multiple digests are provided,
the acceptable state is their cross-product. For example, given the
following Integrity Registers:
{
0: [ [ 0, h'00' ] ],
1: [ [ 0, h'11' ], [ 1, h'12' ] ]
}
then both
{
0: [ 0, h'00' ],
1: [ 0, h'11' ]
}
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and
{
0: [ 0, h'00' ],
1: [ 1, h'12' ]
}
are acceptable states.
Integrity Registers can be used to model the PCRs in a TPM or vTPM,
in which case the identifier is the register index, or other kinds of
vendor-specific measured objects.
3.1.4.1.8. Domain Types
A domain is a context for bundling a collection of related
environments and their measurements.
Three types are defined: uint and text for local scope, UUID for
global scope.
$domain-type-choice /= uint
$domain-type-choice /= text
$domain-type-choice /= tagged-uuid-type
$domain-type-choice /= tagged-oid-type
3.1.4.2. Reference Values Triple
A Reference Values triple relates reference measurements to a Target
Environment. For Reference Value Claims, the subject identifies a
Target Environment, the object contains measurements, and the
predicate asserts that these are the expected (i.e., reference)
measurements for the Target Environment.
reference-triple-record = [
environment-map
measurement-map
]
3.1.4.3. Endorsed Values Triple
An Endorsed Values triple declares additional measurements that are
valid when a Target Environment has been verified against reference
measurements. For Endorsed Value Claims, the subject is either a
Target or Attesting Environment, the object contains measurements,
and the predicate defines semantics for how the object relates to the
subject.
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endorsed-triple-record = [
environment-map
measurement-map
]
3.1.4.4. Device Identity Triple
A Device Identity triple relates one or more cryptographic keys to a
device. The subject of an Identity triple uses an instance or class
identifier to refer to a device, and a cryptographic key is the
object. The predicate asserts that the identity is authenticated by
the key. A common application for this triple is device identity.
identity-triple-record = [
environment-map
[ + $crypto-key-type-choice ]
]
3.1.4.5. Attestation Keys Triple
An Attestation Keys triple relates one or more cryptographic keys to
an Attesting Environment. The Attestation Key triple subject is an
Attesting Environment whose object is a cryptographic key. The
predicate asserts that the Attesting Environment signs Evidence that
can be verified using the key.
attest-key-triple-record = [
environment-map
[ + $crypto-key-type-choice ]
]
3.1.4.6. Domain Dependency Triple
A Domain Dependency triple defines trust dependencies between
measurement sources. The subject identifies a domain
(Section 3.1.4.1.8) that has a predicate relationship to the object
containing one or more dependent domains. Dependency means the
subject domain’s trustworthiness properties rely on the object
domain(s) trustworthiness having been established before the
trustworthiness properties of the subject domain exists.
domain-dependency-triple-record = [
$domain-type-choice
[ + $domain-type-choice ]
]
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3.1.4.7. Domain Membership Triple
A Domain Membership triple assigns domain membership to environments.
The subject identifies a domain (Section 3.1.4.1.8) that has a
predicate relationship to the object containing one or more
environments. Endorsed environments (Section 3.1.4.3) membership is
conditional upon successful matching of Reference Values
(Section 3.1.4.2) to Evidence.
domain-membership-triple-record = [
$domain-type-choice
[ + environment-map ]
]
3.1.4.8. CoMID-CoSWID Linking Triple
A CoSWID triple relates reference measurements contained in one or
more CoSWIDs to a Target Environment. The subject identifies a
Target Environment, the object one or more unique tag identifiers of
existing CoSWIDs, and the predicate asserts that these contain the
expected (i.e., reference) measurements for the Target Environment.
coswid-triple-record = [
environment-map
[ + concise-swid-tag-id ]
]
concise-swid-tag-id = text / bstr .size 16
3.1.4.9. Conditional Endorsement Series Triple
A Conditional Endorsement Series triple uses a stateful environment,
(i.e., stateful-environment-record), that identifies a Target
Environment based on an environment-map plus the measurement-map
measurements that have matching Evidence.
The stateful Target Environment is a triple subject that MUST be
satisfied before the series triple object is matched.
; an environment with a set of measurements that must match evidence
stateful-environment-record = [
environment-map,
measurement-map
]
The series object is an array of conditional-series-record that has
both Reference and Endorsed Values. Each conditional-series-record
record is evaluated in the order it appears in the series array. The
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Endorsed Values are accepted if the series condition in a
conditional-series-record matches the ACS. The first conditional-
series-record that successfully matches an ACS Entry terminates the
matching and the corresponding Endorsed Values are accepted. If none
of the series conditions match an ACS Entry, the triple is not
matched, and no Endorsed values are accepted.
The authorized-by value in measurement-map in the stateful
environment, if present, applies to all measurements in the triple,
including conditional-series-record records.
conditional-endorsement-series-triple-record = [
stateful-environment-record
; order matters: the first matching record wins and halts matching
[ + conditional-series-record ]
]
conditional-series-record = [
; reference values to be matched against evidence
refv: measurement-values-map
; endorsed values that apply in case revf matches
endv: measurement-values-map
]
3.1.4.10. Conditional Endorsement Triple
A Conditional Endorsement triple uses a stateful environment, (i.e.,
stateful-environment-record), that identifies a Target Environment
based on an environment-map plus the measurement-map measurements
that have matching Evidence.
The stateful Target Environment is a triple subject that MUST be
satisfied before the Endorsed Values in the triple object are
accepted.
; an environment with a set of measurements that must match evidence
stateful-environment-record = [
environment-map,
measurement-map
]
The authorized-by value in measurement-map in the stateful
environment, if present, applies to all measurements in the triple,
including those in measurement-values-map.
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conditional-endorsement-triple-record = [
stateful-environment-record,
; endorsed values
measurement-values-map
]
3.1.4.11. Multi-Environment Conditional (MEC) Endorsement Triple
The semantics of the Multi-Environment Conditional (MEC) Endorsement
Triple is as follows:
"IF accepted state matches all conds values, THEN every entry in
the endorsements is added to the accepted state"
mec-endorsement-triple-record = [
conds: [ + stateful-environment-record ]
endorsements: [ + endorsed-triple-record ]
]
A mec-endorsement-triple-record has the following parameters:
* conds: all target environments, along with a specific state, that
need to match state-triples entries in the ACS for the
endorsement(s) to apply
* endorsements: endorsements that are added to the ACS state-triples
if all conds match.
The order in which MEC Endorsement triples are evaluated is
important: different sorting may produce different end-results in the
computed ACS.
Therefore, the set of applicable MEC Endorsement triple MUST be
topologically sorted based on the criterion that a MEC Endorsement
triple is evaluated before another if its Target Environment and
Endorsement pair is found in any of the stateful environments of the
second triple.
Notes:
* In order to give the expected result, the condition must describe
the expected context completely.
* The scope of a single MEC triple encompasses an arbitrary amount
of environments across all layers in an Attester.
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There are scope-related questions that need to be answered. (
// Tracked at: https://github.com/ietf-rats-wg/draft-ietf-rats-corim/
issues/176)
3.2. Extensibility
The base CORIM schema is described using CDDL [RFC8610] that can be
extended only at specific allowed points known as "extension points"
The following types of extensions are supported in CoRIM
3.2.1. Map Extensions
Map Extensions provides extensibility support to CoRIM Map
structures. CDDL map extensibility enables a CoRIM profile to extend
the base CoRIM definition. CDDL map extension points have the form
($$NAME-extension) where "NAME" is the name of the map and '$$'
signifies map extensibility. Typically, map extension requires a
convention for code point naming that avoids code-point reuse. Well-
known code points may be in a registry, such as CoSWID [IANA.coswid].
Additionally, a range of code points may be reserved for vendor-
specific use such as negative integers.
3.2.2. Data Type Extensions
Data type extensibility has the form ($NAME-type-choice) where "NAME"
is the type name and '$' signifies type extensibility.
Schema extensions (Map or Data Type) should be documented to
facilitate interoperability. CoRIM profiles are best used to
document vendor or industry defined extensions.
4. CoBOM
A Concise Bill of Material (CoBOM) object represents the signal for
the Verifier to activate the listed tags. Verifier policy determines
whether CoBOMs are required.
When CoBOMs are required, each tag MUST be activated by a CoBOM
before being processed. All the tags listed in the CoBOM MUST be
activated atomically. If any tag activated by a CoBOM is not
available to the Verifier, the entire CoBOM is rejected.
The number of CoBOMs required in a given supply chain ecosystem is
dependent on Verifier Owner's Appraisal Policy for Evidence.
Corresponding policies are often driven by the complexity and nature
of the use case.
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If a Verifier Owner has a policy that does not require CoBOM, tags
within a CoRIM received by a Verifier are activated immediately and
treated valid for appraisal.
There may be cases when Verifier receives CoRIMs from multiple
Reference Value providers and Endorsers. In such cases, a supplier
(or other authorities, such as integrators) may be designated to
issue a single CoBOM to activate all the tags submitted to the
Verifier in these CoRIMs.
In a more complex case, there may be multiple authorities that issue
CoBOMs at different points in time. An Appraisal Policy for Evidence
may dictate how multiple CoBOMs are to be processed within the
Verifier.
4.1. Structure
The CDDL specification for the concise-bom-tag map is as follows and
this rule and its constraints MUST be followed when creating or
validating a CoBOM tag:
concise-bom-tag = {
&(tag-identity: 0) => tag-identity-map
&(tags-list: 1) => [ + tag-identity-map ],
&(bom-validity: 2) => validity-map
* $$concise-bom-tag-extension
}
The following describes each member of the concise-bom-tag map.
* tag-identity (index 0): A tag-identity-map containing unique
identification information for the CoBOM. Described in
Section 3.1.1.
* tags-list (index 1): A list of one or more tag-identity-maps
identifying the CoMID and CoSWID tags that constitute the "bill of
material", i.e., a complete set of verification-related
information. The tags-list behaves like a signaling mechanism
from the supply chain (e.g., a product vendor) to a Verifier that
activates the tags in tags-list for use in the Evidence appraisal
process. The activation is atomic: all tags listed in tags-list
MUST be activated or no tags are activated.
* bom-validity (index 2): Specifies the validity period of the
CoBOM. Described in Section 1.3.3
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* $$concise-bom-tag-extension: This CDDL socket is used to add new
information structures to the concise-bom-tag. See Section 8.5.
The $$concise-bom-tag-extension extension socket is empty in this
specification.
5. CoRIM-based Appraisal of Evidence
The verification procedure is divided into three separate phases:
* Appraisal Context initialisation
* Evidence collection
* Accepted Claims Set Augmentation
At a few well-defined points in the procedure, the Verifier behaviour
will depend on the specific CoRIM profile. Each CoRIM profile MUST
provide a description of the expected Verifier behavior for each of
those well-defined points.
Note that what follows describes a simplified and standard algorithm.
Verifiers claiming compliance with this specification MUST exhibit
the same externally visible behavior as described here, they are not
required to use the same internal data structures. For example, it
is expected that the resources used during the initialisation phase
can be amortised across multiple appraisals.
5.1. Verifier Abstraction
This document assumes Verifier implementations may differ. To
facilitate description of normative Verifier behavior, this document
uses abstract representation of Verifier internals.
* Claim: A piece of information, in the form of a key-value pair.
* Environment Measurement Tuple (EMT): A structure containing a set
of environment Claims that describe a Target Environment and a set
of measurement Claims that describe attributes of the Target
Environment.
* reference state: Claims that describe various alternative states
of a Target Environment. Reference Values Claims typically
describe various possible states due to versioning, manufactruing
practices, or supplier configuration options.
* actual state: Claims that describe a Target Environment instance
at a given point in time. Endorsed Values and Evidence typically
are Claims about actual state.
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* Group: A set of Evidence, Reference Values, Endorsed Values and
Appraisal Policies which are processed together. An Attester may
be composed of multiple components, where each component may
represent a scope of appraisal.
* Authority: The entity asserting that a claim is true. Typically,
a Claim is asserted using a cryptographic key to digitally sign
the Claim. A cryptographic key can be a proxy for a human or
organizational entity.
* Accepted Claims Set (ACS): A structure that holds EMT Claims that
have been vetted following the appraisal process. The ACS
describes the actual state of an Attester that has been vetted by
Appraisal Policy. The ACS also keeps track of a Claim's
authority.
* Appraisal Policy: A description of the conditions that, if met,
allow acceptance of Claims. Typically, the entity asserting a
Claim should have knowledge, expertise, or context that gives
credibility to the assertion. Appraisal Policy resolves which
entities are credible and under what conditions.
5.2. Appraisal Context initialisation
The goal of the initialisation phase is to load the CoRIM Appraisal
Context with objects such as tags (CoMID, CoSWID, etc.) from CoRIM
files, cryptographic validation key material (e.g., raw public keys,
root certificates, intermediate CA certificate chains), etc. that
will be used in the subsequent Evidence Appraisal phase.
5.2.1. CoRIM Selection
All available CoRIMs are collected. A Verifier may be pre-configured
with a large number of CoRIMs describing many types of device. All
CoRIMs are loaded at this stage, later stages will select the CoRIMs
appropriate to the Evidence Appraisal step.
CoRIMs that are not within their validity period, or that cannot be
associated with an authenticated and authorised source MUST be
discarded.
CoRIM that are secured by a cryptographic mechanism such as a
signature which does not pass validation MUST be discarded.
Other selection criteria MAY be applied.
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For example, if the Evidence format is known in advance, CoRIMs using
a profile that is not understood by a Verifier can be readily
discarded.
The selection process MUST yield at least one usable tag.
5.2.2. CoBOM Extraction
This section is not applicable if the Verifier policy does not
require CoBOMs.
All the available Concise Bill Of Material (CoBOMs) tags are then
collected from the selected CoRIMs.
CoBOMs which are not within their validity period, or which reference
tags not available to the verifier, are discarded.
The Verifier processes all CoBOMs that are valid at the point in time
of Evidence Appraisal, and activates all tags referenced therein.
A Verifier may decide to discard some of the available and valid
CoBOMs depending on any locally configured authorization policies.
(Such policies model the trust relationships between the Verifier
Owner and the relevant suppliers, and are out of scope of the present
document.)
For example, a composite device (Section 3.3 of [RFC9334]) is likely
to be fully described by multiple CoRIMs, each signed by a different
supplier. In such case, the Verifier Owner may instruct the Verifier
to discard tags activated by supplier CoBOMs that are not activated
by the trusted integrator.
After the Verifier has processed all CoBOMs it MUST discard any tags
which have not been activated by a CoBOM.
5.2.3. Tags Identification and Validation
The Verifier chooses tags -- including Concise Module ID Tags (CoMID,
Section 3), Concise Software ID Tags (CoSWID,
[I-D.ietf-sacm-coswid]), and/or Concise Trust Anchor Stores (CoTS,
[I-D.ietf-rats-concise-ta-stores]) -- from the selected CoRIMs.
The Verifier MUST discard all tags which are not syntactically and
semantically valid. In particular, any cross-referenced triples
(e.g., CoMID-CoSWID linking triples) MUST be successfully resolved.
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5.2.4. Appraisal Context Construction
All of the validated and potentially useful tags are loaded into the
Appraisal Context.
This concludes the initialisation phase.
5.3. Evidence Collection
In the Evidence collection phase the Verifier communicates with
attesters to collect Evidence.
The first part of the Evidence collection phase does not perform any
cryptographic validation. This allows Verifiers to use untrusted
code for their initial Evidence collection.
The results of the evidence collection are protocol specific data and
transcripts which are used as input to appraisal by the Verifier.
5.3.1. Cryptographic validation of Evidence
If the authenticity of Evidence is secured by a cryptographic
mechanism such as a signature, the first step in the Evidence
Appraisal is to perform cryptographic validation of the Evidence.
The exact cryptographic signature validation mechanics depend on the
specific Evidence collection protocol.
For example: In DICE, a proof of liveness is performed on the final
key in the certificate chain. If this passes then a suitable
certification path anchored on a trusted root certificate is looked
up -- e.g., based on linking information obtained from the DeviceID
certificate (see Section 9.2.1 of [DICE.Layer]) -- in the Appraisal
Context. If found, then usual X.509 certificate validation is
performed. In PSA, the verification public key is looked up in the
appraisal context using the ueid claim found in the PSA claims-set
(see Section 4.2.1 of [I-D.tschofenig-rats-psa-token]). If found,
COSE Sign1 verification is performed accordingly.
Independent of the specific integrity protection method used, the
integrity of Evidence MUST be successfully verified.
A CoRIM profile MUST describe:
- How cryptographic verification key material is represented
(e.g., using Attestation Keys triples, or CoTS tags)
- How key material is associated with the Attesting Environment
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- How the Attesting Environment is identified in Evidence
5.3.2. The Accepted Claims Set
At the end of the Evidence collection process Evidence has been
converted into a format suitable for appraisal. To this end, this
document describes an accepted-claims-set format and the algorithms
used to compare it against CoMID Reference Values.
accepted-claims-set = {
&(state-triples: 0) => [ + endorsed-triple-record ]
? &(identity-triples: 1) => [ + identity-triple-record ]
? &(coswid-triples: 2) => [ + ev-coswid-triple-record ]
* $$accepted-claims-set-extension
}
Verifiers are not required to use this as their internal state, for
the purposes of this document a sample Verifier is discussed which
uses this format.
The Accepted Claims Set (ACS) contains the actual state of Target
Environments (TEs). The state-triples field contains Evidence (from
Attesters) and Endorsements (e.g. from endorsed-triple-record).
CoMID Reference Values will be matched against the Accepted Claims
Set, as per the appraisal policy of the Verifier. This document
describes an example evidence structure which can be easily matched
against these Reference Values.
Each entry within state-triples uses the syntax of endorsed-triple-
record. When an endorsed-triple-record appears within state-triples
it indicates that the authority named by measurement-map/authorized-
by asserts that the actual state of one or more Claims within the
Target Environment, as identified by environment-map, have the
measurement values in measurement-map/mval.
In authorized-by, authority is represented by cryptographic keys.
Authority is asserted by digitally signing a Claim using the key.
Hence, Claims are added to the ACS under the authority of a key.
Each Claim is encoded as an Environment Measurement Tuple (a
contraction of environment-map, measurement-map tuple). The
environment-map and a key within measurement-values-map encode the
name of the Claim. The value matching that key within measurement-
values-map is the actual state of the Claim.
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This specification does not assign special meanings to any Claim
name, it only specifies rules for determining when two Claim names
are the same.
If two Claims have the same environment-map encoding then this does
not trigger special encoding in the Verifier. The Verifier follows
instructions in the CoRIM file which tell it how claims are related.
If Evidence or Endorsements from different sources has the same
environment-map and authorized-by then the measurement-values-maps
are merged.
The ACS must maintain the authority information for each EMT. There
can be multiple entries in state-triples which have the same
environment-map and a different authorized-by field (see
Section 5.3.2.2).
If the merged measurement-value-map contains duplicate codepoints and
the measurement values are equivalent, then duplicate claims SHOULD
be omitted. Equivalence typically means values MUST be binary
identical.
If the merged measurement-value-map contains duplicate codepoints and
the measurement values are not equivalent then the verifier SHALL
report an error and stop validation processing.
5.3.2.1. Accepted Claims Set Initialization
The Accepted Claims Set is initialized by copying Evidence claims
describing authenticated Attester's Target Environments into the
Verifier's Accepted Claims Set.
Evidence formats may require format translation before being added to
the Accepted Claims Set. If format translation is required, a CoRIM
profile, see Section 2.1.4, defines an Evidence translation function.
Section 5.5 provides information on how DICE and SPDM Evidence is
reformatted into CoMID schema compliant expressions before being
added to the Accepted Claims Set.
5.3.2.2. The authorized-by field in Accepted Claims Set
The authorized-by field in an Accepted Claims Set entry indicates the
entity whose authority backs the claim.
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An entity is authoritative when it makes Claims that are inside its
area of competence. The Verifier keeps track of the authorities that
assert Claims so that it can filter out claims from entities that do
not satisfy appraisal policies.
When adding an Evidence Claim to the Accepted Claims Set, the
Verifier SHALL set the authorized-by field in that Claim to the
trusted authority keys at the head of each key chain which signed
that Evidence. This key is often the subject of a self-signed
certificate. The Verifier has already verified the certificate chain
(see Section 5.3.1).
If multiple authorities approve the same Claim, for example if
multiple key chains are available, then the authorized-by field SHALL
be set to include the trusted authority keys used by each of those
authorities.
When adding Endorsement Claims to the Accepted Claims Set that
resulted from CoRIM processing (see Section 5.4.5) the Verifier SHALL
set the authorized-by field in that Evidence to the trusted authority
key that is at the head of the key chain that signed the CoRIM.
When searching the Accepted Claims Set for an entry which matches a
Reference Value containing an authorized-by field, the Verifier SHALL
ignore ACS entries if none of the keys present in the Reference Value
authorized-by field are also present in the ACS authorized-by field.
The Verifier SHOULD set the authorized-by field in Accepted Claims
Set entries to a format which contains only a key, for example the
tagged-cose-key-type format. Using a common format makes it easier
to compare the field.
5.4. Accepted Claims Set augmentation using CoMID triples
In the Accepted Claims Set augmentation phase, a CoRIM Appraisal
Context and an Evidence Appraisal Policy are used by the Verifier to
find CoMID triples which match the Accepted Claims Set (ACS).
Triples that specify an ACS matching condition will augment the ACS
with Endorsements if the condition is met.
Each triple is processed independently of other triples. However,
the ACS state may change as a result of processing a triple. If a
triple condition does not match, then the Verifier continues to
process other triples.
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5.4.1. Ordering of triple processing
Triples interface with the ACS by either adding new ACS entries or by
matching existing ACS entries before updating the ACS. Most triples
use an environment-map field to select the AES entries to match or
modify. This field may be contained in an explicit matching
condition, such as stateful-environment-record.
The order of triples processing is important. Processing a triple
may result in ACS modifications that affect matching behavior of
other triples.
The Verifier MUST ensure that a triple including a matching condition
is processed after any other triple that modifies or adds an ACS
entry with an environment-map that is in the matching condition.
This can be acheived by sorting the triples before processing, by
repeating processing of some triples after ACS modifications or by
other algorithms.
5.4.2. Processing Reference Values Triple
Reference Value Providers (RVP) publish Reference Values triples that
are matched against ACS entries. Reference Values may describe
multiple acceptable states for Attesters; hence "matching" determines
that Evidence (contained in the ACS) satisfies an appropriate subset
of the available Reference Values. If the appropriate subset
matches, the authority of the RVP is added to the appropriate ACS
entries.
The Verifier compares each reference-triple-record against ACS
entries as described in Section 5.4.4.4, where the reference-triple-
record takes the place of a stateful-environment-record. If all
fields of the reference-triple-record match the ACS, then the
Verifier MUST add the RVP authority to each matching ACS field.
If any reference-triple-record in the Reference Value triple does not
match the ACS then the entire triple is ignored.
5.4.3. Processing Endorsed Value Triple
5.4.4. Processing triples representing Conditional Endorsements
An Endorser may use CoMID tags to publish Conditional Endorsements,
which are added to the Accepted Claims Set only if specified
conditions are satisfied. This section describes the process
performed by the Verifier to determine which Conditional Endorsements
from the candidate CoMIDs should be added to the ACS.
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The verifier checks whether Conditional Endorsements are applicable
by comparing Accepted Claims Set entries against expected values
provided in stateful-environment-record object which are part of the
triple.
5.4.4.1. Processing Conditional Endorsement Triple
For each Conditional Endorsement Triple the Verifier compares the
stateful-environment-record field in the triple against the ACS (see
Section 5.4.4.4).
If the stateful environment matches, then the Verifier MUST add an
Endorsement entry to the ACS (see Section 5.4.5). The Endorsement
consists of the measurement-values-map field in the triple, plus the
authority of the entity that signed the Conditional Endorsement
Triple.
5.4.4.2. Processing Multi-Environment Conditional (MEC) Endorsement
Triple
For each MEC Endorsement Triple the Verifier compares each of the
stateful-environment-record fields from the cond field in the triple
against the ACS (see Section 5.4.4.4).
If every stateful environment matches a corresponding ACS entry, then
the Verifier MUST add an Endorsement entry to the ACS (see
Section 5.4.5) for each endorsed-triple-record in the endorsements
field. Each Endorsement from the endorsed-triple-record includes the
authority which signed the MEC Endorsement Triple.
5.4.4.3. Processing Conditional Endorsement Series Triple
For each Conditional Endorsement Series Triple the Verifier iterates
over the conditional-series-records within the triple, stopping if it
finds a match.
For each iteration, the Verifier creates a temporary stateful-
environment-record by merging the stateful-environment-record in the
triple with the refv field in the conditional-series-record. It
compares this temporary record against the ACS (see Section 5.4.4.4).
If one of the temporary records matches then the Verifier MUST add
the endv Endorsement entry to the ACS. This Endorsement includes the
authority which signed the Conditional Endorsement Series Triple.
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5.4.4.4. Matching a stateful environment against the Accepted Claims
Set
This section describes how a stateful environment is matched against
an Accepted Claims Set entry. If any part of the processing
indicates that the stateful environment does not match then the
remaining steps in this section are skipped for that stateful
environment.
The Verifier initializes a temporary "candidate entries" variable
with all entries in the Accepted Claims Set (ACS) where the stateful
enviromnment environment-map is a subset of the ACS environment-map.
A stateful environment environment-map is a subset of an ACS entry
environment-map if each field (for example class, instance etc.)
which is present in the stateful environment environment-map is also
present in the ACS entry, and the CBOR encoded field values in the
stateful environment and ACS entry are binary identical. If a field
is not present in the stateful environment environment-map then the
presence of, and value of, the corresponding ACS entry field does not
affect whether the environment-maps are subsets.
Before performing the binary comparison, a Verifier SHOULD convert
environment-map fields into a form which meets CBOR Core
Deterministic Encoding Requirements [STD94].
If the stateful environment contains an authorized-by field then the
Verifier SHALL remove all candidate entries whose authorized-by field
does not contain one of the keys listed in the stateful environment
authorized-by field (see Section 5.3.2.2 for more details).
If there are no candidate entries then the triple containing the
stateful environment does not match.
The stateful environment entry is compared against each of the
candidate entries.
For each of the candidate entries, the Verifier SHALL iterate over
the codepoints which are present in the measurement-values-map field
within the stateful environment measurement-map. Each of the
codepoints present in the stateful environment is compared against
the candidate entry.
If any codepoint present in the stateful environment measurement-
values-map does not match the same codepoint within the candidate
entry measurement-values-map then the stateful environment does not
match.
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If all checks above have been performed successfully then the
stateful environment matches. If none of the candidate entries match
the stateful environment entry then the stateful environment does not
match.
5.4.4.5. Matching a single measurement-values-map codepoint
The algorithm used to match the measurement-values-map codepoints is
described in this section. The comparison performed depends on the
value of the codepoint being compared and whether the measurement-
values-map value associated with that codepoint is tagged.
If the stateful environment measurement-values-map value is tagged
with a CBOR tag [STD94] then the Verifier MUST use the comparison
algorithm associated with that tag.
If the value is not tagged then the Verifier MUST use the comparison
algorithm associated with the measurement-values-map codepoint for
the entry.
This specification defines the matching algorithm for some codepoints
and CBOR tagged values, which are described in sub-sections below.
A CoRIM profile may define additional tags and their matching
algorithms.
If the Verifier does not recognize the stateful environment CBOR tag
value then the stateful environment does not match.
If the stateful environment is not tagged and the measurement-value-
map key is a value with handling described in the sub-sections below,
then the algorithm appropriate to that key is used to match the
entries.
If the stateful environment is not tagged, and the measurement-
values-map key is not a value described below, then the entries are
compared using binary comparison of their CBOR encoded values. If
the values are not binary identical then the stateful environment
does not match.
Note that while specifications may extend the matching semantics
using CBOR tags, there is no way to extend the matching semantics of
codepoints. Any new codepoints requiring non-default comparison must
add a CBOR tag to the Reference Value describing the desired
behaviour.
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5.4.4.5.1. Comparison for svn entries
The value stored under measurement-values-map key 1 is an SVN, which
must have type UINT.
If the Reference value for measurement-values-map key 1 is an
untagged UINT or a UINT tagged with #6.552 then an equality
comparison is performed. If the value of the SVN in Accepted Claims
Set is not equal to the value in the Reference Value then the
Reference Value does not match.
If the Reference value for measurement-values-map key 1 is a UINT
tagged with #6.553 then a minimum comparison is performed. If the
value of the SVN in Accepted Claims Set less than the value in the
Reference Value then the Reference Value does not match.
5.4.4.5.2. Comparison for digests entries
The value stored under measurement-values-map key 2, or a value
tagged with #6.TBD is a digest entry. It contains one or more
digests, each measuring the same object. A Reference Value may
contain multiple digests, each with a different algorithm acceptable
to the Reference Value provider. If the digest in Evidence contains
a single value with an algorithm and value matching one of the
algorithms and values in the Reference Value then it matches.
To prevent downgrade attacks, if there are multiple algorithms which
are in both the Evidence and Reference Value then the digests
calculated using all shared algorithms must match.
If the CBOR encoding of the digests entry in the Reference Value or
the Accepted Claim Set value with the same key is incorrect (for
example if fields are missing or the wrong type) then the Reference
Value does not match.
The Verifier MUST iterate over the Reference Value digests array,
locating hash algorithm identifiers that are present in the Reference
Value and in the Accepted Claims Set entry.
If the hash algorithm identifier which is present in the Reference
Value differs from the hash algorithm identifier in the Accepted
Claims Set entry then the Reference Value does not match.
If a hash algorithm identifier is present in both the Reference Value
and the Accepted Claims Set, but the value of the hash is not binary
identical between the Reference Value and the Accepted Claims Set
entry then the Reference Value does not match.
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5.4.4.5.3. Comparison for raw-value entries
I think this comparison method only works if the entry is at key 4
(because there needs to be a mask at key 5). Should we have a
Reference Value of this which stores [expect-raw-value raw-value-
mask] in an array?
5.4.4.5.4. Comparison for cryptokeys entries
The value stored under measurement-values-map key 12 is an array of
$crypto-key-type-choice entries. $crypto-key-type-choice entries are
CBOR tagged values. The array contains one or more entries in
sequence.
The CBOR tag of the first entry of the Reference Value cryptokeys
array is compared with the CBOR tag of the first entry of the
Accepted Claims Set cryptokeys value. If the CBOR tags match, then
the bytes following the CBOR tag from the Reference Value entry are
compared with the bytes following the CBOR tag from the Accepted
Claims Set entry. If the byte strings match, and there is another
array entry, then the next entry from the Reference Values array is
likewise compared with the next entry of the Accepted Claims Set
array. If all entries of the Reference Values array match a
corresponding entry in the Accepted Claims Set array, then the
cryptokeys Reference Value matches. Otherwise, cryptokeys does not
match.
5.4.4.5.5. Comparison for Integrity Registers
For each Integrity Register entry in the Reference Value, the
Verifier will use the associated identifier (i.e., integrity-
register-id-type-choice) to look up the matching Integrity Register
entry in Evidence. If no entry is found, the Reference Value does
not match. Instead, if an entry is found, the digest comparison
proceeds as defined in Section 5.4.4.5.2 after equivalence has been
found according to Section 3.1.4.1.7. Note that it is not required
for all the entries in Evidence to be used during matching: the
Reference Value could consist of a subset of the device's register
space. In TPM parlance, a TPM "quote" may report all PCRs in
Evidence, while a Reference Value could describe a subset of PCRs.
5.4.4.5.6. Handling of new tags
A profile may specify handling for new CBOR tagged Reference Values.
The profile must specify how to compare the CBOR tagged Reference
Value against the Accepted Claims Set.
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Note that the verifier may compare Reference Values in any order, so
the comparison should not be stateful.
5.4.5. Adding CoMID Endorsed Values to the Accepted Claims Set
5.5. Adding DICE/SPDM Evidence to the Accepted Claims Set
This section defines how Evidence from DICE [DICE.AA] and/or SPDM
[SPDM] is transformed into a format where it can be added to an
accepted claims set. A Verifier supporting DICE/SPDM format Evidence
should implement this section.
5.5.1. Transforming SPDM Evidence to a format usable for matching
The TCG DICE Concise Evidence Binding for SPDM specification
[CE.SPDM] describes the process by which measurements in an SPDM
Measurement Block are converted to Evidence suitable for matching
using the rules below. The SPDM measurements are converted to
concise-evidence which has a format that is similar to CoRIM triples-
map (their semantics follows the matching rules described above).
5.5.2. Transforming DICE Evidence to a format usable for matching
DICE Evidence appears in certificates in the TcbInfo or MultiTcbInfo
extension. Each TcbInfo, and each entry in the MultiTcbInfo, is
converted to an endorsed-triple-record using the rules in this
section. In a MultiTcbInfo each entry in the sequence is treated as
independent and translated into a separate Evidence object.
The Verifier SHALL translate each field in the TcbInfo into a field
in the created endorsed-triple-record
* The TcbInfo type field SHALL be copied to the field named
environment-map / class / class-id and tagged with tag #6.111
* The TcbInfo vendor field SHALL be copied to the field named
environment-map / class / vendor
* The TcbInfo model field SHALL be copied to the field named
environment-map / class / model
* The TcbInfo layer field SHALL be copied to the field named
environment-map / class / layer
* The TcbInfo index field SHALL be copied to the field named
environment-map / class / index
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* The TcbInfo version field SHALL be translated to the field named
measurement-map / mval / version / version
* The TcbInfo svn field SHALL be copied to the field named
measurement-map / mval / svn
* The TcbInfo fwids field SHALL be translated to the field named
measurement-map / mval / digests
- Each digest within fwids is translated to a CoMID digest
object, with an appropriate algorithm identifier
* The TcbInfo flags field SHALL be translated to the field named
measurement-map / mval / flags
- Each flag is translated independently
* The TcbInfo vendorInfo SHALL shall be copied to the field named
measurement-map / mval / raw-value
If there are multiple endorsed-triple-records with the same
environment-map then they MUST be merged into a single entry. If the
measurement-values-map fields in Evidence triples have conflicting
values then the Verifier MUST fail validation.
6. Implementation Status
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 [RFC7942].
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 catalogue of available implementations or their
features. Readers are advised to note that other implementations may
exist.
According to [RFC7942], "this will allow reviewers and working groups
to assign due consideration to documents that have the benefit of
running code, which may serve as Evidence of valuable experimentation
and feedback that have made the implemented protocols more mature.
It is up to the individual working groups to use this information as
they see fit".
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6.1. Veraison
* Organization responsible for the implementation: Veraison Project,
Linux Foundation
* Implementation's web page: https://github.com/veraison/corim/
README.md (https://github.com/veraison/corim/blob/main/README.md)
* Brief general description: The corim/corim and corim/comid
packages provide a golang API for low-level manipulation of
Concise Reference Integrity Manifest (CoRIM) and Concise Module
Identifier (CoMID) tags respectively. The corim/cocli package
uses the API above (as well as the API from the veraison/swid
package) to provide a user command line interface for working with
CoRIM, CoMID and CoSWID. Specifically, it allows creating,
signing, verifying, displaying, uploading, and more. See
https://github.com/cocli/README.md
(https://github.com/veraison/corim/blob/main/cocli/README.md) for
further details.
* Implementation's level of maturity: alpha.
* Coverage: the whole protocol is implemented, including PSA-
specific extensions [I-D.fdb-rats-psa-endorsements].
* Version compatibility: Version -02 of the draft
* Licensing: Apache 2.0 https://github.com/veraison/corim/blob/main/
LICENSE (https://github.com/veraison/corim/blob/main/LICENSE)
* Implementation experience: n/a
* Contact information: https://veraison.zulipchat.com
(https://veraison.zulipchat.com)
* Last updated: https://github.com/veraison/corim/commits/main
(https://github.com/veraison/corim/commits/main)
7. Security and Privacy Considerations
// Content missing. Tracked at: https://github.com/ietf-rats-wg/
draft-ietf-rats-corim/issues/11
8. IANA Considerations
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8.1. New COSE Header Parameters
// Content missing. Tracked at: https://github.com/ietf-rats-wg/
draft-ietf-rats-corim/issues/12
8.2. New CBOR Tags
IANA is requested to allocate the following tags in the "CBOR Tags"
registry [IANA.cbor-tags], preferably with the specific CBOR tag
value requested:
+=======+===========+====================================+=========+
|Tag |Data Item | Semantics |Reference|
+=======+===========+====================================+=========+
|500 |tag | A tagged-concise-rim-type-choice, |RFCthis |
| | | see Section 2.1.2 | |
+-------+-----------+------------------------------------+---------+
|501 |map | A tagged-corim-map, see |RFCthis |
| | | Section 2.1 | |
+-------+-----------+------------------------------------+---------+
|502 |tag | A tagged-signed-corim, see |RFCthis |
| | | Section 2.2 | |
+-------+-----------+------------------------------------+---------+
|503-504|any | Earmarked for CoRIM |RFCthis |
+-------+-----------+------------------------------------+---------+
|505 |bytes | A tagged-concise-swid-tag, see |RFCthis |
| | | Section 2.1.2 | |
+-------+-----------+------------------------------------+---------+
|506 |bytes | A tagged-concise-mid-tag, see |RFCthis |
| | | Section 2.1.2 | |
+-------+-----------+------------------------------------+---------+
|507 |any | Earmarked for CoRIM |RFCthis |
+-------+-----------+------------------------------------+---------+
|508 |bytes | A tagged-concise-bom-tag, see |RFCthis |
| | | Section 2.1.2 | |
+-------+-----------+------------------------------------+---------+
|509-549|any | Earmarked for CoRIM |RFCthis |
+-------+-----------+------------------------------------+---------+
|550 |bytes .size| tagged-ueid-type, see |RFCthis |
| |33 | Section 1.3.5 | |
+-------+-----------+------------------------------------+---------+
|551 |int | tagged-int-type, see Section 1.3.7 |RFCthis |
+-------+-----------+------------------------------------+---------+
|552 |uint | tagged-svn, see |RFCthis |
| | | Section 3.1.4.1.5.4 | |
+-------+-----------+------------------------------------+---------+
|553 |uint | tagged-min-svn, see |RFCthis |
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| | | Section 3.1.4.1.5.4 | |
+-------+-----------+------------------------------------+---------+
|554 |text | tagged-pkix-base64-key-type, see |RFCthis |
| | | Section 3.1.4.1.6 | |
+-------+-----------+------------------------------------+---------+
|555 |text | tagged-pkix-base64-cert-type, see |RFCthis |
| | | Section 3.1.4.1.6 | |
+-------+-----------+------------------------------------+---------+
|556 |text | tagged-pkix-base64-cert-path-type, |RFCthis |
| | | see Section 3.1.4.1.6 | |
+-------+-----------+------------------------------------+---------+
|557 |[int/text, | tagged-thumbprint-type, see |RFCthis |
| |bytes] | Section 1.3.8 | |
+-------+-----------+------------------------------------+---------+
|558 |COSE_Key/ | tagged-cose-key-type, see |RFCthis |
| |COSE_KeySet| Section 3.1.4.1.6 | |
+-------+-----------+------------------------------------+---------+
|559 |digest | tagged-cert-thumbprint-type, see |RFCthis |
| | | Section 3.1.4.1.6 | |
+-------+-----------+------------------------------------+---------+
|560 |bytes | tagged-bytes, see Section 1.3.9 |RFCthis |
+-------+-----------+------------------------------------+---------+
|561 |digest | tagged-cert-path-thumbprint-type, |RFCthis |
| | | see Section 3.1.4.1.6 | |
+-------+-----------+------------------------------------+---------+
|562-599|any | Earmarked for CoRIM |RFCthis |
+-------+-----------+------------------------------------+---------+
Table 2
Tags designated as "Earmarked for CoRIM" can be reassigned by IANA
based on advice from the designated expert for the CBOR Tags
registry.
8.3. New CoRIM Registries
// Content missing. Tracked at: https://github.com/ietf-rats-wg/
draft-ietf-rats-corim/issues/14
8.4. New CoMID Registries
// Content missing. Tracked at: https://github.com/ietf-rats-wg/
draft-ietf-rats-corim/issues/15
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8.5. New CoBOM Registries
// Content missing. Tracked at: https://github.com/ietf-rats-wg/
draft-ietf-rats-corim/issues/45
8.6. New Media Types
IANA is requested to add the following media types to the "Media
Types" registry [IANA.media-types].
+=====================+=====================+===============+
| Name | Template | Reference |
+=====================+=====================+===============+
| corim-signed+cbor | application/corim- | RFCthis, |
| | signed+cbor | Section 8.6.1 |
+---------------------+---------------------+---------------+
| corim-unsigned+cbor | application/corim- | RFCthis, |
| | unsigned+cbor | Section 8.6.2 |
+---------------------+---------------------+---------------+
Table 3: New Media Types
8.6.1. corim-signed+cbor
Type name: application
Subtype name: corim-signed+cbor
Required parameters: n/a
Optional parameters: "profile" (CoRIM profile in string format.
OIDs MUST use the dotted-decimal notation.)
Encoding considerations: binary
Security considerations: Section 7 of RFCthis
Interoperability considerations: n/a
Published specification: RFCthis
Applications that use this media type: Attestation Verifiers,
Endorsers and Reference-Value providers that need to transfer COSE
Sign1 wrapped CoRIM payloads over HTTP(S), CoAP(S), and other
transports.
Fragment identifier considerations: n/a
Magic number(s): D9 01 F6 D2, D9 01 F4 D9 01 F6 D2
File extension(s): n/a
Macintosh file type code(s): n/a
Person & email address to contact for further information: RATS WG
mailing list (rats@ietf.org)
Intended usage: COMMON
Restrictions on usage: none
Author/Change controller: IETF
Provisional registration? Maybe
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8.6.2. corim-unsigned+cbor
Type name: application
Subtype name: corim-unsigned+cbor
Required parameters: n/a
Optional parameters: "profile" (CoRIM profile in string format.
OIDs MUST use the dotted-decimal notation.)
Encoding considerations: binary
Security considerations: Section 7 of RFCthis
Interoperability considerations: n/a
Published specification: RFCthis
Applications that use this media type: Attestation Verifiers,
Endorsers and Reference-Value providers that need to transfer
unprotected CoRIM payloads over HTTP(S), CoAP(S), and other
transports.
Fragment identifier considerations: n/a
Magic number(s): D9 01 F5, D9 01 F4 D9 01 F5
File extension(s): n/a
Macintosh file type code(s): n/a
Person & email address to contact for further information: RATS WG
mailing list (rats@ietf.org)
Intended usage: COMMON
Restrictions on usage: none
Author/Change controller: IETF
Provisional registration? Maybe
8.7. CoAP Content-Formats Registration
IANA is requested to register the two following Content-Format
numbers in the "CoAP Content-Formats" sub-registry, within the
"Constrained RESTful Environments (CoRE) Parameters" Registry
[IANA.core-parameters]:
+===============================+================+======+===========+
| Content-Type | Content Coding | ID | Reference |
+===============================+================+======+===========+
| application/corim- | - | TBD1 | RFCthis |
| signed+cbor | | | |
+-------------------------------+----------------+------+-----------+
| application/corim- | - | TBD2 | RFCthis |
| unsigned+cbor | | | |
+-------------------------------+----------------+------+-----------+
Table 4: New Content-Formats
9. References
9.1. Normative References
Birkholz, et al. Expires 5 September 2024 [Page 58]
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[I-D.ietf-rats-concise-ta-stores]
Wallace, C., Housley, R., Fossati, T., and Y. Deshpande,
"Concise TA Stores (CoTS)", Work in Progress, Internet-
Draft, draft-ietf-rats-concise-ta-stores-02, 5 December
2023, <https://datatracker.ietf.org/doc/html/draft-ietf-
rats-concise-ta-stores-02>.
[I-D.ietf-rats-eat]
Lundblade, L., Mandyam, G., O'Donoghue, J., and C.
Wallace, "The Entity Attestation Token (EAT)", Work in
Progress, Internet-Draft, draft-ietf-rats-eat-25, 15
January 2024, <https://datatracker.ietf.org/doc/html/
draft-ietf-rats-eat-25>.
[I-D.ietf-sacm-coswid]
Birkholz, H., Fitzgerald-McKay, J., Schmidt, C., and D.
Waltermire, "Concise Software Identification Tags", Work
in Progress, Internet-Draft, draft-ietf-sacm-coswid-24, 24
February 2023, <https://datatracker.ietf.org/doc/html/
draft-ietf-sacm-coswid-24>.
[IANA.cbor-tags]
IANA, "Concise Binary Object Representation (CBOR) Tags",
<https://www.iana.org/assignments/cbor-tags>.
[IANA.core-parameters]
IANA, "Constrained RESTful Environments (CoRE)
Parameters",
<https://www.iana.org/assignments/core-parameters>.
[IANA.language-subtag-registry]
IANA, "Language Subtag Registry",
<https://www.iana.org/assignments/language-subtag-
registry>.
[IANA.media-types]
IANA, "Media Types",
<https://www.iana.org/assignments/media-types>.
[IANA.named-information]
IANA, "Named Information",
<https://www.iana.org/assignments/named-information>.
[RFC2119] Bradner, S., "Key words for use in RFCs to Indicate
Requirement Levels", BCP 14, RFC 2119,
DOI 10.17487/RFC2119, March 1997,
<https://www.rfc-editor.org/rfc/rfc2119>.
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[RFC4122] Leach, P., Mealling, M., and R. Salz, "A Universally
Unique IDentifier (UUID) URN Namespace", RFC 4122,
DOI 10.17487/RFC4122, July 2005,
<https://www.rfc-editor.org/rfc/rfc4122>.
[RFC7468] Josefsson, S. and S. Leonard, "Textual Encodings of PKIX,
PKCS, and CMS Structures", RFC 7468, DOI 10.17487/RFC7468,
April 2015, <https://www.rfc-editor.org/rfc/rfc7468>.
[RFC8174] Leiba, B., "Ambiguity of Uppercase vs Lowercase in RFC
2119 Key Words", BCP 14, RFC 8174, DOI 10.17487/RFC8174,
May 2017, <https://www.rfc-editor.org/rfc/rfc8174>.
[RFC8610] Birkholz, H., Vigano, C., and C. Bormann, "Concise Data
Definition Language (CDDL): A Notational Convention to
Express Concise Binary Object Representation (CBOR) and
JSON Data Structures", RFC 8610, DOI 10.17487/RFC8610,
June 2019, <https://www.rfc-editor.org/rfc/rfc8610>.
[RFC9090] Bormann, C., "Concise Binary Object Representation (CBOR)
Tags for Object Identifiers", RFC 9090,
DOI 10.17487/RFC9090, July 2021,
<https://www.rfc-editor.org/rfc/rfc9090>.
[RFC9334] Birkholz, H., Thaler, D., Richardson, M., Smith, N., and
W. Pan, "Remote ATtestation procedureS (RATS)
Architecture", RFC 9334, DOI 10.17487/RFC9334, January
2023, <https://www.rfc-editor.org/rfc/rfc9334>.
[STD66] Berners-Lee, T., Fielding, R., and L. Masinter, "Uniform
Resource Identifier (URI): Generic Syntax", STD 66,
RFC 3986, DOI 10.17487/RFC3986, January 2005,
<https://www.rfc-editor.org/rfc/rfc3986>.
[STD94] Bormann, C. and P. Hoffman, "Concise Binary Object
Representation (CBOR)", STD 94, RFC 8949,
DOI 10.17487/RFC8949, December 2020,
<https://www.rfc-editor.org/rfc/rfc8949>.
[STD96] Schaad, J., "CBOR Object Signing and Encryption (COSE):
Structures and Process", STD 96, RFC 9052,
DOI 10.17487/RFC9052, August 2022,
<https://www.rfc-editor.org/rfc/rfc9052>.
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[X.690] International Telecommunications Union, "Information
technology — ASN.1 encoding rules: Specification of Basic
Encoding Rules (BER), Canonical Encoding Rules (CER) and
Distinguished Encoding Rules (DER)", ITU-T Recommendation
X.690, August 2015, <https://www.itu.int/rec/T-REC-X.690>.
9.2. Informative References
[CE.SPDM] Trusted Computing Group, "TCG DICE Concise Evidence
Binding for SPDM", Version 1.00, Revision 0.53, public
review , June 2023, <https://trustedcomputinggroup.org/wp-
content/uploads/TCG-DICE-Concise-Evidence-Binding-for-
SPDM-Version-1.0-Revision-53_1August2023.pdf>.
[DICE.AA] Trusted Computing Group, "DICE Attestation Architecture",
Version 1.1, Revision 0.17, public review , May 2023,
<https://trustedcomputinggroup.org/wp-content/uploads/
DICE-Attestation-Architecture-Version-1.1-Revision-
17_1August2023.pdf>.
[DICE.Layer]
Trusted Computing Group, "DICE Layering Architecture",
Version 1.0, Revision 0.19 , July 2020,
<https://trustedcomputinggroup.org/wp-content/uploads/
DICE-Layering-Architecture-r19_pub.pdf>.
[I-D.fdb-rats-psa-endorsements]
Fossati, T., Deshpande, Y., and H. Birkholz, "Arm's
Platform Security Architecture (PSA) Attestation Verifier
Endorsements", Work in Progress, Internet-Draft, draft-
fdb-rats-psa-endorsements-04, 4 March 2024,
<https://datatracker.ietf.org/doc/html/draft-fdb-rats-psa-
endorsements-04>.
[I-D.tschofenig-rats-psa-token]
Tschofenig, H., Frost, S., Brossard, M., Shaw, A. L., and
T. Fossati, "Arm's Platform Security Architecture (PSA)
Attestation Token", Work in Progress, Internet-Draft,
draft-tschofenig-rats-psa-token-22, 21 February 2024,
<https://datatracker.ietf.org/doc/html/draft-tschofenig-
rats-psa-token-22>.
[IANA.coswid]
IANA, "Concise Software Identifier (CoSWID)",
<https://www.iana.org/assignments/coswid>.
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[RFC7942] Sheffer, Y. and A. Farrel, "Improving Awareness of Running
Code: The Implementation Status Section", BCP 205,
RFC 7942, DOI 10.17487/RFC7942, July 2016,
<https://www.rfc-editor.org/rfc/rfc7942>.
[SPDM] Distributed Management Task Force, "Security Protocol and
Data Model (SPDM)", Version 1.3.0 , May 2023,
<https://www.dmtf.org/sites/default/files/standards/
documents/DSP0274_1.3.0.pdf>.
Appendix A. Full CoRIM CDDL
corim = tagged-concise-rim-type-choice
$concise-rim-type-choice /= tagged-corim-map
$concise-rim-type-choice /= tagged-signed-corim
concise-bom-tag = {
&(tag-identity: 0) => tag-identity-map
&(tags-list: 1) => [ + tag-identity-map ],
&(bom-validity: 2) => validity-map
* $$concise-bom-tag-extension
}
$concise-tag-type-choice /= tagged-concise-swid-tag
$concise-tag-type-choice /= tagged-concise-mid-tag
$concise-tag-type-choice /= tagged-concise-bom-tag
corim-entity-map =
entity-map<$corim-role-type-choice, $$corim-entity-map-extension>
$corim-id-type-choice /= tstr
$corim-id-type-choice /= uuid-type
corim-locator-map = {
&(href: 0) => uri
? &(thumbprint: 1) => digest
}
corim-map = {
&(id: 0) => $corim-id-type-choice
&(tags: 1) => [ + $concise-tag-type-choice ]
? &(dependent-rims: 2) => [ + corim-locator-map ]
? &(profile: 3) => $profile-type-choice
? &(rim-validity: 4) => validity-map
? &(entities: 5) => [ + corim-entity-map ]
* $$corim-map-extension
}
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corim-meta-map = {
&(signer: 0) => corim-signer-map
? &(signature-validity: 1) => validity-map
}
$corim-role-type-choice /= &(manifest-creator: 1)
corim-signer-map = {
&(signer-name: 0) => $entity-name-type-choice
? &(signer-uri: 1) => uri
* $$corim-signer-map-extension
}
COSE-Sign1-corim = [
protected: bstr .cbor protected-corim-header-map
unprotected: unprotected-corim-header-map
payload: bstr .cbor tagged-corim-map
signature: bstr
]
$profile-type-choice /= uri
$profile-type-choice /= tagged-oid-type
protected-corim-header-map = {
&(alg-id: 1) => int
&(content-type: 3) => "application/corim-unsigned+cbor"
&(issuer-key-id: 4) => bstr
&(corim-meta: 8) => bstr .cbor corim-meta-map
* cose-label => cose-value
}
signed-corim = #6.18(COSE-Sign1-corim)
tagged-corim-map = #6.501(corim-map)
tagged-concise-rim-type-choice = #6.500($concise-rim-type-choice)
tagged-signed-corim = #6.502(signed-corim)
tagged-concise-swid-tag = #6.505(bytes .cbor concise-swid-tag)
tagged-concise-mid-tag = #6.506(bytes .cbor concise-mid-tag)
tagged-concise-bom-tag = #6.508(bytes .cbor concise-bom-tag)
unprotected-corim-header-map = {
* cose-label => cose-value
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}
validity-map = {
? &(not-before: 0) => time
&(not-after: 1) => time
}
concise-mid-tag = {
? &(language: 0) => text
&(tag-identity: 1) => tag-identity-map
? &(entities: 2) => [ + comid-entity-map ]
? &(linked-tags: 3) => [ + linked-tag-map ]
&(triples: 4) => triples-map
* $$concise-mid-tag-extension
}
accepted-claims-set = {
&(state-triples: 0) => [ + endorsed-triple-record ]
? &(identity-triples: 1) => [ + identity-triple-record ]
? &(coswid-triples: 2) => [ + ev-coswid-triple-record ]
* $$accepted-claims-set-extension
}
attest-key-triple-record = [
environment-map
[ + $crypto-key-type-choice ]
]
$class-id-type-choice /= tagged-oid-type
$class-id-type-choice /= tagged-uuid-type
$class-id-type-choice /= tagged-int-type
$class-id-type-choice /= tagged-bytes
class-map = non-empty<{
? &(class-id: 0) => $class-id-type-choice
? &(vendor: 1) => tstr
? &(model: 2) => tstr
? &(layer: 3) => uint
? &(index: 4) => uint
}>
comid-entity-map =
entity-map<$comid-role-type-choice, $$comid-entity-map-extension>
$comid-role-type-choice /= &(tag-creator: 0)
$comid-role-type-choice /= &(creator: 1)
$comid-role-type-choice /= &(maintainer: 2)
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conditional-endorsement-series-triple-record = [
stateful-environment-record
; order matters: the first matching record wins and halts matching
[ + conditional-series-record ]
]
conditional-endorsement-triple-record = [
stateful-environment-record,
; endorsed values
measurement-values-map
]
conditional-series-record = [
; reference values to be matched against evidence
refv: measurement-values-map
; endorsed values that apply in case revf matches
endv: measurement-values-map
]
COSE_KeySet = [ + COSE_Key ]
COSE_Key = {
1 => tstr / int
? 2 => bstr
? 3 => tstr / int
? 4 => [+ (tstr / int) ]
? 5 => bstr
* cose-label => cose-value
}
cose-label = int / tstr
cose-value = any
coswid-triple-record = [
environment-map
[ + concise-swid-tag-id ]
]
concise-swid-tag-id = text / bstr .size 16
$crypto-key-type-choice /= tagged-pkix-base64-key-type
$crypto-key-type-choice /= tagged-pkix-base64-cert-type
$crypto-key-type-choice /= tagged-pkix-base64-cert-path-type
$crypto-key-type-choice /= tagged-cose-key-type
$crypto-key-type-choice /= tagged-thumbprint-type
$crypto-key-type-choice /= tagged-cert-thumbprint-type
$crypto-key-type-choice /= tagged-cert-path-thumbprint-type
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tagged-pkix-base64-key-type = #6.554(tstr)
tagged-pkix-base64-cert-type = #6.555(tstr)
tagged-pkix-base64-cert-path-type = #6.556(tstr)
tagged-thumbprint-type = #6.557(digest)
tagged-cose-key-type = #6.558(COSE_KeySet / COSE_Key)
tagged-cert-thumbprint-type = #6.559(digest)
tagged-cert-path-thumbprint-type = #6.561(digest)
domain-dependency-triple-record = [
$domain-type-choice
[ + $domain-type-choice ]
]
domain-membership-triple-record = [
$domain-type-choice
[ + environment-map ]
]
mec-endorsement-triple-record = [
conds: [ + stateful-environment-record ]
endorsements: [ + endorsed-triple-record ]
]
$domain-type-choice /= uint
$domain-type-choice /= text
$domain-type-choice /= tagged-uuid-type
$domain-type-choice /= tagged-oid-type
endorsed-triple-record = [
environment-map
measurement-map
]
entity-map<role-type-choice, extension-socket> = {
&(entity-name: 0) => $entity-name-type-choice
? &(reg-id: 1) => uri
&(role: 2) => [ + role-type-choice ]
* extension-socket
}
$entity-name-type-choice /= text
environment-map = non-empty<{
? &(class: 0) => class-map
? &(instance: 1) => $instance-id-type-choice
? &(group: 2) => $group-id-type-choice
}>
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flags-map = {
? &(is-configured: 0) => bool
? &(is-secure: 1) => bool
? &(is-recovery: 2) => bool
? &(is-debug: 3) => bool
? &(is-replay-protected: 4) => bool
? &(is-integrity-protected: 5) => bool
? &(is-runtime-meas: 6) => bool
? &(is-immutable: 7) => bool
? &(is-tcb: 8) => bool
? &(is-confidentiality-protected: 9) => bool
* $$flags-map-extension
}
$group-id-type-choice /= tagged-uuid-type
$group-id-type-choice /= tagged-bytes
identity-triple-record = [
environment-map
[ + $crypto-key-type-choice ]
]
$instance-id-type-choice /= tagged-ueid-type
$instance-id-type-choice /= tagged-uuid-type
$instance-id-type-choice /= $crypto-key-type-choice
$instance-id-type-choice /= tagged-bytes
ip-addr-type-choice = ip4-addr-type / ip6-addr-type
ip4-addr-type = bytes .size 4
ip6-addr-type = bytes .size 16
linked-tag-map = {
&(linked-tag-id: 0) => $tag-id-type-choice
&(tag-rel: 1) => $tag-rel-type-choice
}
mac-addr-type-choice = eui48-addr-type / eui64-addr-type
eui48-addr-type = bytes .size 6
eui64-addr-type = bytes .size 8
$measured-element-type-choice /= tagged-oid-type
$measured-element-type-choice /= tagged-uuid-type
$measured-element-type-choice /= uint
measurement-map = {
? &(mkey: 0) => $measured-element-type-choice
&(mval: 1) => measurement-values-map
? &(authorized-by: 2) => [ + $crypto-key-type-choice ]
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}
measurement-values-map = non-empty<{
? &(version: 0) => version-map
? &(svn: 1) => svn-type-choice
? &(digests: 2) => [ + digest ]
? &(flags: 3) => flags-map
? (
&(raw-value: 4) => $raw-value-type-choice,
? &(raw-value-mask: 5) => raw-value-mask-type
)
? &(mac-addr: 6) => mac-addr-type-choice
? &(ip-addr: 7) => ip-addr-type-choice
? &(serial-number: 8) => text
? &(ueid: 9) => ueid-type
? &(uuid: 10) => uuid-type
? &(name: 11) => text
? &(cryptokeys: 13) => [ + $crypto-key-type-choice ]
? &(integrity-registers: 14) => integrity-registers
* $$measurement-values-map-extension
}>
non-empty<M> = (M) .and ({ + any => any })
oid-type = bytes
tagged-oid-type = #6.111(oid-type)
$raw-value-type-choice /= tagged-bytes
raw-value-mask-type = bytes
reference-triple-record = [
environment-map
measurement-map
]
stateful-environment-record = [
environment-map,
measurement-map
]
svn-type = uint
svn = svn-type
min-svn = svn-type
tagged-svn = #6.552(svn)
tagged-min-svn = #6.553(min-svn)
svn-type-choice = tagged-svn / tagged-min-svn
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$tag-id-type-choice /= tstr
$tag-id-type-choice /= uuid-type
tag-identity-map = {
&(tag-id: 0) => $tag-id-type-choice
? &(tag-version: 1) => tag-version-type
}
$tag-rel-type-choice /= &(supplements: 0)
$tag-rel-type-choice /= &(replaces: 1)
tag-version-type = uint .default 0
tagged-int-type = #6.551(int)
tagged-bytes = #6.560(bytes)
triples-map = non-empty<{
? &(reference-triples: 0) =>
[ + reference-triple-record ]
? &(endorsed-triples: 1) =>
[ + endorsed-triple-record ]
? &(identity-triples: 2) =>
[ + identity-triple-record ]
? &(attest-key-triples: 3) =>
[ + attest-key-triple-record ]
? &(dependency-triples: 4) =>
[ + domain-dependency-triple-record ]
? &(membership-triples: 5) =>
[ + domain-membership-triple-record ]
? &(coswid-triples: 6) =>
[ + coswid-triple-record ]
? &(conditional-endorsement-series-triples: 8) =>
[ + conditional-endorsement-series-triple-record ]
? &(conditional-endorsement-triples: 9) =>
[ + conditional-endorsement-triple-record ]
? &(mec-endorsement-triples: 10) =>
[ + mec-endorsement-triple-record ]
* $$triples-map-extension
}>
ueid-type = bytes .size 33
tagged-ueid-type = #6.550(ueid-type)
uuid-type = bytes .size 16
tagged-uuid-type = #6.37(uuid-type)
version-map = {
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&(version: 0) => text
? &(version-scheme: 1) => $version-scheme
}
digest = [
alg: (int / text),
val: bytes
]
integrity-register-id-type-choice = uint / text
integrity-registers = {
+ integrity-register-id-type-choice => [ + digest ]
}
concise-swid-tag = {
tag-id => text / bstr .size 16,
tag-version => integer,
? corpus => bool,
? patch => bool,
? supplemental => bool,
software-name => text,
? software-version => text,
? version-scheme => $version-scheme,
? media => text,
? software-meta => one-or-more<software-meta-entry>,
entity => one-or-more<entity-entry>,
? link => one-or-more<link-entry>,
? payload-or-evidence,
* $$coswid-extension,
global-attributes,
}
payload-or-evidence //= ( payload => payload-entry )
payload-or-evidence //= ( evidence => evidence-entry )
any-uri = uri
label = text / int
$version-scheme /= multipartnumeric
$version-scheme /= multipartnumeric-suffix
$version-scheme /= alphanumeric
$version-scheme /= decimal
$version-scheme /= semver
$version-scheme /= int / text
any-attribute = (
label => one-or-more<text> / one-or-more<int>
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)
one-or-more<T> = T / [ 2* T ]
global-attributes = (
? lang => text,
* any-attribute,
)
hash-entry = [
hash-alg-id: int,
hash-value: bytes,
]
entity-entry = {
entity-name => text,
? reg-id => any-uri,
role => one-or-more<$role>,
? thumbprint => hash-entry,
* $$entity-extension,
global-attributes,
}
$role /= tag-creator
$role /= software-creator
$role /= aggregator
$role /= distributor
$role /= licensor
$role /= maintainer
$role /= int / text
link-entry = {
? artifact => text,
href => any-uri,
? media => text,
? ownership => $ownership,
rel => $rel,
? media-type => text,
? use => $use,
* $$link-extension,
global-attributes,
}
$ownership /= shared
$ownership /= private
$ownership /= abandon
$ownership /= int / text
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$rel /= ancestor
$rel /= component
$rel /= feature
$rel /= installationmedia
$rel /= packageinstaller
$rel /= parent
$rel /= patches
$rel /= requires
$rel /= see-also
$rel /= supersedes
$rel /= supplemental
$rel /= -256..64436 / text
$use /= optional
$use /= required
$use /= recommended
$use /= int / text
software-meta-entry = {
? activation-status => text,
? channel-type => text,
? colloquial-version => text,
? description => text,
? edition => text,
? entitlement-data-required => bool,
? entitlement-key => text,
? generator => text / bstr .size 16,
? persistent-id => text,
? product => text,
? product-family => text,
? revision => text,
? summary => text,
? unspsc-code => text,
? unspsc-version => text,
* $$software-meta-extension,
global-attributes,
}
path-elements-group = ( ? directory => one-or-more<directory-entry>,
? file => one-or-more<file-entry>,
)
resource-collection = (
path-elements-group,
? process => one-or-more<process-entry>,
? resource => one-or-more<resource-entry>,
* $$resource-collection-extension,
)
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file-entry = {
filesystem-item,
? size => uint,
? file-version => text,
? hash => hash-entry,
* $$file-extension,
global-attributes,
}
directory-entry = {
filesystem-item,
? path-elements => { path-elements-group },
* $$directory-extension,
global-attributes,
}
process-entry = {
process-name => text,
? pid => integer,
* $$process-extension,
global-attributes,
}
resource-entry = {
type => text,
* $$resource-extension,
global-attributes,
}
filesystem-item = (
? key => bool,
? location => text,
fs-name => text,
? root => text,
)
payload-entry = {
resource-collection,
* $$payload-extension,
global-attributes,
}
evidence-entry = {
resource-collection,
? date => integer-time,
? device-id => text,
? location => text,
* $$evidence-extension,
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global-attributes,
}
integer-time = #6.1(int)
tag-id = 0
software-name = 1
entity = 2
evidence = 3
link = 4
software-meta = 5
payload = 6
hash = 7
corpus = 8
patch = 9
media = 10
supplemental = 11
tag-version = 12
software-version = 13
version-scheme = 14
lang = 15
directory = 16
file = 17
process = 18
resource = 19
size = 20
file-version = 21
key = 22
location = 23
fs-name = 24
root = 25
path-elements = 26
process-name = 27
pid = 28
type = 29
entity-name = 31
reg-id = 32
role = 33
thumbprint = 34
date = 35
device-id = 36
artifact = 37
href = 38
ownership = 39
rel = 40
media-type = 41
use = 42
activation-status = 43
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channel-type = 44
colloquial-version = 45
description = 46
edition = 47
entitlement-data-required = 48
entitlement-key = 49
generator = 50
persistent-id = 51
product = 52
product-family = 53
revision = 54
summary = 55
unspsc-code = 56
unspsc-version = 57
multipartnumeric = 1
multipartnumeric-suffix = 2
alphanumeric = 3
decimal = 4
semver = 16384
tag-creator=1
software-creator=2
aggregator=3
distributor=4
licensor=5
maintainer=6
abandon=1
private=2
shared=3
ancestor=1
component=2
feature=3
installationmedia=4
packageinstaller=5
parent=6
patches=7
requires=8
see-also=9
supersedes=10
optional=1
required=2
recommended=3
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Acknowledgments
Carl Wallace for review and comments on this document.
Contributors
Carsten Bormann
Universität Bremen TZI
Postfach 330440
D-28359 Bremen
Germany
Phone: +49-421-218-63921
Email: cabo@tzi.org
Carsten Bormann contributed to the CDDL specifications and the IANA
considerations.
Authors' Addresses
Henk Birkholz
Fraunhofer SIT
Email: henk.birkholz@ietf.contact
Thomas Fossati
arm
Email: Thomas.Fossati@arm.com
Yogesh Deshpande
arm
Email: yogesh.deshpande@arm.com
Ned Smith
Intel
Email: ned.smith@intel.com
Wei Pan
Huawei Technologies
Email: william.panwei@huawei.com
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