| Internet-Draft | CoRIM | October 2024 |
| Birkholz, et al. | Expires 21 April 2025 | [Page] |
Remote Attestation Procedures (RATS) enable Relying Parties to assess the trustworthiness of a remote Attester and therefore to decide whether or not 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.¶
This note is to be removed before publishing as an RFC.¶
Source for this draft and an issue tracker can be found at https://github.com/ietf-rats-wg/draft-ietf-rats-corim.¶
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This Internet-Draft will expire on 21 April 2025.¶
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.¶
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. Endorsements and Reference Values are obtained from relevant supply chain actors, such as manufacturers, distributors, or device owners. In a complex supply chain, multiple actors will likely produce these values over several points in time. As such, one supply chain actor will only provide the subset of characteristics that they know about the Attester. A proper subset is typical because a certain supply chain actor will be the responsible authority for only a system component/module that is measured amongst a long chain of measurements. Attesters vary across vendors and even across products from a single vendor. 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 distributed supply chain into a single homogeneous view. See Section 2.¶
This document uses terms and concepts defined by the RATS architecture. For a complete glossary, see Section 4 of [RFC9334].¶
In this document, the term CoRIM message and CoRIM documents are used as synonyms. A CoRIM data structure can be at rest (e.g., residing in a file system as a document) or can be in flight (e.g., conveyed as a message in a protocol exchange). The bytes composing the CoRIM data structure are the same either way.¶
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]. Terms and concepts are always referenced as proper nouns, i.e., with Capital Letters.¶
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.¶
This specification describes the CoRIM format and documents how a Verifier must process the CoRIM. This ensures that the behaviour of the CoRIM-based appraisal is predictable and consistent, in a word deterministic.¶
A Verifier needs to reconcile its various inputs, with CoRIM being one of them. In addition to the external CoRIM documents, the Verifier is expected to create an internal representation for each input and map each external representation to an internal one. By using the internal representation, the Verifier processes inputs as if they are part of a conversation, keeping track of who said what. The origin of the inputs is tracked as authority. The authority for the Claims in a CoRIM is the CoRIM issuer. To this effect, this specification defines one possible internal representation of the attester's actual state for use during the appraisal procedure, known as Appraisal Claims Set (ACS).¶
Effectively, Attesters, Reference Value Providers, Endorsers, Verifier Owners, Relying Parties, and even the Verifier potentially all contribute to the conversation. Each producer of corresponding RATS Conceptual Messages can assert Claims about an Attester's actual or allowed state. The Verifier's objective is to produce a list of Claims that describe the Attester's presumed actual state. Producers of RATS Conceptual Messages can assert contradictory assertions. For example, a compromised Attester may produce false claims that conflict with the Reference Values provided by a Reference Value Provider (RVP). In essence, if Evidence is not corroborated by an RVP's Claims, then the RVP's Claims are not included in the ACS.¶
A Verifier relies on input from appraisal policy to identify relevant assertions included in the ACS. For example, if a policy requires corroborated assertions issued by a particular RVP, then those assertions may be conveyed as Attestation Results. The Verifier may produce new assertions as a result of an applied appraisal policy. For example, if an appraisal procedure finds all of the components of a subsystem are configured correctly, the policy may direct the Verifier to produce new assertions, "Subsystem=X" has the Claim "TRUSTED=TRUE". Consequently, the internal ACS structure is a reconciled conversation between several producers of RATS Conceptual Messages that has mapped each message into a consistent internal representation, has associated the identity of the corresponding RATS role with each assertion (the authority), and has applied Conceptual Message constraints to the assertion.¶
The CoRIM data model specified in this document covers the RATS Conceptual Message types, "Reference Values" and "Endorsements". Reference values and Endorsements are required for Verifier reconciliation, and Evidence is required for corresponding internal ACS creation as illustrated in Section 2.2.¶
In this document CDDL is used to specify both the CoRIM structure and to specify an internal representation for use in the appraisal procedure. The actual internal representation of a Verifier is implementation-specific and out-of-scope of this document. Requirements for an internal representation of Conceptual Messages are defined in Table 1, where each Conceptual Message type has a structure as depicted by the Structure column. The internal representations used by this document are defined in Section 8.2.1.¶
Conceptual Messages interact with an ACS by specifying criteria that should be met by the ACS and by presenting the assertions that should be added to the ACS if the criteria are satisfied. Internal representations of Conceptual Messages, ACS, and Attestation Results Set (ARS) should satisfy the following requirements for Verifier reconciliation and appraisal processing:¶
| CM Type | Structure | Description |
|---|---|---|
| Evidence | List of Evidence claims | If the Attester is authenticated, add Evidence claims to the ACS with Attester authority |
| Reference Values | List of Reference Values claims | If a reference value in a CoRIM matches claims in the ACS, then the authority of the CoRIM issuer is added to those claims. |
| Endorsements | List of expected actual state claims, List of Endorsed Values claims | If the list of expected claims are in the ACS, then add the list of Endorsed Values claims to the ACS with Endorser authority |
| Series Endorsements | List of expected actual state claims and a series of selection-addition tuples | If the expected claims are in the ACS, and if the series selection condition is satisfied, then add the additional claims to the ACS with Endorser authority. See Section 8.2.1.3 |
| Verifier | List of expected actual state claims, List of Verifier-generated claims | If the list of expected claims are in the ACS, then add the list of Verifier-generated claims to the ACS with Verifier authority |
| Policy | List of expected actual state claims, List of Policy-generated claims | If the list of expected claims are in the ACS, then add the list of Policy-generated claims to the ACS with Policy Owner authority |
| Attestation Results | List of expected actual state claims, List of expected Attestation Results claims | If the list of expected claims are in the ACS, then copy the list of Attestation Results claims into the ARS. See Section 8.2.3 |
Tracked at: https://github.com/ietf-rats-wg/draft-ietf-rats-corim/issues/242¶
The CDDL definitions in this document follows the naming conventions illustrated in Table 2.¶
| Type trait | Example | Typographical convention |
|---|---|---|
| extensible type choice |
int / text / ...
|
$NAME-type-choice
|
| closed type choice |
int / text
|
NAME-type-choice
|
| group choice |
( 1 => int // 2 => text )
|
$$NAME-group-choice
|
| group |
( 1 => int, 2 => text )
|
NAME-group
|
| type |
int
|
NAME-type
|
| tagged type |
#6.123(int)
|
tagged-NAME-type
|
| map |
{ 1 => int, 2 => text }
|
NAME-map
|
| flags |
&( a: 1, b: 2 )
|
NAME-flags
|
A CoRIM is a collection of tags and related metadata in a concise CBOR [STD94] encoding. A CoRIM can be digitally signed with a COSE [STD96] signature. A tag identifies and describes properties of modules or components of a system.¶
Tags can be of different types:¶
Concise Module ID (CoMID) tags (Section 5) contain metadata and claims about the hardware and firmware modules.¶
Concise Software ID (CoSWID) tags ([RFC9393]) describe software components.¶
Concise Bill of Material (CoBOM) tags (Section 6) 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¶
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 CDDL definition to be customized to fit a specific Attester by augmenting the base CDDL data definition via the specified extension points or by constraining types defined. A profile MUST NOT change the base CoRIM CDDL definition's semantics, which includes not changing or overloading names and numbers registered at IANA registries used by this document. For more detail, see Section 4.1.4.¶
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 4.2) 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 4.1) 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¶
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 4.1.1.¶
tags (index 1): An array of one or more CoMID or CoSWID tags. Described
in Section 4.1.2.¶
dependent-rims (index 2): One or more services supplying additional,
possibly dependent, manifests or related files.
Described in Section 4.1.3.¶
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.
See Section 4.1.4¶
rim-validity (index 4): Specifies the validity period of the CoRIM.
Described in Section 7.3.¶
entities (index 5): A list of entities involved in a CoRIM life-cycle.
Described in Section 4.1.5.¶
$$corim-map-extension: This CDDL socket is used to add new information
structures to the corim-map.
Described in Section 11.3.¶
tagged-corim-map = #6.501(corim-map)¶
A CoRIM Identifier uniquely identifies a CoRIM instance. The base CDDL definition 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¶
The locator map contains pointers to repositories where dependent manifests, certificates, or other relevant information can be retrieved by the Verifier.¶
corim-locator-map = {
&(href: 0) => uri
? &(thumbprint: 1) => digest
}
¶
The following describes each child element of this type.¶
Profiling is the mechanism that allows the base CoRIM CDDL definition to be customized 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 CoRIM types defined in this document.¶
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 (Section 5.2). 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 11.6.1 and
Section 11.6.2 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¶
For an example profile definition, see [I-D.fdb-rats-psa-endorsements].¶
The CoRIM Entity is an instantiation of the Entity generic (Section 7.2) using a $corim-role-type-choice.¶
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)¶
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 4.2.2).¶
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.¶
protected-corim-header-map = {
&(alg: 1) => int
&(content-type: 3) => "application/corim-unsigned+cbor"
&(kid: 4) => bstr
&(corim-meta: 8) => bstr .cbor corim-meta-map
* cose-label => cose-value
}
¶
The CoRIM protected header map uses some common COSE header parameters plus an additional corim-meta parameter.
The following describes each child item of this map.¶
alg (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.¶
kid (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 4.2.2.¶
Additional data can be included in the COSE header map as per (Section 3 of [STD96]).¶
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 4.2.2.1.¶
signature-validity (index 1): Validity period for the CoRIM.
Described in Section 7.3.¶
corim-signer-map = {
&(signer-name: 0) => $entity-name-type-choice
? &(signer-uri: 1) => uri
* $$corim-signer-map-extension
}
¶
unprotected-corim-header-map = {
* cose-label => cose-value
}
¶
A CoMID tag contains information about hardware, firmware, or module composition.¶
Each CoMID has a unique ID that is used to unambiguously 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 5.1.4.2).¶
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 5.1.4.3).¶
Device Identity triples: containing cryptographic credentials - for example, an IDevID - uniquely identifying a device (Section 5.1.4.6).¶
Attestation Key triples: containing cryptographic keys that are used to verify the integrity protection on the Evidence received from the Attester (Section 5.1.4.7).¶
Domain dependency triples: describing trust relationships between domains, i.e., collection of related environments and their measurements (Section 5.1.4.8).¶
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 5.1.4.9).¶
CoMID-CoSWID linking triples: associating a Target Environment with existing CoSWID tags (Section 5.1.4.10).¶
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.¶
tag-identity (index 1): A tag-identity-map containing unique
identification information for the CoMID.
Described in Section 5.1.1.¶
entities (index 2): Provides information about one or more organizations
responsible for producing the CoMID tag.
Described in Section 5.1.2.¶
linked-tags (index 3): A list of one or more linked-tag-map providing typed relationships between this and
other CoMIDs.
Described in Section 5.1.3).¶
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 5.1.4.¶
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 5.1.1.1.¶
tag-version (index 1): Optional versioning information for the tag-id.
Described in Section 5.1.1.2.¶
$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].¶
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.¶
comid-entity-map = entity-map<$comid-role-type-choice, $$comid-entity-map-extension>¶
The CoMID Entity is an instantiation of entity-map (Section 7.2) 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:¶
The linked tag map represents a typed relationship between the embedding CoMID tag (the source) and another CoMID tag (the target).¶
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.
See Section 5.1.1.1.¶
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:¶
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.¶
In most cases, the supply chain entity that is responsible for providing a triple (i.e., Reference Values or Endorsed Values) is by default the CoRIM signer. The signer of a triple is said to be its authority. However, multiple authorities may be involved in signing triples. See [STD96]. Consequently, authority may differ for search criteria. See Section 5.1.4.1.4.¶
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: 10) =>
[ + conditional-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 5.1.4.2.¶
endorsed-triples (index 1): Triples containing endorsed values.
Described in Section 5.1.4.3.¶
identity-triples (index 2): Triples containing identity credentials.
Described in Section 5.1.4.6.¶
attest-key-triples (index 3): Triples containing verification keys associated with attesting environments.
Described in Section 5.1.4.7.¶
dependency-triples (index 4): Triples describing trust relationships between domains.
Described in Section 5.1.4.8.¶
membership-triples (index 5): Triples describing topological relationships between (sub-)modules.
Described in Section 5.1.4.9.¶
coswid-triples (index 6): Triples associating modules with existing CoSWID tags.
Described in Section 5.1.4.10.¶
conditional-endorsement-series-triples (index 8): Triples describing a series of
conditional Endorsements based on the acceptance of a stateful environment.
Described in Section 5.1.4.5.¶
conditional-endorsement-triples (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 5.1.4.4.¶
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).¶
An environment MUST be globally unique.
The combination of values within class-map must combine to form a globally unique identifier.¶
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 5.1.4.1.1.¶
instance (index 1): Contains a unique identifier of a module's instance.
Described in Section 5.1.4.1.2.¶
group (index 2): identifier for a group of instances, e.g., if an
anonymization scheme is used.
Described in Section 5.1.4.1.3.¶
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.¶
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-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 7.8) 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.¶
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 7.8), or cryptographic key identifier.¶
$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¶
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 7.8).¶
$group-id-type-choice /= tagged-uuid-type $group-id-type-choice /= tagged-bytes¶
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 a 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.¶
An environment may have multiple measured elements. Measured elements are distinguished from each other by measurement keys. Measurement keys may be used to disambiguate measurements of the same type originating from different elements.¶
Triples that have search conditions may specify authority as matching criteria by populating authorized-by.¶
measurement-map = {
? &(mkey: 0) => $measured-element-type-choice
&(mval: 1) => measurement-values-map
? &(authorized-by: 2) => [ + $crypto-key-type-choice ]
}
¶
The following describes each member of the measurement-map:¶
mkey (index 0): An optional measurement key.
Described in Section 5.1.4.1.4.1.
A measurement-map without an mkey is said to be anonymous.¶
mval (index 1): The measurements associated with the environment.
Described in Section 5.1.4.1.4.2.¶
authorized-by (index 2): The cryptographic identity of the entity (individual or organization) that is
the designated authority for measurement Claims.
For example, the signer of a CoMID triple.
See Section 5.1.4.1.5.
An entity is authoritative when it makes Claims that are inside its area of
competence.¶
Measurement keys are locally scoped extensible identifiers.
The initial types defined are OID, UUID, uint, and tstr.
mkey may be necessary to disambiguate multiple measurements of the same type or to distinguish multiple measured elements within the same environment.
A single anonymous measurement-map is allowed within the same environment.
Two or more measurement-map entries within the same environment MUST populate mkey.¶
$measured-element-type-choice /= tagged-oid-type $measured-element-type-choice /= tagged-uuid-type $measured-element-type-choice /= uint $measured-element-type-choice /= tstr¶
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.¶
measurement-values-map = non-empty<{
? &(version: 0) => version-map
? &(svn: 1) => svn-type-choice
? &(digests: 2) => digests-type
? &(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 5.1.4.1.4.3.¶
svn (index 1): The security version number typically changes only when a security relevant change is made to the measured environment.
Described in Section 5.1.4.1.4.4.¶
digests (index 2): Contains the digest(s) of the measured environment
together with the respective hash algorithm used in the process.
It uses the digests-type.
Described in Section 7.7.¶
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 5.1.4.1.4.5.¶
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 5.1.4.1.4.7.¶
ip-addr (index 7): An IPv4 or IPv6 address associated with the measured environment.
Described in Section 5.1.4.1.4.7.¶
serial-number (index 8): A text string representing the product serial number.¶
ueid (index 9): UEID associated with the measured environment.
Described in Section 7.5.¶
uuid (index 10): UUID associated with the measured environment.
Described in Section 7.4.¶
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 5.1.4.1.5 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 8.9.6.1.5.¶
integrity-registers (index 14): A group of one or more named measurements associated with the environment. Described in Section 5.1.4.1.6.¶
A version-map contains details about the versioning of a measured
environment.¶
version-map = {
&(version: 0) => text
? &(version-scheme: 1) => $version-scheme
}
¶
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 [RFC9393].
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¶
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 cannot be decremented.
If a security relevant flaw is discovered in the Target Environment and is subsequently fixed, 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 = svn / tagged-svn / tagged-min-svn¶
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.¶
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.¶
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 7.8).
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¶
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¶
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].¶
tagged-pkix-asn1der-cert-type: a bstr of ASN.1 DER encoded X.509 public key certificate.
Defined in Section 4 of [RFC5280].¶
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.¶
tagged-bytes: a key identifier with no prescribed construction method.¶
$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 $crypto-key-type-choice /= tagged-pkix-asn1der-cert-type $crypto-key-type-choice /= tagged-bytes 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) tagged-pkix-asn1der-cert-type = #6.562(bstr)¶
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".
The digests use digests-type semantics (Section 7.7).¶
integrity-register-id-type-choice = uint / text
integrity-registers = {
+ integrity-register-id-type-choice => digests-type
}
¶
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' ]
}
¶
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.¶
A domain is a context for bundling a collection of related environments and their measurements.¶
The following CDDL describes domain type choices.¶
$domain-type-choice /= uint $domain-type-choice /= text $domain-type-choice /= tagged-uuid-type $domain-type-choice /= tagged-oid-type¶
The uint and text types MUST NOT be interpreted in a global scope.¶
Content missing. Tracked at: https://github.com/ietf-rats-wg/draft-ietf-rats-corim/issues/310¶
The Reference Values Triple has the following structure:¶
reference-triple-record = [ ref-env: environment-map ref-claims: [ + measurement-map ] ]¶
The reference-triple-record has the following parameters:¶
ref-env: Search criterion that locates an Evidence environment that matches the reference environment.¶
ref-claims: Search criteria that locates the Evidence measurements that match the reference Claims.¶
To process reference-triple-record both the ref-env and ref-claims criteria are compared with Evidence entries.
If the search criteria are satisfied, the matching entry is re-asserted, except with the Reference Value Provider's authority.
By re-asserting Evidence using the RVP's authority, the Verifier can avoid mixing Reference Values (reference state) with Evidence (actual state).
See [I-D.ietf-rats-endorsements].
Re-asserted Evidence using RVP authority is said to be "corroborated".¶
Content missing. Tracked at: https://github.com/ietf-rats-wg/draft-ietf-rats-corim/issues/310¶
The Endorsed Values Triple has the following structure:¶
endorsed-triple-record = [ condition: environment-map endorsement: [ + measurement-map ] ]¶
The endorsed-triple-record has the following parameters:¶
condition: Search criterion that locates an Evidence, corroborated Evidence, or Endorsements environment.¶
endorsement: Additional Endorsement Claims.¶
To process a endorsed-triple-record the condition is compared with existing Evidence, corroborated Evidence, and Endorsements.
If the search criterion is satisfied, the endorsement Claims are combined with the condition environment-map to form a new (actual state) entry.
The new entry is added to the existing set of entries using the Endorser's authority.¶
Content missing. Tracked at: https://github.com/ietf-rats-wg/draft-ietf-rats-corim/issues/310¶
The Conditional Endorsement Triple has the following structure:¶
conditional-endorsement-triple-record = [ conditions: [ + stateful-environment-record ] endorsements: [ + endorsed-triple-record ] ] stateful-environment-record = [ environment: environment-map, claims-list: [ + measurement-map ] ]¶
The conditional-endorsement-triple-record has the following parameters:¶
conditions: Search criteria that locates Evidence, corroborated Evidence, or Endorsements.¶
endorsements: Additional Endorsements.¶
To process a conditional-endorsement-triple-record the conditions are compared with existing Evidence, corroborated Evidence, and Endorsements.
If the search criteria are satisfied, the endorsements entries are asserted with the Endorser's authority as new Endorsements.¶
Content missing. Tracked at: https://github.com/ietf-rats-wg/draft-ietf-rats-corim/issues/310¶
The Conditional Endorsement Series Triple has the following structure:¶
conditional-endorsement-series-triple-record = [ condition: stateful-environment-record series: [ + conditional-series-record ] ] conditional-series-record = [ selection: [ + measurement-map] addition: [ + measurement-map ] ]¶
The conditional-endorsement-series-triple-record has the following parameters:¶
condition: Search criteria that locates Evidence, corroborated Evidence, or Endorsements.¶
series: A set of selection-addition tuples.¶
The conditional-series-record has the following parameters:¶
selection: Search criteria that locates Evidence, corroborated Evidence, or Endorsements from the condition result.¶
addition: Additional Endorsements if the selection criteria are satisfied.¶
To process a conditional-endorsement-series-record the conditions are compared with existing Evidence, corroborated Evidence, and Endorsements.
If the search criteria are satisfied, the series tuples are processed.¶
The series array contains a list of conditional-series-record entries.¶
For each series entry, if the selection criteria matches an entry found in the condition result, the series addition is combined with the environment-map from the condition result to form a new Endorsement entry.
The new entry is added to the existing set of Endorsements.¶
The first series entry that successfully matches the selection criteria terminates series processing.¶
A Device Identity triple record relates one or more cryptographic keys to a device identity.
The cryptographic keys are bound to or associated with a Target Environment that is within the device.
The device identifier may be part of the Target Environment's environment-map or may be part of some other device identity credential, such as a certificate.
The cryptographic keys are expected to be used to authenticate the device.¶
Device Identity triples instruct a Verifier to perform key validation checks, such as revocation, certificate path construction & verification, or proof of possession. The Verifier SHOULD verify keys contained in Device Identity triples.¶
A Device Identity triple endorses that the keys were securely provisioned to the named Target Environment.
Additional details about how a key was provisioned or is protected may be asserted using Endorsements such as endorsed-triples.¶
Depending on key formatting, as defined by $crypto-key-type-choice, the Verifier may take different steps to locate and verify the key.¶
If a key has usage restrictions that limit its use to device identity challenges, Verifiers SHOULD check for key use that violates usage restrictions.¶
Verification of a key, including its use restrictions, MAY produce Claims that are added to the ACS. Alternatively, Verifiers MAY report key verification results as part of an error reporting function.¶
identity-triple-record = [ environment-map [ + $crypto-key-type-choice ] ]¶
An Attest Key triple record relates one or more cryptographic keys to an Attesting Environment. The cryptographic keys are wielded by an Attesting Environment that collects measurements from a Target Environment. The cryptographic keys sign Evidence.¶
Attest Key triples instruct a Verifier to perform key validation checks, such as revocation, certificate path construction & verification, or proof of possession. The Verifier SHOULD verify keys contained in Attest Key triples.¶
Attest Key triples endorse that the keys were securely provisioned to the named (identified via an environment-map) Attesting Environment.
Additional details about how a key was provisioned or is protected may be asserted using Endorsements such as endorsed-triples.¶
Depending on key formatting, as defined by $crypto-key-type-choice, the Verifier may take different steps to locate and verify the key.
If a key has usage restrictions that limits its use to Evidence signing, Verifiers SHOULD check for key use that violates usage restrictions.¶
Verification of a key, including its use restrictions, MAY produce Claims that are added to the ACS. Alternatively, Verifiers MAY report key verification results as part of an error reporting function.¶
attest-key-triple-record = [ environment-map [ + $crypto-key-type-choice ] ]¶
A Domain Dependency triple defines trust dependencies between measurement sources. The subject identifies a domain (Section 5.1.4.1.7) 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 ] ]¶
A Domain Membership triple assigns domain membership to environments. The subject identifies a domain (Section 5.1.4.1.7) that has a predicate relationship to the object containing one or more environments. Endorsed environments (Section 5.1.4.3) membership is conditional upon successful matching of Reference Values (Section 5.1.4.2) to Evidence.¶
domain-membership-triple-record = [ $domain-type-choice [ + environment-map ] ]¶
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¶
The base CoRIM document definition 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.¶
Map extensions provide extensibility support to CoRIM map structures.
CDDL map extensibility enables a CoRIM profile to extend the base CoRIM CDDL 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].
Non-negative integers are reserved for IANA to assign meaning globally.¶
Data type extensibility has the form ($NAME-type-choice) where "NAME" is the type name and '$' signifies type extensibility.¶
New data type extensions SHOULD be documented to facilitate interoperability. CoRIM profiles are best used to document vendor or industry defined extensions.¶
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.¶
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.¶
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
* $$concise-bom-tag-extension
}
¶
The following describes each member of the concise-bom-tag map.¶
tag-identity (index 0): A tag-identity-map containing unique
identification information for the CoBOM.
Described in Section 5.1.1.¶
tags-list (index 1): A list of one or more tag-identity-maps identifying
the CoMID and CoSWID tags that constitute the "bill of material", i.e.,
a complete set of verification-related information. The tags-list behaves
like a signaling mechanism from the supply chain (e.g., a product vendor) to
a Verifier that activates the tags in tags-list for use in the Evidence
appraisal process. The activation is atomic: all tags listed in tags-list
MUST be activated or no tags are activated.¶
bom-validity (index 2): Specifies the validity period of the CoBOM.
Described in Section 7.3.¶
$$concise-bom-tag-extension: This CDDL socket is used to add new information structures to the concise-bom-tag.
See Section 11.5.
The $$concise-bom-tag-extension extension socket is empty in this specification.¶
The following CDDL types may be shared by CoRIM, CoMID, and CoBOM.¶
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 })
¶
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¶
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 11.4.¶
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 4.1.5) and (Section 5.1.2).¶
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
}
¶
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)¶
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)¶
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)¶
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 and is interpreted according to the [IANA.named-information] registry.
Specifically, int values are matched against "ID" entries, text values are matched against "Hash Name String" entries.
Whenever possible, using the int encoding is RECOMMENDED.¶
digest = [ alg: (int / text), val: bytes ] digests-type = [ + digest ]¶
A measurement can be obtained using different hash algorithms.
A digests-type can be used to collect multiple digest values obtained by applying different hash algorithms on the same input.
Each entry in the digests-type MUST have a unique alg value.¶
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)¶
Inputs to a Verifier are mapped from their external representation to an internal representation. CoRIM defines CBOR structures and content media types for Conceptual Messages that include Endorsements and Reference Values. CoRIM data structures may also be used by Evidence and Attestation Results that wish to describe overlapping structure. CoRIM-based data structures define an external representation of Conceptual Messages that are mapped to an internal representation. Appraisal processing describes both mapping transformations and Verifier reconciliation (Section 2). Non-CoRIM-based data structures require mapping transformation, but these are out of scope for this document.¶
If a CoRIM profile is specified, there are a few well-defined points in the procedure where Verifier behaviour depends on the profile. The CoRIM profile MUST provide a description of the expected Verifier behavior for each of those well-defined points.¶
Verifier implementations MUST exhibit the same externally visible behavior as described in this specification. They are not required to use the same internal representation or evaluation order described by this specification.¶
The appraisal procedure is divided into several logical phases for clarity.¶
Phase 1: Input Validation and Transformation¶
During Phase 1, Conceptual Message inputs are cryptographically validated, such as checking digital signatures. Inputs are transformed from their external representations to an internal representation. Internal representations are staged for appraisal processing, such as populating an input queue.¶
Phase 2: Evidence Augmentation¶
During Phase 2, Evidence inputs are added to a list that describes the Attester's actual state. These inputs are added with the Attester's authority.¶
Phase 3: Reference Values Corroboration and Augmentation¶
During Phase 3, Reference Values inputs are compared with Evidence inputs. Reference Values inputs describe possible states of Attesters. If the actual state of the Attester is described by the possible Attester states, then the overlapping (corroborated) actual states are added to the Attester's actual state. These inputs are added with the Reference Value Provider's authority.¶
Phase 4: Endorsed Values Augmentation¶
During Phase 4, Endorsed Values inputs containing conditions that describe expected Attester state are processed. If the comparison is satisfied, then additional Claims about the Attester are added to the ACS. These inputs are added with the Endorser's authority.¶
Phase 5: Verifier Augmentation¶
During Phase 5, the Verifier may perform consistency, integrity, or additional validity checks.¶
These checks may result in additional Claims about the Attester that are added to the ACS. These Claims are added with the Verifier's authority.¶
Phase 6: Policy Augmentation¶
During Phase 6, appraisal policies are processed that describe Attester states that are desirable or undesirable. If these conditions exist, the policy may add additional Claims about the Attester, to the ACS. These Claims are added with the policy author's authority.¶
Phase 7: Attestation Results Production and Transformation¶
During Phase 7, the outcome of Appraisal and the set of Attester Claims that are interesting to a Relying Party are copied from the Attester state to an output staging area. The Claims in the output staging area and other Verifier related metadata are transformed into an external representation suitable for consumption by a Relying Party.¶
This document assumes that Verifier implementations may differ. To facilitate the description of normative Verifier behavior, this document uses an abstract representation of Verifier internals.¶
The following terms are used:¶
A piece of information, in the form of a key-value pair.¶
A structure containing a set of values that describe a Target Environment plus a set of measurement / Claim values that describe properties of the Target Environment. The ECT also contains authority which identifies the entity that authored the ECT.¶
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. See also Section 2 of [I-D.ietf-rats-endorsements].¶
Claims that describe a Target Environment instance at a given point in time. Endorsed Values and Evidence typically are Claims about actual state. An Attester may be composed of multiple components, where each component may represent a scope of appraisal. See also (Section 2 of [I-D.ietf-rats-endorsements]).¶
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.¶
A structure that holds ECTs that have been appraised. The ACS contains Attester state that has been authorized by Verifier processing and 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. See also "Appraisal Policy for Evidence" in [RFC9334].¶
A structure that holds results of Appraisal and ECTs that are to be conveyed to a Relying Party.¶
Conceptual Messages are Verifier input and output values such as Evidence, Reference Values, Endorsed Values, Appraisal Policy, and Attestation Results.¶
The internal representation of Conceptual Messages, as well as the ACS (Section 8.2.2) and ARS (Section 8.2.3), are constructed from a common building block structure called Environment-Claims Tuple (ECT).¶
ECTs have five attributes:¶
Environment : Identifies the Target Environment. Environments are identified using instance, class, or group identifiers. Environments may be composed of elements, each having an element identifier.¶
Elements : Identifies the set of elements contained within a Target Environment and their trustworthiness Claims.¶
Authority : Identifies the entity that issued the tuple. A certain type of key material by which the authority (and corresponding provenance) of the tuple can be determined, such as the public key of an asymmetric key pair that is associated with an authority's PKIX certificate.¶
Conceptual Message Type : Identifies the type of Conceptual Message that originated the tuple.¶
Profile : The profile that defines this tuple. If no profile is used, this attribute is omitted.¶
The following CDDL describes the ECT structure in more detail.¶
ECT = {
? environment: environment-map
? element-list: [ + element-map ]
? authority: [ + $crypto-key-type-choice ]
cmtype: cm-type
? profile: $profile-type-choice
}
element-map = {
? element-id: $measured-element-type-choice
element-claims: measurement-values-map
}
cm-type = &(
reference-values: 0
endorsements: 1
evidence: 2
attestation-results: 3
verifier: 4
policy: 5
)
¶
The Conceptual Message type determines which attributes are mandatory.¶
An internal representation of attestation Evidence uses the ae relation.¶
ae = [ addition: [ + ECT ] ]¶
The addition is a list of ECTs with Evidence to be appraised.¶
A Verifier may maintain multiple simultaneous sessions to different Attesters.
Each Attester has a different ACS. The Verifier ensures the Evidence inputs are associated with the correct ACS.
The addition is added to the ACS for a specific Attester.¶
Table 3 contains the requirements for the ECT fields of the Evidence tuple:¶
| ECT type | ECT Field | Requirement |
|---|---|---|
| addition |
environment
|
Mandatory |
element-list
|
Mandatory | |
authority
|
Mandatory | |
cmtype
|
Mandatory | |
profile
|
Optional |
An internal representation of Reference Values uses the rv relation, which is a list of ECTs that contains possible states and a list of ECTs that contain actual states asserted with RVP authority.¶
rv = [ + {
condition: ECT
addition: ECT
} ]
¶
The rv relation is a list of condition-addition pairings where each pairing is evaluated together.
If the condition containing reference ECTs overlaps Evidence ECTs then the Evidence ECTs are re-asserted, but with RVP authority as contained in the addition.¶
The reference ECTs define the matching conditions that are applied to Evidence ECTs. If the matching condition is satisfied, then the re-asserted ECTs are added to the ACS.¶
Table 4 contains the requirements for the ECT fields of the Reference Values tuple:¶
| ECT type | ECT Field | Requirement |
|---|---|---|
| condition |
environment
|
Mandatory |
element-list
|
Mandatory | |
authority
|
Optional | |
cmtype
|
n/a | |
profile
|
n/a | |
| addition |
environment
|
Mandatory |
element-list
|
Mandatory | |
authority
|
Mandatory | |
cmtype
|
Mandatory | |
profile
|
Optional |
An internal representation of Endorsed Values uses the ev and evs relations, which are lists of ECTs that describe matching conditions and the additions that are added if the conditions are satisfied.¶
ev = [
condition: [ + ECT ]
addition: [ + ECT ]
]
evs = [
condition: [ + ECT ]
series: [ + {
selection: [ + ECT ]
addition: [ + ECT ]
} ]
]
¶
The ev relation compares the condition ECTs to the ACS and if all of the ECTs are found in the ACS then the addition ECTs are added to the ACS.¶
The evs relation compares the condition ECTs to the ACS and if all of the ECTs are found in the ACS then each entry in the series list is evaluated.
The selection ECTs are compared with the ACS and if the selection criteria is satisfied, then the addition ECTs are added to the ACS and evaluation of the series ends.
If the selection criteria is not satisfied, then evaluation procedes to the next series list entry.¶
Table 5 contains the requirements for the ECT fields of the Endorsed Values and Endorsed Values Series tuples:¶
| ECT type | ECT Field | Requirement |
|---|---|---|
| condition |
environment
|
Mandatory |
element-list
|
Mandatory | |
authority
|
Optional | |
cmtype
|
n/a | |
profile
|
n/a | |
| selection |
environment
|
Mandatory |
element-list
|
Mandatory | |
authority
|
Optional | |
cmtype
|
n/a | |
profile
|
n/a | |
| addition |
environment
|
Mandatory |
element-list
|
Mandatory | |
authority
|
Mandatory | |
cmtype
|
Mandatory | |
profile
|
Optional |
The policy relation compares the condition ECTs to the ACS.¶
policy = [ condition: [ + ECT ] addition: [ + ECT ] ]¶
If all of the ECTs are found in the ACS then the addition ECTs are added to the ACS with the policy author's authority.¶
Table 6 contains the requirements for the ECT fields of the Policy tuple:¶
| ECT type | ECT Field | Requirement |
|---|---|---|
| condition |
environment
|
Optional |
element-list
|
Optional | |
authority
|
Optional | |
cmtype
|
n/a | |
profile
|
n/a | |
| addition |
environment
|
Mandatory |
element-list
|
Mandatory | |
authority
|
Mandatory | |
cmtype
|
Mandatory | |
profile
|
Optional |
The ar relation compares the acs-condition to the ACS.¶
ar = [ acs-condition: [ + ECT ] ars-addition: [ + ECT ] ]¶
If the condition is satisfied, the ars-additions are copied from the ACS to the ARS.
If any of the ars-additions are not found in the ACS then these ACS entries are not copied to the ARS.¶
Table 7 contains the requirements for the ECT fields of the Attestation Results tuple:¶
| ECT type | ECT Field | Requirement |
|---|---|---|
| acs-condition |
environment
|
Optional |
element-list
|
Optional | |
authority
|
Optional | |
cmtype
|
n/a | |
profile
|
n/a | |
| ars-addition |
environment
|
Mandatory |
element-list
|
Mandatory | |
authority
|
Mandatory | |
cmtype
|
Mandatory | |
profile
|
Optional |
An ACS is a list of ECTs that describe an Attester's actual state.¶
ACS = [ + ECT ]¶
An ARS is a list of ECTs that describe ACS entries that are selected for use as Attestation Results.¶
ARS = [ + ECT ]¶
During the initialization phase, the CoRIM Appraisal Context is loaded with various conceptual message inputs such as CoMID tags (Section 5), CoSWID tags [RFC9393], CoBOM tags [I-D.ietf-rats-cobom], and cryptographic validation key material (including raw public keys, root certificates, intermediate CA certificate chains), and Concise Trust Anchor Stores (CoTS) [I-D.ietf-rats-concise-ta-stores]. These objects will be utilized in the Evidence Appraisal phase that follows. The primary goal of this phase is to ensure that all necessary information is available for subsequent processing.¶
After context initialization, additional inputs are held back until appraisal processing has completed.¶
All available CoRIMs are collected.¶
CoRIMs that are not within their validity period, or that cannot be associated with an authenticated and authorized source MUST be discarded.¶
Any CoRIM that has been secured by a cryptographic mechanism, such as a signature, that fails validation MUST be discarded.¶
Other selection criteria MAY be applied. 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.¶
Later stages will further select the CoRIMs appropriate to the Evidence Appraisal stage.¶
This section is not applicable if the Verifier appraisal policy does not require CoBOMs.¶
CoBOMs which are not within their validity period 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 the 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 also 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.¶
During the Evidence collection phase, the Verifier communicates with Attesters to gather Evidence. The first part of this phase does not require any cryptographic validation. This means that Verifiers can use untrusted code to discover Evidence sources. Attesters are Evidence sources.¶
Verifiers may rely on conveyance protocol specific context to identify an Evidence source, which is the Evidence input oracle for appraisal.¶
The collected Evidence is then transformed to an internal representation, making it suitable for appraisal processing.¶
If Evidence is cryptographically signed, its validation is applied before transforming Evidence to an internal representation.¶
If Evidence is not cryptographically signed, the security context of the conveyance protocol that collected it is used to cryptographically validate Evidence.¶
The way cryptographic signature validation works depends on the specific Evidence collection method used. For example, in DICE, a proof of liveness is carried out on the final key in the certificate chain (a.k.a., the alias certificate). If this is successful, a suitable certification path is looked up in the Appraisal Context, based on linking information obtained from the DeviceID certificate. See Section 9.2.1 of [DICE.Layer]. If a trusted root certificate is found, the usual X.509 certificate validation is performed.¶
As a second example, in PSA [I-D.tschofenig-rats-psa-token] the verification public key is looked up in the appraisal context using the ueid claim found in the PSA claims-set.
If found, COSE Sign1 verification is performed accordingly.¶
Regardless of the specific integrity protection method used, the Evidence's integrity MUST be validated successfully.¶
Input Conceptual Messages, whether Endorsements, Reference Values, Evidence, or Policies, are transformed to an internal representation that is based on ECTs (Section 8.2.1).¶
The following mapping conventions apply to all forms of input transformation:¶
The environment field is populated with a Target Environment identifier.¶
The element-list field is populated with the measurements collected by an Attesting Environment.¶
The authority field is populated with the identity of the entity that asserted (e.g., signed) the Conceptual Message.¶
The cmtype field is set based on the type of Conceptual Message inputted or to be output.¶
The profile field is set based on the corim-map profile value.¶
All of the extracted and validated tags are loaded into an appraisal context. The Appraisal Context contains an internal representation of the inputted Conceptual Messages. The selected tags are mapped to an internal representation, making them suitable for appraisal processing.¶
An rv list entry (Section 8.2.1.2) is allocated.¶
The cmtype of the addition ECT in the rv entry is set to reference-values.¶
The Reference Values Triple (RVT) (Section 5.1.4.2) populates the rv ECTs.¶
RVT.ref-env¶
copy(environment-map, rv.condition.environment.environment-map)¶
copy(environment-map, rv.addition.environment.environment-map)¶
For each e in RVT.ref-claims:¶
copy(e.measurement-map, rv.addition.element-list.element-map)¶
Endorsed Values Triple Transformation :¶
An ev entry (Section 8.2.1.3) is allocated.¶
The cmtype of the ev entry's addition ECT is set to endorsements.¶
The Endorsed Values Triple (EVT) (Section 5.1.4.3) populates the ev ECTs.¶
EVT.condition¶
copy(environment-map, ev.condition.environment.environment-map)¶
copy(environment-map, ev.addition.environment.environment-map)¶
For each e in EVT.endorsement:¶
copy(e.endorsement.measurement-map, ev.addition.element-list.element-map)¶
The signer of the Endorsement conceptual message is copied to the ev.addition.authority field.¶
If the Endorsement conceptual message has a profile, the profile is copied to the ev.addition.profile field.¶
Conditional Endorsement Triple Transformation :¶
An ev entry (Section 8.2.1.3) is allocated.¶
The cmtype of the ev entry's addition ECT is set to endorsements.¶
Entries in the Conditional Endorsement Triple (CET) (Section 5.1.4.4) conditions list are copied to a suitable ECT in the internal representation.¶
For each e in CET.conditions:¶
copy(e.stateful-environment-record.environment.environment-map, ev.condition.environment.environment-map)¶
copy(e.stateful-environment-record.claims-list.measurement-map, ev.condition.element-list.element-map)¶
For each e in CET.endorsements:¶
copy(e.endorsed-triple-record.condition.environment-map, ev.addition.environment.environment-map)¶
copy(e.endorsed-triple-record.endorsement.measurement-map, ev.addition.element-list.element-map)¶
The signer of the Conditional Endorsement conceptual message is copied to the ev.addition.authority field.¶
If the Endorsement conceptual message has a profile, the profile is copied to the ev.addition.profile field.¶
Conditional Endorsement Series Triple Transformation :¶
An evs entry (Section 8.2.1.3) is allocated.¶
The cmtype of the evs entry's addition ECT is set to endorsements.¶
Populate the evs ECTs using the Conditional Endorsement Series Triple (CEST) (Section 5.1.4.5).¶
CEST.condition:¶
copy(stateful-environment-record.environment.environment-map, evs.condition.environment.environment-map)¶
copy(stateful-environment-record.claims-list.measurement-map, evs.condition.element-list.element-map)¶
For each e in CEST.series:¶
copy(evs.condition.environment.environment-map, evs.series.selection.environment.environment-map)¶
copy(e.conditional-series-record.selection.measurement.measurement-map, evs.series.selection.element-list.element-map)¶
copy(evs.condition.environment.environment-map, evs.series.addition.environment.environment-map)¶
copy(e.conditional-series-record.addition.measurement-map, evs.series.addition.element-list.element-map)¶
Evidence is transformed from an external representation to an internal representation based on the ae relation (Section 8.2.1.1).
The Evidence is mapped into one or more addition ECTs.
If the Evidence does not have a value for the mandatory ae fields, the Verifier MUST NOT process the Evidence.¶
Evidence transformation algorithms may be well-known, defined by a CoRIM profile (Section 4.1.4), or supplied dynamically. The handling of dynamic Evidence transformation algorithms is out of scope for this document.¶
The ACS is initialized by copying the internal representation of Evidence claims to the ACS. See Section 8.8.¶
In the ACS augmentation phase, a CoRIM Appraisal Context and an Evidence Appraisal Policy are used by the Verifier to find CoMID triples which match the 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.¶
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 ACS 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.¶
Reference Value Providers (RVP) publish Reference Values using the Reference Values Triple (Section 5.1.4.2) which are transformed (Section 8.3.3.2) into an internal representation (Section 8.2.1.2). Reference Values may describe multiple possible Attester states.¶
Corroboration is the process of determining whether actual Attester state (as contained in the ACS) can be satisfied by Reference Values. If satisfied, the RVP authority is added to the matching ACS entry.¶
Reference Values are matched with ACS entries by iterating through the rv list.
For each rv entry, the condition ECT is compared with an ACS ECT, where the ACS ECT cmtype contains evidence.¶
Content missing. Tracked at: https://github.com/ietf-rats-wg/draft-ietf-rats-corim/issues/302¶
If the ECTs match except for authority, the rv addition ECT authority is added to the ACS ECT authority.¶
Content missing. Tracked at: https://github.com/ietf-rats-wg/draft-ietf-rats-corim/issues/179¶
Endorsers publish Endorsements using endorsement triples (see Section 5.1.4.3), Section 5.1.4.4, and Section 5.1.4.5) which are transformed (Section 8.3.3.3) into an internal representation (Section 8.2.1.3). Endorsements describe actual Attester state. Endorsements are added to the ACS if the Endorsement condition is satisifed by the ACS.¶
Endorsements are matched with ACS entries by iterating through the ev list.
For each ev entry, the condition ECT is compared with an ACS ECT, where the ACS ECT cmtype contains either evidence or endorsements.
If the ECTs match (Section 8.9), the ev addition ECT is added to the ACS.¶
Conditional Endorsement Triples are transformed into an internal representation based on ev.
Conditional endorsements have the same processing steps as shown in (Section 8.6.1).¶
Conditional Endorsement Series Triples are transformed into an internal representation based on evs.
Conditional series endorsements are matched with ACS entries first by iterating through the evs list,
where for each evs entry, the condition ECT is compared with an ACS ECT, where the ACS ECT cmtype contains either evidence or endorsements.
If the ECTs match (Section 8.9), the evs series array is iterated,
where for each series entry, if the selection ECT matches an ACS ECT,
the addition ECT is added to the ACS.
Series processing terminates when the first series entry matches.¶
Phases 5, 6, and 7 are optional depending on implementation design. Verifier implementations that apply consistency, integrity, or validity checks could be represented as Claims that augment the ACS or could be handled by application specific interfaces. Processing appraisal policies may result in augmentation or modification of the ACS, but techniques for tracking the application of policies during appraisal need not result in ACS augmentation. Additionally, the creation of Attestation Results is out-of-scope for this document, nevertheless internal staging may facilitate processing of Attestation Results.¶
Phase 5: Verifier Augmentation¶
Claims related to Verifier-applied consistency checks are asserted under the authority of the Verifier.
For example, the attest-key-triple-record may contain a cryptographic key to which the Verifier applies certificate path construction and validation.
Validation may reveal an expired certificate.
The Verifier implementation might generate a certificate path validation exception that is handled externally, or it could generate a Claim that the certificate path is invalid.¶
Phase 6: Policy Augmentation¶
Appraisal policy inputs could result in Claims that augment the ACS. For example, an Appraisal Policy for Evidence may specify that if all of a collection of subcomponents satisfy a particular quality metric, the top-level component also satisfies the quality metric. The Verifier might generate an Endorsement ECT for the top-level component that asserts a quality metric. Details about the policy applied may also augment the ACS. An internal representation of policy details, based on the policy ECT, as described in Section 8.2.1.4, contains the environments affected by the policy with policy identifiers as Claims.¶
Phase 7: Attestation Results Production and Transformation¶
Attestation Results rely on input from the ACS, but may not bear any similarity to its content. For example, Attestation Results processing may map the ACS state to a generalized trustworthiness state such as [I-D.ietf-rats-ar4si]. Generated Attestation Results Claims may be specific to a particular Relying Party. Hence, the Verifier may need to maintain multiple Attestation Results contexts. An internal representation of Attestation Results as separate contexts (Section 8.2.3) ensures Relying Party–specific processing does not modify the ACS, which is common to all Relying Parties. Attestation Results contexts are the inputs to Attestation Results procedures that produce external representations.¶
At the end of the Evidence collection process Evidence has been converted into an internal represenetation suitable for appraisal. See Section 8.2.1.¶
Verifiers are not required to use this as their internal representation. For the purposes of this document, appraisal is described in terms of the above cited internal representation.¶
ACS entries contain Evidence (from Attesters), corroborated Reference Values, and Endorsements. The ACS SHALL contain the Attester's actual state as defined by its Target Environments (TEs).¶
Each ACS ECT entry SHALL contain authority.
See Section 8.4.1.1.
There can be multiple entries in the ACS which have the same environment-map and a different authority.¶
Each ACS entry is an ECT Claim.
The ECT environment and element-id together define the Claim's name.
The ECT element-claims are the Claim's actual state.¶
This specification defines rules for determining when two Claim names are equivalent. See Section 8.9.2 and Section 8.9.5. Equivalence typically means values MUST be binary identical.¶
If two Claims have the same Claim name, the CoRIM triples instruct the Verifier on how these Claims are related.¶
If multiple Claims have the same name and the measurement values (i.e., measurement-values-map codepoints and values) are equivalent, they are considered duplicates.
Duplicate claims SHOULD be omitted.¶
If multiple Claims have the same name and measurement-values-map contains duplicate codepoints but the measurement values are not equivalent, then a Verifier SHALL report an error and stop validation processing.¶
The ordering of ECTs in the ACS is not significant. Logically, new ECT entries are appended to the existing ACS. Nevertheless, implementations may optimize ECT order, to achieve better performance. Additions to the ACS MUST be atomic.¶
Content missing. Tracked at: https://github.com/ietf-rats-wg/draft-ietf-rats-corim/issues/71¶
A Verifier SHALL iterate over all ACS entries and SHALL attempt to match the condition ECT against each ACS entry. See Section 8.9.1. A Verifier SHALL create a "matched entries" set, and SHALL populate it with all ACS entries which matched the condition ECT.¶
If the matched entries array is not empty, then the condition ECT matches the ACS.¶
If the matched entries array is empty, then the condition ECT does not match the ACS.¶
If the condition ECT contains a profile and the profile defines an algorithm for a codepoint and environment-map then a Verifier MUST use the algorithm defined by the profile (or a standard algorithm if the profile defines that).
If the condition ECT contains a profile, but the profile does not define an algorithm for a particular codepoint and environment-map then the verifier MUST use the standard algorithm described in this document to compare the data at that codepoint.¶
A Verifier SHALL perform all of the comparisons defined in Section 8.9.2, Section 8.9.3, and Section 8.9.4.¶
Each of these comparisons compares one field in the condition ECT against the same field in the ACS entry.¶
If all of the fields match, then the condition ECT matches the ACS entry.¶
If any of the fields does not match, then the condition ECT does not match the ACS entry.¶
A Verifier SHALL compare each field which is present in the condition ECT environment-map against the corresponding field in the ACS entry environment-map using binary comparison.
Before performing the binary comparison, a Verifier SHOULD convert both environment-map fields into a form which meets CBOR Core Deterministic Encoding Requirements [STD94].¶
If all fields which are present in the condition ECT environment-map are present in the ACS entry and are binary identical, then the environments match.¶
If any field which is present in the condition ECT environment-map is not present in the ACS entry, then the environments do not match.¶
If any field which is present in the condition ECT environment-map is not binary identical to the corresponding ACS entry field, then the environments do not match.¶
If a field is not present in the condition ECT environment-map then the presence of, and value of, the corresponding ACS entry field SHALL NOT affect whether the environments match.¶
A Verifier SHALL iterate over all the entries in the condition ECT element-list and compare each one against the corresponding entry in the ACS entry element-list.¶
If every entry in the condition ECT element-list has a matching entry in the ACS entry element-list field then the element lists match.¶
The order of the fields in each element-list field do not affect the result of the comparison.¶
If any entry in the condition ECT element-list does not have a matching entry in the ACS entry element-list field then the element-list do not match.¶
A Verifier shall compare each element-map within the condition ECT element-list against the ACS entry element-list.¶
First, a Verifier SHALL locate the entries in the ACS entry element-list which have a matching element-id as the condition ECT element-map.
Two element-id fields are the same if they are either both omitted, or both present with binary identical deterministic encodings.¶
Before performing the binary comparison, a Verifier SHOULD convert both fields into a form which meets CBOR Core Deterministic Encoding Requirements [STD94].¶
If any condition ECT entry element-id does not have a corresponding element-id in the ACS entry then the element map does not match.¶
If any condition ECT entry has multiple corresponding element-ids then the element map does not match.¶
Second, a Verifier SHALL compare the element-claims field within the condition ECT element-list and the corresponding field from the ACS entry.
See Section 8.9.6.¶
A Verifier SHALL iterate over the codepoints which are present in the condition ECT element's measurement-values-map.
Each of the codepoints present in the condition ECT measurement-values-map is compared against the same codepoint in the candidate entry measurement-values-map.¶
If any codepoint present in the condition ECT measurement-values-map does not have a corresponding codepoint within the candidate entry measurement-values-map then Verifier SHALL remove that candidate entry from the candidate entries array.¶
If any codepoint present in the condition ECT measurement-values-map does not match the same codepoint within the candidate entry measurement-values-map then Verifier SHALL remove that candidate entry from the candidate entries array.¶
A Verifier SHALL compare each condition ECT measurement-values-map value against the corresponding ACS entry value using the appropriate algorithm.¶
Non-negative codepoints represent standard data representations.
The comparison algorithms for these are defined in this document (in the sections below) or in other specifications.
For some non-negative codepoints their behavior is modified by the CBOR tag at the start of the condition ECT measurement-values-map value.¶
Negative codepoints represent profile defined data representations. A Verifier SHALL use the codepoint number, the profile associated with the condition ECT, and the tag value (if present) to select the comparison algorithm.¶
If a Verifier is unable to determine the comparison algorithm which applies to a codepoint then it SHALL behave as though the candidate entry does not match the condition ECT.¶
Profile writers SHOULD use CBOR tags for widely applicable comparison methods to ease Verifier implementation compliance across profiles.¶
The following subsections define the comparison algorithms for the measurement-values-map codepoints defined by this specification.¶
The value stored under measurement-values-map codepoint 0 is an version label, which must have type version-map.
Two version-map values can only be compared for equality, as they are colloquial versions that cannot specify ordering.¶
The ACS entry value stored under measurement-values-map codepoint 1 is a security version number, which must have type svn-type.¶
If the entry svn-type is a uint or a uint tagged with #6.552, then comparison with the uint named as SVN is as follows.¶
If the condition ECT value for measurement-values-map codepoint 1 is an untagged uint or a uint tagged with #6.552 then an equality comparison is performed on the uint components.
The comparison MUST return true if the value of SVN is equal to the uint value in the condition ECT.¶
If the condition ECT value for measurement-values-map codepoint 1 is a uint tagged with #6.553 then a minimum comparison is performed.
The comparison MUST return true if the value of SVN is less or equal to than the uint value in the condition ECT.¶
If the entry svn-type is a uint tagged with #6.553, then comparison with the uint named as MINSVN is as follows.¶
If the condition ECT value for measurement-values-map codepoint 1 is an untagged uint or a uint tagged with #6.552 then the comparison MUST return false.¶
If the condition ECT value for measurement-values-map codepoint 1 is a uint tagged with #6.553 then an equality comparison is performed.
The comparison MUST return true if the value of MINSVN is equal to the uint value in the condition ECT.¶
The meaning of a minimum SVN as an entry value is only meaningful as an endorsed value that has been added to the ACS. The condition therefore treats the minimum SVN as an exact state and not one to compare with inequality.¶
A digests entry contains one or more digests, each measuring the same object.
When multiple digests are provided, each represents a different algorithm acceptable to the condition ECT author.¶
In the simple case, a condition ECT digests entry containing one digest matches matches a candidate entry containing a single entry with the same algorithm and value.¶
To prevent downgrade attacks, if there are multiple algorithms in common between the condition ECT and candidate entry, then the bytes paired with common algorithms must be equal. A Verifier SHALL treat two algorithm identifiers as equal if they have the same deterministic binary encoding. If both an integer and a string representation are defined for an algorithm then entities creating ECTs SHOULD use the integer representation. If condition ECT and ACS entry use different names for the same algorithm, and the Verifier does not recognize that they are the same, then a downgrade attack is possible.¶
The comparison MUST return false if the CBOR encoding of the digests entry in the condition ECT or the ACS value with the same codepoint is incorrect (for example if fields are missing or the wrong type).¶
The comparison MUST return false if the condition ECT digests entry does not contain any digests.¶
The comparison MUST return false if either digests entry contains multiple values for the same hash algorithm.¶
The Verifier MUST iterate over the condition ECT digests array, locating common hash algorithm identifiers (which are present in the condition ECT and in the candidate entry).
If the value associated with any common hash algorithm identifier in the condition ECT differs from the value for the same algorithm identifier in the candidate entry then the comparison MUST return false.¶
The comparison MUST return false if there are no hash algorithms from the condition ECT in common with the hash algorithms from the candidate entry ECT.¶
Content missing. Tracked at: https://github.com/ietf-rats-wg/draft-ietf-rats-corim/issues/71¶
The CBOR tag of the first entry of the condition ECT cryptokeys array is compared with the CBOR tag of the first entry of the candidate entry cryptokeys value.
If the CBOR tags match, then the bytes following the CBOR tag from the condition ECT entry are compared with the bytes following the CBOR tag from the candidate entry.
If the byte strings match, and there is another array entry, then the next entry from the condition ECTs array is likewise compared with the next entry of the ACS array.
If all entries of the condition ECTs array match a corresponding entry in the ACS array, then the cryptokeys condition ECT matches.
Otherwise, cryptokeys does not match.¶
For each Integrity Register entry in the condition ECT, the Verifier will use the associated identifier (i.e., integrity-register-id-type-choice) to look up the matching Integrity Register entry in the candidate entry.
If no entry is found, the comparison MUST return false.
Instead, if an entry is found, the digest comparison proceeds as defined in Section 8.9.6.1.3 after equivalence has been found according to Section 5.1.4.1.6.
Note that it is not required for all the entries in the candidate entry to be used during matching: the condition ECT 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 condition ECT could describe a subset of PCRs.¶
A profile MUST specify comparison algorithms for its additions to $-prefixed CoRIM CDDL codepoints when this specification does not prescribe binary comparison.
The profile must specify how to compare the CBOR tagged Reference Value against the ACS.¶
Note that a Verifier may compare Reference Values in any order, so the comparison should not be stateful.¶
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".¶
Organization responsible for the implementation: Veraison Project, Linux Foundation¶
Implementation's web page: https://github.com/veraison/corim/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 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¶
Implementation experience: n/a¶
Contact information: https://veraison.zulipchat.com¶
Last updated: https://github.com/veraison/corim/commits/main¶
Evidence appraisal is at the core of any RATS protocol flow, mediating all interactions between Attesters and their Relying Parties. The Verifier is effectively part of the Attesters' and Relying Parties' trusted computing base (TCB). Any mistake in the appraisal process could have security implications. For instance, it could lead to the subversion of an access control function, which creates a chance for privilege escalation.¶
Therefore, the Verifier’s code and configuration, especially those of the CoRIM processor, are primary security assets that must be built and maintained as securely as possible.¶
The protection of the Verifier system should be considered throughout its entire lifecycle, from design to operation. This includes the following aspects:¶
Minimizing implementation complexity (see also Section 6.1 of [I-D.ietf-rats-endorsements]);¶
Using memory-safe programming languages;¶
Using secure defaults;¶
Minimizing the attack surface by avoiding unnecessary features that could be exploited by attackers;¶
Applying the principle of least privilege to the system's users;¶
Minimizing the potential impact of security breaches by implementing separation of duties in both the software and operational architecture;¶
Conducting regular, automated audits and reviews of the system, such as ensuring that users' privileges are correctly configured and that any new code has been audited and approved by independent parties;¶
Failing securely in the event of errors to avoid compromising the security of the system.¶
The appraisal process should be auditable and reproducible. The integrity of the code and data during execution should be made an explicit objective, for example ensuring that the appraisal functions are computed in an attestable trusted execution environment (TEE).¶
The integrity of public and private key material and the secrecy of private key material must be ensured at all times. This includes key material carried in attestation key triples and key material used to verify the authority of triples (such as public keys that identify trusted supply chain actors). For more detailed information on protecting Trust Anchors, refer to Section 12.4 of [RFC9334].¶
The Verifier should use cryptographically protected, mutually authenticated secure channels to all its trusted input sources (Endorsers, RVPs, Verifier Owners). These links must reach as deep as possible - possibly terminating within the appraisal session context - to avoid man-in-the-middle attacks. Also consider minimizing the use of intermediaries: each intermediary becomes another party that needs to be trusted and therefore factored in the Attesters and Relying Parties' TCBs. Refer to Section 12.2 of [RFC9334] for information on Conceptual Messages protection.¶
Content missing. Tracked at: https://github.com/ietf-rats-wg/draft-ietf-rats-corim/issues/11¶
Content missing. Tracked at: https://github.com/ietf-rats-wg/draft-ietf-rats-corim/issues/12¶
This document defines a new registry titled "CoRIM Map". The registry uses integer values as index values for items in 'unsigned-corim-map' CBOR maps.¶
Future registrations for this registry are to be made based on [RFC8126] as follows:¶
| Range | Registration Procedures |
|---|---|
| 0-127 | Standards Action |
| 128-255 | Specification Required |
All negative values are reserved for Private Use.¶
Initial registrations for the "CoRIM Map" registry are provided below. Assignments consist of an integer index value, the item name, and a reference to the defining specification.¶
| Index | Item Name | Specification |
|---|---|---|
| 0 | id | RFCthis |
| 1 | tags | RFCthis |
| 2 | dependent-rims | RFCthis |
| 3 | profile | RFCthis |
| 4 | rim-validity | RFCthis |
| 5 | entities | RFCthis |
| 3-255 | Unassigned |
This document defines a new registry titled "CoMID Map". The registry uses integer values as index values for items in 'concise-mid-tag' CBOR maps.¶
Future registrations for this registry are to be made based on [RFC8126] as follows:¶
| Range | Registration Procedures |
|---|---|
| 0-127 | Standards Action |
| 128-255 | Specification Required |
All negative values are reserved for Private Use.¶
Initial registrations for the "CoMID Map" registry are provided below. Assignments consist of an integer index value, the item name, and a reference to the defining specification.¶
| Index | Item Name | Specification |
|---|---|---|
| 0 | language | RFCthis |
| 1 | tag-identity | RFCthis |
| 2 | entity | RFCthis |
| 3 | linked-tags | RFCthis |
| 4 | triples | RFCthis |
| 5-255 | Unassigned |
This document defines a new registry titled "CoBOM Map". The registry uses integer values as index values for items in 'concise-bom-tag' CBOR maps.¶
Future registrations for this registry are to be made based on [RFC8126] as follows:¶
| Range | Registration Procedures |
|---|---|
| 0-127 | Standards Action |
| 128-255 | Specification Required |
All negative values are reserved for Private Use.¶
Initial registrations for the "CoBOM Map" registry are provided below. Assignments consist of an integer index value, the item name, and a reference to the defining specification.¶
| Index | Item Name | Specification |
|---|---|---|
| 0 | tag-identity | RFCthis |
| 1 | tags-list | RFCthis |
| 2 | bom-validity | RFCthis |
| 5-255 | Unassigned |
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-signed+cbor | RFCthis, (Section 11.6.1) |
| corim-unsigned+cbor | application/corim-unsigned+cbor | RFCthis, (Section 11.6.2) |
application¶
corim-signed+cbor¶
n/a¶
"profile" (CoRIM profile in string format. OIDs MUST use the dotted-decimal notation.)¶
binary¶
(Section 10) of RFCthis¶
n/a¶
RFCthis¶
Attestation Verifiers, Endorsers and Reference-Value providers that need to transfer COSE Sign1 wrapped CoRIM payloads over HTTP(S), CoAP(S), and other transports.¶
n/a¶
D9 01 F6 D2, D9 01 F4 D9 01 F6 D2¶
n/a¶
n/a¶
RATS WG mailing list (rats@ietf.org)¶
COMMON¶
none¶
IETF¶
Maybe¶
application¶
corim-unsigned+cbor¶
n/a¶
"profile" (CoRIM profile in string format. OIDs MUST use the dotted-decimal notation.)¶
binary¶
Section 10 of RFCthis¶
n/a¶
RFCthis¶
Attestation Verifiers, Endorsers and Reference-Value providers that need to transfer unprotected CoRIM payloads over HTTP(S), CoAP(S), and other transports.¶
n/a¶
D9 01 F5, D9 01 F4 D9 01 F5¶
n/a¶
n/a¶
RATS WG mailing list (rats@ietf.org)¶
COMMON¶
none¶
IETF¶
Maybe¶
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-signed+cbor | - | TBD1 | RFCthis |
| application/corim-unsigned+cbor | - | TBD2 | RFCthis |
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
}
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
* $$corim-signer-map-extension
}
COSE-Sign1-corim = [
protected: bstr .cbor protected-corim-header-map
unprotected: unprotected-corim-header-map
payload: bstr .cbor tagged-corim-map
signature: bstr
]
$profile-type-choice /= uri
$profile-type-choice /= tagged-oid-type
protected-corim-header-map = {
&(alg: 1) => int
&(content-type: 3) => "application/corim-unsigned+cbor"
&(kid: 4) => bstr
&(corim-meta: 8) => bstr .cbor corim-meta-map
* cose-label => cose-value
}
signed-corim = #6.18(COSE-Sign1-corim)
tagged-corim-map = #6.501(corim-map)
tagged-concise-rim-type-choice = #6.500($concise-rim-type-choice)
tagged-signed-corim = #6.502(signed-corim)
tagged-concise-swid-tag = #6.505(bytes .cbor concise-swid-tag)
tagged-concise-mid-tag = #6.506(bytes .cbor concise-mid-tag)
tagged-concise-bom-tag = #6.508(bytes .cbor concise-bom-tag)
unprotected-corim-header-map = {
* cose-label => cose-value
}
validity-map = {
? &(not-before: 0) => time
&(not-after: 1) => time
}
concise-mid-tag = {
? &(language: 0) => text
&(tag-identity: 1) => tag-identity-map
? &(entities: 2) => [ + comid-entity-map ]
? &(linked-tags: 3) => [ + linked-tag-map ]
&(triples: 4) => triples-map
* $$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 ]
* $$accepted-claims-set-extension
}
attest-key-triple-record = [
environment-map
[ + $crypto-key-type-choice ]
]
$class-id-type-choice /= tagged-oid-type
$class-id-type-choice /= tagged-uuid-type
$class-id-type-choice /= tagged-bytes
class-map = non-empty<{
? &(class-id: 0) => $class-id-type-choice
? &(vendor: 1) => tstr
? &(model: 2) => tstr
? &(layer: 3) => uint
? &(index: 4) => uint
}>
comid-entity-map =
entity-map<$comid-role-type-choice, $$comid-entity-map-extension>
$comid-role-type-choice /= &(tag-creator: 0)
$comid-role-type-choice /= &(creator: 1)
$comid-role-type-choice /= &(maintainer: 2)
conditional-endorsement-series-triple-record = [
condition: stateful-environment-record
series: [ + conditional-series-record ]
]
conditional-series-record = [
selection: [ + measurement-map]
addition: [ + measurement-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
$crypto-key-type-choice /= tagged-pkix-asn1der-cert-type
$crypto-key-type-choice /= tagged-bytes
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)
tagged-pkix-asn1der-cert-type = #6.562(bstr)
domain-dependency-triple-record = [
$domain-type-choice
[ + $domain-type-choice ]
]
domain-membership-triple-record = [
$domain-type-choice
[ + environment-map ]
]
conditional-endorsement-triple-record = [
conditions: [ + 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 = [
condition: environment-map
endorsement: [ + 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
}>
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
* $$flags-map-extension
}
$group-id-type-choice /= tagged-uuid-type
$group-id-type-choice /= tagged-bytes
identity-triple-record = [
environment-map
[ + $crypto-key-type-choice ]
]
$instance-id-type-choice /= tagged-ueid-type
$instance-id-type-choice /= tagged-uuid-type
$instance-id-type-choice /= $crypto-key-type-choice
$instance-id-type-choice /= tagged-bytes
ip-addr-type-choice = ip4-addr-type / ip6-addr-type
ip4-addr-type = bytes .size 4
ip6-addr-type = bytes .size 16
linked-tag-map = {
&(linked-tag-id: 0) => $tag-id-type-choice
&(tag-rel: 1) => $tag-rel-type-choice
}
mac-addr-type-choice = eui48-addr-type / eui64-addr-type
eui48-addr-type = bytes .size 6
eui64-addr-type = bytes .size 8
$measured-element-type-choice /= tagged-oid-type
$measured-element-type-choice /= tagged-uuid-type
$measured-element-type-choice /= uint
$measured-element-type-choice /= tstr
measurement-map = {
? &(mkey: 0) => $measured-element-type-choice
&(mval: 1) => measurement-values-map
? &(authorized-by: 2) => [ + $crypto-key-type-choice ]
}
measurement-values-map = non-empty<{
? &(version: 0) => version-map
? &(svn: 1) => svn-type-choice
? &(digests: 2) => digests-type
? &(flags: 3) => flags-map
? (
&(raw-value: 4) => $raw-value-type-choice,
? &(raw-value-mask: 5) => raw-value-mask-type
)
? &(mac-addr: 6) => mac-addr-type-choice
? &(ip-addr: 7) => ip-addr-type-choice
? &(serial-number: 8) => text
? &(ueid: 9) => ueid-type
? &(uuid: 10) => uuid-type
? &(name: 11) => text
? &(cryptokeys: 13) => [ + $crypto-key-type-choice ]
? &(integrity-registers: 14) => integrity-registers
* $$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 = [
ref-env: environment-map
ref-claims: [ + measurement-map ]
]
stateful-environment-record = [
environment: environment-map,
claims-list: [ + 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 = svn / tagged-svn / tagged-min-svn
$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-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: 10) =>
[ + conditional-endorsement-triple-record ]
* $$triples-map-extension
}>
ueid-type = bytes .size 33
tagged-ueid-type = #6.550(ueid-type)
uuid-type = bytes .size 16
tagged-uuid-type = #6.37(uuid-type)
version-map = {
&(version: 0) => text
? &(version-scheme: 1) => $version-scheme
}
digest = [
alg: (int / text),
val: bytes
]
digests-type = [ + digest ]
integrity-register-id-type-choice = uint / text
integrity-registers = {
+ integrity-register-id-type-choice => digests-type
}
concise-swid-tag = {
tag-id => text / bstr .size 16,
tag-version => integer,
? corpus => bool,
? patch => bool,
? supplemental => bool,
software-name => text,
? software-version => text,
? version-scheme => $version-scheme,
? media => text,
? software-meta => one-or-more<software-meta-entry>,
entity => one-or-more<entity-entry>,
? link => one-or-more<link-entry>,
? payload-or-evidence,
* $$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
$version-scheme /= int / text
any-attribute = (
label => one-or-more<text> / one-or-more<int>
)
one-or-more<T> = T / [ 2* T ]
global-attributes = (
? lang => text,
* any-attribute,
)
hash-entry = [
hash-alg-id: int,
hash-value: bytes,
]
entity-entry = {
entity-name => text,
? reg-id => any-uri,
role => one-or-more<$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
$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,
)
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,
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
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
¶
Carl Wallace for review and comments on this document.¶
Carsten Bormann contributed to the CDDL specifications and the IANA considerations.¶
Andrew contributed the concept, description, and semantics of conditional endorsements as well as consistent contribution to weekly reviews of others' edits.¶
Dionna contributed many clarifying questions and disambiguations to the semantics of attestation appraisal as well as consistent contribution to weekly reviews of others' edits.¶