< draft-tschofenig-rats-psa-token-07.txt   draft-tschofenig-rats-psa-token-08.txt >
RATS H. Tschofenig RATS H. Tschofenig
Internet-Draft S. Frost Internet-Draft S. Frost
Intended status: Informational M. Brossard Intended status: Informational M. Brossard
Expires: 5 August 2021 A. Shaw Expires: 25 September 2021 A. Shaw
T. Fossati T. Fossati
Arm Limited Arm Limited
1 February 2021 24 March 2021
Arm's Platform Security Architecture (PSA) Attestation Token Arm's Platform Security Architecture (PSA) Attestation Token
draft-tschofenig-rats-psa-token-07 draft-tschofenig-rats-psa-token-08
Abstract Abstract
The Platform Security Architecture (PSA) is a family of hardware and The Platform Security Architecture (PSA) is a family of hardware and
firmware security specifications, as well as open-source reference firmware security specifications, as well as open-source reference
implementations, to help device makers and chip manufacturers build implementations, to help device makers and chip manufacturers build
best-practice security into products. Devices that are PSA compliant best-practice security into products. Devices that are PSA compliant
are able to produce attestation tokens as described in this memo, are able to produce attestation tokens as described in this memo,
which are the basis for a number of different protocols, including which are the basis for a number of different protocols, including
secure provisioning and network access control. This document secure provisioning and network access control. This document
specifies the PSA attestation token structure and semantics. specifies the PSA attestation token structure and semantics.
At its core, the CWT (COSE Web Token) format is used and populated The PSA attestation token is a profiled Entity Attestation Token
with a set of claims in a way similar to EAT (Entity Attestation (EAT).
Token). This specification describes what claims are used by PSA
compliant systems. This specification describes what claims are used in an attestation
token generated by PSA compliant systems, how these claims get
serialized to the wire, and how they are cryptographically protected.
Note to Readers Note to Readers
Source for this draft and an issue tracker can be found at Source for this draft and an issue tracker can be found at
https://github.com/thomas-fossati/draft-psa-token https://github.com/thomas-fossati/draft-psa-token
(https://github.com/thomas-fossati/draft-psa-token). (https://github.com/thomas-fossati/draft-psa-token).
Status of This Memo Status of This Memo
This Internet-Draft is submitted in full conformance with the This Internet-Draft is submitted in full conformance with the
skipping to change at page 2, line 4 skipping to change at page 2, line 9
Internet-Drafts are working documents of the Internet Engineering Internet-Drafts are working documents of the Internet Engineering
Task Force (IETF). Note that other groups may also distribute Task Force (IETF). Note that other groups may also distribute
working documents as Internet-Drafts. The list of current Internet- working documents as Internet-Drafts. The list of current Internet-
Drafts is at https://datatracker.ietf.org/drafts/current/. Drafts is at https://datatracker.ietf.org/drafts/current/.
Internet-Drafts are draft documents valid for a maximum of six months Internet-Drafts are draft documents valid for a maximum of six months
and may be updated, replaced, or obsoleted by other documents at any and may be updated, replaced, or obsoleted by other documents at any
time. It is inappropriate to use Internet-Drafts as reference time. It is inappropriate to use Internet-Drafts as reference
material or to cite them other than as "work in progress." material or to cite them other than as "work in progress."
This Internet-Draft will expire on 5 August 2021.
This Internet-Draft will expire on 25 September 2021.
Copyright Notice Copyright Notice
Copyright (c) 2021 IETF Trust and the persons identified as the Copyright (c) 2021 IETF Trust and the persons identified as the
document authors. All rights reserved. document authors. All rights reserved.
This document is subject to BCP 78 and the IETF Trust's Legal This document is subject to BCP 78 and the IETF Trust's Legal
Provisions Relating to IETF Documents (https://trustee.ietf.org/ Provisions Relating to IETF Documents (https://trustee.ietf.org/
license-info) in effect on the date of publication of this document. license-info) in effect on the date of publication of this document.
Please review these documents carefully, as they describe your rights Please review these documents carefully, as they describe your rights
and restrictions with respect to this document. Code Components and restrictions with respect to this document. Code Components
extracted from this document must include Simplified BSD License text extracted from this document must include Simplified BSD License text
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provided without warranty as described in the Simplified BSD License. provided without warranty as described in the Simplified BSD License.
Table of Contents Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 3 1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 3
2. Conventions and Definitions . . . . . . . . . . . . . . . . . 3 2. Conventions and Definitions . . . . . . . . . . . . . . . . . 3
2.1. Glossary . . . . . . . . . . . . . . . . . . . . . . . . 4 2.1. Glossary . . . . . . . . . . . . . . . . . . . . . . . . 3
3. PSA Claims . . . . . . . . . . . . . . . . . . . . . . . . . 4 3. PSA Claims . . . . . . . . . . . . . . . . . . . . . . . . . 4
3.1. Caller Claims . . . . . . . . . . . . . . . . . . . . . . 4 3.1. Caller Claims . . . . . . . . . . . . . . . . . . . . . . 4
3.1.1. Nonce . . . . . . . . . . . . . . . . . . . . . . . . 4 3.1.1. Nonce . . . . . . . . . . . . . . . . . . . . . . . . 4
3.1.2. Client ID . . . . . . . . . . . . . . . . . . . . . . 5 3.1.2. Client ID . . . . . . . . . . . . . . . . . . . . . . 5
3.2. Target Identification Claims . . . . . . . . . . . . . . 5 3.2. Target Identification Claims . . . . . . . . . . . . . . 5
3.2.1. Instance ID . . . . . . . . . . . . . . . . . . . . . 5 3.2.1. Instance ID . . . . . . . . . . . . . . . . . . . . . 5
3.2.2. Implementation ID . . . . . . . . . . . . . . . . . . 6 3.2.2. Implementation ID . . . . . . . . . . . . . . . . . . 6
3.2.3. Certification Reference . . . . . . . . . . . . . . . 6 3.2.3. Certification Reference . . . . . . . . . . . . . . . 6
3.3. Target State Claims . . . . . . . . . . . . . . . . . . . 6 3.3. Target State Claims . . . . . . . . . . . . . . . . . . . 6
3.3.1. Security Lifecycle . . . . . . . . . . . . . . . . . 6 3.3.1. Security Lifecycle . . . . . . . . . . . . . . . . . 7
3.3.2. Boot Seed . . . . . . . . . . . . . . . . . . . . . . 8 3.3.2. Boot Seed . . . . . . . . . . . . . . . . . . . . . . 8
3.4. Software Inventory Claims . . . . . . . . . . . . . . . . 8 3.4. Software Inventory Claims . . . . . . . . . . . . . . . . 8
3.4.1. Software Components . . . . . . . . . . . . . . . . . 8 3.4.1. Software Components . . . . . . . . . . . . . . . . . 8
3.4.2. No Software Measurements . . . . . . . . . . . . . . 10 3.4.2. No Software Measurements . . . . . . . . . . . . . . 10
3.5. Verification Claims . . . . . . . . . . . . . . . . . . . 11 3.5. Verification Claims . . . . . . . . . . . . . . . . . . . 11
3.5.1. Verification Service Indicator . . . . . . . . . . . 11 3.5.1. Verification Service Indicator . . . . . . . . . . . 11
3.5.2. Profile Definition . . . . . . . . . . . . . . . . . 11 3.5.2. Profile Definition . . . . . . . . . . . . . . . . . 11
4. Token Encoding and Signing . . . . . . . . . . . . . . . . . 11 4. Backwards Compatibility Considerations . . . . . . . . . . . 12
5. Collated CDDL . . . . . . . . . . . . . . . . . . . . . . . . 11 5. Token Encoding and Signing . . . . . . . . . . . . . . . . . 12
6. Security and Privacy Considerations . . . . . . . . . . . . . 14 6. Freshness Model . . . . . . . . . . . . . . . . . . . . . . . 12
7. Verification . . . . . . . . . . . . . . . . . . . . . . . . 15 7. Collated CDDL . . . . . . . . . . . . . . . . . . . . . . . . 13
8. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 15 8. Security and Privacy Considerations . . . . . . . . . . . . . 15
8.1. CBOR Web Token Claims Registration . . . . . . . . . . . 15 9. Verification . . . . . . . . . . . . . . . . . . . . . . . . 16
8.1.1. Nonce Claim . . . . . . . . . . . . . . . . . . . . . 15 10. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 16
8.1.2. Client ID Claim . . . . . . . . . . . . . . . . . . . 16 10.1. Media Type Registration . . . . . . . . . . . . . . . . 16
8.1.3. Instance ID Claim . . . . . . . . . . . . . . . . . . 16 10.2. CoAP Content-Formats Registration . . . . . . . . . . . 17
8.1.4. Implementation ID Claim . . . . . . . . . . . . . . . 16 10.2.1. Registry Contents . . . . . . . . . . . . . . . . . 17
8.1.5. Certification Reference Claim . . . . . . . . . . . . 17 11. References . . . . . . . . . . . . . . . . . . . . . . . . . 18
8.1.6. Security Lifecycle Claim . . . . . . . . . . . . . . 17 11.1. Normative References . . . . . . . . . . . . . . . . . . 18
8.1.7. Boot Seed Claim . . . . . . . . . . . . . . . . . . . 17 11.2. Informative References . . . . . . . . . . . . . . . . . 19
8.1.8. Software Components Claim . . . . . . . . . . . . . . 18 Appendix A. Reference Implementation . . . . . . . . . . . . . . 20
8.1.9. No Software Measurements Claim . . . . . . . . . . . 18 Appendix B. Example . . . . . . . . . . . . . . . . . . . . . . 20
8.1.10. Verification Service Indicator Claim . . . . . . . . 18 Contributors . . . . . . . . . . . . . . . . . . . . . . . . . . 21
8.1.11. Profile Definition Claim . . . . . . . . . . . . . . 19 Acknowledgments . . . . . . . . . . . . . . . . . . . . . . . . . 22
8.2. Media Type Registration . . . . . . . . . . . . . . . . . 19 Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 22
8.3. CoAP Content-Formats Registration . . . . . . . . . . . . 20
8.3.1. Registry Contents . . . . . . . . . . . . . . . . . . 20
9. References . . . . . . . . . . . . . . . . . . . . . . . . . 20
9.1. Normative References . . . . . . . . . . . . . . . . . . 20
9.2. Informative References . . . . . . . . . . . . . . . . . 22
Appendix A. Reference Implementation . . . . . . . . . . . . . . 22
Appendix B. Example . . . . . . . . . . . . . . . . . . . . . . 23
Contributors . . . . . . . . . . . . . . . . . . . . . . . . . . 24
Acknowledgments . . . . . . . . . . . . . . . . . . . . . . . . . 25
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 25
1. Introduction 1. Introduction
Trusted execution environments are now present in many devices, which Trusted execution environments are now present in many devices, which
provide a safe environment to place security sensitive code such as provide a safe environment to place security sensitive code such as
cryptography, secure boot, secure storage, and other essential cryptography, secure boot, secure storage, and other essential
security functions. These security functions are typically exposed security functions. These security functions are typically exposed
through a narrow and well-defined interface, and can be used by through a narrow and well-defined interface, and can be used by
operating system libraries and applications. Various APIs have been operating system libraries and applications. Various APIs have been
developed by Arm as part of the Platform Security Architecture [PSA] developed by Arm as part of the Platform Security Architecture [PSA]
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CDDL [RFC8610] along with text descriptions is used to define each CDDL [RFC8610] along with text descriptions is used to define each
claim independent of encoding. The following CDDL type(s) are reused claim independent of encoding. The following CDDL type(s) are reused
by different claims: by different claims:
psa-hash-type = bytes .size 32 / bytes .size 48 / bytes .size 64 psa-hash-type = bytes .size 32 / bytes .size 48 / bytes .size 64
3.1. Caller Claims 3.1. Caller Claims
3.1.1. Nonce 3.1.1. Nonce
The Nonce claim is a challenge from the caller. The length must be The Nonce claim is used to carry the challenge provided by the caller
32, 48, or 64 bytes. to demonstrate freshness of the generated token.
The EAT [I-D.ietf-rats-eat] "nonce" (claim key 10) is used. The
following constraints apply to the "nonce-type":
* The length MUST be either 32, 48, or 64 bytes.
* Only a single nonce value is conveyed. Per [I-D.ietf-rats-eat]
the array notation is not used for encoding the nonce value.
This claim MUST be present in a PSA attestation token. This claim MUST be present in a PSA attestation token.
psa-nonce = ( psa-nonce = (
psa-nonce-key => psa-hash-type 10 => psa-hash-type
) )
3.1.2. Client ID 3.1.2. Client ID
The Client ID claim represents the security domain of the caller. The Client ID claim represents the security domain of the caller.
In PSA, a security domain is represented by a signed integer whereby In PSA, a security domain is represented by a signed integer whereby
negative values represent callers from the NSPE and where positive negative values represent callers from the NSPE and where positive
IDs represent callers from the SPE. The value 0 is not permitted. IDs represent callers from the SPE. The value 0 is not permitted.
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psa-client-id-type = psa-client-id-nspe-type / psa-client-id-spe-type psa-client-id-type = psa-client-id-nspe-type / psa-client-id-spe-type
psa-client-id = ( psa-client-id = (
psa-client-id-key => psa-client-id-type psa-client-id-key => psa-client-id-type
) )
3.2. Target Identification Claims 3.2. Target Identification Claims
3.2.1. Instance ID 3.2.1. Instance ID
The Instance ID claim represents the unique identifier of the device The Instance ID claim represents the unique identifier of the Initial
instance. It is a 32 bytes hash of the public key corresponding to Attestation Key (IAK). The full definition is in [PSA-SM].
the Initial Attestation Key (IAK). If the IAK is a symmetric key
then the Instance ID is a hash of the hash of the IAK itself. It is The EAT "ueid" (claim key 11) of type RAND is used. The following
encoded as a Universal Entity ID of type RAND [I-D.ietf-rats-eat], constraints apply to the "ueid-type":
i.e., prepending a 0x01 type byte to the key hash. The full
definition is in [PSA-SM]. * The length MUST be 33 bytes.
* The first byte MUST be 0x01 (RAND) followed by the 32-bytes key
hash.
This claim MUST be present in a PSA attestation token. This claim MUST be present in a PSA attestation token.
psa-instance-id-type = bytes .size 33 psa-instance-id-type = bytes .size 33
psa-instance-id = ( psa-instance-id = (
psa-instance-id-key => psa-instance-id-type 11 => psa-instance-id-type
) )
3.2.2. Implementation ID 3.2.2. Implementation ID
The Implementation ID claim uniquely identifies the underlying The Implementation ID claim uniquely identifies the underlying
immutable PSA RoT. A verification service can use this claim to immutable PSA RoT. A verification service can use this claim to
locate the details of the verification process. Such details include locate the details of the verification process. Such details include
the implementation's origin and associated certification state. The the implementation's origin and associated certification state. The
full definition is in [PSA-SM]. full definition is in [PSA-SM].
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psa-verification-service-indicator-type = text psa-verification-service-indicator-type = text
psa-verification-service-indicator = ( psa-verification-service-indicator = (
? psa-verification-service-indicator-key => ? psa-verification-service-indicator-key =>
psa-verification-service-indicator-type psa-verification-service-indicator-type
) )
3.5.2. Profile Definition 3.5.2. Profile Definition
The Profile Definition claim contains the name of a document that The Profile Definition claim encodes the unique identifier that
describes the "profile" of the report. The document name may include corresponds to the EAT profile described by this document. This
versioning. The value for this specification MUST be allows a receiver to assign the intended semantics to the rest of the
PSA_IOT_PROFILE_1. claims found in the token.
psa-profile-type = "PSA_IOT_PROFILE_1" The EAT "profile" (claim key 18) is used. The following constraints
apply to its type:
* The URI encoding MUST be used.
* The value MUST be "http://arm.com/psa/2.0.0".
This claim MUST be present in a PSA attestation token.
See Section 4, for considerations about backwards compatibility with
previous versions of the PSA attestation token format.
psa-profile-type = "http://arm.com/psa/2.0.0"
psa-profile = ( psa-profile = (
? psa-profile-key => psa-profile-type 18 => psa-profile-type
) )
4. Token Encoding and Signing 4. Backwards Compatibility Considerations
The report is encoded as a COSE Web Token (CWT) [RFC8392], similar to Previous versions of this specification used different claim key
the Entity Attestation Token (EAT) [I-D.ietf-rats-eat]. The token values for the following claims:
consists of a series of claims declaring evidence as to the nature of
the instance of hardware and software. The claims are encoded in * Nonce (claim key -75008);
CBOR [RFC7049] format. For asymmetric key algorithms, the signature
structure MUST be COSE_Sign1. For symmetric key algorithms, the * Instance ID (claim key -75009);
structure MUST be COSE_Mac0.
* Profile Description (claim key -75000 and value
"PSA_IOT_PROFILE_1").
These claim keys have been retired and their use is deprecated.
Unless compatibility with existing infrastructure is a concern,
emitters (e.g., devices that implement the PSA Attestation API)
SHOULD produce tokens with their standard equivalent instead, as
described in Section 3.1.1, Section 3.2.1 and Section 3.5.2
respectively.
To simplify the transition to the token format described in this
document it is RECOMMENDED that receivers (e.g., PSA Attestation
Verifiers) accept tokens encoded according to the old profile
("PROFILE_IOT_1") as well as to the new profile ("http://arm.com/
psa/2.0.0"), at least for the time needed to their clients to
upgrade.
5. Token Encoding and Signing
The PSA attestation token is encoded in CBOR [RFC7049] format. Only
definite-length string, arrays, and maps are allowed.
Cryptographic protection is obtained by wrapping the "psa-token" map
in a COSE Web Token (CWT) [RFC8392]. For asymmetric key algorithms,
the signature structure MUST be COSE_Sign1. For symmetric key
algorithms, the signature structure MUST be COSE_Mac0.
The CWT CBOR tag (61) is not used. An application that needs to
exchange PSA attestation tokens can use the media type defined in
Section 10.1 or the CoAP Content-Format defined in Section 10.2.
6. Freshness Model
The PSA Token supports the freshness models for attestation Evidence
based on nonces and epoch handles (Section 10.2 and 10.3 of
[I-D.ietf-rats-architecture]) using the "nonce" claim to convey the
nonce or epoch handle supplied by the Verifier. No further
assumption on the specific remote attestation protocol is made.
7. Collated CDDL
5. Collated CDDL
psa-token = { psa-token = {
psa-nonce, psa-nonce,
psa-instance-id, psa-instance-id,
psa-verification-service-indicator, psa-verification-service-indicator,
psa-profile, psa-profile,
psa-implementation-id, psa-implementation-id,
psa-client-id, psa-client-id,
psa-lifecycle, psa-lifecycle,
psa-certification-reference, psa-certification-reference,
psa-boot-seed, psa-boot-seed,
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psa-client-id = ( psa-client-id = (
psa-client-id-key => psa-client-id-type psa-client-id-key => psa-client-id-type
) )
psa-certification-reference-type = text .regexp "[0-9]{13}" psa-certification-reference-type = text .regexp "[0-9]{13}"
psa-certification-reference = ( psa-certification-reference = (
? psa-certification-reference-key => ? psa-certification-reference-key =>
psa-certification-reference-type psa-certification-reference-type
) )
psa-implementation-id-type = bytes .size 32 psa-implementation-id-type = bytes .size 32
psa-implementation-id = ( psa-implementation-id = (
psa-implementation-id-key => psa-implementation-id-type psa-implementation-id-key => psa-implementation-id-type
) )
psa-instance-id-type = bytes .size 33 psa-instance-id-type = bytes .size 33
psa-instance-id = ( psa-instance-id = (
psa-instance-id-key => psa-instance-id-type 11 => psa-instance-id-type
) )
psa-no-sw-measurements-type = 1 psa-no-sw-measurements-type = 1
psa-no-sw-measurement = ( psa-no-sw-measurement = (
psa-no-sw-measurement-key => psa-no-sw-measurements-type psa-no-sw-measurement-key => psa-no-sw-measurements-type
) )
psa-nonce = ( psa-nonce = (
psa-nonce-key => psa-hash-type 10 => psa-hash-type
) )
psa-profile-type = "PSA_IOT_PROFILE_1" psa-profile-type = "http://arm.com/psa/2.0.0"
psa-profile = ( psa-profile = (
? psa-profile-key => psa-profile-type 18 => psa-profile-type
) )
psa-lifecycle-unknown-type = 0x0000..0x00ff psa-lifecycle-unknown-type = 0x0000..0x00ff
psa-lifecycle-assembly-and-test-type = 0x1000..0x10ff psa-lifecycle-assembly-and-test-type = 0x1000..0x10ff
psa-lifecycle-psa-rot-provisioning-type = 0x2000..0x20ff psa-lifecycle-psa-rot-provisioning-type = 0x2000..0x20ff
psa-lifecycle-secured-type = 0x3000..0x30ff psa-lifecycle-secured-type = 0x3000..0x30ff
psa-lifecycle-non-psa-rot-debug-type = 0x4000..0x40ff psa-lifecycle-non-psa-rot-debug-type = 0x4000..0x40ff
psa-lifecycle-recoverable-psa-rot-debug-type = 0x5000..0x50ff psa-lifecycle-recoverable-psa-rot-debug-type = 0x5000..0x50ff
psa-lifecycle-decommissioned-type = 0x6000..0x60ff psa-lifecycle-decommissioned-type = 0x6000..0x60ff
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psa-lifecycle-assembly-and-test-type / psa-lifecycle-assembly-and-test-type /
psa-lifecycle-psa-rot-provisioning-type / psa-lifecycle-psa-rot-provisioning-type /
psa-lifecycle-secured-type / psa-lifecycle-secured-type /
psa-lifecycle-non-psa-rot-debug-type / psa-lifecycle-non-psa-rot-debug-type /
psa-lifecycle-recoverable-psa-rot-debug-type / psa-lifecycle-recoverable-psa-rot-debug-type /
psa-lifecycle-decommissioned-type psa-lifecycle-decommissioned-type
psa-lifecycle = ( psa-lifecycle = (
psa-lifecycle-key => psa-lifecycle-type psa-lifecycle-key => psa-lifecycle-type
) )
psa-software-component = { psa-software-component = {
? 1 => text, ; measurement type ? 1 => text, ; measurement type
2 => psa-hash-type, ; measurement value 2 => psa-hash-type, ; measurement value
? 4 => text, ; version ? 4 => text, ; version
5 => psa-hash-type, ; signer id 5 => psa-hash-type, ; signer id
? 6 => text, ; measurement description ? 6 => text, ; measurement description
} }
psa-software-components = ( psa-software-components = (
psa-software-components-key => [ + psa-software-component ] psa-software-components-key => [ + psa-software-component ]
) )
psa-verification-service-indicator-type = text psa-verification-service-indicator-type = text
psa-verification-service-indicator = ( psa-verification-service-indicator = (
? psa-verification-service-indicator-key => ? psa-verification-service-indicator-key =>
psa-verification-service-indicator-type psa-verification-service-indicator-type
) )
6. Security and Privacy Considerations 8. Security and Privacy Considerations
This specification re-uses the CWT and the EAT specification. Hence, This specification re-uses the CWT and the EAT specification. Hence,
the security and privacy considerations of those specifications apply the security and privacy considerations of those specifications apply
here as well. here as well.
Since CWTs offer different ways to protect the token, this Since CWTs offer different ways to protect the token, this
specification profiles those options and allows signatures based on specification profiles those options and allows signatures based on
use of public key cryptography as well as MAC authentication. The use of public key cryptography as well as MAC authentication. The
token MUST be signed following the structure of the COSE token MUST be signed following the structure of the COSE
specification [RFC8152]. The COSE type MUST be COSE_Sign1 for public specification [RFC8152]. The COSE type MUST be COSE_Sign1 for public
skipping to change at page 15, line 5 skipping to change at page 16, line 5
associated infrastructure costs for key management and protocol associated infrastructure costs for key management and protocol
complexities. It may also restrict the ability to interoperate with complexities. It may also restrict the ability to interoperate with
third parties. third parties.
Attestation tokens contain information that may be unique to a device Attestation tokens contain information that may be unique to a device
and therefore they may allow to single out an individual device for and therefore they may allow to single out an individual device for
tracking purposes. Implementations that have privacy requirements tracking purposes. Implementations that have privacy requirements
must take appropriate measures to ensure that the token is only used must take appropriate measures to ensure that the token is only used
to provision anonymous/pseudonym keys. to provision anonymous/pseudonym keys.
7. Verification 9. Verification
To verify the token, the primary need is to check correct formation To verify the token, the primary need is to check correct formation
and signing as for any CWT token. In addition though, the verifier and signing as for any CWT token. In addition though, the verifier
can operate a policy where values of some of the claims in this can operate a policy where values of some of the claims in this
profile can be compared to reference values, registered with the profile can be compared to reference values, registered with the
verifier for a given deployment, in order to confirm that the device verifier for a given deployment, in order to confirm that the device
is endorsed by the manufacturer supply chain. The policy may require is endorsed by the manufacturer supply chain. The policy may require
that the relevant claims must have a match to a registered reference that the relevant claims must have a match to a registered reference
value. All claims may be worthy of additional appraisal. It is value. All claims may be worthy of additional appraisal. It is
likely that most deployments would include a policy with appraisal likely that most deployments would include a policy with appraisal
skipping to change at page 15, line 39 skipping to change at page 16, line 39
verification policy may then allow this value to match any point verification policy may then allow this value to match any point
on that release sequence or expect some minimum level of maturity on that release sequence or expect some minimum level of maturity
related to the sequence. related to the sequence.
* Software Component, Signer ID - where present in a deployment, * Software Component, Signer ID - where present in a deployment,
this could allow a verifier to operate a more general policy than this could allow a verifier to operate a more general policy than
that for Measurement Value as above, by allowing a token to that for Measurement Value as above, by allowing a token to
contain any firmware entries signed by a known Signer ID, without contain any firmware entries signed by a known Signer ID, without
checking for a uniquely registered version. checking for a uniquely registered version.
8. IANA Considerations 10. IANA Considerations
8.1. CBOR Web Token Claims Registration
This specification registers the following claims in the IANA "CBOR
Web Token (CWT) Claims" registry [IANA-CWT], established by
[RFC8392].
8.1.1. Nonce Claim
* Claim Name: "psa-nonce"
* Claim Description: Nonce
* JWT Claim Name: "psa-nonce"
* Claim Key: [[Proposed: -75008]]
* Claim Value Type(s): bytes (32, 48, or 64 bytes in length)
* Change Controller: [[Authors of this RFC]]
* Specification Document(s): Section 3.1.1 of [[this RFC]]
8.1.2. Client ID Claim
* Claim Name: "psa-client-id"
* Claim Description: Client ID
* JWT Claim Name: "psa-client-id"
* Claim Key: [[Proposed: -75001]]
* Claim Value Type(s): signed integer
* Change Controller: [[Authors of this RFC]]
* Specification Document(s): Section 3.1.2 of [[this RFC]]
8.1.3. Instance ID Claim
* Claim Name: "psa-instance-id"
* Claim Description: Instance ID
* JWT Claim Name: "psa-instance-id"
* Claim Key: [[Proposed: -75009]]
* Claim Value Type(s): bytes (33 bytes in length)
* Change Controller: [[Authors of this RFC]]
* Specification Document(s): Section 3.2.1 of [[this RFC]]
8.1.4. Implementation ID Claim
* Claim Name: "psa-implementation-id"
* Claim Description: Implementation ID
* JWT Claim Name: "psa-implementation-id"
* Claim Key: [[Proposed: -75003]]
* Claim Value Type(s): bytes (32 bytes in length)
* Change Controller: [[Authors of this RFC]]
* Specification Document(s): Section 3.2.2 of [[this RFC]]
8.1.5. Certification Reference Claim
* Claim Name: "psa-certification-reference"
* Claim Description: Certification Reference
* JWT Claim Name: "psa-certification-reference"
* Claim Key: [[Proposed: -75005]]
* Claim Value Type(s): text
* Change Controller: [[Authors of this RFC]]
* Specification Document(s): Section 3.2.3 of [[this RFC]]
8.1.6. Security Lifecycle Claim
* Claim Name: "psa-lifecycle"
* Claim Description: Security Lifecycle
* JWT Claim Name: "psa-lifecycle"
* Claim Key: [[Proposed: -75002]]
* Claim Value Type(s): unsigned integer
* Change Controller: [[Authors of this RFC]]
* Specification Document(s): Section 3.3.1 of [[this RFC]]
8.1.7. Boot Seed Claim
* Claim Name: "psa-boot-seed"
* Claim Description: Boot Seed
* JWT Claim Name: "psa-boot-seed"
* Claim Key: [[Proposed: -75004]]
* Claim Value Type(s): bytes (32 bytes in length)
* Change Controller: [[Authors of this RFC]]
* Specification Document(s): Section 3.3.2 of [[this RFC]]
8.1.8. Software Components Claim
* Claim Name: "psa-software-components"
* Claim Description: Software Components
* JWT Claim Name: "psa-software-components"
* Claim Key: [[Proposed: -75006]]
* Claim Value Type(s): array
* Change Controller: [[Authors of this RFC]]
* Specification Document(s): Section 3.4.1 of [[this RFC]]
8.1.9. No Software Measurements Claim
* Claim Name: "psa-no-sw-measurement"
* Claim Description: No Software Measurements
* JWT Claim Name: "psa-no-sw-measurement"
* Claim Key: [[Proposed: -75007]]
* Claim Value Type(s): unsigned integer
* Change Controller: [[Authors of this RFC]]
* Specification Document(s): Section 3.4.2 of [[this RFC]]
8.1.10. Verification Service Indicator Claim
* Claim Name: "psa-verification-service-indicator"
* Claim Description: Verification Service Indicator
* JWT Claim Name: "psa-verification-service-indicator"
* Claim Key: [[Proposed: -75010]]
* Claim Value Type(s): text
* Change Controller: [[Authors of this RFC]]
* Specification Document(s): Section 3.5.1 of [[this RFC]]
8.1.11. Profile Definition Claim
* Claim Name: "psa-profile"
* Claim Description: Profile Definition
* JWT Claim Name: "psa-profile"
* Claim Key: [[Proposed: -75000]]
* Claim Value Type(s): text
* Change Controller: [[Authors of this RFC]]
* Specification Document(s): Section 3.5.2 of [[this RFC]]
8.2. Media Type Registration 10.1. Media Type Registration
IANA is requested to register the "application/psa-attestation-token" IANA is requested to register the "application/psa-attestation-token"
media type [RFC2046] in the "Media Types" registry [IANA-MediaTypes] media type [RFC2046] in the "Media Types" registry [IANA-MediaTypes]
in the manner described in RFC 6838 [RFC6838], which can be used to in the manner described in RFC 6838 [RFC6838], which can be used to
indicate that the content is a PSA Attestation Token. indicate that the content is a PSA Attestation Token.
* Type name: application * Type name: application
* Subtype name: psa-attestation-token * Subtype name: psa-attestation-token
skipping to change at page 20, line 33 skipping to change at page 17, line 42
* Intended usage: COMMON * Intended usage: COMMON
* Restrictions on usage: none * Restrictions on usage: none
* Author: Hannes Tschofenig, Hannes.Tschofenig@arm.com * Author: Hannes Tschofenig, Hannes.Tschofenig@arm.com
* Change controller: IESG * Change controller: IESG
* Provisional registration? No * Provisional registration? No
8.3. CoAP Content-Formats Registration 10.2. CoAP Content-Formats Registration
IANA is requested to register the CoAP Content-Format ID for the IANA is requested to register the CoAP Content-Format ID for the
"application/psa-attestation-token" media type in the "CoAP Content- "application/psa-attestation-token" media type in the "CoAP Content-
Formats" registry [IANA-CoAP-Content-Formats]. Formats" registry [IANA-CoAP-Content-Formats].
8.3.1. Registry Contents 10.2.1. Registry Contents
* Media Type: application/psa-attestation-token * Media Type: application/psa-attestation-token
* Encoding: - * Encoding: -
* Id: [[To-be-assigned by IANA]] * Id: [[To-be-assigned by IANA]]
* Reference: [[this RFC]] * Reference: [[this RFC]]
9. References 11. References
9.1. Normative References 11.1. Normative References
[EAN-13] GS1, "International Article Number - EAN/UPC barcodes", [EAN-13] GS1, "International Article Number - EAN/UPC barcodes",
2019, <https://www.gs1.org/standards/barcodes/ean-upc>. 2019, <https://www.gs1.org/standards/barcodes/ean-upc>.
[I-D.ietf-rats-eat]
Mandyam, G., Lundblade, L., Ballesteros, M., and J.
O'Donoghue, "The Entity Attestation Token (EAT)", Work in
Progress, Internet-Draft, draft-ietf-rats-eat-06, 2
December 2020, <http://www.ietf.org/internet-drafts/draft-
ietf-rats-eat-06.txt>.
[PSA-FF] Arm, "Platform Security Architecture Firmware Framework [PSA-FF] Arm, "Platform Security Architecture Firmware Framework
1.0 (PSA-FF)", February 2019, <https://developer.arm.com/- 1.0 (PSA-FF)", February 2019, <https://developer.arm.com/-
/media/Files/pdf/PlatformSecurityArchitecture/Architect/ /media/Files/pdf/PlatformSecurityArchitecture/Architect/
DEN0063-PSA_Firmware_Framework-1.0.0-2.pdf>. DEN0063-PSA_Firmware_Framework-1.0.0-2.pdf>.
[PSA-SM] Arm, "Platform Security Architecture Security Model 1.0 [PSA-SM] Arm, "Platform Security Architecture Security Model 1.0
(PSA-SM)", February 2019, <https://developer.arm.com/- (PSA-SM)", February 2019, <https://developer.arm.com/-
/media/Files/pdf/PlatformSecurityArchitecture/Architect/ /media/Files/pdf/PlatformSecurityArchitecture/Architect/
DEN0079_PSA_SM_ALPHA-03_RC01.pdf>. DEN0079_PSA_SM_ALPHA-03_RC01.pdf>.
skipping to change at page 22, line 11 skipping to change at page 19, line 23
[RFC8392] Jones, M., Wahlstroem, E., Erdtman, S., and H. Tschofenig, [RFC8392] Jones, M., Wahlstroem, E., Erdtman, S., and H. Tschofenig,
"CBOR Web Token (CWT)", RFC 8392, DOI 10.17487/RFC8392, "CBOR Web Token (CWT)", RFC 8392, DOI 10.17487/RFC8392,
May 2018, <https://www.rfc-editor.org/info/rfc8392>. May 2018, <https://www.rfc-editor.org/info/rfc8392>.
[RFC8610] Birkholz, H., Vigano, C., and C. Bormann, "Concise Data [RFC8610] Birkholz, H., Vigano, C., and C. Bormann, "Concise Data
Definition Language (CDDL): A Notational Convention to Definition Language (CDDL): A Notational Convention to
Express Concise Binary Object Representation (CBOR) and Express Concise Binary Object Representation (CBOR) and
JSON Data Structures", RFC 8610, DOI 10.17487/RFC8610, JSON Data Structures", RFC 8610, DOI 10.17487/RFC8610,
June 2019, <https://www.rfc-editor.org/info/rfc8610>. June 2019, <https://www.rfc-editor.org/info/rfc8610>.
9.2. Informative References 11.2. Informative References
[I-D.ietf-rats-architecture] [I-D.ietf-rats-architecture]
Birkholz, H., Thaler, D., Richardson, M., Smith, N., and Birkholz, H., Thaler, D., Richardson, M., Smith, N., and
W. Pan, "Remote Attestation Procedures Architecture", Work W. Pan, "Remote Attestation Procedures Architecture", Work
in Progress, Internet-Draft, draft-ietf-rats-architecture- in Progress, Internet-Draft, draft-ietf-rats-architecture-
08, 8 December 2020, <http://www.ietf.org/internet-drafts/ 08, 8 December 2020, <http://www.ietf.org/internet-drafts/
draft-ietf-rats-architecture-08.txt>. draft-ietf-rats-architecture-08.txt>.
[I-D.ietf-rats-eat]
Mandyam, G., Lundblade, L., Ballesteros, M., and J.
O'Donoghue, "The Entity Attestation Token (EAT)", Work in
Progress, Internet-Draft, draft-ietf-rats-eat-06, 2
December 2020, <http://www.ietf.org/internet-drafts/draft-
ietf-rats-eat-06.txt>.
[IANA-CoAP-Content-Formats] [IANA-CoAP-Content-Formats]
IANA, "CoAP Content-Formats", 2021, IANA, "CoAP Content-Formats", 2021,
<https://www.iana.org/assignments/core-parameters>. <https://www.iana.org/assignments/core-parameters>.
[IANA-CWT] IANA, "CBOR Web Token (CWT) Claims", 2021, [IANA-CWT] IANA, "CBOR Web Token (CWT) Claims", 2021,
<https://www.iana.org/assignments/cwt/cwt.xhtml>. <https://www.iana.org/assignments/cwt/cwt.xhtml>.
[IANA-MediaTypes] [IANA-MediaTypes]
IANA, "Media Types", 2021, IANA, "Media Types", 2021,
<http://www.iana.org/assignments/media-types>. <http://www.iana.org/assignments/media-types>.
skipping to change at page 23, line 14 skipping to change at page 20, line 19
Appendix B. Example Appendix B. Example
The following example shows a PSA attestation token for an The following example shows a PSA attestation token for an
hypothetical system comprising two measured software components (a hypothetical system comprising two measured software components (a
boot loader and a trusted RTOS). The attesting device is in a boot loader and a trusted RTOS). The attesting device is in a
lifecycle state Section 3.3.1 of SECURED. The attestation has been lifecycle state Section 3.3.1 of SECURED. The attestation has been
requested from a client residing in the SPE: requested from a client residing in the SPE:
{ {
/ psa-profile / -75000: "PSA_IOT_PROFILE_1", / profile / 18: "http://arm.com/psa/2.0.0",
/ psa-client-id / -75001: 1, / psa-client-id / -75001: 1,
/ psa-lifecycle / -75002: 12288, / psa-lifecycle / -75002: 12288,
/ psa-implementation-id / -75003: h'50515253545556575051 / psa-implementation-id / -75003: h'50515253545556575051
52535455565750515253545556575051525354555657', 52535455565750515253545556575051525354555657',
/ psa-boot-seed / -75004: h'DEADBEEFDEADBEEFDEAD / psa-boot-seed / -75004: h'DEADBEEFDEADBEEFDEAD
BEEFDEADBEEFDEADBEEFDEADBEEFDEADBEEFDEADBEEF', BEEFDEADBEEFDEADBEEFDEADBEEFDEADBEEFDEADBEEF',
/ psa-certification-reference / -75005: "1234567890123", / psa-certification-reference / -75005: "1234567890123",
/ psa-software-components / -75006: [ / psa-software-components / -75006: [
{ {
/ measurement type / 1: "BL", / measurement type / 1: "BL",
skipping to change at page 23, line 38 skipping to change at page 20, line 43
F519200FF519200FF519200FF519200FF' F519200FF519200FF519200FF519200FF'
}, },
{ {
/ measurement type / 1: "PRoT", / measurement type / 1: "PRoT",
/ measurement value / 2: h'0506070805060708050607080506070 / measurement value / 2: h'0506070805060708050607080506070
805060708050607080506070805060708', 805060708050607080506070805060708',
/ signer ID / 5: h'519200FF519200FF519200FF519200F / signer ID / 5: h'519200FF519200FF519200FF519200F
F519200FF519200FF519200FF519200FF' F519200FF519200FF519200FF519200FF'
} }
], ],
/ psa-nonce / -75008: h'00010203000102030001020300010203 / nonce / 10: h'00010203000102030001020300010203
00010203000102030001020300010203', 00010203000102030001020300010203',
/ psa-instance-id / -75009: h'01A0A1A2A3A0A1A2A3A0A1A2A3A0A1A2 / ueid / 11: h'01A0A1A2A3A0A1A2A3A0A1A2A3A0A1A2
A3A0A1A2A3A0A1A2A3A0A1A2A3A0A1A2A3', A3A0A1A2A3A0A1A2A3A0A1A2A3A0A1A2A3',
/ psa-verification-service-indicator / -75010: "https://psa-ve / psa-verification-service-indicator / -75010: "https://psa-ve
rifier.org" rifier.org"
} }
The JWK representation of the IAK used for creating the COSE Sign1 The JWK representation of the IAK used for creating the COSE Sign1
signature over the PSA token is: signature over the PSA token is:
{ {
"kty": "EC", "kty": "EC",
skipping to change at page 24, line 21 skipping to change at page 21, line 21
"use": "enc", "use": "enc",
"kid": "1" "kid": "1"
} }
The resulting COSE object is: The resulting COSE object is:
18( 18(
[ [
/ protected / h'A10126', / protected / h'A10126',
/ unprotected / {}, / unprotected / {},
/ payload / h'AA3A000124F7715053415F494F545F50524F46494C / payload / h'AD127818687474703A2F2F61726D2E636F6D2F7073
455F313A000124F8013A000124F91930003A000124FA58205051525354555657 612F322E302E303A000124F8013A000124F91930003A000124FA582050515253
5051525354555657505152535455565750515253545556573A000124FB5820DE 545556575051525354555657505152535455565750515253545556573A000124
ADBEEFDEADBEEFDEADBEEFDEADBEEFDEADBEEFDEADBEEFDEADBEEFDEADBEEF3A FB5820DEADBEEFDEADBEEFDEADBEEFDEADBEEFDEADBEEFDEADBEEFDEADBEEFDE
000124FC6D313233343536373839303132333A000124FD82A30162424C025820 ADBEEF3A000124FC6D313233343536373839303132333A000124FD82A3016242
0001020400010204000102040001020400010204000102040001020400010204 4C02582000010204000102040001020400010204000102040001020400010204
055820519200FF519200FF519200FF519200FF519200FF519200FF519200FF51 00010204055820519200FF519200FF519200FF519200FF519200FF519200FF51
9200FFA3016450526F5402582005060708050607080506070805060708050607 9200FF519200FFA3016450526F54025820050607080506070805060708050607
08050607080506070805060708055820519200FF519200FF519200FF519200FF 0805060708050607080506070805060708055820519200FF519200FF519200FF
519200FF519200FF519200FF519200FF3A000124FF5820000102030001020300 519200FF519200FF519200FF519200FF519200FF0A5820000102030001020300
01020300010203000102030001020300010203000102033A00012500582101A0 01020300010203000102030001020300010203000102030B582101A0A1A2A3A0
A1A2A3A0A1A2A3A0A1A2A3A0A1A2A3A0A1A2A3A0A1A2A3A0A1A2A3A0A1A2A33A A1A2A3A0A1A2A3A0A1A2A3A0A1A2A3A0A1A2A3A0A1A2A3A0A1A2A33A00012501
00012501781868747470733A2F2F7073612D76657269666965722E6F7267', 781868747470733A2F2F7073612D76657269666965722E6F72673A00012500F6
/ signature / h'7C0FA38F80E5EA2A5C710A4BB37ABE63B26B25F17D 3A000124F7F63A000124FFF6',
B6BE9489587F9B3F8FEB80E0E410D8CDAAFAE5588024CB3E18D60C1F96CED9E0 / signature / h'8C92FDC99CFDB0016F27008744B3730266342D2881
6743824614019E99BF13FE' 861DC9A3F89E02394DE7F906EE2D1A3C164A59D580CDD7DFA077290CBFB55069
C55A5D9A2AE17FA31D2108'
] ]
) )
Contributors Contributors
We would like to thank the following colleagues for their We would like to thank the following colleagues for their
contributions: contributions:
* Laurence Lundblade * Laurence Lundblade
Security Theory LLC Security Theory LLC
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