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Add Evidence Claims Certificate Extension
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tireddy2 authored Jun 26, 2024
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Expand Up @@ -58,6 +58,13 @@ author:
name: Hannes Tschofenig
organization: Siemens
email: [email protected]
-
fullname: Tirumaleswar Reddy
organization: Nokia
city: Bangalore
region: Karnataka
country: India
email: "[email protected]"
-
ins: M. Wiseman
name: Monty Wiseman
Expand All @@ -76,7 +83,14 @@ informative:
RFC4211:
RFC5912:
RFC9344:
RFC6268:
I-D.ietf-lamps-csr-attestation:
X.680:
title: "Information technology -- Abstract Syntax Notation One (ASN.1): Specification of basic notation"
author:
org: ITU-T
date: false
target: https://www.itu.int/rec/T-REC-X.680

--- abstract

Expand Down Expand Up @@ -753,6 +767,89 @@ appraisal policy of claims to look for, and where appropriate the expected
values (for example, FipsMode: true), and any additional claims that may be in the
evidence SHOULD be ignored.

# Evidence Claims Certificate Extension {#extclaims-extension}

This section specifies the syntax and semantics of the Evidence Claims certificate extension which
provides a list of claims associated with the certificate subject appraised by the CA.

The Evidence Claims certificate extension MAY be included in public key certificates [RFC5280].
The Evidence Claims certificate extension MUST be identified by the following object identifier:

~~~~
id-pe-evidenceclaims OBJECT IDENTIFIER ::=
{ iso(1) identified-organization(3) dod(6) internet(1)
security(5) mechanisms(5) pkix(7) id-pe(1) 34 }
~~~~

This extension MUST NOT be marked critical.

The Evidence Claims extension MUST have the following syntax:

~~~~
EvidenceClaims ::= SET SIZE (1..MAX) OF EVIDENCE-CLAIM
~~~~

The EvidenceClaims represents an unsigned version of the evidence claims appraised by the CA.
It MUST contain at least one claim. The CA may include in their certificate profile a
list of verified evidence claims (identified by OID) that MAY be copied from the CSR to
the certificate, while any other claims MUST NOT be copied.

The extension MUST NOT reveal any privacy-sensitive information beyond confirming that:

* The evidence was appraised by the CA
* The private key is non-exportable.
* The cryptographic module was booted in FIPS mode.
* The keys have a defined expiry.
* Any other information that indicates the private key is stored in a safe environment.

This ensures that the certificate contains only essential information necessary for
security verification. No additional information should be included to protect the privacy
of the Attester. Avoiding unnecessary claims also mitigates the risk of targeted attacks, where an
attacker could exploit knowledge of hardware versions, models, etc.

## ASN.1 Module {#extclaims-asn}

This section provides an ASN.1 Module {{X.680}} for the Evidence Claims
certificate extension, and it follows the conventions established in
{{RFC5912}} and {{RFC6268}}.

~~~~
<CODE BEGINS>
EvidenceClaimsCertExtn
{ iso(1) identified-organization(3) dod(6) internet(1)
security(5) mechanisms(5) pkix(7) id-mod(0)
id-mod-evidenceclaims(TBD) }

DEFINITIONS IMPLICIT TAGS ::=
BEGIN

IMPORTS
EXTENSION
FROM PKIX-CommonTypes-2009 -- RFC 5912
{ iso(1) identified-organization(3) dod(6) internet(1)
security(5) mechanisms(5) pkix(7) id-mod(0)
id-mod-pkixCommon-02(57) } ;

-- Evidence Claims Certificate Extension

ext-EvidenceClaims EXTENSION ::= {
SYNTAX EvidenceClaims
IDENTIFIED BY id-pe-evidenceclaims }

-- EvidenceClaims Certificate Extension OID

id-pe-evidenceclaims OBJECT IDENTIFIER ::=
{ iso(1) identified-organization(3) dod(6) internet(1)
security(5) mechanisms(5) pkix(7) id-pe(1) 34 }

-- Evidence Claims Certificate Extension Syntax

EvidenceClaims ::= SET SIZE (1..MAX) OF EVIDENCE-CLAIM

END
<CODE ENDS>
~~~~

# Implementation Considerations

## API for requesting evidence from an attesting device
Expand Down Expand Up @@ -845,6 +942,7 @@ The Key Claims are:
~~~



# Security Considerations {#sec-cons}

This specification re-uses the claims from the EAT specification and
Expand Down Expand Up @@ -878,6 +976,18 @@ may be worthy of additional appraisal.

TBD: OIDs for all the claims listed in this document.

## OIDs for Evidence Claims Certificate Extension

For the EvidenceClaims certificate extension in {{extclaims-extension}},
IANA is requested to assign an object identifier (OID) for the certificate extension.
The OID for the certificate extension should be allocated in the "SMI
Security for PKIX Certificate Extension" registry (1.3.6.1.5.5.7.1).

For the ASN.1 Module in {{extclaims-asn}}, IANA is requested to assign an
object identifier (OID) for the module identifier. The OID for the
module should be allocated in the "SMI Security for PKIX Module
Identifier" registry (1.3.6.1.5.5.7.0).

--- back

# Acknowledgements
Expand Down

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