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Enterprise packed attestation guidance #1954

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merged 9 commits into from
Sep 24, 2024
14 changes: 13 additions & 1 deletion index.bs
Original file line number Diff line number Diff line change
Expand Up @@ -5750,7 +5750,7 @@ implementable by [=authenticators=] with limited resources (e.g., secure element
[=attestation trust path=].


### Packed Attestation Statement Certificate Requirements ### {#sctn-packed-attestation-cert-requirements}
### Certificate Requirements for Packed Attestation Statements ### {#sctn-packed-attestation-cert-requirements}

The attestation certificate MUST have the following fields/extensions:

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are both OPTIONAL as the status of many attestation certificates is available through authenticator metadata services.
See, for example, the FIDO Metadata Service [[FIDOMetadataService]].

### Certificate Requirements for Enterprise Packed Attestation Statements ### {#sctn-enterprise-packed-attestation-cert-requirements}
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There are two potential sources for Enterprise Attestestations in Packed format:

1. From a hardware device which is manufactured with a device-specific attestation statement and key
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2. Via a provisioned attestation statement, such as with a platform authenticator configured via managed policy

For attestation statements provisioned at manufacturing, the Extension OID `1.3.6.1.4.1.45724.1.1.2` (`id-fido-gen-ce-sernum`)
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You enumerate two cases just above, but then only mention one here. Are provisioned enterprise attestations forbidden from using this extension? Or can either use them?

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I'd raise to someone more familiar such as @ve7jtb

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We are still pending guidance here on usage for MDM-provisioned EAs. Since these can be dynamic (reprovisioned by the MDM or by switching which software provides the credentials), I would lean toward either saying this should not be used, or that it must indicate a persistent device identifier (and not some software value).

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will update to recommend against this for software-provisioned EAs

MUST be present, containing a unique serial number for the device as an OCTET STRING. The extension MUST NOT be marked as critical.
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As enterprise attestations are normally consumed by [=[RPS]=] which are looking for particular authenticators,
there MAY be additional extensions used to convey information based on prior agreement.

## TPM Attestation Statement Format ## {#sctn-tpm-attestation}

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