Attestation Notes

Attestation Notes

wolfSPDM supports SPDM attestation through both measurement retrieval and challenge authentication.

Measurement attestation (GET_MEASUREMENTS)

Primary API:

int wolfSPDM_GetMeasurements(WOLFSPDM_CTX* ctx, byte measOperation,
    int requestSignature);

Behavior:

• requestSignature=1: requests signed measurements; verifies signature when verification support is compiled in
• requestSignature=0: retrieves unsigned measurements (informational)

Signature verification (measurements and CHALLENGE_AUTH) uses whichever asymmetric algorithm was negotiated — ECDSA P-384 or, on SPDM 1.4 with ML-DSA built in, ML-DSA-44/65/87. See Post-Quantum ML-DSA.

Result access:

• wolfSPDM_GetMeasurementCount
• wolfSPDM_GetMeasurementBlock

Relevant return codes:

• WOLFSPDM_SUCCESS
• WOLFSPDM_E_MEAS_NOT_VERIFIED
• WOLFSPDM_E_MEAS_SIG_FAIL
• WOLFSPDM_E_MEASUREMENT

Sessionless challenge attestation (CHALLENGE_AUTH)

Primary API:

int wolfSPDM_Challenge(WOLFSPDM_CTX* ctx, int slotId, byte measHashType);

Typical prerequisite state:

• Version/capabilities/algorithms negotiated
• Digest and cert chain retrieved

Trust anchor handling

Load trusted CA material with:

int wolfSPDM_SetTrustedCAs(WOLFSPDM_CTX* ctx, const byte* derCerts,
    word32 derCertsSz);

wolfSPDM_SetTrustedCAs currently accepts a single DER certificate buffer for root-hash matching.

Feature toggles

• NO_WOLFSPDM_MEAS disables measurements
• NO_WOLFSPDM_MEAS_VERIFY disables measurement signature verification
• NO_WOLFSPDM_CHALLENGE disables challenge API

For deeper measurement details and test examples, see docs/ATTESTATION.md.