What the format of sample attestation report?

[cowbon]

Following up #73, is there a documentation explaining the bit fields of the attestation report format? I've checked Hopper Single GPU Attestation Example and GPU Claims. None of them contain the information on the bit range of each field.

[amshinde]

Thanks for raising this, and sorry for the delayed response.
The GPU attestation report follows the DMTF SPDM 1.1 GET_MEASUREMENT message format. The canonical reference for the wire format is the
https://www.dmtf.org/standards/spdm.

In the meantime, the field layouts are documented directly in the parsing code within this repo:

• Request message (first 37 bytes):
  https://github.com/NVIDIA/nvtrust/blob/main/guest_tools/gpu_verifiers/local_gpu_verifier/src/verifier/attestation/spdm_msrt_req_msg.py —
  defines SPDMVersion (1B), RequestResponseCode (1B), Param1 (1B), Param2 (1B), Nonce (32B), SlotIDParam (1B)
• Response message (byte 37+):
  https://github.com/NVIDIA/nvtrust/blob/main/guest_tools/gpu_verifiers/local_gpu_verifier/src/verifier/attestation/spdm_msrt_resp_msg.py —
  includes a docstring with full byte offset table and field sizes
• Measurement record and opaque data TLV types: defined in the same response message module, with 30+ opaque field type constants

All multi-byte fields are little-endian.

We'll work towards adding a standalone format documentation file to the repo so this information is easier to find without reading the source. Linking #73 as well since it's the same ask.