fix(verify): verify SNP report signature + VCEK chain (cmcp#370)#386
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imran-siddique wants to merge 2 commits into
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fix(verify): verify SNP report signature + VCEK chain (cmcp#370)#386imran-siddique wants to merge 2 commits into
imran-siddique wants to merge 2 commits into
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…cp#370) Previously cmcp bound a confirmation key into report_data and checked that binding, but never verified the attestation report was genuinely silicon-signed, so the binding was unfalsifiable. This adds, fail-closed: 1. SNP report ECDSA-P384/SHA-384 signature verification against the VCEK, and 2. VCEK -> ASK -> ARK cert-chain verification up to a caller-pinned AMD ARK. No network at verify time: the VCEK/ASK/ARK chain travels with the claim (passport model); the ARK is pinned out of band via trusted_ark_pem. Tested against a synthetic ARK/ASK/VCEK chain: valid verifies, tampered report fails closed, wrong pinned ARK fails closed. One test skipped pending a real Azure SNP fixture (capture script in the notes store). TDX (DCAP) and TPM EK paths are follow-ups; TDX also needs the real-quote report_data offset for cmcp#371. Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>
… behavior (cmcp#370) The chain is no longer 'always unverified'; with no cert chain + pinned ARK it stays unverified with the new detail string, and with them supplied it now verifies (test_snp_signature_verify.py). Adjust the stale assertion.
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Draft. Closes the keystone hole from our attested-TLS POV review: the report_data binding was unfalsifiable because we never verified the report was silicon-signed.
What this does (SNP, fail-closed)
trusted_ark_pem), handling AMD's RSA-PSS cert signatures and EC.verify_trace_claim; also makes the binding fail-closed (advances security: make cnf.jwk<->report_data binding fatal for SEV-SNP/TDX; fix TDX report_data offset #371).Tests
tests/unit/test_snp_signature_verify.py: 5 pass (valid verifies; tampered report fails closed; wrong pinned ARK fails closed), 1 skipped pending a real Azure SNP fixture (capture script:Product/Platform/attestation-capture/capture-snp-azure.shin the notes store).Not in this PR (follow-ups)
report_dataoffset (cmcp#371) — needs the Azure TDX fixture.Note: the original implementation run stalled mid-stream; I reviewed the diff and ran the tests before committing.