Disclosed and Fixed: Project Veraison's TPM Reference Schemes Accept Replayed Attestation Quotes Because Nonce Freshness Is Not Enforced

arXiv 2608.03534·medium signalXBlueskyLinkedInCopy link

Chasing the problem that an AI agent's signed action log proves which key wrote a record but not what runtime produced it, the authors bind an Action Evidence Package outcome digest into a hardware-rooted TPM quote and push it end-to-end through a conformant Project Veraison RATS Verifier (RFC 9334). Good evidence appraises as affirming while an outcome swap or one-byte signature tamper yields contraindicated — but they found the reference scheme does not enforce challenge-nonce freshness, so a replayed quote still appraises as affirming. They responsibly disclosed it, supply an upstreamable two-part fix, and validate that with the fix active the same valid quote flips to contraindicated on replay.