How to verify an LLM agent's audit log without the decryption key

Description and use

Verifying an LLM agent’s audit log integrity without decrypting it, by checking header hashes and an external anchor.

Verifying that an LLM agent’s audit log has not been tampered with without decrypting its contents or revealing the decryption key.

The verifier confirms log integrity without decrypting bodies, detects tampering or truncation, and provides exit codes suitable for CI integration.

Install Palimpsests via pip and run the demo to generate a deterministic audit log.
Use palimpsests pala verify <file> to check internal consistency of the log headers and body hashes.
Extract the head hash from the verification output and supply it as an anchor with --anchor to detect truncation or replacement.
Tamper with a byte in the log file and rerun verification to see how the tool reports the specific link break.
Interpret the exit codes: 0 for success, 1 for integrity failure, 2 for incomplete checks.

The verifier walks the headers one by one and compares each body with the digest stored for it. It never decrypts a body, so it never needs the key.

Exit code 0. No key was used at any point.

The log implementation has not been through an independent penetration test yet.