WitnessKit (Python) · v0

Tamper-evident audit trails for AI agents. Every action becomes a signed, hash-chained log entry; any later tamper is detected and located.

v0, experimental, unaudited. Not yet on PyPI — install from source.

Signing uses the vetted cryptography library and RFC 8785 canonicalization; pure-Python fallbacks keep it runnable with zero deps. The signing key stays local.

Install

Not yet on PyPI (v0). From source:

git clone https://github.com/major-matters/witnesskit
pip install -e witnesskit/python

Or drop the witnesskit/ folder next to your code.

Quick start

from witnesskit import Chain, generate_keypair, verify_chain

key, public_key = generate_keypair()
trail = Chain(key, actor="agent-7")
trail.append("tool_call", {"tool": "search", "query": "running shoes"})
trail.append("payment",   {"merchant": "Fleet Feet", "amount": 240, "currency": "USD"})

verdict = verify_chain(trail.to_json(), trusted_keys=[public_key])
print(verdict["valid"], verdict["reason"])   # True  chain intact

A tampered entry returns {"valid": False, "broken_at": <index>, "reason": ...}.

Security model

A valid signature proves integrity, not authority — pin the issuer with trusted_keys; without it (or allow_unverified_issuer=True) verification fails closed. verify_chain never throws. Tamper-evident, not tamper-proof; see ../SECURITY.md.

Tests

PYTHONPATH=. python3 tests/test_witnesskit.py      # unit (no pytest needed)
PYTHONPATH=. python3 tests/test_properties.py    # property-based (needs hypothesis)

License

MIT.