Date: August 13, 2026
The verifier for cybiont's signed AI response records is now public under the MIT licence at
cybiont/device-presence-bound-record.
standalone_verify.py is one readable Python file. Its runtime dependencies are the Python standard
library and cryptography; it has no network capability and needs no cybiont service to check a
retained record offline, including after the original device and signing process are unavailable.
The repository includes fixed-seed known-answer test vectors and nineteen named refusal cases. The cases deliberately alter signatures, signed material, trust inputs, claim boundaries, package membership and verification policy, then require the verifier to name the corresponding refusal.
What a record establishes, and what it does not, arrives as fields in the verifier's own output — before you have read a word of ours.