One key, many objects

The KEYSTONE evidence key signs CODEGUARD receipts, Black Box seals and ledger records. If a verifier only checks "is the signature good?", any of those can be passed off as another.

That is what we found on 2026-11-02: a genuine Black Box seal (whose agent field anyone can choose when recording) verified as a "valid" decision receipt, on the server and in our own published checker. It had no decision field, so a careless consumer would read "valid" and move on.

The fix is domain separation: each verifier first checks the object's schema and required fields, and refuses everything else. Approval tokens gained a typ claim for the same reason. Try it in the lab: the last button presents a real seal as a receipt.

FIRME AI CORPORATION · CAIN-42 is a Byzantine trust fabric. Numbers marked "our own check" were run by us, not by an independent party. Nothing on these pages is a certification.