Checkpoint 1's signing-body digest is included under a Merkle root signed by a separately operated witness. The returned receipt and two independently fetched copies agree; verification runs offline against an explicitly pinned witness key. This was demonstrated on September 7, 2026, ahead of the September 9 briefing.
-The response reports countersigned-observed. Whether a receipt carries a witness time or a signed grade is a property of that receipt rather than of the profile, so the verifier reports witness_time_established and grade_cryptographically_bound instead of asserting either. Both are false for the September 7 capture and stay false for it: that receipt's protected header is algorithm and tree profile only, and the witness signature covers that header, so a receipt carrying either field is a separately signed receipt rather than this one re-read. The receipt does not certify registry continuity. It authenticates inclusion of the signing-body digest, with the registry signature checked separately.
The response reports countersigned-observed. Whether a receipt carries a witness time or a signed grade is a property of that receipt rather than of the profile, so the verifier reports witness_time_established and grade_cryptographically_bound instead of asserting either. Both are false for the September 7 capture and stay false for it: that receipt's protected header is algorithm and tree profile only, and the witness signature covers that header, so a receipt carrying either field is a separately signed receipt rather than this one re-read. The witness deployed support for both fields on September 12, 2026, and that does not change this capture: it registers a checkpoint by a content-addressed entry hash and deduplicates on it, so re-submitting checkpoint 1 returns the original receipt. Because that hash is derived from the signed fields rather than the submitted bytes, reformatting the submission does not produce a new one either. A receipt carrying a witness time therefore requires a checkpoint the witness has not seen. The receipt does not certify registry continuity. It authenticates inclusion of the signing-body digest, with the registry signature checked separately.
No recurring witness submission, reciprocal witnessing, or second witness is claimed. Parallel independent witnesses remain a deployment choice; original records stay with their holders.
Receipt, key provenance and offline verification