1. Compute SHA-256 of OTSCanonicalRecord value → must equal OTSHash 2. Open OTSProofURL → extract Bitcoin block number → must equal OTSBitcoinBlock 3. GET OTSBitcoinBlockVerifyURL → returns the Bitcoin block hash at height OTSBitcoinBlock; GET https://blockstream.info/api/block/{that hash} → its timestamp must match OTSTimestamp 4. Read CopyrightID inside OTSCanonicalRecord → must equal the CopyrightID above 5. GET OTSVerificationAPI → pre-computed 6-check result from server 6. If all match: this entity was registered on CopyrightChains at OTSTimestamp, independently verifiable on Bitcoin Note: an OTS proof may carry multiple Bitcoin attestations; OTSBitcoinBlock is the earliest confirmed one — a later attestation inside the proof corroborates it and is not a mismatch
Dual-chain trust anchor. Chain 1 (CopyrightChains): CopyrightID 0x7a35f71e6e8fff90ca08f6c6bb403bd5f3dfed314732e36fcc0910d8d3d9b28e. Chain 2 (Bitcoin): anchored in block 954346 (2026-06-19T03:51:26Z). Bridge: the canonical record inside this Bitcoin proof contains the same CopyrightID. Verify: download https://artists.proofprofile.net/proofs/artist/96ee1432-a6b7-464a-b270-139e98f1e935.json and https://artists.proofprofile.net/proofs/artist/96ee1432-a6b7-464a-b270-139e98f1e935.ots, the client at https://opentimestamps.org runs `ots verify -f record.json proof.ots`.
Zieleński: Offertoria et Communiones Totius Anni
Zielenski: Opera Omnia, Vol. 1 - Offertoria Totius Anni