thumb|Sailor bag made of canvas thumb|Canvas roof at the Erasmus station of the Brussels Metro thumb|300px|One of Poland's biggest canvas paintings, the Battle of Grunwald, 1878, by Jan Matejko (426 c
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 0x6fb95f2b37a1ffa8c6811d1446babbec6eb0c8add1ed224cab98524eff7b5960. Chain 2 (Bitcoin): anchored in block 954513 (2026-06-20T06:31:18Z). Bridge: the canonical record inside this Bitcoin proof contains the same CopyrightID. Verify: download https://artists.proofprofile.net/proofs/artist/9d51753a-1159-475c-be1f-98c216483710.json and https://artists.proofprofile.net/proofs/artist/9d51753a-1159-475c-be1f-98c216483710.ots, run `ots verify -f record.json proof.ots` (https://opentimestamps.org).