thumb|250px|Ossian playing his harp, by François Pascal Simon Gérard, 1801 thumb|Oisín and Niamh on their way to Tír na nÓg, illustration by Albert Herter, 1899 Oisín (), Osian, Ossian ( ), or anglic
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 0x6ff6268e023a112e18483d53cb331ec7de2967ff0b501716eb9cb5a49934d329. Chain 2 (Bitcoin): anchored in block 954784 (2026-06-22T02:53:59Z). Bridge: the canonical record inside this Bitcoin proof contains the same CopyrightID. Verify: download https://artists.proofprofile.net/proofs/artist/eb5373e8-6464-470c-be8a-a8cda3f4aa54.json and https://artists.proofprofile.net/proofs/artist/eb5373e8-6464-470c-be8a-a8cda3f4aa54.ots, the client at https://opentimestamps.org runs `ots verify -f record.json proof.ots`.