thumb|Sjoerd Hofstra: Boys returning from their initiation in the Poro. Panguma, Sierra Leone, 1936 The Poro, or Purrah or Purroh, is a men's secret society in Sierra Leone, Liberia, Guinea, and the I
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 0x9d08c5883a6c7dedf4404d16eada6d8630b98975907a73c7062abf57d8027fed. Chain 2 (Bitcoin): anchored in block 954010 (2026-06-16T21:41:36Z). Bridge: the canonical record inside this Bitcoin proof contains the same CopyrightID. Verify: download https://artists.proofprofile.net/proofs/artist/33ef1990-c1ae-4c8c-bead-6019c8922545.json and https://artists.proofprofile.net/proofs/artist/33ef1990-c1ae-4c8c-bead-6019c8922545.ots, the client at https://opentimestamps.org runs `ots verify -f record.json proof.ots`.