thumb|Pierre Lambert in 1988 in the city of Montpellier Pierre Lambert (; real name Pierre Boussel ; June 9, 1920 – January 16, 2008) was a French Trotskyist leader, who for many years acted as the
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 0x3b37aeccf345510c5220e4bca3c01226134b69fc9cbd9911e6be724586c072f5. Chain 2 (Bitcoin): anchored in block 953695 (2026-06-14T21:42:01Z). Bridge: the canonical record inside this Bitcoin proof contains the same CopyrightID. Verify: download https://artists.proofprofile.net/proofs/artist/71f1bac5-6aa5-419d-b180-d620a9a95456.json and https://artists.proofprofile.net/proofs/artist/71f1bac5-6aa5-419d-b180-d620a9a95456.ots, the client at https://opentimestamps.org runs `ots verify -f record.json proof.ots`.