The Sketch was a British illustrated weekly journal. It ran for 2,989 issues between 1 February 1893 and 17 June 1959. It was published by the Illustrated London News Company and was primarily a socie
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 0xe1fa8a31af6b887a025658fa287bbd469cf634a42e5cf8ab67b2414da95d8e44. Chain 2 (Bitcoin): anchored in block 953741 (2026-06-15T04:44:49Z). Bridge: the canonical record inside this Bitcoin proof contains the same CopyrightID. Verify: download https://artists.proofprofile.net/proofs/artist/9ffbe47f-2a61-488f-b6a6-dba6b61e4312.json and https://artists.proofprofile.net/proofs/artist/9ffbe47f-2a61-488f-b6a6-dba6b61e4312.ots, the client at https://opentimestamps.org runs `ots verify -f record.json proof.ots`.