thumb|upright=1.25|New York's 21 Club was a Prohibition-era speakeasy. A speakeasy, also called a beer flat, blind pig, or blind tiger, was an illicit establishment that sold alcoholic beverages. 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 0x4c98df58f040d4b1c6ec4b1b6fb00bb2f24585b09c6b2b6bc72026fa4a01a655. Chain 2 (Bitcoin): anchored in block 954025 (2026-06-17T00:32:47Z). Bridge: the canonical record inside this Bitcoin proof contains the same CopyrightID. Verify: download https://artists.proofprofile.net/proofs/artist/386bf865-7953-49c0-9ae6-c8d677a6e654.json and https://artists.proofprofile.net/proofs/artist/386bf865-7953-49c0-9ae6-c8d677a6e654.ots, run `ots verify -f record.json proof.ots` (https://opentimestamps.org).