thumb|right|Two child sisters, the elder tending to the younger . thumb|The Game of Chess (1555) by Sofonisba Anguissola (It depicts her sisters Lucia (left), Minerva (right) and Europa (middle) Angui
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 0x79d5db1a292d92dfc19a8d680fb537d0cc3b2c23548be9130332ad85ebb9d5ef. Chain 2 (Bitcoin): anchored in block 954667 (2026-06-21T07:29:20Z). Bridge: the canonical record inside this Bitcoin proof contains the same CopyrightID. Verify: download https://artists.proofprofile.net/proofs/artist/ba173323-0c9f-462e-9591-796e45c39650.json and https://artists.proofprofile.net/proofs/artist/ba173323-0c9f-462e-9591-796e45c39650.ots, run `ots verify -f record.json proof.ots` (https://opentimestamps.org).