thumb|Estoc The French estoc is a type of sword, also called a tuck in English, in use from the 14th to the 17th century. It is characterized by a cruciform hilt with a grip for two-handed use and a
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 0xd717f122ff2ac78b96809b792ad39db6ca66967e106612382e0bb30007fe8f42. Chain 2 (Bitcoin): anchored in block 954533 (2026-06-20T08:57:02Z). Bridge: the canonical record inside this Bitcoin proof contains the same CopyrightID. Verify: download https://artists.proofprofile.net/proofs/artist/a5bd71c0-cde9-42b0-8fe5-7abdf21077c5.json and https://artists.proofprofile.net/proofs/artist/a5bd71c0-cde9-42b0-8fe5-7abdf21077c5.ots, run `ots verify -f record.json proof.ots` (https://opentimestamps.org).