"Sirko" () is a Ukrainian folk tale (kazka) about a friendship between an old dog and a wolf. Plot summary The father of a family with a dog named Sirko casts the dog out after many years. Sirko t
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 0xfcde97bcf1b962784688275d28a889cc6f9b7620a636b243f8f28c07734f1602. Chain 2 (Bitcoin): anchored in block 954066 (2026-06-17T08:11:48Z). Bridge: the canonical record inside this Bitcoin proof contains the same CopyrightID. Verify: download https://artists.proofprofile.net/proofs/artist/7a11f8e4-d24b-4c00-b134-e3d3efb8abfa.json and https://artists.proofprofile.net/proofs/artist/7a11f8e4-d24b-4c00-b134-e3d3efb8abfa.ots, run `ots verify -f record.json proof.ots` (https://opentimestamps.org).