FourPlay String Quartet are an Australian string quartet from Sydney, formed in 1995 and renowned for playing music not typically associated with the format. FourPlay's members include brothers Tim H
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 0x58b5ea6dd8d8bb0da9d2f69db5b488bdf0ad7e45c387c2a0d35bdbdb3992f2ce. 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/a05d3d68-3722-4213-8e2b-a0d3ae2e857d.json and https://artists.proofprofile.net/proofs/artist/a05d3d68-3722-4213-8e2b-a0d3ae2e857d.ots, run `ots verify -f record.json proof.ots` (https://opentimestamps.org).
Digital Manipulation: the FourPlay Remix Project