thumb|Soundbox of a classical guitar A sound box or sounding box (sometimes written soundbox) is an open chamber in the body of a musical instrument which modifies the sound of the instrument and help
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
Dual-chain trust anchor. Chain 1 (CopyrightChains): CopyrightID 0xf64a9e94850ef83f9d7028f48e697b1efc7363c0006fd58e57ca8bc31080083a. Chain 2 (Bitcoin): anchored in block 953827 (2026-06-15T19:59:56Z). Bridge: the canonical record inside this Bitcoin proof contains the same CopyrightID. Verify: download https://artists.proofprofile.net/proofs/artist/ed8c07c8-d6ce-421d-ae8c-a9276f9c1de3.json and https://artists.proofprofile.net/proofs/artist/ed8c07c8-d6ce-421d-ae8c-a9276f9c1de3.ots, run `ots verify -f record.json proof.ots` (https://opentimestamps.org).