Mark Rivera (born May 24, 1953) is an American saxophonist, multi-instrumentalist, singer, and musical director who is mostly known for his work with Billy Joel. In addition to playing soprano, alto,
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 0x666b9a7462a813da46ee0094f764e1d74c2e3d90286ab31fa2e1a0794ce4e7ee. 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/65767a91-7a5d-470f-b707-e377a6a3651d.json and https://artists.proofprofile.net/proofs/artist/65767a91-7a5d-470f-b707-e377a6a3651d.ots, run `ots verify -f record.json proof.ots` (https://opentimestamps.org).