Sina may refer to: Relating to China Chin (China), or Sina (), old Chinese form of the Sanskrit name Cina () Shina (word), or Sina (), archaic Japanese word for China Sinae, Latin name for China
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 0xa3f4515939383c27c9e6a22bfe563bdc8d66e2a5a512878b09bc6f60bf173c4d. Chain 2 (Bitcoin): anchored in block 953778 (2026-06-15T11:57:35Z). Bridge: the canonical record inside this Bitcoin proof contains the same CopyrightID. Verify: download https://artists.proofprofile.net/proofs/artist/b7a17e38-8ab0-4ce0-b9e9-52d502d61dc0.json and https://artists.proofprofile.net/proofs/artist/b7a17e38-8ab0-4ce0-b9e9-52d502d61dc0.ots, run `ots verify -f record.json proof.ots` (https://opentimestamps.org).