Tan or TAN may refer to: Math Tangent function, a trigonometric function often referred to as tan. Arts and entertainment Tan, a 1989 album by the Polish rock band Kult "Tan", a 2026 song by th
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 0xbee83396a7c4f81e55f2f5053d33d07776067ea301293c3e13888fd6a83bf5e8. Chain 2 (Bitcoin): anchored in block 953407 (2026-06-12T19:24:56Z). Bridge: the canonical record inside this Bitcoin proof contains the same CopyrightID. Verify: download https://artists.proofprofile.net/proofs/artist/0288227a-a6cc-405d-af6a-18cb8f5ac6ff.json and https://artists.proofprofile.net/proofs/artist/0288227a-a6cc-405d-af6a-18cb8f5ac6ff.ots, run `ots verify -f record.json proof.ots` (https://opentimestamps.org).