CU or cu may refer to: Businesses and organizations CU (store), a chain of South Korean convenience stores Customs union, a type of intergovernmental trade bloc ChristianUnion, a political party in
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 0xaa38272bbe92edc3de98a476c2fcee3f935153a161dd725630076fa90932addf. Chain 2 (Bitcoin): anchored in block 954693 (2026-06-21T11:50:32Z). Bridge: the canonical record inside this Bitcoin proof contains the same CopyrightID. Verify: download https://artists.proofprofile.net/proofs/artist/e9c7e024-bc16-450a-90d7-2005011d4b3b.json and https://artists.proofprofile.net/proofs/artist/e9c7e024-bc16-450a-90d7-2005011d4b3b.ots, run `ots verify -f record.json proof.ots` (https://opentimestamps.org).