DAC may refer to: Businesses and organisations DacEasy, originally Dac Software, Inc. Danish Architecture Centre, an international cultural attraction Defense Ammunition Center (United States), of
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 0xa50623d355ed287398ddb1081833251ad218b849371924564d5d28d6ed98c691. Chain 2 (Bitcoin): anchored in block 954131 (2026-06-17T19:19:19Z). Bridge: the canonical record inside this Bitcoin proof contains the same CopyrightID. Verify: download https://artists.proofprofile.net/proofs/artist/7da75eaa-55c6-4382-bfd5-42be86d69c28.json and https://artists.proofprofile.net/proofs/artist/7da75eaa-55c6-4382-bfd5-42be86d69c28.ots, run `ots verify -f record.json proof.ots` (https://opentimestamps.org).