EX-3 was a Spanish mákina group composed of David Amo, Alex Castellano, and Julio Navas. They are known for being one of the most representative groups of the 90's Spanish "Mákina" phenomenon, at the
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 0xa9ed9a4751e46ee02bbbda078eeb016ee84cf1559e546e139cd83752c506ab98. Chain 2 (Bitcoin): anchored in block 954647 (2026-06-21T04:36:58Z). Bridge: the canonical record inside this Bitcoin proof contains the same CopyrightID. Verify: download https://artists.proofprofile.net/proofs/artist/d7ad3862-1f48-40e8-9223-7e114b99a19a.json and https://artists.proofprofile.net/proofs/artist/d7ad3862-1f48-40e8-9223-7e114b99a19a.ots, run `ots verify -f record.json proof.ots` (https://opentimestamps.org).