SEF may refer to: Sankara Eye Foundation, a non-profit that works for eradicating curable blindness in India Serviço de Estrangeiros e Fronteiras, Portuguese Border and Alien Service Sinfonia Educ
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 0x045f32a0d11b64a123568f38f8e4a1f6719b4aa1fc26a3768464794e852f0181. Chain 2 (Bitcoin): anchored in block 954069 (2026-06-17T08:30:25Z). Bridge: the canonical record inside this Bitcoin proof contains the same CopyrightID. Verify: download https://artists.proofprofile.net/proofs/artist/792c445b-67be-46e4-bc2e-dbae78475c9b.json and https://artists.proofprofile.net/proofs/artist/792c445b-67be-46e4-bc2e-dbae78475c9b.ots, run `ots verify -f record.json proof.ots` (https://opentimestamps.org).