NDF or ndf may refer to: Arts and entertainment , a German film production company; formed 1947 Neutral-density filter, in photography Finance Non-deliverable forward Nordic Development Fund
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
Dual-chain trust anchor. Chain 1 (CopyrightChains): CopyrightID 0x31d638f2cdc2ae2d9bf2318974f6b162d6aab4abe48b3be35e8d177ff1f73743. Chain 2 (Bitcoin): anchored in block 954516 (2026-06-20T07:04:44Z). Bridge: the canonical record inside this Bitcoin proof contains the same CopyrightID. Verify: download https://artists.proofprofile.net/proofs/artist/9f63527f-ac8c-494e-b7ae-bef712ff2f63.json and https://artists.proofprofile.net/proofs/artist/9f63527f-ac8c-494e-b7ae-bef712ff2f63.ots, run `ots verify -f record.json proof.ots` (https://opentimestamps.org).
Since We Last Met (Ricardo Villalobos Remixes)