FK or fk may refer to: Arts and entertainment Fox Kids, an American TV programming block (1990–2002) Funky Kong, a 1994 video game character Language Finders keepers (English adage) 'Footbal
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 0xcd520af92db6fff73a677f527b31f128853c3ce066e203271069e9e7c332c224. Chain 2 (Bitcoin): anchored in block 953817 (2026-06-15T18:10:31Z). Bridge: the canonical record inside this Bitcoin proof contains the same CopyrightID. Verify: download https://artists.proofprofile.net/proofs/artist/fbf7f60a-efcb-483b-80a9-a2d70c6c8c25.json and https://artists.proofprofile.net/proofs/artist/fbf7f60a-efcb-483b-80a9-a2d70c6c8c25.ots, run `ots verify -f record.json proof.ots` (https://opentimestamps.org).