K4 or K-4 may refer to: Military Daewoo K4, a South Korean automatic grenade launcher HMS K4, a 1915 British K class submarine K 4 or Norrland Dragoon Regiment, a Swedish Army cavalry regiment K
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 0x9cb727b53eb3cfba2a4b0485b39af17b6b822c764a5d9dcdf11e85384cb83521. Chain 2 (Bitcoin): anchored in block 954784 (2026-06-22T02:53:59Z). Bridge: the canonical record inside this Bitcoin proof contains the same CopyrightID. Verify: download https://artists.proofprofile.net/proofs/artist/fc9dcfb6-448e-4c6d-be71-5e080e1edfb7.json and https://artists.proofprofile.net/proofs/artist/fc9dcfb6-448e-4c6d-be71-5e080e1edfb7.ots, run `ots verify -f record.json proof.ots` (https://opentimestamps.org).