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 0x1b599cf9e281389c5b39bab6d3501cd0ea2843dec4ccba274518a0677720ad4f. Chain 2 (Bitcoin): anchored in block 953618 (2026-06-14T09:16:10Z). Bridge: the canonical record inside this Bitcoin proof contains the same CopyrightID. Verify: download https://artists.proofprofile.net/proofs/artist/1d7ec7f9-470f-43e2-a828-1a600e1c2958.json and https://artists.proofprofile.net/proofs/artist/1d7ec7f9-470f-43e2-a828-1a600e1c2958.ots, run `ots verify -f record.json proof.ots` (https://opentimestamps.org).
1. Confirm isrcCode identifies the recording in the pre-2022 source corpus and cc-db-prod record 2. GET OTSVerificationAPI → server-side canonical-record, hash, and attestation checks must pass 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. Confirm CopyrightID is the CopyrightChains transaction hash 5. If all match: the cc-db-prod record is independently anchored on Bitcoin at OTSTimestamp 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 0x6ef837484459eb211cab39d5b2fc85e735f5295c23b658ff9eae24fe7259ad28. Chain 2 (Bitcoin): anchored in block 958063 (2026-07-14T21:07:34Z), registered by our registry partner. The server verifies the private canonical record against OTSHash without exposing internal provider keys. Confirm the public ISRC, CopyrightID, and Bitcoin evidence via https://artists.proofprofile.net/api/v1/bot/ots/verify/track/KRA112200017.
Dual-chain trust anchor. Chain 1 (CopyrightChains): CopyrightID 0xd1367d60a7ebfe041f17587accee11f7fc7983b6c8cfacd8468064b2bbd309bb. Chain 2 (Bitcoin): anchored in block 958211 (2026-07-15T23:24:33Z), registered by our registry partner. The server verifies the private canonical record against OTSHash without exposing internal provider keys. Confirm the public ISRC, CopyrightID, and Bitcoin evidence via https://artists.proofprofile.net/api/v1/bot/ots/verify/track/JPU902303755.
Dual-chain trust anchor. Chain 1 (CopyrightChains): CopyrightID 0x338f5c7751c69bbb9a8387f09029bcc129f3d299fe4f3a77dd94fc95ff30897b. Chain 2 (Bitcoin): anchored in block 958714 (2026-07-19T09:51:44Z), registered by our registry partner. The server verifies the private canonical record against OTSHash without exposing internal provider keys. Confirm the public ISRC, CopyrightID, and Bitcoin evidence via https://artists.proofprofile.net/api/v1/bot/ots/verify/track/JPU902303756.
Dual-chain trust anchor. Chain 1 (CopyrightChains): CopyrightID 0x961a33db46c778502be57bcc6f0d42261d0b923f113cad6e7c4c305feba98a01. Chain 2 (Bitcoin): anchored in block 958951 (2026-07-21T02:01:41Z), registered by our registry partner. The server verifies the private canonical record against OTSHash without exposing internal provider keys. Confirm the public ISRC, CopyrightID, and Bitcoin evidence via https://artists.proofprofile.net/api/v1/bot/ots/verify/track/JPU902303758.
Dual-chain trust anchor. Chain 1 (CopyrightChains): CopyrightID 0x5e2b00269d2027a97e068eeaa501b0b03c91a9011c8002c82347e0c0165cb3da. Chain 2 (Bitcoin): anchored in block 958340 (2026-07-17T00:53:26Z), registered by our registry partner. The server verifies the private canonical record against OTSHash without exposing internal provider keys. Confirm the public ISRC, CopyrightID, and Bitcoin evidence via https://artists.proofprofile.net/api/v1/bot/ots/verify/track/KRA252402369.
Dual-chain trust anchor. Chain 1 (CopyrightChains): CopyrightID 0x3d3daf5aa2bd6fd72bc7bc53a27603fd5d7b982852d3fc09ea4ad87bc378e146. Chain 2 (Bitcoin): anchored in block 956545 (2026-07-03T19:59:51Z), registered by our registry partner. The server verifies the private canonical record against OTSHash without exposing internal provider keys. Confirm the public ISRC, CopyrightID, and Bitcoin evidence via https://artists.proofprofile.net/api/v1/bot/ots/verify/track/KRA252402371.
Dual-chain trust anchor. Chain 1 (CopyrightChains): CopyrightID 0x92a357e8011a50a45a1ee80ddbfa0a5d05faae70caa672f79a0202c1b5153e35. Chain 2 (Bitcoin): anchored in block 956474 (2026-07-03T08:56:35Z), registered by our registry partner. The server verifies the private canonical record against OTSHash without exposing internal provider keys. Confirm the public ISRC, CopyrightID, and Bitcoin evidence via https://artists.proofprofile.net/api/v1/bot/ots/verify/track/JPU902404083.