thumb|Machine-made watermark on a 19th century letter A watermark is an identifying image or pattern in paper that appears as varying shades of light and dark when viewed by either transmitted light o
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 0xd83eb1303ab591e99afa75fb34e8d70d9fdcaf91811793b04964b79d859f165a. Chain 2 (Bitcoin): anchored in block 953407 (2026-06-12T19:24:56Z). Bridge: the canonical record inside this Bitcoin proof contains the same CopyrightID. Verify: download https://artists.proofprofile.net/proofs/artist/08b04b91-bd07-4f3b-93d7-6f65146bc6a7.json and https://artists.proofprofile.net/proofs/artist/08b04b91-bd07-4f3b-93d7-6f65146bc6a7.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 0x070b1bfbaa2bce8478fd878ee27e2867f03baf9e7ac5b4abac7a3dc17d71e7ef. Chain 2 (Bitcoin): anchored in block 958761 (2026-07-19T20:01:57Z), 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/USSM19804938.
Dual-chain trust anchor. Chain 1 (CopyrightChains): CopyrightID 0x20aa9400071de2c0c8831cdd782b66b4d7247d4cb6a36e2a3802b7478b78b549. Chain 2 (Bitcoin): anchored in block 958060 (2026-07-14T20:39:42Z), 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/USSM19804940.
Dual-chain trust anchor. Chain 1 (CopyrightChains): CopyrightID 0x6ef8000a1ce52d448cc30bf3b9843ff361723f964a387411d90621c5b56de1cd. Chain 2 (Bitcoin): anchored in block 958991 (2026-07-21T12:08:55Z), 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/USSM19804942.
Dual-chain trust anchor. Chain 1 (CopyrightChains): CopyrightID 0x2ff3e8dca566e72ff013afffafccf56b7726dc0e130483d43a0e8e72eff82917. Chain 2 (Bitcoin): anchored in block 956725 (2026-07-05T01:12:41Z), 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/US1RR0400351.
Dual-chain trust anchor. Chain 1 (CopyrightChains): CopyrightID 0xc76e06a0f6f98a012c7867faa6386d2720571d9c39c04ff2729dcc9edacf663a. 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/US1RR0400355.
Dual-chain trust anchor. Chain 1 (CopyrightChains): CopyrightID 0xc5683accbfcbebee403053405ba1649f64169aedc1a7b144f46d7bcd65464a4b. Chain 2 (Bitcoin): anchored in block 956725 (2026-07-05T01:12:41Z), 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/US1RR0400357.
Dual-chain trust anchor. Chain 1 (CopyrightChains): CopyrightID 0x39152f9c72ca8678c87aaf273fe28cc27592708065d1cafec0a828dbf489f597. 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/US1RR0400361.
Dual-chain trust anchor. Chain 1 (CopyrightChains): CopyrightID 0xe24c29df8e0c1aeb94c7c7454c0d55f480953cd615ea126e8d0c76dec8345183. Chain 2 (Bitcoin): anchored in block 956772 (2026-07-05T10:01:46Z), 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/US1RR0500474.
Dual-chain trust anchor. Chain 1 (CopyrightChains): CopyrightID 0x64d13991d209c51ac3eee635fcb689d5388cac1fc082c31d205c7888d1ca7aad. Chain 2 (Bitcoin): anchored in block 958600 (2026-07-18T19:24:05Z), 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/US1RR0500475.
Dual-chain trust anchor. Chain 1 (CopyrightChains): CopyrightID 0x54a0d02887dcbedaa8f57520987c8c483c12c98aa237fea78a75643a49207401. Chain 2 (Bitcoin): anchored in block 958690 (2026-07-19T07:14:39Z), 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/US1RR0500476.
Dual-chain trust anchor. Chain 1 (CopyrightChains): CopyrightID 0xee84aab03e72078b33dde4b6a175c01ec30bdeb95d46b25d72259e660b4b5997. Chain 2 (Bitcoin): anchored in block 959058 (2026-07-21T23:25:49Z), 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/US1RR0500477.
Dual-chain trust anchor. Chain 1 (CopyrightChains): CopyrightID 0x79cbccb4f19c81daa5c38d21854c4f6e0d8af5afa6bc0f5ad06e2be3427ccdeb. Chain 2 (Bitcoin): anchored in block 958251 (2026-07-16T06:29:25Z), 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/US1RR0500479.
Dual-chain trust anchor. Chain 1 (CopyrightChains): CopyrightID 0xb0684bcc09b69348e19dfb64b3fc30b6d716ac44a6d547f79c84db9efc63fd72. Chain 2 (Bitcoin): anchored in block 958700 (2026-07-19T08:09:50Z), 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/US1RR0500483.
Dual-chain trust anchor. Chain 1 (CopyrightChains): CopyrightID 0x7a061c264752dec8e56369f87975ed125b6aaf7325d2e187cc555a786d8bbaa8. Chain 2 (Bitcoin): anchored in block 956772 (2026-07-05T10:01:46Z), 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/US1RR0500484.
Dual-chain trust anchor. Chain 1 (CopyrightChains): CopyrightID 0xec9cf2e489cd49d95a121ba8676444cb02572cf25bd1130f07501427e73d6c11. 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/US1RR0500486.
Dual-chain trust anchor. Chain 1 (CopyrightChains): CopyrightID 0x92f01db7eb86242ec1151489ac54cb47858a763f7ee7bd2e6d367353d37e5d36. Chain 2 (Bitcoin): anchored in block 956725 (2026-07-05T01:12:41Z), 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/US1RR0500487.
What We Mean When We Say "Watermark". 4 Suites