Leiden ( ; ; in English and archaic Dutch also Leyden) is a city and municipality in the province of South Holland, Netherlands. The municipality of Leiden has a population of 127,046 (31 January 2023
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 0x95ed7a25a2b82ce2938ca2eddcb7586c7751d8e8c88a8fd839935e8bfe23525e. Chain 2 (Bitcoin): anchored in block 953408 (2026-06-12T19:28:13Z). Bridge: the canonical record inside this Bitcoin proof contains the same CopyrightID. Verify: download https://artists.proofprofile.net/proofs/artist/798214f3-3667-4299-b88e-791c902008fb.json and https://artists.proofprofile.net/proofs/artist/798214f3-3667-4299-b88e-791c902008fb.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
Dual-chain trust anchor. Chain 1 (CopyrightChains): CopyrightID 0x065e10bb52751cacc7b11b00b9298f34a01f8e686216bc3f2608bb9c43a23ef1. Chain 2 (Bitcoin): anchored in block 958627 (2026-07-18T23:33:54Z), 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/MX3451400027.
Dual-chain trust anchor. Chain 1 (CopyrightChains): CopyrightID 0x64735310589649fc1ab976c132097ea397ecb4a130bb6d8531f9c0d5acdb836c. Chain 2 (Bitcoin): anchored in block 958554 (2026-07-18T13:17:01Z), 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/MX3451400032.
Dual-chain trust anchor. Chain 1 (CopyrightChains): CopyrightID 0x1e81c7f993e852d1de5b59d76ed07b98ae34549e76368720396678b9db65a1cc. Chain 2 (Bitcoin): anchored in block 956375 (2026-07-02T16:51:38Z), 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/MX5332000088.
Dual-chain trust anchor. Chain 1 (CopyrightChains): CopyrightID 0xc4ca77ee299a60462a61ee61021e23db80cc7d03669e042279a7c4785ca4207d. 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/USCGJ2127833.
VOLVER AL CORAZÓN (Canciones testimoniales compuestas con mujeres en prisión)
Dual-chain trust anchor. Chain 1 (CopyrightChains): CopyrightID 0x8c21907200cbc581ca87ff9d11e65335fd27ab54d974beb00e6d155047cd7179. Chain 2 (Bitcoin): anchored in block 957118 (2026-07-08T03:20:19Z), 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/QZTV32314227.
Dual-chain trust anchor. Chain 1 (CopyrightChains): CopyrightID 0x5bd23082bfa4e9351a570b6e53413486502820def424467fbc27cd22dde06944. Chain 2 (Bitcoin): anchored in block 957145 (2026-07-08T08:56:20Z), 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/BXSSW2300683.
Dual-chain trust anchor. Chain 1 (CopyrightChains): CopyrightID 0x8eefb6e927e014ee408d6b0fba73b2901fda1966254425013223c17834563da6. 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/GBWUL2459978.
Dual-chain trust anchor. Chain 1 (CopyrightChains): CopyrightID 0x2af89ffa64235d8e90fc6272cb96658dd9748fff36634e1f281afd8f427bc113. Chain 2 (Bitcoin): anchored in block 957884 (2026-07-13T16:55:06Z), 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/QZZEB2409080.
Las crónicas del diablo (Canción original de la obra de teatro)
Dual-chain trust anchor. Chain 1 (CopyrightChains): CopyrightID 0x252ed444d23cb26fb757882239f59c491260ea61164b388d8cf4bc5a4b6d2e16. 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/QZWDD2585540.
Dual-chain trust anchor. Chain 1 (CopyrightChains): CopyrightID 0x75512b9a22de693ef27378d7d3a549c0b5cd52c4932b85114b92fc42ce0cf383. Chain 2 (Bitcoin): anchored in block 953528 (2026-06-13T15:41:10Z), 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/USUYG1060938.
Dual-chain trust anchor. Chain 1 (CopyrightChains): CopyrightID 0x615f544091d05c92d7b8c5e9e7c22f62976e2610a624efcddb71cc252ccbfa2d. Chain 2 (Bitcoin): anchored in block 953528 (2026-06-13T15:41:10Z), 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/TCAGH2232603.
Dual-chain trust anchor. Chain 1 (CopyrightChains): CopyrightID 0x8df97d7c18753aa5b11eada5fc7eca9b71f4b9661cd80c4076c6602abe8826a1. Chain 2 (Bitcoin): anchored in block 953536 (2026-06-13T17:25:41Z), 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/GBLFP2216102.
Dual-chain trust anchor. Chain 1 (CopyrightChains): CopyrightID 0x2e0deaf12c4e68e0b7ec2ab1d8671b9be1f2a85ad667b14c00b94e6531ee2d32. Chain 2 (Bitcoin): anchored in block 953536 (2026-06-13T17:25:41Z), 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/MXUM62000004.
Dual-chain trust anchor. Chain 1 (CopyrightChains): CopyrightID 0x8a81b10c799bee1471ca5dc3635546537d585bf7c1d03377068cca9df411912a. Chain 2 (Bitcoin): anchored in block 960138 (2026-07-29T19:35:34Z), 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/MXD782300575.
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