thumb|right|240px|"Cantus" (c. 1900), painting by Georg Mühlberg A cantus (Latin for "singing", derived from cantare) is an activity organised by Belgian, Dutch, German, French, and Baltic fraterniti
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 0x80bf184f85eef53116ba97e66e0f2092d42298c97ba6cbceaef143b5b62d2800. 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/101a4889-4eeb-4e98-8a5d-e144ea090149.json and https://artists.proofprofile.net/proofs/artist/101a4889-4eeb-4e98-8a5d-e144ea090149.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 0x665d6e8a9a7b1f2a466e4ea9ba4e23ef23e1c8b20c8996bca390be240dbb904c. 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/USHM20552280.
Dual-chain trust anchor. Chain 1 (CopyrightChains): CopyrightID 0xe6d9f248b9e1be9883ec17b32d7d92aca495c89025846d9e3d6149983444837f. 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/USHM20552282.
Dual-chain trust anchor. Chain 1 (CopyrightChains): CopyrightID 0x0d8e8a0692135995c27e863c9f88228ca707b1cfd6f364d82f11da16fa8754ed. Chain 2 (Bitcoin): anchored in block 960291 (2026-07-30T18:23:33Z), 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/USHM90655971.
Dual-chain trust anchor. Chain 1 (CopyrightChains): CopyrightID 0x1bf61496e405fb7cc95b3d0f5c2a82108431ef22b2d3051bcf55dad4e3bf7b84. Chain 2 (Bitcoin): anchored in block 960430 (2026-07-31T16:09:41Z), 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/USHM90655972.
Dual-chain trust anchor. Chain 1 (CopyrightChains): CopyrightID 0x341c7a511718f5f31fd6c435f88ed81641f29b189d82052f167b5694d09f8d24. 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/USHM90655976.
Dual-chain trust anchor. Chain 1 (CopyrightChains): CopyrightID 0x5d97c92bb52d035ac6859b7cdee860440def03b1cbb89d6925281542f4e16ee3. Chain 2 (Bitcoin): anchored in block 958728 (2026-07-19T12:24:55Z), 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/USX9P1096948.
Dual-chain trust anchor. Chain 1 (CopyrightChains): CopyrightID 0xf0d78e7fb2b184a263ddd7a8be30092c087663b6c420eb4a99b481ae6311ab9a. Chain 2 (Bitcoin): anchored in block 956578 (2026-07-04T02:23:20Z), 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/USX9P1096950.
Dual-chain trust anchor. Chain 1 (CopyrightChains): CopyrightID 0xc0ff160ff42700456cc4d60fa5bfb257e644418ce0ecce31ebda86f5f99a5eaa. Chain 2 (Bitcoin): anchored in block 957888 (2026-07-13T17:43:59Z), 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/USX9P1096960.
Dual-chain trust anchor. Chain 1 (CopyrightChains): CopyrightID 0xcaf8b6def09eb0a6b73b1f74131132ef794a8746fdeb270f1f74dc90137abb01. Chain 2 (Bitcoin): anchored in block 959073 (2026-07-21T23:25:37Z), 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/QMMKY1200002.
Dual-chain trust anchor. Chain 1 (CopyrightChains): CopyrightID 0xb6ee10bb5bcec6470c67ecc158050a5cfda4048405164db9e950f8b48a2162b5. Chain 2 (Bitcoin): anchored in block 956422 (2026-07-03T01:01:38Z), 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/QMMKY1200008.
Song of a Czech: Dvořák and Janáček for Men’s Voices
For the Beauty of the Earth (Live for Broadcast)
Dual-chain trust anchor. Chain 1 (CopyrightChains): CopyrightID 0x25246a5d9cec795f1b9f2ebc6b827630f15bf87943bfe02538e5750261a24336. Chain 2 (Bitcoin): anchored in block 958728 (2026-07-19T12:24:55Z), 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/QMMKY1400001.
How Can I Keep from Singing? (Live for Broadcast)
Dual-chain trust anchor. Chain 1 (CopyrightChains): CopyrightID 0xed38aee6ac2cba13be3974cdd4532972b46b155c612759215e73fa1ffa14eded. Chain 2 (Bitcoin): anchored in block 959001 (2026-07-21T11:41:42Z), 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/QMMKY1400015.
Dual-chain trust anchor. Chain 1 (CopyrightChains): CopyrightID 0x3253e56fc91b71f74984ff5ba9c741a25d5d740f52c69680530d75da11cf83ca. 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/GBLLH2168607.
Dual-chain trust anchor. Chain 1 (CopyrightChains): CopyrightID 0x0656a42e173752a1cc5a72e4baec3357618626aa67373e2b10a8d07a4f31b008. Chain 2 (Bitcoin): anchored in block 960284 (2026-07-30T17:23:26Z), 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/GBLLH2081901.
Steal Away - Arr. for Vocal Ensemble by Stacey V. Gibbs
Dual-chain trust anchor. Chain 1 (CopyrightChains): CopyrightID 0x11f45a5d9b1459e3ac38f690724dc9e5779b6567e30db88b4e0c2ddb1e8d7730. Chain 2 (Bitcoin): anchored in block 960481 (2026-07-31T23:51:35Z), 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/GBLLH2081904.
O Frondens Virga - Arr. for Vocal Ensemble by Chris Foss
Dual-chain trust anchor. Chain 1 (CopyrightChains): CopyrightID 0xc6652106f651dd95e1abc45d30857b283470b0d128bbe439a493114919e4fbcd. 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/GBLLH2081907.
Dual-chain trust anchor. Chain 1 (CopyrightChains): CopyrightID 0x8bde35d7f4e5789236257fec783e8ea06745ff814ccb2f42d3aacc2161ac7db4. Chain 2 (Bitcoin): anchored in block 960266 (2026-07-30T14:44:50Z), 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/GBLLH2081910.
Dual-chain trust anchor. Chain 1 (CopyrightChains): CopyrightID 0x70f0a26dca8d841acb179f5ffa53cdd84433ccd0bf6d18691b61cf1ee578dac7. Chain 2 (Bitcoin): anchored in block 960354 (2026-07-31T05:48:18Z), 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/GBLLH2081912.
Dual-chain trust anchor. Chain 1 (CopyrightChains): CopyrightID 0x802e286a82d8e7506fd6448f5e5448a9cf00a7b69e60277aa93280d2c1da330c. 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/GBLLH2081913.
Dual-chain trust anchor. Chain 1 (CopyrightChains): CopyrightID 0xa8c66b2b9b3245d8cc3a2cc4b9a609b470bb02ea0477854622bf40d593f851ac. Chain 2 (Bitcoin): anchored in block 960459 (2026-07-31T20:22:46Z), 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/GBLLH2081915.
Dual-chain trust anchor. Chain 1 (CopyrightChains): CopyrightID 0x6504f9d8cbbce95cd28a5ddafe51eb6f3a47cde6e7837d6c76aea9b15a122153. 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/GBLLH2081916.
Dual-chain trust anchor. Chain 1 (CopyrightChains): CopyrightID 0xc52e3fa6fef7994306c174d94b346d39acfa7d37bc19922119e09659f53c5ee5. Chain 2 (Bitcoin): anchored in block 960448 (2026-07-31T18:48:12Z), 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/GBLLH2081919.
Dual-chain trust anchor. Chain 1 (CopyrightChains): CopyrightID 0x70f0a26dca8d841acb179f5ffa53cdd84433ccd0bf6d18691b61cf1ee578dac7. Chain 2 (Bitcoin): anchored in block 960185 (2026-07-30T01:32:48Z), 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/GBLLH2081912.
Dual-chain trust anchor. Chain 1 (CopyrightChains): CopyrightID 0x4eeaa28fa2f6da46a42e6bd1a057a0586dac26ff298450fc3335c9cba5141ce6. Chain 2 (Bitcoin): anchored in block 956776 (2026-07-05T10:59:37Z), 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/GBLLH2592401.
Calme des Nuits - Arr. for choir by Chris Foss
Dual-chain trust anchor. Chain 1 (CopyrightChains): CopyrightID 0xad9b21e541b515f7a33f3c9777a5f9f88164b682defa0eac334f9c025d9f8c1f. Chain 2 (Bitcoin): anchored in block 959058 (2026-07-21T21:09:36Z), 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/GBLLH2592414.