Kurt Widmer (28 December 1940 – 31 May 2023) was a Swiss baritone and voice teacher, who appeared and recorded internationally. He focused on concert singing, especially of oratorios from the Romantic
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 0x009aa126826f4dfc84e974377ad6298a55dfcb88905c480aab8745d2ca953253. Chain 2 (Bitcoin): anchored in block 953899 (2026-06-16T06:37:25Z). Bridge: the canonical record inside this Bitcoin proof contains the same CopyrightID. Verify: download https://artists.proofprofile.net/proofs/artist/136a10c2-181e-4cc2-8e57-dd818b921307.json and https://artists.proofprofile.net/proofs/artist/136a10c2-181e-4cc2-8e57-dd818b921307.ots, the client at https://opentimestamps.org runs `ots verify -f record.json proof.ots`.
Requiem: Introitus - Requiem Aeternam - Kyrie - Graduale
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 0x89d3f037cb6e22dbbed0c58db3c19cb8235848afad49766520b59a7804581e57. Chain 2 (Bitcoin): anchored in block 960368 (2026-07-31T08:26:41Z), 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 at https://artists.proofprofile.net/api/v1/bot/ots/verify/track/NLA506800800 — a six-check JSON result.
Requiem: Sequentia - Dies Irae - Tuba Mirum - Mors Stupebit - Judex Ergo - Rex Tremendae
Dual-chain trust anchor. Chain 1 (CopyrightChains): CopyrightID 0x6c389eaaf6f135e6b98523ec16d3ecbcdb95d6030771c9980de633a19ea7f3d7. 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 at https://artists.proofprofile.net/api/v1/bot/ots/verify/track/NLA506800810 — a six-check JSON result.
Dual-chain trust anchor. Chain 1 (CopyrightChains): CopyrightID 0xf74897f3a2bb24a1390aaacab2a10dd8fb89a276b5397b4f8a84f0288e5424df. Chain 2 (Bitcoin): anchored in block 960410 (2026-07-31T13:50:38Z), 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 at https://artists.proofprofile.net/api/v1/bot/ots/verify/track/NLA506800366 — a six-check JSON result.
Oratorio de Noel, Op. 12: Tollite hostias (Chorus)
Saint-Saens: Oratorio De Noel (Christmas Oratorio), Op. 12
Dual-chain trust anchor. Chain 1 (CopyrightChains): CopyrightID 0x2f9e0cfcdb739e71710ec6ecf02b5d00610e9f73840f858d2fab178e8a1e8c10. Chain 2 (Bitcoin): anchored in block 959128 (2026-07-22T12:33:25Z), 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 at https://artists.proofprofile.net/api/v1/bot/ots/verify/track/DEAD60502310 — a six-check JSON result.
Oratorio de Noel, Op. 12: Prelude (In the Style of Seb. Bach)
Dual-chain trust anchor. Chain 1 (CopyrightChains): CopyrightID 0x724b66ff13bbb811415f9404d336abc4921589cca1c7239d6c9a3f5f22fa5552. Chain 2 (Bitcoin): anchored in block 956304 (2026-07-02T03:55:08Z), 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 at https://artists.proofprofile.net/api/v1/bot/ots/verify/track/DEAD60502301 — a six-check JSON result.
Oratorio de Noel, Op. 12: Duet: Benedictus qui venit (Soprano, Basso)
Dual-chain trust anchor. Chain 1 (CopyrightChains): CopyrightID 0x7fdfed2f104715fb619b32a39796ad00495a800676e7987b93ee61a3ee8564da. 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 at https://artists.proofprofile.net/api/v1/bot/ots/verify/track/DEAD60502305 — a six-check JSON result.
Oratorio de Noel, Op. 12: Recitative and Chorus: Et Pastores erant - Gloria (Chorus)
Dual-chain trust anchor. Chain 1 (CopyrightChains): CopyrightID 0xf3b4952836c41f12b7a761103bda6686d620479694bfe606853ebabe888c98b4. Chain 2 (Bitcoin): anchored in block 960300 (2026-07-30T19:42:40Z), 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 at https://artists.proofprofile.net/api/v1/bot/ots/verify/track/DEAD60502302 — a six-check JSON result.
Oratorio de Noel, Op. 12: Quare fremuerunt gentes (Chorus)
Dual-chain trust anchor. Chain 1 (CopyrightChains): CopyrightID 0xa57dc6c3b5e8c5636de0b8675dca2c7f32c913fa7ce405fce744af621c3ef52e. Chain 2 (Bitcoin): anchored in block 960183 (2026-07-30T01:10:20Z), 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 at https://artists.proofprofile.net/api/v1/bot/ots/verify/track/DEAD60502306 — a six-check JSON result.
Oratorio de Noel, Op. 12: Air: Expectants expectavi Dominum (Soprano)
Dual-chain trust anchor. Chain 1 (CopyrightChains): CopyrightID 0xd9011c0134a9ebc65f0e0cb958ee2dbf1a6b4b83f8add04a1a4c3d4fb273295f. Chain 2 (Bitcoin): anchored in block 960397 (2026-07-31T12:24:41Z), 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 at https://artists.proofprofile.net/api/v1/bot/ots/verify/track/DEAD60502303 — a six-check JSON result.
Oratorio de Noel, Op. 12: Air: Domine, ego credidi (Tenor, Chorus)
Dual-chain trust anchor. Chain 1 (CopyrightChains): CopyrightID 0xcf3a3f2f4693e1874a511dc0f9b3fef3217e0bd2ae36f5d18d39da94dbbc556c. Chain 2 (Bitcoin): anchored in block 960334 (2026-07-31T02:19:15Z), 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 at https://artists.proofprofile.net/api/v1/bot/ots/verify/track/DEAD60502304 — a six-check JSON result.
Oratorio de Noel, Op. 12: Trio: Tecum principium (Soprano, Tenor, Basso)
Dual-chain trust anchor. Chain 1 (CopyrightChains): CopyrightID 0x87dcf210dba839ac413823ac91c9bc6777e5e49d83fd364613449177af66cbb0. Chain 2 (Bitcoin): anchored in block 960349 (2026-07-31T05:23:41Z), 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 at https://artists.proofprofile.net/api/v1/bot/ots/verify/track/DEAD60502307 — a six-check JSON result.
Oratorio de Noel, Op. 12: Quartet: Alleluja (Soprano, Soprano, Alto, Basso)
Dual-chain trust anchor. Chain 1 (CopyrightChains): CopyrightID 0xa42ea3e93425d926baa2f62b2d61f45876a606f9d2186f1c08392a8a24b7edf9. Chain 2 (Bitcoin): anchored in block 960368 (2026-07-31T08:26:41Z), 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 at https://artists.proofprofile.net/api/v1/bot/ots/verify/track/DEAD60502308 — a six-check JSON result.
Oratorio de Noel, Op. 12: Quintet and Chorus: Consurge, Filia Sion (Soprano, Soprano, Alto, Basso, Chorus)
Dual-chain trust anchor. Chain 1 (CopyrightChains): CopyrightID 0x03d9ab36b912ac867e7b9b50cc025dec9bd0b92b97a2c1202256609a9e588934. Chain 2 (Bitcoin): anchored in block 960334 (2026-07-31T02:19:15Z), 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 at https://artists.proofprofile.net/api/v1/bot/ots/verify/track/DEAD60502309 — a six-check JSON result.