Claude Helffer (18 June 1922 – 27 October 2004) was a French pianist. Early life Helffer was born in Paris, and began piano lessons at the age of five. From the age of ten, until the outbreak of Wo
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 0x0ea5fa1196e060d6307ca93fedaf5b4dd4c25849bd71030b6fc53afa0d2badeb. Chain 2 (Bitcoin): anchored in block 953958 (2026-06-16T14:52:44Z). Bridge: the canonical record inside this Bitcoin proof contains the same CopyrightID. Verify: download https://artists.proofprofile.net/proofs/artist/27715a59-6c2f-42ee-aebb-1d267f63a5ac.json and https://artists.proofprofile.net/proofs/artist/27715a59-6c2f-42ee-aebb-1d267f63a5ac.ots, run `ots verify -f record.json proof.ots` (https://opentimestamps.org).
Le Petit Ménestrel: Scènes d'enfants - Conte pour enfants d'après l'oeuvre de Schumann
Britten: The Young Person's Guide to the Orchestra, Turina: Danzas Fantásticas & Milhaud: Le carnaval d'Aix (Remastered, Mono Version)
Britten: The Young Person's Guide to the Orchestra, Turina: Danzas Fantásticas & Milhaud: Le carnaval d'Aix (Mono Version)
Britten: The Young Person's Guide to the Orchestra - Turina: Danzas fantásticas - Milhaud: Le Carnaval d'Aix (Stereo Version)
Leibowitz: Suite / Serenade / Flute Sonata / 3 Pieces for Piano / Motifs
Darmstadt Aural Documents, Box 4: Pianists
Barraud: Symphonie n 3 / Roussel: Concerto pour piano et orchestre
Roussel: Le festin de l'araignée, Op. 17 & Concerto pour piano, Op. 36 (Stereo Version)
Michael Gielen Edition, Vol. 7 (1961-2006)
Boulez: Piano Sonata No. 2; Berg: Piano Sonata Op. 1; Milhaud: Le Carnaval d'Aix
Jarrell: Trei II / Modifications / Eco / Trace-Ecart
Debussy: Works for two pianos & four-hand piano
Beethoven: Sonates pour piano Nos. 10 & 26 "Les adieux" (Mono Version)
Ravel: Trio, M. 67 & Quatuor, M. 35 (Mono Version)
L'évolution de la musique de piano (Mono Version)
Debussy: Quatuor à cordes, Sonate pour violoncelle & Sonate pour flûte, alto et harpe (Mono Version)
Beethoven: Trio pour piano No. 7, Op. 97 "Archiduc" (Mono Version)
Beethoven: Piano Sonatas & 32 Variations in C Minor (Mono Version)
Prokofiev: Sonate pour piano No. 2, Toccata & Visions fugitives (Mono Version)
Fauré: Quatuor avec piano No. 1, Op. 15 & Sonate pour violoncelle et piano No. 2, Op. 117 (Mono Version)
Concerto For Piano And Orchestra, Op. 42 / Three Piano Pieces, Op. 11, And Suite For Piano, Op. 25
Beethoven: Sonate pour piano No. 9 (Mono Version)
Mendelssohn: Trio pour piano, violon et violoncelle No. 1 (Mono Version)
Suite bergamasque, L. 75: III. Clair de lune
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 0xca23c54cb3a2d5f367f2b8ea091a0c2e2b27e5846dc7e3edf9a2d40f1f4221d5. 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/FRZ140504030.
Images, Première Série, L. 110: I. Reflets dans l'eau
Dual-chain trust anchor. Chain 1 (CopyrightChains): CopyrightID 0x909596879aa252e13558697e59c7dd6c3323252336a13f3eca4d51fbc150d07c. 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 via https://artists.proofprofile.net/api/v1/bot/ots/verify/track/FRZ140014040.
Dual-chain trust anchor. Chain 1 (CopyrightChains): CopyrightID 0xa43bbbcedaa0877a49c7a3c3dcee19fdcd49f7fa515dbe39bc052c73586f535d. 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 via https://artists.proofprofile.net/api/v1/bot/ots/verify/track/FRZ140622050.
Images inédites, L. 87: I. Lent, doux et mélancolique
Dual-chain trust anchor. Chain 1 (CopyrightChains): CopyrightID 0xd25149007bdda67b8dd0aef59ab6ab9533abbae7a78168d1fb89595e9a8103f6. 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 via https://artists.proofprofile.net/api/v1/bot/ots/verify/track/FRZ140622010.
Images inédites, L. 87: II. Souvenir du Louvre
Dual-chain trust anchor. Chain 1 (CopyrightChains): CopyrightID 0x24529a947cdc194906e9a406fde05f9d38052ca759ba0a33d0f546b32ba9a649. 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 via https://artists.proofprofile.net/api/v1/bot/ots/verify/track/FRZ140622020.
Images inédites, L. 87: III. Quelques aspects de "Nous n'irons plus au bois" parce qu'il fait un temps épouvantable
Dual-chain trust anchor. Chain 1 (CopyrightChains): CopyrightID 0xb5de6d2d9e66f8d5a99f657a7977b5df9f4f8ece1cc1d1336758d00293d2aa09. Chain 2 (Bitcoin): anchored in block 960095 (2026-07-29T11:07:37Z), 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/FRZ140622030.
2 Arabesques, L. 66: No. 1, Andante con moto
Dual-chain trust anchor. Chain 1 (CopyrightChains): CopyrightID 0x005fb3cfc11e423e9e48874997641cf6cc14aada91b8558e5259855f95c09858. Chain 2 (Bitcoin): anchored in block 960327 (2026-07-31T00:26:26Z), 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/FRZ396101880.
Dual-chain trust anchor. Chain 1 (CopyrightChains): CopyrightID 0x4e28eba896984aac1e3e1cbeaa9da9cc50368de0ffb78304acee4b0fbe4ab1fb. Chain 2 (Bitcoin): anchored in block 960478 (2026-07-31T23:30:38Z), 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/FRZ036303410.
Suite bergamasque, L. 75: 3. Clair de lune
Dual-chain trust anchor. Chain 1 (CopyrightChains): CopyrightID 0xe8661d56b9a122a8fe4bfe382fa0f9c35ecfeedc422e438c07cd932967e57cc0. 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/FRZ396300050.
Dual-chain trust anchor. Chain 1 (CopyrightChains): CopyrightID 0x537cbd5668f2d3d7d910ba2e5dea6408b7d977a4e436feb9af51b35c8d3ed446. Chain 2 (Bitcoin): anchored in block 957120 (2026-07-08T03:22:41Z), 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/FRZ286901030.
Préludes / Livre 1, L. 117: 8. La fille aux cheveux de lin
Dual-chain trust anchor. Chain 1 (CopyrightChains): CopyrightID 0xe712fd3de13228f6fc18327effdc972500bc22b6f6add74821309b01eef3e429. Chain 2 (Bitcoin): anchored in block 960473 (2026-07-31T22:27:44Z), 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/FRZ079001320.
Dual-chain trust anchor. Chain 1 (CopyrightChains): CopyrightID 0xbd68ec4b27f211fe9f505ea2893885d4444efa35c67fef7778da6fcf80acd19a. 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/FRZ287101080.
Dual-chain trust anchor. Chain 1 (CopyrightChains): CopyrightID 0x777af43116af1061b8ac1a09c5542a7065272fddb985b15915ec15ca46a8326c. Chain 2 (Bitcoin): anchored in block 960478 (2026-07-31T23:30:38Z), 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/GBBBA0200802.
Dual-chain trust anchor. Chain 1 (CopyrightChains): CopyrightID 0x35c7dee7c122fcc4cd7c9317db18a041539f5dff8a2a99e1e3eeb3b8ce39169d. Chain 2 (Bitcoin): anchored in block 960463 (2026-07-31T20:42:35Z), 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/FRZ079102830.
Dual-chain trust anchor. Chain 1 (CopyrightChains): CopyrightID 0xda61cc18dc373f039227bc664a6e09be51b68f2c75ea9b40c34d31299e7af573. Chain 2 (Bitcoin): anchored in block 956889 (2026-07-06T06:56:49Z), 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/FRZ287101150.
Dual-chain trust anchor. Chain 1 (CopyrightChains): CopyrightID 0x156b995020df6603589f5bd3a3fbc74c930fe4b339a58c4595a42e457f73fafa. Chain 2 (Bitcoin): anchored in block 960478 (2026-07-31T23:30:38Z), 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/ITP900900037.
Dual-chain trust anchor. Chain 1 (CopyrightChains): CopyrightID 0x680b7adce5b4cc28971043c0a025b96d6b0b14e626b793ef3e89e201d83d6015. Chain 2 (Bitcoin): anchored in block 960441 (2026-07-31T17:29:52Z), 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/NLA508005429.
Dual-chain trust anchor. Chain 1 (CopyrightChains): CopyrightID 0xa53d492ab1f82b5fed18f3931ce85662cf2762fdfa00382d02de0a9aae1e81ca. 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 via https://artists.proofprofile.net/api/v1/bot/ots/verify/track/FRUM76500227.
Debussy: La Boîte A Joujoux, Children's Corner (Petit Menestrel)