thumb|Yakov Zak in 1937 Yakov Izrailevich Zak (; – 28 June 1976) was a Soviet pianist and pedagogue. People's Artist of the USSR (1966). Life Born in Odessa, Zak studied piano at the Odessa Conserva
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 0x522da02872bab3e862149c58fb17f72a775cc15220d56e1a17021c998bdf6aa9. Chain 2 (Bitcoin): anchored in block 954065 (2026-06-17T08:10:43Z). Bridge: the canonical record inside this Bitcoin proof contains the same CopyrightID. Verify: download https://artists.proofprofile.net/proofs/artist/4d6fc7f0-64d1-425e-aead-4b72152ade54.json and https://artists.proofprofile.net/proofs/artist/4d6fc7f0-64d1-425e-aead-4b72152ade54.ots, the client at https://opentimestamps.org runs `ots verify -f record.json proof.ots`.
Milestones of a Legend: Sergei Prokofiev, Vol. 1
Johannes Brahms: Piano Concerto No. 2 - Sergei Prokofiev: Piano Concerto No. 2
J.S. Bach: Concerto for 2 Harpsichords in C Major, BWV 1061 - Beethoven: Piano Concerto No. 5 in E-Flat Major, Op. 73
Saint-Saens: Carnival of the Animals - Mendelssohn: Ruy Blas
Prokofiev: Peter and the Wolf - Saint-Saëns: Carnival of the Animals
Saint-Saëns: Les chefs-d'oeuvre - La discothèque idéale de Diapason, Vol. 23
Rachmaninoff: Complete Operas, Cantatas & Fragments
Russian Performing Art: Yakov Zak, Piano
The Russian Piano Tradition: The First Soviet Recordings (Recorded 1947-1955)
The Russian Piano Tradition: Emil Gilels & Yakov Zak
Introduction and Royal March of the Lion
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 0x2e52d88b026a128400ca1ab1ca462cc1d6cfde1732f4d654c3a3102f0e0b7f50. 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 at https://artists.proofprofile.net/api/v1/bot/ots/verify/track/USFX30600768 — a six-check JSON result.
Dual-chain trust anchor. Chain 1 (CopyrightChains): CopyrightID 0xd09a41ce1f9d582f223f7ddcc9fc3241e59b46c94b9c81e8efdb41ad7eacf965. 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 at https://artists.proofprofile.net/api/v1/bot/ots/verify/track/USFX30600769 — a six-check JSON result.
Dual-chain trust anchor. Chain 1 (CopyrightChains): CopyrightID 0x776e1aaa0d756b3f0788016d6a44ed69ad6ed203c397a29f9de175a140312516. Chain 2 (Bitcoin): anchored in block 960404 (2026-07-31T13:06:57Z), 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 at https://artists.proofprofile.net/api/v1/bot/ots/verify/track/USFX30600770 — a six-check JSON result.
Dual-chain trust anchor. Chain 1 (CopyrightChains): CopyrightID 0x59770392526269a7da541d4c425d8e3a5ce0706f403e37dab5c7f8664c58fc24. Chain 2 (Bitcoin): anchored in block 960427 (2026-07-31T15:59:18Z), 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 at https://artists.proofprofile.net/api/v1/bot/ots/verify/track/USFX30600771 — a six-check JSON result.
Dual-chain trust anchor. Chain 1 (CopyrightChains): CopyrightID 0x03f0cf354bb2f25b4ee5fec7b902a084beaf05e22005e186920a95c02b652310. Chain 2 (Bitcoin): anchored in block 960337 (2026-07-31T02:51:48Z), 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 at https://artists.proofprofile.net/api/v1/bot/ots/verify/track/USFX30600774 — a six-check JSON result.
Dual-chain trust anchor. Chain 1 (CopyrightChains): CopyrightID 0x1faec8931be20ca317caa134b0ac687b3ce0d47b9a637f09ee3360619cf5902f. 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 at https://artists.proofprofile.net/api/v1/bot/ots/verify/track/USFX30600780 — a six-check JSON result.
Fryderyk Chopin: Best Mazurka Performances 1927-2015
Oeuvres de Bach, Liszt, Mozart, Rameau, Scarlatti & Schumann (Les indispensables de Diapason)
Saint-Saëns: The Carnival of the Animals, R. 125 - Prokofiev: Peter and the Wolf, Op. 67 (Remastered 2023)
Kurt Sanderling - The Soviet Recordings: Brahms & Schumann
Prokofiev: Piano Concertos No. 2 & No. 4