Christian Hartmann (born 15 April 1959) is a German historian. He is a research fellow at the Institute of Contemporary History (Institut für Zeitgeschichte) in Munich. Life and work Hartmann grew
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 0x1ca8296289d4c961e6c93f2279b6bb161c3d2d432321d2d50a1bdd49945e653b. Chain 2 (Bitcoin): anchored in block 954533 (2026-06-20T08:57:02Z). Bridge: the canonical record inside this Bitcoin proof contains the same CopyrightID. Verify: download https://artists.proofprofile.net/proofs/artist/a723b07d-3cdf-472d-95d3-112d481fc2ab.json and https://artists.proofprofile.net/proofs/artist/a723b07d-3cdf-472d-95d3-112d481fc2ab.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 0xdf1649518ca967f5a636b861541b29ef8236dda61501e4bde6c12737d098e55d. 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/NOHMA1254010.
Dual-chain trust anchor. Chain 1 (CopyrightChains): CopyrightID 0x189fb637ce5235484177e974e05ee06677c2a892256a6a90ad964b082b01ea90. Chain 2 (Bitcoin): anchored in block 960317 (2026-07-30T21:35:24Z), 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/NOHMA1254020.
Dual-chain trust anchor. Chain 1 (CopyrightChains): CopyrightID 0xec9e2c38cf229c2d7d22820754bf475241262020b0524f54dc7dbf51ddbbd494. 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/NOHMA1254030.
Dual-chain trust anchor. Chain 1 (CopyrightChains): CopyrightID 0x7f56d43bd6d3e9f181c4a6c4ece25154004d417f14a545fe93c23aa80a0a58de. Chain 2 (Bitcoin): anchored in block 960229 (2026-07-30T08:30:10Z), 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/NOHMA1254040.
Dual-chain trust anchor. Chain 1 (CopyrightChains): CopyrightID 0xe373a3afb6682bc95bfe3a2dfba600c93e72cdc6c4a7e012c254c4efcdabf4df. 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/NOHMA1254050.
Dual-chain trust anchor. Chain 1 (CopyrightChains): CopyrightID 0xc8e661da76e03d1f83d67e8846510bb6d8888e687f5700611cbea6639e86d51b. Chain 2 (Bitcoin): anchored in block 960362 (2026-07-31T06:58:00Z), 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/NOHMA1254060.
Dual-chain trust anchor. Chain 1 (CopyrightChains): CopyrightID 0x64aed192967dfa401577a5a256f402dfb079bdc42d15c911a5bda97fd8394ad9. 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/NOHMA1254070.
Dual-chain trust anchor. Chain 1 (CopyrightChains): CopyrightID 0xeafdfbbb3c2779cc3d58fa5a474ee2701349ce0cf1e985e1887e56f4f3db4402. 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 via https://artists.proofprofile.net/api/v1/bot/ots/verify/track/NOHMA1254080.
Dual-chain trust anchor. Chain 1 (CopyrightChains): CopyrightID 0x0a8b9f1bd776469886ae0ac4ffb2e18405d6548701db3ef986a2881063c61343. 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 via https://artists.proofprofile.net/api/v1/bot/ots/verify/track/NOHMA1254090.
Dual-chain trust anchor. Chain 1 (CopyrightChains): CopyrightID 0xc97270e37317965f85f438f9c420d8705f722ba3dd5e1d271d38324e1cb2c858. 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/NOHMA1254100.
Dual-chain trust anchor. Chain 1 (CopyrightChains): CopyrightID 0x5557ebe6a1d04838380d6fe63bba38a9c179e15a2463e80b5b8e73966c7e59f2. 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/NOHMA1254110.
Dual-chain trust anchor. Chain 1 (CopyrightChains): CopyrightID 0x7e709a63efd3746d3e4fb93ae53c9a1522e8dab65c96885157ce731d4f7bc9e9. 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/NOHMA1254120.
Dual-chain trust anchor. Chain 1 (CopyrightChains): CopyrightID 0x06be828aeefaeedbc8319ea9319186b568cbd2ab3387ad6b2b6b2e7299fa3fec. 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/NOHMA1254130.
Dual-chain trust anchor. Chain 1 (CopyrightChains): CopyrightID 0xa6ba27ef377e6f7763fea0f619d2d365d3f32dda386ceb5bcbbbefde3e549430. Chain 2 (Bitcoin): anchored in block 960179 (2026-07-30T00:39:11Z), 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/NOHMA1254140.
Piano Exam Pieces 2021 & 2022, ABRSM Grade 6
Dual-chain trust anchor. Chain 1 (CopyrightChains): CopyrightID 0x3a39885d8094164e70fd029c7533f859e0e22c164187f942409f580caf11c52f. 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/GBEYQ2032317.