Maria Krüger (1904–1999) was a Polish children's literature writer and journalist. Krüger participated in the Warsaw Uprising. Several of her children's books received radio and television adaptations
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 0x1e0772b5a292d6dadc1989e45f8fb3b4616507ef9de5e895209f7712e83ce358. 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/e37e31e8-d6be-43fb-b061-e23f34a4cc69.json and https://artists.proofprofile.net/proofs/artist/e37e31e8-d6be-43fb-b061-e23f34a4cc69.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 0xc1a8a7052f69afa982135b888e95f1aa87676f665afb63b65c456209d5f7d82e. Chain 2 (Bitcoin): anchored in block 956375 (2026-07-02T16:51:38Z), 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/TCAGP2258923.
Dual-chain trust anchor. Chain 1 (CopyrightChains): CopyrightID 0x8986892e21d02af108d67a96646bf6924c0a03972b6ac80c93eeff56a1449627. Chain 2 (Bitcoin): anchored in block 958153 (2026-07-15T12:03:04Z), 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/TCAGP2258942.
Dual-chain trust anchor. Chain 1 (CopyrightChains): CopyrightID 0x91240445ed29f2f66055eb203a005b7d45ad3a92489fc17042987ef038374eb0. Chain 2 (Bitcoin): anchored in block 957778 (2026-07-13T00:08:48Z), 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/TCAGP2258956.
Dual-chain trust anchor. Chain 1 (CopyrightChains): CopyrightID 0xe515b5d9a235f2e36f1cc58e6a7d81b8b7b1e60cb4352fb2c0e0dba9800d814e. Chain 2 (Bitcoin): anchored in block 957782 (2026-07-13T00:52:48Z), 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/TCAGP2258962.
Dual-chain trust anchor. Chain 1 (CopyrightChains): CopyrightID 0x5754fb193b43b3cb9c7fb641188f1ec6324b26d5a986ba1ecc50a4a6dd565025. Chain 2 (Bitcoin): anchored in block 958110 (2026-07-15T06:57:12Z), 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/TCAGP2258967.
Dual-chain trust anchor. Chain 1 (CopyrightChains): CopyrightID 0x77d71c2b43653fdcdafaad31f779b5f65e88e87315dfc446469b64ab75a67322. Chain 2 (Bitcoin): anchored in block 958110 (2026-07-15T06:57:12Z), 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/TCAGP2258969.
Co Się Działo Dalej W Piernikowym Domku, Pt. 2
Dual-chain trust anchor. Chain 1 (CopyrightChains): CopyrightID 0x3dd4871019be669533137a9affbae90e4d7b879161d0cd8ef5e25cc70a374ef9. Chain 2 (Bitcoin): anchored in block 958115 (2026-07-15T07:27:09Z), 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/TCAGP2258973.
Co Się Działo Dalej W Piernikowym Domku, Pt. 3
Dual-chain trust anchor. Chain 1 (CopyrightChains): CopyrightID 0xe5f491411dd2cce7b05e6e02ff591ce62d12290c3418dac631b7f1d8fc0f3316. Chain 2 (Bitcoin): anchored in block 956474 (2026-07-03T08:56:35Z), 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/TCAGP2258978.
Co Się Działo Dalej W Piernikowym Domku, Pt. 4
Dual-chain trust anchor. Chain 1 (CopyrightChains): CopyrightID 0xe3b5f5d6ac0a68c4197885d365d8d9c94330f257b400757d8ac37184eb4da189. Chain 2 (Bitcoin): anchored in block 956545 (2026-07-03T19:59:51Z), 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/TCAGP2258981.
Dual-chain trust anchor. Chain 1 (CopyrightChains): CopyrightID 0xa15acb675d9f7a57c46753f361988c9b57fffd52b39ff793ea39782184862fb8. Chain 2 (Bitcoin): anchored in block 956474 (2026-07-03T08:56:35Z), 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/TCAGP2258982.
Dual-chain trust anchor. Chain 1 (CopyrightChains): CopyrightID 0x1150647a9826dbdf431a7279c425e63585244d2cca1ddb02eb86d484c97d1b73. Chain 2 (Bitcoin): anchored in block 956545 (2026-07-03T19:59:51Z), 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/TCAGP2258984.
Dual-chain trust anchor. Chain 1 (CopyrightChains): CopyrightID 0x1005efd8ac648ade70a0e6e4a23b66b16cc98791d11a019708e1d6322793aa2f. Chain 2 (Bitcoin): anchored in block 958157 (2026-07-15T13:14:32Z), 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/TCAGP2259192.
Dual-chain trust anchor. Chain 1 (CopyrightChains): CopyrightID 0xedf2d5dbcc067558918ec1c0fc4ae112ac5c251058a8e1b80fc27b228d1b8481. Chain 2 (Bitcoin): anchored in block 956545 (2026-07-03T19:59:51Z), 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/TCAGP2259195.
Dual-chain trust anchor. Chain 1 (CopyrightChains): CopyrightID 0xb6b4b76249e6f92b914b8a1557f066280c3bc52a8b8a07141aab7f1ce042c15b. Chain 2 (Bitcoin): anchored in block 956545 (2026-07-03T19:59:51Z), 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/TCAGP2259199.
Dual-chain trust anchor. Chain 1 (CopyrightChains): CopyrightID 0x9670630dfb92a53238fbcfc91dbc4fd914e07b6c92158e603e17a9b3fe7c586a. Chain 2 (Bitcoin): anchored in block 956545 (2026-07-03T19:59:51Z), 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/TCAGP2265574.
Dual-chain trust anchor. Chain 1 (CopyrightChains): CopyrightID 0xd1a88555a8c1e4e62a985122e1eeb1b9cb6b867a6ec4576b932ca5ab8645c92d. Chain 2 (Bitcoin): anchored in block 958286 (2026-07-16T12:43:37Z), 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/TCAGP2265611.
Dual-chain trust anchor. Chain 1 (CopyrightChains): CopyrightID 0x3f8650022f65c68bec31d5740140467e38932151fc8f653726a3d4c15ca9eebb. Chain 2 (Bitcoin): anchored in block 956545 (2026-07-03T19:59:51Z), 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/TCAGP2265618.
Dual-chain trust anchor. Chain 1 (CopyrightChains): CopyrightID 0x0f4bebc30c7491e2572ef3a206b39f9f773821f222fac7f290ce91bc549946e6. Chain 2 (Bitcoin): anchored in block 956545 (2026-07-03T19:59:51Z), 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/TCAGP2265632.
Dual-chain trust anchor. Chain 1 (CopyrightChains): CopyrightID 0xc6fcbdab3009b3fb162d07b2953b3def975ad381c56fc762acefb4837a363eb6. Chain 2 (Bitcoin): anchored in block 956545 (2026-07-03T19:59:51Z), 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/TCAGP2265644.
Dual-chain trust anchor. Chain 1 (CopyrightChains): CopyrightID 0x95e40c9051573bf3618a959745ebd9a59319cdd90eefeec34a4e1868670718cc. Chain 2 (Bitcoin): anchored in block 956634 (2026-07-04T10:04:33Z), 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/TCAGP2265654.
Dual-chain trust anchor. Chain 1 (CopyrightChains): CopyrightID 0x085fb712b7dc1a8b05a3a71152d064bd54fc2bab894f2b9af40daba5a20d0876. Chain 2 (Bitcoin): anchored in block 958444 (2026-07-17T19:12:23Z), 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/TCAGP2265665.
Dual-chain trust anchor. Chain 1 (CopyrightChains): CopyrightID 0xdca78814c85ad3a376357323c684b4916cf0805f269e62957a738f09eb409db5. Chain 2 (Bitcoin): anchored in block 956634 (2026-07-04T10:04:33Z), 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/TCAGP2265679.
Dual-chain trust anchor. Chain 1 (CopyrightChains): CopyrightID 0x533bd9523eed0d2165a9f208eb753bf5dadd319486c276f3451b7937c2875d24. Chain 2 (Bitcoin): anchored in block 958380 (2026-07-17T07:07:02Z), 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/TCAGP2265706.
Dual-chain trust anchor. Chain 1 (CopyrightChains): CopyrightID 0xf3f458072b649309bdc1b71a2d953699f7822af299f712f85b8a90b23f496e64. Chain 2 (Bitcoin): anchored in block 958110 (2026-07-15T06:57:12Z), 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/TCAGP2265711.
Dual-chain trust anchor. Chain 1 (CopyrightChains): CopyrightID 0x7dab1d6f8b70be7e4e76200bec03deffdc2c7993a228da2c3e027acfbdc1ddd2. Chain 2 (Bitcoin): anchored in block 958383 (2026-07-17T08:20:01Z), 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/TCAGP2265718.
Dual-chain trust anchor. Chain 1 (CopyrightChains): CopyrightID 0xb92c11852153dad6e63fc16a3c29433ddb6a2c5e3694d160f5d5de8bea79b85e. Chain 2 (Bitcoin): anchored in block 956634 (2026-07-04T10:04:33Z), 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/TCAGP2265723.
Dual-chain trust anchor. Chain 1 (CopyrightChains): CopyrightID 0x7b4600b7af29534fd8a54ff8c949bc4e2d49713eca8c406f1848cd47be18fb74. Chain 2 (Bitcoin): anchored in block 956634 (2026-07-04T10:04:33Z), 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/TCAGP2265729.
Dual-chain trust anchor. Chain 1 (CopyrightChains): CopyrightID 0x3febcb9cdecd8d15ae027b6cdb8e0012f505be1246c018d8b36a1bd3ec68705b. Chain 2 (Bitcoin): anchored in block 956725 (2026-07-05T01:12:41Z), 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/TCAGP2265733.
Dual-chain trust anchor. Chain 1 (CopyrightChains): CopyrightID 0xcfaa072ed2753ec09ecd0c9457781be2ec6d5687db4a3eec607926373e7ac772. Chain 2 (Bitcoin): anchored in block 956725 (2026-07-05T01:12:41Z), 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/TCAGP2265738.
Dual-chain trust anchor. Chain 1 (CopyrightChains): CopyrightID 0x3584a3c7a5c42ad1d3885b441a794cd95b3e48c96042541e60e5e813af432739. Chain 2 (Bitcoin): anchored in block 956639 (2026-07-04T11:19:20Z), 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/TCAGP2265745.
Dual-chain trust anchor. Chain 1 (CopyrightChains): CopyrightID 0xc7b0f86cb66b512e000b626d152e97b85bbef78d091cdc10699d4d3533955588. Chain 2 (Bitcoin): anchored in block 956725 (2026-07-05T01:12:41Z), 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/TCAGP2265749.
Dual-chain trust anchor. Chain 1 (CopyrightChains): CopyrightID 0x116e0f1f25aaa9d09c42a120599ab160c5fd2b6b789a5787b273bc0dc0db5525. Chain 2 (Bitcoin): anchored in block 956634 (2026-07-04T10:04:33Z), 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/TCAGP2265754.
Dual-chain trust anchor. Chain 1 (CopyrightChains): CopyrightID 0x574900f2c19dbb72613b1ff71fccc7dd73823677cd49f7034e2814cc8d3fff86. Chain 2 (Bitcoin): anchored in block 956551 (2026-07-03T21:18:05Z), 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/TCAGP2265755.
Dual-chain trust anchor. Chain 1 (CopyrightChains): CopyrightID 0x490ae8badbb4e64225eae766596e765826edd91c6f82c553d3d7b2c08d612a4b. Chain 2 (Bitcoin): anchored in block 956545 (2026-07-03T19:59:51Z), 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/TCAGP2265757.
Dual-chain trust anchor. Chain 1 (CopyrightChains): CopyrightID 0xd8a640d79d62bc77de097839656a9901326013c80f5ab9f269c08e5e2668d4e8. Chain 2 (Bitcoin): anchored in block 956634 (2026-07-04T10:04:33Z), 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/TCAGP2265759.
Dual-chain trust anchor. Chain 1 (CopyrightChains): CopyrightID 0x7826837b6d6d680a6a7ee9714568af58c785f3c583258421c15e41ac4885f524. Chain 2 (Bitcoin): anchored in block 956639 (2026-07-04T11:19:20Z), 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/TCAGP2265765.