Playing For Change is a multimedia music project, featuring musicians and singers from across the globe, co-founded in 2002 by Mark Johnson and Whitney Kroenke. Playing For Change also created in 2007
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 0x423ee70868d1b5c891eb1e4a443be123943d6b780a23b2c83bc2a47c06b03e3d. 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/55ee3b84-f0f6-4c9e-a8e0-12549cd8cfb5.json and https://artists.proofprofile.net/proofs/artist/55ee3b84-f0f6-4c9e-a8e0-12549cd8cfb5.ots, run `ots verify -f record.json proof.ots` (https://opentimestamps.org).
Playing for Change 3: Songs Around the World
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 0x1256c02d795187847910d72211cb257345ed34baae03a56fd7b045f21036e3b8. Chain 2 (Bitcoin): anchored in block 953513 (2026-06-13T12:47:07Z), 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/QMHW41400012.
Dual-chain trust anchor. Chain 1 (CopyrightChains): CopyrightID 0x12acefeecf748577db5c6546347c4b8b7027fa1ffb4f57411c35a1bbadfab7cb. Chain 2 (Bitcoin): anchored in block 953513 (2026-06-13T12:47:07Z), 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/QMHW41400013.
Dual-chain trust anchor. Chain 1 (CopyrightChains): CopyrightID 0x77d4a71e216df0ca6f7e33dec32e2e492c3cad0e19b42787f9d194e3dbc9964a. Chain 2 (Bitcoin): anchored in block 953513 (2026-06-13T12:47:07Z), 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/QMHW41400014.
Dual-chain trust anchor. Chain 1 (CopyrightChains): CopyrightID 0x10fffc0a9970236ce3a7fe0df90f75e99920ced035326f45048e489ff81401bb. Chain 2 (Bitcoin): anchored in block 953515 (2026-06-13T12:53:06Z), 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/QMHW41400019.
Dual-chain trust anchor. Chain 1 (CopyrightChains): CopyrightID 0xce15394d0ebf08b213e0fbaabbaa711f1c41da9eafe797106cfd19be8f00820d. Chain 2 (Bitcoin): anchored in block 953520 (2026-06-13T13:32:09Z), 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/QMHW41400016.
Dual-chain trust anchor. Chain 1 (CopyrightChains): CopyrightID 0x10aeb3d6902f7ba9a2f768225012a48ed6c4009f35d6293d9a6afce797e1606a. Chain 2 (Bitcoin): anchored in block 953520 (2026-06-13T13:32:09Z), 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/QMHW41400017.
Dual-chain trust anchor. Chain 1 (CopyrightChains): CopyrightID 0x9b31476e676901d3b55896cc3559e7561a8a95e58939475712c484bdbb54b992. Chain 2 (Bitcoin): anchored in block 953513 (2026-06-13T12:47:07Z), 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/QMHW41400029.
Dual-chain trust anchor. Chain 1 (CopyrightChains): CopyrightID 0xe20f905e7f68359469906211fa8096f43846511fb7c27d7aba07632d3dc2165c. Chain 2 (Bitcoin): anchored in block 953513 (2026-06-13T12:47:07Z), 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/QMHW41400018.
Dual-chain trust anchor. Chain 1 (CopyrightChains): CopyrightID 0x4b1d090139928598672d55889f632f096f0e636b7c71cdd2b6c152478fe5b591. Chain 2 (Bitcoin): anchored in block 953513 (2026-06-13T12:47:07Z), 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/QZWV32432213.
Dual-chain trust anchor. Chain 1 (CopyrightChains): CopyrightID 0xaf58f9297067ad28400f9572893e9ef28f23f151862391c7b9c5d70a533d8bed. Chain 2 (Bitcoin): anchored in block 953515 (2026-06-13T12:53:06Z), 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/QZWV32432214.
Dual-chain trust anchor. Chain 1 (CopyrightChains): CopyrightID 0xe5007f417481d83c102ea55131f063f19196723df29813e3d5bf26a1d410b078. Chain 2 (Bitcoin): anchored in block 953513 (2026-06-13T12:47:07Z), 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/QZWV32432248.
Dual-chain trust anchor. Chain 1 (CopyrightChains): CopyrightID 0xe492c1408ffeffe49188787de077904048a92411312696861503882b7a237fc6. Chain 2 (Bitcoin): anchored in block 953513 (2026-06-13T12:47:07Z), 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/USA2P2149159.
Dual-chain trust anchor. Chain 1 (CopyrightChains): CopyrightID 0x5f28d22bde9b0982165529040204484e1c2e535b871ba92bb842e88d748ec555. Chain 2 (Bitcoin): anchored in block 953515 (2026-06-13T12:53:06Z), 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/QZWV32434704.
Dual-chain trust anchor. Chain 1 (CopyrightChains): CopyrightID 0xe457a3d1d7caac8c959054df8c6c0f4e17952ebb74f0df47f882e5b38817d262. Chain 2 (Bitcoin): anchored in block 953515 (2026-06-13T12:53:06Z), 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/QZWV32432274.
Dual-chain trust anchor. Chain 1 (CopyrightChains): CopyrightID 0x1401ef0070b1e6d346c742e79b1240b67fc28a7e433d7c40f7e4d4bd51c86d32. Chain 2 (Bitcoin): anchored in block 953520 (2026-06-13T13:32:09Z), 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/USA2P2223414.
Dual-chain trust anchor. Chain 1 (CopyrightChains): CopyrightID 0x026607f9389bcbb100953b92aaaff17905b0936159e38e6675fe308cfd6c759c. Chain 2 (Bitcoin): anchored in block 953520 (2026-06-13T13:32:09Z), 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/QZWV32432279.
Dual-chain trust anchor. Chain 1 (CopyrightChains): CopyrightID 0x2706c5cd2c93fdf707d017492c7a4c894c16a630d90bc9d9bd40349fd440b4f7. 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/AR1K22000019.