Leonard Joseph Cariou (; born September 30, 1939) is a Canadian actor, singer, and theatre director. He gained prominence for his portrayal of Sweeney Todd in the original cast of Stephen Sondheim's
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 0xa0634058c35f1943051c4bd93cb316260c73ffc0207647b64c493d17ffbd5c7f. 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/7aeadc47-7b6b-4063-b039-f788683f0544.json and https://artists.proofprofile.net/proofs/artist/7aeadc47-7b6b-4063-b039-f788683f0544.ots, run `ots verify -f record.json proof.ots` (https://opentimestamps.org).
A Little Night Music: Send in the Clowns
Original Broadway Cast of A Little Night Music
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 0x530686fa418d980ebb6ed3b41e70ef6d0b6d0091c0972acb4ac94dc66208f478. Chain 2 (Bitcoin): anchored in block 960199 (2026-07-30T02:30:29Z), 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/USSM17300275.
Dual-chain trust anchor. Chain 1 (CopyrightChains): CopyrightID 0x1babbb7e5e8cca37db9209785cb83a9028457612ad067b869a04a64f0a738170. 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/USUMC0000305.
Dual-chain trust anchor. Chain 1 (CopyrightChains): CopyrightID 0x17bfc75dfb5d4279ef3524fe7539b38a0d058e7ba448c0d39ae2b0f45a3b1d1d. Chain 2 (Bitcoin): anchored in block 960309 (2026-07-30T20:35:49Z), 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/USUMC0000307.
Dual-chain trust anchor. Chain 1 (CopyrightChains): CopyrightID 0xe90c95cfe109e6c07514d7635357d6993710a1e8323bc577a27b9256998d6290. 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/USUMC0000314.
Dual-chain trust anchor. Chain 1 (CopyrightChains): CopyrightID 0xeeef7a0386f690740d4dae2fd74473e57bedd6aba115084e31743e4eae82d959. 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/USUMC0000316.
A Little Night Music: A Weekend in the Country
A Little Night Music Original Broadway Cast Ensemble
Dual-chain trust anchor. Chain 1 (CopyrightChains): CopyrightID 0x55c399008c40c1bb977c35961f8c2bddcd74e13d0a2235e2ded46fe38968095e. Chain 2 (Bitcoin): anchored in block 960250 (2026-07-30T11:13:28Z), 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/USSM17300279.
Dual-chain trust anchor. Chain 1 (CopyrightChains): CopyrightID 0xdfe083197fffa0963813fd8ea76b524a07ed6138c98f668e9db0b196e9340704. Chain 2 (Bitcoin): anchored in block 960222 (2026-07-30T07:48:45Z), 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/USBC11600004.
Original Broadway Cast of Sweeney Todd: The Demon Barber of Fleet Street
Dual-chain trust anchor. Chain 1 (CopyrightChains): CopyrightID 0x9010c6f856855bae5d050845abe37e4e516bddaabb7e558a84d070a663215cfc. 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/USBC17900161.