C2 or a derivative (C-2, C2, etc.) may refer to: Mathematics and physics C2, one of the common notations for the cyclic group of order 2 C2 differentiability class C2 or , the complex coordinate p
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 0xf37bffb76524c0dd3b35abe6c24e5ff6c963a42d67216850738e1f457123fbf3. 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/e3d4536f-4fb6-4b5c-990f-12fee11b7a57.json and https://artists.proofprofile.net/proofs/artist/e3d4536f-4fb6-4b5c-990f-12fee11b7a57.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 0x5195a5ea47346c96cd8fed67e1c75b3fa3521cbb27e1af6a067f4969b47b5bf8. Chain 2 (Bitcoin): anchored in block 958121 (2026-07-15T08:02:12Z), 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/QZTAS2181546.
Dual-chain trust anchor. Chain 1 (CopyrightChains): CopyrightID 0x366aeec6450f9a02728b16e387e9ff4073492b775d2499e300480fa5b06527c5. 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/QZHN62249255.
Dual-chain trust anchor. Chain 1 (CopyrightChains): CopyrightID 0x76274f18fb42e80ab13770ed22ee124a9a5e41482d5c359caa8db0b424348767. Chain 2 (Bitcoin): anchored in block 958060 (2026-07-14T20:39:42Z), 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/QZK6K2252344.
Dual-chain trust anchor. Chain 1 (CopyrightChains): CopyrightID 0x90b8e12a09da02b3c86d3cc3697dc0cfae80d48ce3a78a19f99e2f486ecf9c34. Chain 2 (Bitcoin): anchored in block 959144 (2026-07-22T15:38:35Z), 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/QZMEQ2263365.
Dual-chain trust anchor. Chain 1 (CopyrightChains): CopyrightID 0x58c30a339bed945028cf2315cf827bd5ddb1580483cf706de58fa6ada6cb807e. Chain 2 (Bitcoin): anchored in block 958543 (2026-07-18T11:58:44Z), 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/QZDA52371115.
Dual-chain trust anchor. Chain 1 (CopyrightChains): CopyrightID 0x7766ead2292fe5295cd22311d9e5b28aa16afefd46c5fe0f1e53cf4da2984711. Chain 2 (Bitcoin): anchored in block 958211 (2026-07-15T23:24:33Z), 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/QZNWZ2341807.
Dual-chain trust anchor. Chain 1 (CopyrightChains): CopyrightID 0x683c486b1f39969721f35e1b56993fc9ea3fd19724723bd909dee8591f892de6. 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/QZTBB2373515.