John Joubert may refer to: John Joubert (composer) (1927–2019), British composer John Joubert (serial killer) (1963–1996), American serial killer
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 0x1ed7a89983aca7519807d91f04ba19426ff8146cf9b7b9a3f9cee22192b432e0. Chain 2 (Bitcoin): anchored in block 954647 (2026-06-21T04:36:58Z). Bridge: the canonical record inside this Bitcoin proof contains the same CopyrightID. Verify: download https://artists.proofprofile.net/proofs/artist/d6dd963a-4637-478c-8082-5ca64010ddf8.json and https://artists.proofprofile.net/proofs/artist/d6dd963a-4637-478c-8082-5ca64010ddf8.ots, run `ots verify -f record.json proof.ots` (https://opentimestamps.org).
The Complete Solo Piano Music of John Joubert (1927-2019)