John van Leeuwarden (4 July 1941 – 31 January 2019), who recorded under the name Johnny Lion, was a Dutch singer, journalist and actor. His best known song as a solo artist was his hit single "Sophie
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
Dual-chain trust anchor. Chain 1 (CopyrightChains): CopyrightID 0x4c4d6e826af3be4f4797be44dc7bcf518492feda24e45325a2e5b4ca31f2c752. Chain 2 (Bitcoin): anchored in block 953408 (2026-06-12T19:28:13Z). Bridge: the canonical record inside this Bitcoin proof contains the same CopyrightID. Verify: download https://artists.proofprofile.net/proofs/artist/91642a10-906b-4cfd-870f-3b9e9f7ea45c.json and https://artists.proofprofile.net/proofs/artist/91642a10-906b-4cfd-870f-3b9e9f7ea45c.ots, run `ots verify -f record.json proof.ots` (https://opentimestamps.org).
Popinstituut.NL / The Complete Collection