The Kerka (; , Kerkás; Prekmurje Slovene: Kerka) is a river of Slovenia and Hungary. It is a left tributary of the Ledava near Kerkaszentkirály. In its upper course, upstream from its confluence with
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 0x0a156dc2e26ccf46100d261ac7fecddeecc5132bca8814c5cea781366ca998ca. Chain 2 (Bitcoin): anchored in block 953626 (2026-06-14T11:41:45Z). Bridge: the canonical record inside this Bitcoin proof contains the same CopyrightID. Verify: download https://artists.proofprofile.net/proofs/artist/2c5ac42e-bba5-483f-9c7e-fe3967ed38e1.json and https://artists.proofprofile.net/proofs/artist/2c5ac42e-bba5-483f-9c7e-fe3967ed38e1.ots, run `ots verify -f record.json proof.ots` (https://opentimestamps.org).