Mark Sundeen (born 1970) is an American author. His book Car Camping was published by HarperCollins in 2000. His book The Making of Toro was published by Simon & Schuster in 2003. North by Northweste
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 0x92617b00d403d975405989de4cf167b2f67da6325158a366beb334e4fa93cfa5. Chain 2 (Bitcoin): anchored in block 954065 (2026-06-17T08:10:43Z). Bridge: the canonical record inside this Bitcoin proof contains the same CopyrightID. Verify: download https://artists.proofprofile.net/proofs/artist/4a4f4d45-dbf1-484a-9ba7-e43b2f3fa26b.json and https://artists.proofprofile.net/proofs/artist/4a4f4d45-dbf1-484a-9ba7-e43b2f3fa26b.ots, run `ots verify -f record.json proof.ots` (https://opentimestamps.org).