CoSy, short for Conferencing System, was an early computer conferencing system developed at the University of Guelph. The CoS software grew out of an interest in group computer mediated communication
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 0x534ade4262bb4e0b9ab5ee9743cecdbc36d3db95924d72fbc17bcdcc0c3a01ac. Chain 2 (Bitcoin): anchored in block 954063 (2026-06-17T07:49:29Z). Bridge: the canonical record inside this Bitcoin proof contains the same CopyrightID. Verify: download https://artists.proofprofile.net/proofs/artist/4774bb2e-de1b-4684-a82f-7c9e8784493e.json and https://artists.proofprofile.net/proofs/artist/4774bb2e-de1b-4684-a82f-7c9e8784493e.ots, run `ots verify -f record.json proof.ots` (https://opentimestamps.org).