420 may refer to: Science and technology 420 (number), in mathematics 420 Bertholda, a main-belt asteroid 4:2:0, a chroma subsampling layout Cannabis culture 420 (cannabis culture), informal ref
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 0xd61afad4e0b8323a8b387b75f24efd109ce1d00aae347d71f3120ef8e9f39587. Chain 2 (Bitcoin): anchored in block 954667 (2026-06-21T07:29:20Z). Bridge: the canonical record inside this Bitcoin proof contains the same CopyrightID. Verify: download https://artists.proofprofile.net/proofs/artist/c16a7036-43ec-41db-b598-9a87bcb9e057.json and https://artists.proofprofile.net/proofs/artist/c16a7036-43ec-41db-b598-9a87bcb9e057.ots, run `ots verify -f record.json proof.ots` (https://opentimestamps.org).