thumb|upright=1.35|Russian Akula-class submarine of the Northern Fleet, in 2008 thumb|upright=1.35| A submarine (often shortened to sub) is a watercraft capable of independent operation underwater. (
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 0xe9d4cb87ec8f7002bcdd8720e69c215a0990f829fd0315e9c2b9e9de8fb2be28. 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/cf56691b-cd8f-4aa4-b970-bf9365a297b9.json and https://artists.proofprofile.net/proofs/artist/cf56691b-cd8f-4aa4-b970-bf9365a297b9.ots, run `ots verify -f record.json proof.ots` (https://opentimestamps.org).