is a Japanese term for . In popular culture, it is often used for female ninja or practitioner of ninjutsu (ninpo). The term was largely popularized by novelist Futaro Yamada in his novel in 1964.
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 0xaae0fe93cdd5cb2e6c431dba6d2ab5c1f218ad7864d577197605c6f6a7e80fb6. Chain 2 (Bitcoin): anchored in block 954705 (2026-06-21T13:42:37Z). Bridge: the canonical record inside this Bitcoin proof contains the same CopyrightID. Verify: download https://artists.proofprofile.net/proofs/artist/ef0e50f0-3946-4051-ace0-a25ad218a1e8.json and https://artists.proofprofile.net/proofs/artist/ef0e50f0-3946-4051-ace0-a25ad218a1e8.ots, run `ots verify -f record.json proof.ots` (https://opentimestamps.org).