Yoo Si-ah (; born Yoo Yeon-joo on September 17, 1995), known professionally as YooA (), is a South Korean singer and actress. She is a member of the girl group Oh My Girl under WM Entertainment. She m
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 0x15d1361be1be77d53ff093aa3ba78f147eb6b729c6b2f714db29f50eff24d3ef. Chain 2 (Bitcoin): anchored in block 954784 (2026-06-22T02:53:59Z). Bridge: the canonical record inside this Bitcoin proof contains the same CopyrightID. Verify: download https://artists.proofprofile.net/proofs/artist/ed51dff8-901d-4a35-80fc-2c1991711db0.json and https://artists.proofprofile.net/proofs/artist/ed51dff8-901d-4a35-80fc-2c1991711db0.ots, run `ots verify -f record.json proof.ots` (https://opentimestamps.org).