"Mr. Chu" is a song by South Korean girl group Apink. The song is their 5th Korean single and served as the lead single from their 4th mini-album Pink Blossom. The song was composed by Duble Sidekick.
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 0x2626fa21006c61b875466f21f9393ba258f60246befa98baa3a0b1f07fa76f99. Chain 2 (Bitcoin): anchored in block 954587 (2026-06-20T19:10:41Z). Bridge: the canonical record inside this Bitcoin proof contains the same CopyrightID. Verify: download https://artists.proofprofile.net/proofs/artist/b94ec66f-62d8-4132-855a-ea6c930b8f7d.json and https://artists.proofprofile.net/proofs/artist/b94ec66f-62d8-4132-855a-ea6c930b8f7d.ots, run `ots verify -f record.json proof.ots` (https://opentimestamps.org).