4U or 4 U may refer to: Music 4U (album), by Elva Hsiao, 2002 4U (Christina Milian EP), 2015 4 U (Cody Simpson EP), 2010 4U: Outside, an EP by BtoB, 2021 "4U", a song by Aero Chord, 2015 "4U",
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 0x1552282c85223e4f7cc0e04f80e4304e703daf58fcbb4900ae71a5181159f44a. 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/afad6f2c-71e7-4279-945e-bbb0c93c74b7.json and https://artists.proofprofile.net/proofs/artist/afad6f2c-71e7-4279-945e-bbb0c93c74b7.ots, run `ots verify -f record.json proof.ots` (https://opentimestamps.org).