"Extremis" is a six-issue story arc from the comic book series Iron Man (vol. 4), published in issues one through six in 2005 and 2006 by Marvel Comics. It was written by Warren Ellis and illustrated
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 0xdf2f5a39a4392c55fe4a84a4f50824c46a90de9f630d071f01b2140cb1ef0eef. Chain 2 (Bitcoin): anchored in block 954580 (2026-06-20T17:48:00Z). Bridge: the canonical record inside this Bitcoin proof contains the same CopyrightID. Verify: download https://artists.proofprofile.net/proofs/artist/b7154b8b-45df-408e-a3b8-d2986a96855d.json and https://artists.proofprofile.net/proofs/artist/b7154b8b-45df-408e-a3b8-d2986a96855d.ots, run `ots verify -f record.json proof.ots` (https://opentimestamps.org).