Glossary
What is recompute at the anchored recent horizon?
The property of a hash-chained record that a party outside the emitter can walk a bounded recent window against the external anchor and confirm each entry. Scope is bounded to the recent horizon; a mismatch is a tamper signal.
§ 01 Definition
Walk the window that matters, anchor the rest.
Recompute at the anchored recent horizon is the property of a hash-chained record that a party outside the emitter can walk a bounded recent window of the chain, recomputing each entry’s hash against what is stored, and confirming the window’s terminal checkpoint against the external anchor. The scope of what is verified is bounded to the recent horizon (the high-water mark of the chain, minus a defined window of events); older entries beyond that horizon remain attested by the anchor but are not re-walked as part of a routine verification cycle.
Recompute at the anchored recent horizon is not full-chain recomputation. Full-chain recomputation walks every entry from the genesis of the chain forward and is a stronger guarantee at higher operational cost, particularly at fleet scale where the chain accrues events continuously. Recompute at the recent horizon is the operationally-viable scope for routine verification: an auditor, an examiner, or an independent verifier walks the window that matters for their current question, confirms the anchor at that window’s boundary, and reads the earlier record as anchored history rather than as re-walked history.
§ 02 Why it matters
Scope discipline is what keeps the claim honest.
The buyer’s question in an audit or examination is rarely a demand to walk the whole record from the beginning. It is a demand to verify what happened over the period the question covers: the last quarter, the last incident window, the last regulatory review cycle. Recompute at the recent horizon matches that question directly. The verifier walks the window the auditor cares about, and the anchor covers everything before it.
Scope discipline is what keeps the claim honest. A record that advertises independent verification without scope-bounding invites the reader to assume full-history recomputation. If the operational scope is bounded to a recent horizon, the record must say so; overstating the verification scope is the kind of representation an examiner reads as an accuracy error rather than a technical detail. Match-false at any point in the recent-horizon window is a tamper signal: the chain does not verify, and the party running the check sees the failure at the moment they look.
§ 03 Questions
Recent-horizon recompute, answered.
How is recompute at the recent horizon different from full-chain recomputation?
Full-chain recomputation walks every entry from the genesis of the chain forward. Recompute at the recent horizon walks a bounded recent window and relies on the external anchor to attest the earlier record. Full-chain is a stronger guarantee at higher operational cost; recent-horizon is the routine-verification scope that matches typical audit and examiner interrogation patterns. See what is a hash-chained external anchor for the anchor primitive that makes the earlier record defensible.
What does the verifier need in order to run the recompute?
Read access to the stored entries in the recent-horizon window, the hash-chain algorithm the entries were written under, and the external anchor value at the window’s boundary. The verifier walks the window forward, recomputes each entry’s hash from what is stored, and compares the terminal hash to the anchor. Any mismatch anywhere in the walk indicates tampering or corruption of the record.
What does "match-false" mean in this context?
It means the verifier walked the recent-horizon window, recomputed each entry’s hash from what is stored, and found a hash that did not match. Match-false is a genuine tamper signal: the record does not verify, and the discrepancy is visible to the party running the check. See what is a tamper-evident audit log for the entry-level integrity property that makes the walk possible.
§ 04 Related