Segmented Hash-Chain with Honest Gap Attestation

Executive Summary

The court-grade autonomous-decision ledger described in Claim 64 depends on a hash chain: each entry commits to a hash derived from the entry before it, so any alteration of a past entry is detectable. Real infrastructure, however, occasionally loses a write outright - during an outage, a crash, a network partition - not because anyone altered anything, but because the write never landed at all. A naive hash-chain implementation cannot tell that apart from tampering; both look like a broken link.

This mechanism draws that distinction cryptographically. A body-hash mismatch - where an entry's actual content does not match the hash previously committed to it - is always treated as tampering, with no exception. A link discontinuity - a missing hash reference where a lost write left a gap - can instead be registered exactly once as a cryptographically-anchored "segment boundary": a permanent, honest record that a gap occurred, after which the chain resumes cleanly from that boundary. No prior entry is ever rewritten or removed either way.

Problem Statement

Hash-chained audit logs are a well-established way to make tampering detectable after the fact. But every real deployment eventually experiences an outage, a crash mid-write, or a network partition that can lose an in-flight write before it lands - and a chain-integrity check that cannot distinguish "someone altered this" from "this got lost honestly" forces an uncomfortable choice: either treat every operational hiccup as a security incident, or weaken the tamper check enough that it can no longer be trusted for its actual purpose.

Why Existing Solutions Are Insufficient

• Plain append-only hash chains: A single broken link is a single undifferentiated signal; the verifier cannot determine from the chain alone whether the cause was tampering or an honest lost write.
• Write-ahead-log-only durability guarantees: Reduce the likelihood of lost writes but do not eliminate it entirely, and provide no cryptographic vocabulary for recording a loss that does occur as a distinguishable, permanent, honest fact.
• Periodic full-chain re-signing/re-basing after an incident: Effectively starts a new chain from scratch after a disruption, which can obscure the historical continuity between the pre- and post-incident record rather than cryptographically anchoring the gap itself.
• Immutable ledger services (e.g. QLDB-style, confidential ledger products): Guarantee tamper-evidence for what was successfully written, but generally do not provide a first-class, cryptographically-anchored primitive for honestly registering that a specific write was lost.

Technical Architecture

Standard Hash-Chain Linkage

Each ledger entry includes a hash derived from the immediately preceding entry, the standard hash-chain construction that allows any verifier to confirm the sequence has not been altered.

Tamper Classification

When a verifier computes the hash of a stored entry and it does not match the hash previously committed to that entry, the discrepancy is classified as a tamper event without exception. There is no honest-loss interpretation available for a body-hash mismatch.

Gap Classification and Segment-Boundary Registration

When the discontinuity is instead a missing link - no entry hash-references the position where one was expected, consistent with a write that never completed rather than one that was altered - the system registers a cryptographically-anchored segment-boundary record documenting the discontinuity exactly once. This record itself becomes a permanent part of the evidentiary history.

Chain Resumption

Following a registered segment boundary, the hash chain resumes cleanly from that point. No previously-recorded entry - before or after the boundary - is altered, reordered, or removed as part of this process.

Segment Boundary & Re-Anchoring Protocol

This mechanism directly extends the court-grade autonomous-decision ledger described in Claim 64: the same hash-chained structure that captures every diagnosis, verdict, confidence score, action, and verified outcome for autonomous machine decisions is the structure to which this tamper-versus-gap distinction applies, preserving the ledger's evidentiary value even across genuine operational disruptions.

Prior Art Differentiation

Patent Claim