Proof-of-Unchanged · Methodology · Ordinal 16

Proof-of-Unchanged
Custody-Boundary Verification Methodology

One-sentence summary: Proof-of-Unchanged is a custody-boundary verification methodology that deterministically answers one question: Has this evidence changed since the last verified checkpoint?

• Clinical trials & CRO inspection readiness
• Audit & assurance documentation frameworks

1) Purpose

Proof-of-Unchanged defines a domain-agnostic method for proving whether exported digital evidence has remained byte-unchanged across time and custody transitions, and for cryptographically enumerating divergence when it has not.

2) Scope

What it does

• Produces deterministic Proof-of-Unchanged via paired comparison of canonical checkpoints (T_k vs T_n).
• Detects byte-level divergence at both artefact and membership (ESF) layers.
• Returns informational divergence enumeration to bound proportional human investigation.

What it does not do

• Does not assess correctness, compliance, or intent.
• Does not prevent modification — it detects it.
• Does not operate inside source systems.
• Does not replace SOPs, audits, or regulatory judgment.

3) Core Definitions

Evidence Artefact: Any file or object treated as audit evidence once it exits a source system, immediately post-export.

Custody Boundary: Any transition where evidence moves between systems, storage tiers, custodians, jurisdictions, or sanctioned transformations.

Canonical State (T_k): A frozen, verifiable checkpoint represented by deterministic manifests, cryptographic digests, optional decentralized time attestation, and public hash-only anchoring.

4) Custody-Boundary Model

Verification occurs at custody boundaries, not inside systems.

This design avoids dependence on vendor APIs, platform trust, or internal system claims. Verification remains possible using retained evidence alone.

5) Canonical State Cycle (T₀ → Tₙ)

6) Interpretation Rule (Non-Accusatory)

Canonical claim: If bytes match the canonical state, the evidence is provably unchanged.

Divergence rule: Divergence is informational only. It does not imply error, misconduct, or non-compliance. It exists solely to direct proportional human effort.

PASS reduces reconstructive work. Divergence bounds reconstructive work.

7) Regulatory & Assurance Positioning

Proof-of-Unchanged operates within electronic records and audit documentation frameworks as mapped in C12 — AuditLog.AI Global Compliance Matrix.

• FDA 21 CFR Part 11
• EMA Annex 11 + GCP
• TGA / PIC/S PE 009-17

Additional assurance standards (PCAOB AS 1105 / AS 1215; ISA 230 / 500 / 240) are referenced in the full Compliance Matrix (C12).

This methodology is not clinical decision support and does not generate patient-level recommendations.

8) Public References

C17 — Proof-of-Unchanged Global Application Matrix (Ordinal 16)

C12 — AuditLog.AI Global Compliance Matrix (Ordinal 12)

9) Operational Implementation

The workflow below summarises the post-export verification model. Each step is deterministic, custody-preserving, and verifiable using hash-only artefacts.

Hashing, OTS, and OP_RETURN payload

Verification uses cryptographic identifiers only:

• File-level digests: SHA-256(bytes) → RIPEMD-160(SHA-256).
• OpenTimestamps (OTS): optional .hash.ots proofs can attest that a given hash existed before specific Bitcoin blocks.
• Session-level payload: the frozen session log (hash-only) is reduced to a compact public commitment.

SENTINEL|SESSION|<ripemd160>|<sha8>

Anchoring provides a public timestamp commitment. Verification remains local: any verifier can recompute digests from retained exports and confirm whether an evidence state is unchanged relative to a reference state.