Document

Audit Evidence Model

**Verifiable Semantic Execution Layer (VSEL)**

Verifiable Semantic Execution Layer (VSEL)

AUDIT EVIDENCE MODEL

1. Purpose

This document defines how every audit finding, verification result, and compliance artifact must be captured, structured, and preserved.

Without this model, audits produce opinions. With it, they produce evidence.

An audit without reproducible evidence is a conversation. An audit with reproducible evidence is a proof of diligence.

2. Evidence Structure

Every audit artifact follows this schema:

AuditEvidence {
  id: String,                    // Unique identifier (AE-PHASE-NUMBER)
  phase: UInt,                   // Roadmap phase (0-10)
  category: EvidenceCategory,    // Type of evidence
  hypothesis: String,            // What was being tested/verified
  method: VerificationMethod,    // How it was tested
  artifact_evaluated: String,    // Which document/code/component
  failure_class_sought: String,  // What class of failure was targeted
  result: Result,                // Pass / Fail / Inconclusive
  finding: String?,              // Description if Fail
  severity: Severity?,           // If finding exists
  remediation: String?,          // Fix applied
  remediation_verified: Boolean, // Was the fix re-audited?
  evidence_artifact: String,     // Reference to reproducible evidence
  reproducibility: String,       // How to reproduce the result
  auditor: String,               // Who performed the audit
  date: Date,                    // When
  status: Status                 // Open / Remediated / Verified / Accepted-Risk
}

3. Evidence Categories

CAT-1: Formal Verification Evidence

Evidence from model checking or theorem proving.

{
  tool: "TLA+ / Coq / Lean / Isabelle",
  property_checked: String,
  model_version: String,
  state_space_size: UInt?,
  counterexample: Trace?,       // If found
  proof_artifact: String?,      // If proven
  runtime: Duration,
  configuration: String         // Parameters, bounds, fairness assumptions
}

CAT-2: Differential Testing Evidence

Evidence from comparing implementation against specification.

{
  implementation_version: String,
  specification_version: String,
  test_cases: UInt,
  mismatches_found: UInt,
  mismatch_details: [MismatchRecord],
  coverage: CoverageReport
}

CAT-3: Constraint Analysis Evidence

Evidence from constraint system analysis.

{
  constraint_system_version: String,
  analysis_type: "static / symbolic / fuzzing",
  variables_analyzed: UInt,
  free_variables_found: UInt,
  underconstrained_fields: [String],
  invalid_witnesses_tested: UInt,
  invalid_witnesses_rejected: UInt,
  invalid_witnesses_accepted: UInt  // MUST BE ZERO
}

CAT-4: Adversarial Testing Evidence

Evidence from adversarial attack simulation.

{
  attack_class: String,
  attack_description: String,
  target_property: String,
  attack_successful: Boolean,
  exploit_trace: Trace?,
  mitigation_applied: String?,
  mitigation_verified: Boolean
}

CAT-5: Code Review Evidence

Evidence from manual or automated code review.

{
  component_reviewed: String,
  reviewer: String,
  findings: [Finding],
  coverage: String,
  methodology: String
}

CAT-6: Compliance Evidence

Evidence of compliance with specification requirements.

{
  requirement_id: String,
  requirement_text: String,
  compliance_status: "compliant / non-compliant / partial / N/A",
  evidence_reference: String,
  gap_description: String?
}

4. Severity Classification

Severity	Definition	Required Response
Catastrophic	System correctness guarantee is broken	Immediate halt. Full remediation. Re-audit.
Critical	Significant semantic gap exploitable by adversary	Block phase progression. Remediate. Re-audit.
Serious	Weakness that could lead to failure under specific conditions	Remediate before phase completion.
Moderate	Improvement needed but no immediate exploit path	Track. Remediate within next phase.
Informational	Observation for future consideration	Document. No immediate action required.

5. Evidence Lifecycle

Discovery → Documentation → Triage → Remediation → Verification → Closure

Stage 1: Discovery

Finding is identified during audit activity. Evidence artifact is created immediately.

Stage 2: Documentation

Full AuditEvidence record is created. Reproducibility instructions are written.

Stage 3: Triage

Severity is assigned. Responsible party is identified. Timeline is set.

Stage 4: Remediation

Fix is implemented. Fix is documented with reference to original finding.

Stage 5: Verification

Fix is independently verified. Original test/check is re-run. New evidence artifact is created.

Stage 6: Closure

Status is set to Verified. Evidence chain is complete.

6. Phase Audit Requirements

Each roadmap phase must produce:

PHASE_X_AUDIT_REPORT.md
  - Summary of audit scope
  - Methods used
  - Findings (with severity)
  - Evidence references

PHASE_X_FINDINGS.md
  - Detailed finding descriptions
  - Counterexample traces (if any)
  - Proof artifacts (if any)

PHASE_X_REMEDIATION.md
  - Fix descriptions
  - Verification results
  - Re-audit evidence

PHASE_X_COMPLIANCE.md
  - Per-requirement compliance status
  - Evidence references
  - Gap analysis

Phase progression requires:

∀ findings with severity ≥ Serious: status = Verified
∀ requirements: compliance_status = compliant

7. Evidence Integrity

All evidence artifacts must be:

7.1 Committed

Commit(evidence) = Hash(evidence_content)

Evidence commitments are stored in the audit trail.

7.2 Timestamped

Timestamp(evidence) = trusted_time_source

7.3 Signed

Sign(evidence, auditor_key)

7.4 Immutable

Once created, evidence artifacts cannot be modified. Corrections create new artifacts referencing the original.

7.5 Reproducible

Every evidence artifact must include sufficient information to reproduce the result independently.

8. Audit Trail Structure

audit/
├── phase_0/
│   ├── AUDIT_REPORT.md
│   ├── FINDINGS.md
│   ├── REMEDIATION.md
│   ├── COMPLIANCE.md
│   └── evidence/
│       ├── AE-0-001.json      // Model checking result
│       ├── AE-0-002.json      // Invariant analysis
│       ├── AE-0-003.json      // Counterexample trace
│       └── ...
├── phase_1/
│   └── ...
└── ...

9. Continuous Audit Integration

Audit is not a phase-end activity. It is continuous.

9.1 Automated Checks

Model checking runs on every specification change
Constraint analysis runs on every constraint change
Differential testing runs on every implementation change

9.2 Regression Evidence

Every fix must include a regression test that:

Reproduces the original finding
Verifies the fix prevents it
Is added to the continuous test suite

9.3 Evidence Freshness

Evidence older than the last relevant change is stale and must be refreshed.

∀ evidence E referencing artifact A:
  E.date > A.last_modified
  OR E is marked stale and must be refreshed

10. Audit Independence

10.1 Self-Audit

Performed by the development team. Produces evidence but with inherent bias.

10.2 Independent Audit

Performed by external party. Required for Phase 10 (Pre-Production Gate).

10.3 Adversarial Audit

Performed by party incentivized to find failures. Highest value evidence.

All three types must be represented in the evidence trail.

11. Non-Negotiable Rules

No finding may be closed without verified remediation evidence
No phase may progress with open Catastrophic or Critical findings
No evidence may be modified after creation
No audit may be performed by the author of the audited component (for independent audit)
No "accepted risk" classification for Catastrophic findings

12. Closing Statement

This model exists to make accountability concrete.

Every claim about the system's correctness must be backed by evidence. Every evidence artifact must be reproducible. Every finding must be resolved.

The alternative is trust. And trust, in adversarial systems, is the first thing that fails.

Theorem Proving Plan

Self Audit