How to Maintain Tamper-Proof Audit Trails for AI Agents

A standard log file can be edited, truncated, or deleted after the fact — if an AI agent or attacker modifies your logs, you lose the evidence trail. SafeClaw by Authensor produces hash-chained audit logs where every entry includes a cryptographic hash of the previous entry, making any tampering immediately detectable. If a single log entry is modified, inserted, or deleted, the hash chain breaks and verification fails. This gives you audit trails that regulators, auditors, and security teams can trust.

Quick Start

npx @authensor/safeclaw

Scaffolds a .safeclaw/ directory with hash-chained auditing enabled by default.

How Hash-Chaining Works

Each audit entry includes a prevHash field containing the SHA-256 hash of the previous entry. This creates an unbreakable chain:

Entry 1: { data: ..., hash: H1, prevHash: null }
Entry 2: { data: ..., hash: H2, prevHash: H1 }
Entry 3: { data: ..., hash: H3, prevHash: H2 }
Entry 4: { data: ..., hash: H4, prevHash: H3 }

If someone modifies Entry 2, its hash changes. Entry 3's prevHash no longer matches, and verification fails at that point. You know exactly where the chain was broken and which entries are suspect.

Step 1: Configure Hash-Chained Auditing

# .safeclaw/config.yaml
audit:
  enabled: true
  hashChain:
    enabled: true
    algorithm: "sha256"
    includeFields:
      - timestamp
      - action
      - effect
      - agentId
      - matchedRule
      - requestDetails
  destination: "logs/audit.jsonl"
  rotation:
    maxSize: "100MB"
    maxAge: "90d"
    compress: true

Step 2: Understand the Audit Entry Format

Each log entry is a self-contained JSON object with chain metadata:

{
  "sequence": 1847,
  "timestamp": "2026-02-13T14:23:01.847Z",
  "action": "file.write",
  "effect": "deny",
  "agentId": "coding-assistant-01",
  "matchedRule": "block-config-writes",
  "requestDetails": {
    "path": ".env.production"
  },
  "hash": "sha256:3f2a91bc4d...",
  "prevHash": "sha256:7e1b83af2c..."
}

The hash field is computed over all data fields plus prevHash, creating the chain.

Step 3: Verify Chain Integrity

Run periodic verification to confirm your audit trail has not been tampered with:

npx @authensor/safeclaw audit verify logs/audit.jsonl

Audit Trail Verification
━━━━━━━━━━━━━━━━━━━━━━━━
File: logs/audit.jsonl
Entries: 24,847
Chain status: VALID ✓
First entry: 2026-01-15T09:00:01Z (sequence 1)
Last entry: 2026-02-13T14:23:01Z (sequence 24847)
No gaps detected.
No hash mismatches detected.

If tampering is detected:

Chain status: BROKEN ✗
Break detected at sequence 12,445
  Expected prevHash: sha256:7e1b83af2c...
  Actual prevHash: sha256:9a4c22de8f...

Entries 12,445 through 24,847 may have been tampered with.

Step 4: Configure Immutable Storage

For maximum tamper resistance, write audit logs to append-only storage:

audit:
  destination:
    primary: "logs/audit.jsonl"
    secondary:
      - type: "s3"
        bucket: "company-audit-logs"
        prefix: "safeclaw/"
        objectLock: true  # S3 Object Lock prevents deletion
      - type: "syslog"
        host: "syslog.internal.company.com"
        port: 514
        protocol: "tcp"

Writing to multiple destinations simultaneously means an attacker would need to compromise all storage systems to erase evidence.

Step 5: Set Up Automated Verification

Schedule regular chain verification as part of your operations:

# Cron job or CI schedule
Run verification daily
0 6   * npx @authensor/safeclaw audit verify logs/audit.jsonl --alert-on-failure

Configure the --alert-on-failure flag to send notifications if the chain is broken:

audit:
  verification:
    schedule: "daily"
    alertWebhook: "${SECURITY_ALERT_WEBHOOK}"
    retainVerificationProofs: true

Step 6: Export for Compliance

Generate audit reports for compliance reviews:

# Export all actions for a date range
npx @authensor/safeclaw audit export \
  --from "2026-01-01" \
  --to "2026-02-13" \
  --format csv \
  --output compliance-report-q1.csv

Export with chain verification proof
npx @authensor/safeclaw audit export \
  --from "2026-01-01" \
  --to "2026-02-13" \
  --format pdf \
  --include-verification-proof \
  --output compliance-report-q1.pdf

The PDF export includes the hash chain verification proof, which auditors can independently verify.

Why SafeClaw

• 446 tests covering hash-chain integrity, verification, and edge cases
• Deny-by-default — every action attempt (allowed and denied) is logged in the chain
• Sub-millisecond evaluation — hash computation adds negligible overhead
• Hash-chained audit trail — the core feature: cryptographic tamper detection built into every log entry
• Works with Claude AND OpenAI — one tamper-proof audit trail for all your AI agents

Cross-References

• Tamper-Proof Audit Trail Explained
• Immutable Audit Log Pattern
• Audit Trail Specification Reference
• How to Log Every AI Agent Action for Compliance