Audit Chain

Audit Chain

Verify the integrity of an entire receipt chain, not just a single receipt. Walks every receipt in ./receipts/ (or the specified directory), verifies each signature individually, and confirms that each parent_receipt_id correctly links to the previous receipt.

Usage

/audit-chain                    # Walk all receipts in ./receipts/
/audit-chain --last 50          # Verify only the last 50 receipts
/audit-chain --dir /var/log/receipts  # Use a different directory

What This Command Does

1. Lists all *.json files in the target directory
2. Sorts them by event_time to establish chronological order
3. For each receipt:
   • Verifies the Ed25519 signature independently
   • Confirms parent_receipt_id matches the previous receipt's receipt_id
4. Reports any failures with specific diagnostic information

Implementation

# Default: all receipts
RECEIPT_DIR="${2:-./receipts}"

# Run verification
if [ -n "$1" ] && [ "$1" = "--last" ]; then
    N="$2"
    ls -1 "$RECEIPT_DIR"/*.json | sort | tail -n "$N" | xargs npx @veritasacta/verify
else
    npx @veritasacta/verify "$RECEIPT_DIR"/*.json
fi

For chain-link verification (which @veritasacta/verify handles with --chain flag):

npx @veritasacta/verify --chain "$RECEIPT_DIR"/*.json

What to Show the User

Successful chain

Audit chain verification: PASSED

Scanned:     247 receipts
Time range:  2026-04-12T08:00:00Z to 2026-04-15T10:30:00Z
Chain head:  rec_8f92a3b1
Chain root:  rec_0a1b2c3d

Signatures:    247/247 valid ✓
Chain links:   246/246 correct ✓
Parent breaks: 0
Signer keys:   1 unique (4437ca56815c0516...)

All 247 receipts in the chain verify correctly. No tampering detected.

Chain with breaks

Audit chain verification: FAILED

Scanned:     247 receipts
Signatures:  247/247 valid ✓
Chain links: 245/246 correct (1 break detected)

BREAK DETECTED at receipt #142:
  Receipt:          rec_7a3b9c1e
  Claimed parent:   rec_8d4f2e91
  Expected parent:  rec_6b5c1a8d

This means either:
- A receipt was inserted between #141 and #142 (insertion attack)
- A receipt was deleted from the chain at position #142 (deletion attack)
- The signer used the wrong parent reference (bug)

To diagnose:
1. Check if rec_8d4f2e91 exists anywhere in the receipt directory
2. Check if rec_6b5c1a8d's successor is missing
3. Compare against any external witness or backup

All individual signatures are valid, so the receipts themselves are
authentic. The chain structure is compromised.

Tampered individual receipt

Audit chain verification: FAILED

Scanned:       247 receipts
Signatures:    246/247 valid (1 tampered)

TAMPERED RECEIPT at position #89:
  Receipt:      rec_3e8a9c7d
  Event time:   2026-04-13T14:22:01Z
  Tool:         Bash
  Signer:       4437ca56815c0516...

The signature for this receipt does not verify. The receipt has been
modified after signing.

The chain links ARE intact (parent/child references are consistent),
so this is a payload tampering event rather than a structural attack.

Compare the payload against any known-good copy. The altered field is
hidden in the canonicalized data.

When to Run This

• Before shipping a release — confirm no tampering in the development chain
• During security audits — demonstrate chain integrity to auditors
• After incidents — verify logs were not tampered with during the incident
• Periodically — CI/CD job to catch silent corruption
• Before compliance reviews — provide evidence of continuous integrity

References

• Full chain verification in @veritasacta/verify
• Hash-chained audit trail explainer
• Use /verify-receipt for single-receipt verification