title: AI Compliance - Article 12 receipts slug: ai-compliance-user-guide category: ai order: 80

AI Compliance user guide

PSIS records every AI inference call in a tamper-evident chain so auditors (internal or external) can verify the system has not been silently rewritten. This is how PSIS satisfies EU AI Act Article 12.

What gets logged

Every call to an AI service - LLM completion, HTR extraction, NER tagging, OCR, translation, guardrail check - produces one row in the ai_inference_log table. Each row contains:

the service name, model id and model version
a SHA-256 fingerprint of the input and of the output (full bodies are not retained by default)
the timestamp, request id, user id (if logged in) and tenant id
a chain hash that links to the previous row
an Ed25519 signature

Modifying or deleting a row breaks the chain at a detectable point. The verifier task walks the chain end-to-end and reports the first tamper site.

Where to find the public key

The signing public key is published at:

https://psis.theahg.co.za/.well-known/ai-inference-pubkey

Any external auditor or sibling system can use that key to verify receipts offline.

Verifying the log

A site administrator can verify the chain at any time:

php symfony ai-compliance:verify-inference-log

A successful run prints PASS - <N> receipts verified in <ms> ms. A failed run prints the first broken sequence number and a hint for inspection. Wire this task into your monitoring (cron + alert on non-zero exit) so any tampering is surfaced within hours.

Retention

By default the full payload of each receipt is kept for 7 years (payload_json column). After the retention window, a daily sweep nulls payload_json while preserving the row, its chain hash and its signature - the chain is still verifiable, the PII-bearing payload is gone.

Change the window in AtoM settings (ai_compliance_retention_years) or override per-run with --years=N.

Rotating the signing key

When you rotate (annually, or on suspected compromise):

sudo -u www-data php symfony ai-compliance:install-key --rotate --force

The new key becomes active for new receipts; the old key stays in ai_inference_key with rotated_at set, so historic receipts continue to verify under the key that signed them.

What this does not do

The chain proves the receipts have not been tampered with. It does not prove the receipts were complete - that depends on the AI services actually calling the logger after each inference. Once the Phase-2 wire-up ships, every AI service in ahgAIPlugin will log to the chain.

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