Every exported Case File (JSON and CSV) includes a chain-of-custody certificate that shows the forensic data came from AI Identity and has not been altered after export. The platform signs a compact summary — report ID, generation timestamp, chain verification status, and entry counts — with the same key the audit chain verified under, producing a report_signature that travels with the export. Any recipient holding the organization's forensic verification key can recompute that summary and verify the signature, confirming both the integrity of the underlying hash chain and the authenticity of the export itself. This certificate is the key-holder layer; for verification without the org key, the OCSF export carries per-event ECDSA-P256 signatures and the Case File bundle carries Evidence Anchor inclusion proofs — both check out against our public JWKS at api.ai-identity.co/.well-known/ai-identity-public-keys.json.

# Verify a forensics report export hasn't been tampered with
import hmac, hashlib, json

def verify_report_signature(
    secret_key: bytes,
    report_id: str,
    generated_at: str,        # ISO 8601 UTC
    chain_valid: bool,
    total_entries: int,
    entries_verified: int,
    signature_hex: str,
) -> bool:
    payload = {
        "entries_verified": entries_verified,
        "chain_valid": chain_valid,
        "generated_at": generated_at,
        "report_id": report_id,
        "total_entries": total_entries,
    }
    msg = json.dumps(payload, sort_keys=True, separators=(",", ":"))
    expected = hmac.new(secret_key, msg.encode(), hashlib.sha256).hexdigest()
    return hmac.compare_digest(expected, signature_hex)