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GDPR engineering considerations

LLM-Shield-Proxy provides controls that may support an organization's GDPR program. It does not determine lawful basis, satisfy data-subject rights, set retention policy, or make a deployment GDPR compliant. Controllers and processors remain responsible for those decisions and for legal review.

Data minimization and erasure​

  • The proxy can replace detected values before it builds a request for the configured upstream. Detection has false positives and false negatives, so test it on the languages and data in scope. Note that name (PERSON) redaction requires a loaded ONNX NER model; without it, name redaction is inactive.
  • Structured audit events are designed to record categories and decisions instead of prompt and response bodies. Verify errors, traces, custom attributes, and downstream log systems separately.
  • Local and Redis vault mappings expire after a configured TTL. Expiry does not prove that every copy was erased from memory, replicas, persistence files, backups, logs, or downstream systems.
  • A TTL is not a complete process for Article 17 requests. The organization should identify and handle every other system that stores the data.

Data protection by design​

The masking mode controls how a detected value is represented:

  • SYNTHETIC uses a deterministic, format-aware substitute within the configured mapping scope.
  • STRUCTURAL_TAG uses a token such as [EMAIL_1].
  • SCRUB uses a fixed marker and creates no rehydration mapping for that value.
  • STATELESS_CRYPTO encrypts selected values in the payload with AES-256-GCM. Rehydration requires an intact token and the correct key and context.

These modes do not improve detector recall. They can also change tokenization, model behavior, schemas, and response fidelity. Test the selected mode with the actual provider and workload.

Security of processing​

The proxy can contribute to a layered security design through TLS/mTLS configuration, identity and policy checks, SSRF controls on supported paths, and signed audit records. Each control has a defined boundary. Local audit files are not WORM storage, and the default best-effort audit mode can drop events under queue pressure.

See the architecture, limitations, and compliance evidence boundaries before using these controls in an assessment.