Ocultar PII Refinery — Mistral Le Chat MCP Extension

Zero-egress PII protection for Mistral Le Chat workflows. Runs entirely in your infrastructure — no data ever leaves your environment.

Optimised for French and EU compliance: SIRET/SIREN, IBAN, RGPD Article 25, CNIL requirements.

Tools

Prerequisites

• Ocultar Refinery running locally:

  docker compose up
  

• Python 3.10+

Installation

pip install ocultar-mistral-mcp

Or with uvx (no install needed):

uvx ocultar-mistral-mcp

Mistral Le Chat Configuration

In Mistral Le Chat, open Settings → Tools → MCP Servers and add:

{
  "mcpServers": {
    "ocultar-pii": {
      "command": "ocultar-mistral-mcp",
      "env": {
        "OCULTAR_URL": "http://localhost:4141",
        "OCULTAR_API_KEY": "your-api-key"
      }
    }
  }
}

Or with uvx (no prior install required):

{
  "mcpServers": {
    "ocultar-pii": {
      "command": "uvx",
      "args": ["ocultar-mistral-mcp"],
      "env": {
        "OCULTAR_URL": "http://localhost:4141",
        "OCULTAR_API_KEY": "your-api-key"
      }
    }
  }
}

Environment Variables

Usage

Once connected, Le Chat will automatically call refine_text before processing sensitive data. You can also invoke it explicitly:

"Avant de traiter ce texte, filtre les DCP : Jean Dupont, jean.dupont@banque.fr, IBAN FR76 3000 6000 0112 3456 7890 189"

Le Chat returns:

{
  "cleanText": "[NAME_a1b2c3d4e5f6a7b8], [EMAIL_9c8f7a1b2d3e4f50], IBAN [IBAN_7f3e9a2b1c4d5e60]",
  "tokenMap": {
    "[NAME_a1b2c3d4e5f6a7b8]": "NAME",
    "[EMAIL_9c8f7a1b2d3e4f50]": "EMAIL",
    "[IBAN_7f3e9a2b1c4d5e60]": "IBAN"
  }
}

For authorized workflows that need to restore PII after AI processing:

"Reveal these tokens: [EMAIL_9c8f7a1b2d3e4f50], [IBAN_7f3e9a2b1c4d5e60]"

This call is recorded in the immutable Ed25519-signed audit log.

Why This Matters for French Enterprises

Sending customer data to any external AI API — including Mistral's cloud — without redaction constitutes a RGPD violation under Article 25 (Privacy by Design). The CNIL has issued enforcement guidance specifically targeting AI pipeline data flows.

Ocultar ensures that:

• No raw PII ever reaches Le Chat's API endpoint
• SIRET, SIREN, IBAN, and French address formats are detected and tokenized
• Every vault access is logged in a tamper-evident, Ed25519-signed audit trail
• You remain the data controller — Ocultar is a local processor under your full control

Security Model

• refine_text is safe to expose to any Le Chat session
• reveal_tokens requires OCULTAR_AUDITOR_TOKEN and every call is logged with actor, timestamp, and Ed25519 signature
• The Refinery vault uses AES-256-GCM with HKDF-SHA256 key derivation — tokens are useless without the master key
• If the Refinery is unreachable, both tools fail closed — raw PII is never forwarded

License

AGPLv3 — see LICENSE. Commercial licensing available for organizations that cannot comply with AGPLv3's source-disclosure requirements — see COMMERCIAL_LICENSE.md.