Guardrail: mask U.S. personal data (SSN, phone, card)

Guardrail that masks U.S. personal data in AI assistant replies: SSNs, +1 phone numbers, personal emails and card numbers. Rules, 12 tests, code.

Regole

Mask before sending any data that identifies or reaches a person:
- personal email addresses (john.smith@…);
- U.S. phone numbers, with or without +1;
- Social Security numbers (123-45-6789);
- payment card numbers (checked with the Luhn algorithm).
Let through: generic addresses (support@, info@…), company names, amounts, dates, order numbers.

Casi di test

Codice

import re

PATTERNS = {
    "email": r"[\w.+-]+@[\w-]+\.[\w.-]+",
    "phone": r"(?:\+1[\s.-]?)?\(?\b[2-9]\d{2}\)?[\s.-]?\d{3}[\s.-]?\d{4}\b",
    "ssn": r"\b(?!000|666|9\d{2})\d{3}-(?!00)\d{2}-(?!0000)\d{4}\b",
    "card": r"\b(?:\d[ -]?){13,19}\b",
}
GENERIC = ("support@", "info@", "sales@", "hello@", "contact@")


def luhn(number: str) -> bool:
    digits = [int(c) for c in number if c.isdigit()][::-1]
    total = sum(d if i % 2 == 0 else (d * 2 - 9 if d * 2 > 9 else d * 2) for i, d in enumerate(digits))
    return 13 <= len(digits) <= 19 and total % 10 == 0


def mask(text: str) -> tuple[str, bool]:
    """Replace personal data with [<type> redacted]; return the text and True if anything was masked."""
    found = False
    for kind, pattern in PATTERNS.items():
        def repl(m):
            nonlocal found
            value = m.group(0)
            if kind == "email" and value.lower().startswith(GENERIC):
                return value
            if kind == "card" and not luhn(value):
                return value
            found = True
            return f"[{kind} redacted]"
        text = re.sub(pattern, repl, text)
    return text, found

Costo stimato

Token di input per chiamata : ≈ 871

Solo costo di input, esclusa la risposta del modello. Prezzi pubblici standard dei fornitori (Mistral AI, DeepSeek, OpenAI, Anthropic) convertiti da USD in euro al cambio BCE del 29 settembre 2026. Stima: 1 token ≈ 3,6 caratteri.

Identificativo

contextetech--mask-us-personal-data

Tipo

Salvaguardie

File

mask-us-personal-data.guardrail.json

Formato

JSON (application/json)

Dimensione

1928 byte (1,9 KB)

Codifica

UTF-8

Token stimati

≈ 534

Lingua

Inglese

Licenza

MIT

Uso commerciale

Consentito

Dati personali

Fittizi (inventati)

Versione

1.0

Pubblicato il

2 ottobre 2026 alle ore 21:54

Aggiornato il

2 ottobre 2026 alle ore 21:54

Archiviazione

nel database

Utilizzi

0

Mi piace

0

mask-us-personal-data.guardrail.json

{
  "format": "contextetech/guardrail/v1",
  "id": "contextetech/mask-us-personal-data",
  "description": "Guardrail that masks U.S. personal data in AI assistant replies: SSNs, +1 phone numbers, personal emails and card numbers. Rules, 12 tests, code.",
  "tags": [
    "pii",
    "ccpa",
    "security"
  ],
  "license": "MIT",
  "language": "en",
  "type": "pii",
  "action": "mask",
  "rules": "Mask before sending any data that identifies or reaches a person:\n- personal email addresses (john.smith@…);\n- U.S. phone numbers, with or without +1;\n- Social Security numbers (123-45-6789);\n- payment card numbers (checked with the Luhn algorithm).\nLet through: generic addresses (support@, info@…), company names, amounts, dates, order numbers.",
  "cases": [
    {
      "input": "You can reach John at john.smith@gmail.com for updates.",
      "expected": "block"
    },
    {
      "input": "Call me at (415) 555-0132 tomorrow.",
      "expected": "block"
    },
    {
      "input": "My cell is +1 212-555-0187.",
      "expected": "block"
    },
    {
      "input": "SSN on file: 219-09-9999.",
      "expected": "block"
    },
    {
      "input": "Charge it to 4111 1111 1111 1111, exp 08/28.",
      "expected": "block"
    },
    {
      "input": "Send the invoice to maria.lopez@acme-corp.com.",
      "expected": "block"
    },
    {
      "input": "Email support@contextetech.com with any question.",
      "expected": "allow"
    },
    {
      "input": "Your order #458712 ships tomorrow.",
      "expected": "allow"
    },
    {
      "input": "The total is $1,250.00 including sales tax.",
      "expected": "allow"
    },
    {
      "input": "Your appointment is on 10/12/2026 at 2 pm.",
      "expected": "allow"
    },
    {
      "input": "Acme Corp approved the quote.",
      "expected": "allow"
    },
    {
      "input": "Hi, how can I help you today?",
      "expected": "allow"
    }
  ]
}

Verificare un testo (Python)

import re

PATTERNS = {
    "email": r"[\w.+-]+@[\w-]+\.[\w.-]+",
    "phone": r"(?:\+1[\s.-]?)?\(?\b[2-9]\d{2}\)?[\s.-]?\d{3}[\s.-]?\d{4}\b",
    "ssn": r"\b(?!000|666|9\d{2})\d{3}-(?!00)\d{2}-(?!0000)\d{4}\b",
    "card": r"\b(?:\d[ -]?){13,19}\b",
}
GENERIC = ("support@", "info@", "sales@", "hello@", "contact@")


def luhn(number: str) -> bool:
    digits = [int(c) for c in number if c.isdigit()][::-1]
    total = sum(d if i % 2 == 0 else (d * 2 - 9 if d * 2 > 9 else d * 2) for i, d in enumerate(digits))
    return 13 <= len(digits) <= 19 and total % 10 == 0


def mask(text: str) -> tuple[str, bool]:
    """Replace personal data with [<type> redacted]; return the text and True if anything was masked."""
    found = False
    for kind, pattern in PATTERNS.items():
        def repl(m):
            nonlocal found
            value = m.group(0)
            if kind == "email" and value.lower().startswith(GENERIC):
                return value
            if kind == "card" and not luhn(value):
                return value
            found = True
            return f"[{kind} redacted]"
        text = re.sub(pattern, repl, text)
    return text, found