> ## Documentation Index
> Fetch the complete documentation index at: https://docs.portkey.ai/docs/llms.txt
> Use this file to discover all available pages before exploring further.

# Replace Custom Regex Patterns

> Redact custom patterns with Regex in Prisma AIRS AI Gateway.

For more granular control over pattern redaction, you can create custom patterns using the AI Gateway's **Regex Match** guardrail with redaction capabilities. This allows you to define specific regex patterns for sensitive information unique to your use case.

### Setting Up Custom Regex Patterns

1. **Navigate to Guardrails**: Go to the `Guardrails` page and click `Create`

2. **Select Regex Match**: Choose the "Regex Replace" guardrail from the BASIC category

3. **Configure the Pattern**:
   * **Regex Rule**: Enter your regex pattern to match specific data (e.g., `\b\d{3}-\d{2}-\d{4}\b` for SSN patterns)
   * **Replacement Text**: Define what to replace matches with (e.g., `[REDACTED]`, `*****`, `[SSN_HIDDEN]`)

4. **Save the Guardrail**: Name your guardrail and save it to get the associated Guardrail ID

### Common Regex Patterns for Sensitive Data

| Pattern Type           | Regex Pattern                                        | Replacement Example |
| ---------------------- | ---------------------------------------------------- | ------------------- |
| Credit Card            | `\b\d{4}[- ]?\d{4}[- ]?\d{4}[- ]?\d{4}\b`            | `[CREDIT_CARD]`     |
| Social Security Number | `\b\d{3}-\d{2}-\d{4}\b`                              | `[SSN_REDACTED]`    |
| Phone Numbers          | `\b\d{3}[-.]\d{3}[-.]\d{4}\b`                        | `[PHONE_HIDDEN]`    |
| Email Addresses        | `\b[A-Za-z0-9._%+-]+@[A-Za-z0-9.-]+\.[A-Za-z]{2,}\b` | `[EMAIL_REDACTED]`  |
| Custom Employee IDs    | `EMP-\d{6}`                                          | `[EMPLOYEE_ID]`     |

### Adding to Your Config

Once you've created your custom regex pattern guardrail, add it to your AI Gateway config:

```json theme={"system"}
{
  "before_request_hooks": [
    {"id": "your-guardrail-id"}
  ],
  "after_request_hooks": [
    {"id": "your-guardrail-id"}
  ]
}
```

<Note>
  You can add the same guardrail to both `before_request_hooks` (input guardrails) and `after_request_hooks` (output guardrails) to scan and redact regex patterns in both user inputs and LLM responses.
</Note>

### Example Implementation

With the custom regex guardrail configured, the input would be automatically transformed to:

```
"My SSN is [SSN_REDACTED] and credit card is [CREDIT_CARD]"
```


## Related topics

- [PII Redaction](/docs/aigw/product/guardrails/pii-redaction.md)
- [Enterprise Gateway](/docs/aigw/changelog/enterprise.md)
- [Guardrails](/docs/aigw/product/mcp-gateway/guardrails.md)
- [Guardrails for Embedding Requests](/docs/aigw/product/guardrails/embedding-guardrails.md)
- [JWT Token Validator](/docs/aigw/integrations/guardrails/jwt.md)