# Documentazione Django 6.0.7

# How to use Django’s Content Security Policy

## Basic config

To enable Content Security Policy (CSP) in your Django project:

1. Add the CSP middleware to your `MIDDLEWARE` setting:

       MIDDLEWARE = [
           # ...
           "django.middleware.csp.ContentSecurityPolicyMiddleware",
           # ...
       ]

2. Configure the CSP policies in your `settings.py` using either `SECURE_CSP` or `SECURE_CSP_REPORT_ONLY` (or both). The CSP Settings docs provide more details about the differences between these two:

       from django.utils.csp import CSP

       # To enforce a CSP policy:
       SECURE_CSP = {
           "default-src": [CSP.SELF],
           # Add more directives to be enforced.
       }

       # Or for report-only mode:
       SECURE_CSP_REPORT_ONLY = {
           "default-src": [CSP.SELF],
           # Add more directives as needed.
           "report-uri": "/path/to/reports-endpoint/",
       }

## Nonce config

To use nonces in your CSP policy, beside the basic config, you need to:

1. Include the `NONCE` placeholder value in the CSP settings. This only applies to `script-src` or `style-src` directives:

       from django.utils.csp import CSP

       SECURE_CSP = {
           "default-src": [CSP.SELF],
           # Allow self-hosted scripts and script tags with matching `nonce` attr.
           "script-src": [CSP.SELF, CSP.NONCE],
           # Example of the less secure 'unsafe-inline' option.
           "style-src": [CSP.SELF, CSP.UNSAFE_INLINE],
       }

2. Add the `csp()` context processor to your `TEMPLATES` setting. This makes the generated nonce value available in the Django templates as the `csp_nonce` context variable:

       TEMPLATES = [
           {
               "BACKEND": "django.template.backends.django.DjangoTemplates",
               "OPTIONS": {
                   "context_processors": [
                       # ...
                       "django.template.context_processors.csp",
                   ],
               },
           },
       ]

3. In your templates, add the nonce to elements that require it:

   For inline `<style>` or `<script>` tags, use the `csp_nonce` context variable directly:

       <style nonce="{{ csp_nonce }}">
         /* These inline styles will be allowed. */
       </style>

       <script nonce="{{ csp_nonce }}">
         // This inline JavaScript will be allowed.
       </script>

   For external `<script src="...">` and `<link rel="stylesheet">` elements, use the `csp_nonce_attr` template tag:

       <script src="/path/to/script.js" {% csp_nonce_attr %}></script>
       <link rel="stylesheet" href="/path/to/style.css" {% csp_nonce_attr %}>

   To render a `Media` object’s assets with the nonce applied to each element, pass the object to the `csp_nonce_attr` tag:

       {% csp_nonce_attr form.media %}

   Changed in Django 6.1:

   The `csp_nonce_attr` template tag was added, including support for rendering `Media` objects.

Caching and Nonce Reuse

The `ContentSecurityPolicyMiddleware` automatically handles generating a unique nonce and inserting the appropriate `nonce-<value>` source expression into the `Content-Security-Policy` (or `Content-Security-Policy-Report-Only`) header when the nonce is used in a template.

To ensure correct behavior, make sure both the HTML and the header are generated within the same request and not served from cache. See the reference documentation on Nonce usage for implementation details and important caching considerations.