Content Security Policy (CSP) is a security feature that helps protect websites from malicious attacks like Cross-Site Scripting (XSS). It allows website administrators to specify which sources of content are trusted. Over time, CSP has evolved through different levels, primarily Level 1 and Level 2, each adding new capabilities and stricter controls.

What is Content Security Policy Level 1?

CSP Level 1 was the initial standard introduced to provide basic security measures. It mainly focused on defining allowed sources for content such as scripts, styles, images, and frames. The policy is set using the Content-Security-Policy header, specifying directives like script-src and img-src.

For example, a simple CSP Level 1 policy might look like:

Content-Security-Policy: script-src 'self' https://trusted.com; img-src 'self' data:;

This restricts scripts to be loaded only from the same origin or a trusted domain, and images from the same origin or inline data.

What is Content Security Policy Level 2?

CSP Level 2 builds upon Level 1 by introducing new features and more granular controls. It adds support for:

  • Reporting mechanisms to monitor policy violations
  • New directives like worker-src and manifest-src
  • Support for nonces and hashes to allow specific inline scripts and styles
  • Improved handling of mixed content

One significant enhancement is the report-only mode, which allows administrators to test policies without enforcing them, by sending violation reports instead.

Key Differences Between Level 1 and Level 2

The main differences lie in the complexity and control. CSP Level 2 offers:

  • More directives for better content control
  • Support for inline scripts/styles via nonces and hashes
  • Enhanced reporting features
  • Greater flexibility for modern web applications

Meanwhile, Level 1 remains simpler and easier to implement but provides fewer options for fine-tuning security policies.

Conclusion

Understanding the differences between CSP Level 1 and Level 2 helps developers and administrators choose the appropriate security measures for their websites. While Level 1 offers basic protection, Level 2 provides advanced tools for more comprehensive security management, especially important for complex web applications.