Implementing the Public-key-pinning (hpkp) Policy in 2024

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In 2024, website security continues to be a top priority for organizations worldwide. One effective method to enhance security is implementing the Public-Key-Pinning (HPKP) policy. HPKP helps prevent attackers from impersonating a website by ensuring browsers only trust specific cryptographic keys.

What is Public-Key-Pinning?

Public-Key-Pinning is a security feature that allows website administrators to specify which public keys browsers should trust for their site. When a user visits a pinned site, the browser checks the server’s presented keys against the pinned keys. If they don’t match, the connection is blocked, preventing man-in-the-middle attacks.

Why Use HPKP in 2024?

Although HPKP was deprecated in 2018, some organizations still find value in its principles, especially when combined with modern security measures. Implementing HPKP in 2024 can:

  • Enhance trustworthiness of your website
  • Prevent certificate impersonation attacks
  • Complement other security protocols like HTTPS and HSTS

Steps to Implement HPKP

Implementing HPKP involves several key steps:

  • Generate your public and private keys: Use a trusted tool to create cryptographic key pairs.
  • Configure your server: Add the pinning policy via HTTP headers, specifying your trusted keys.
  • Set the max-age: Define how long browsers should remember the pinned keys.
  • Include backup keys: Specify additional keys to use if the primary keys are compromised or changed.

For example, a header might look like:

Public-Key-Pins: pin-sha256="base64=="; pin-sha256="backupBase64=="; max-age=5184000; includeSubDomains

Challenges and Considerations

While HPKP offers strong security benefits, it also presents challenges:

  • Risk of misconfiguration: Incorrect pins can lock out legitimate users.
  • Deprecation: Major browsers no longer support HPKP, favoring alternatives like Expect-CT and Certificate Transparency.
  • Operational complexity: Managing key rotations requires careful planning.

Given these challenges, many organizations choose to implement other security headers alongside or instead of HPKP, such as HSTS with includeSubDomains and preload options.

Conclusion

Although HPKP is deprecated in many browsers, understanding its principles remains valuable. In 2024, focus on comprehensive security strategies that include modern protocols and best practices to protect your website and users effectively.