Implementing a Content Security Policy (CSP) with nonces in an Electron application enhances security by mitigating risks associated with inline scripts and styles. Here's how you can achieve this:
A nonce (number used once) should be unique for every request to ensure security. In Node.js, you can generate a 16-byte (128-bit) nonce and encode it in base64
In your Electron application's main process, intercept HTTP responses to append the CSP header.
Replace YOUR_GENERATED_NONCE with the actual nonce value generated in your main process. Ensure that this value is securely passed from the main process to the renderer process, possibly through context bridging or preload scripts.
Important Considerations:
Avoid Using 'unsafe-inline': Including 'unsafe-inline' in your CSP allows the execution of inline scripts and styles, which can be a security risk. Instead, rely on nonces to permit specific inline code.
Consistent Nonce Usage: The nonce value must match between the CSP header and the nonce attributes in your HTML. Ensure that the nonce is generated once per request and applied consistently.
By following these steps, you can implement a robust CSP with nonces in your Electron application, enhancing its security posture.