Support configurable key sizes for Let’s Encrypt certificates

[KalebCheng]

Summary

This PR improves the Let’s Encrypt certificate workflow by adding support for configurable key sizes during certificate issuance and renewal.
Users can now choose appropriate security levels based on their environment while keeping sensible defaults and full backward compatibility.

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Changes

• Added support for selecting key type (ECDSA / RSA) and corresponding key sizes:
  • ECDSA: 256 (default), 384
  • RSA: 2048 (default), 3072, 4096
• Key size options dynamically adapt to the selected key type, with smart defaults applied automatically.
• Key size configuration is consistently applied to both certificate creation and renewal (HTTP & DNS).
• Existing certificates remain unaffected, and unspecified key sizes fall back to Let’s Encrypt defaults.
• Full internationalization support across all supported languages.

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Testing

• Verified certificate issuance with multiple ECDSA and RSA key sizes.
• Verified key type switching correctly resets the default key size.
• Verified HTTP certificate renewal preserves the configured key parameters.

[nginxproxymanagerci]

Docker Image for build 1 is available on DockerHub:

nginxproxymanager/nginx-proxy-manager-dev:pr-5177

Note

Ensure you backup your NPM instance before testing this image! Especially if there are database changes.
This is a different docker image namespace than the official image.

Warning

Changes and additions to DNS Providers require verification by at least 2 members of the community!

[CamelT0E]

Thank you for the very quick implementation.