Inline PGP Decryption

This repository contains a userscript that detects inline PGP-encrypted message blocks on a specific domain and decrypts them in place using a private key loaded from a local file and a passphrase stored in the browser session.

The script is designed to be used with browser userscript managers (such as Tampermonkey or Violentmonkey).

Screenshots

Files

• userscript.js: The main userscript. It is parameterized by a placeholder string <domain> which must be replaced with the actual target domain before use.
• configure.sh: Unix shell script that prompts for a domain and replaces all instances of <domain> in userscript.js.
• configure.bat: Windows batch script that performs the same replacement using PowerShell.

Initial setup

From the project root (e.g. /home/jack/repos/inline-pgp):

1. Configure the target domain

   • On Linux/macOS:

     ./configure.sh

   • On Windows (from Command Prompt or PowerShell in this directory):

     configure.bat

   When prompted, enter the domain (for example example.com). All occurrences of <domain> in userscript.js will be replaced with your value.

2. Install the userscript

   • Open userscript.js in your browser.
   • Use your userscript manager (e.g. Tampermonkey/Violentmonkey) to create a new script and paste the contents of userscript.js, or drag/drop / import the file if supported.

How it works (high level)

• Scans page content for -----BEGIN PGP MESSAGE----- ... -----END PGP MESSAGE----- blocks.
• Provides a small floating control panel to:
  • Load an armored private key file for the current browser session.
  • Set or change the passphrase (stored only in sessionStorage).
  • Toggle auto-decryption on and off.
  • Clear key and passphrase from the current session.
• Automatically replaces detected PGP blocks with decrypted plaintext (when possible), or shows a failure indicator if decryption fails.

Development notes

• The userscript expects openpgp v5 to be available via the @require metadata line.
• The code avoids use of any in its JSDoc typings and aims to stay lint-clean; after modifying userscript.js, run your preferred linter in your environment if applicable.