Encrypt Facebook Messenger - Chrome Extension

This extension will encrypt and decrypt your messages locally in the browser (using AES encryption via CryptoJS) so that no plain text is sent over the network to Facebook servers.

Background

After reading this article, I was motivated to build something that would help resist the forces of surveillance capitalism.

N.B. This extension is not intended to be a fully-functioning tool for encrypted messaging (Signal and Telegram are much better for that). Rather, it was built as a proof of concept, an act of resistance, and (hopefully) a source of inspiration.

Installing the extension

Because the extension is unpublished (for now), you have to jump through some hoops to install it.

• Download this repo
• Open Chrome
• Go to chrome://extensions
• Turn on "Developer Mode" in the top right corner
• Click "Load unpacked"
• Navigate to and select the "Source" folder

Setup

• Click on the "E" icon in your toolbar
• Click "Options"
• For each friend/group who also has the extension, type in the conversation ID and a previously-agreed-upon secret passphrase
  • Conversation IDs can be found in the address bar when you are in a conversation with someone: https://messenger.com/t/[id]
• Click "Save"
• You will need to refresh messenger.com whenever you update your secret passphrases

Usage

Just go to messenger.com and use it as normal! (although for now, in order to encrypt messages you have to send by pressing "Enter"; clicking the little paper plane will instead send the message unencrypted).

Only conversations for which you have set a passphrase in "Options" will be encrypted (other conversations will continue to work unencrypted as normal).

Note that only text messages (i.e. not images, stickers, reactions, gifs) are encrypted for now.

TODO

• facebook.com support
• change message color if encrypted (option)
• attempt to warn if extension no longer working due to FB code changes
• make click send button work (in addition to pressing enter)
• handle images
• handle gifs, stickers
• handle reactions
• handle multi-line messages more elegantly