generate-known-pem

Generate Known PEM

This Node.js script generates RSA key-pairs in PEM format, then selects those which map to a Chromium extension ID with a specified prefix and/or suffix.

Quick Start

Run node generate-known-pem.module.js to see the options.

For example:

Run node generate-known-pem.module.js --prefix=mega --n=3 to generate three PEM files starting with "mega".

FAQ

Why would you want this?

If you've worked with browser extensions on Chromium-based browsers such as Chrome or Edge, you will be accustomed to seeing long meaningless IDs like:

• cjpalhdlnbpafiamejdnhcphjbkeiagm - uBlock Origin
• fnplhdldnhaodknidfddmkfdhlhjihpd - Scientific Calculator
• cdnapgfjopgaggbmfgbiinmmbdcglnam - Open Dyslexic

This script allows you to choose the first few characters of the ID, giving you something more friendly like:

• blockhdlnbpafiamejdnhcphjbkeiagm
• calchdldnhaodknidfddmkfdhlhjihpd
• opendgfjopgaggbmfgbiinmmbdcglnam

Why can I only have letters A to P?

The characters are based on hexadecimal 0-F, but mapped to A-P:

• 0123456789abcdef - before
• abcdefghijklmnop - after

How does this script work?

The script generates random RSA key-pairs, then derives the Extension ID that each one would create. If the derived ID matches the sought pattern, it is saved to a .pem file.

Can I use this in my own code?

Yes; this is written as a Node.js module, so you can just import it.

How fast is it?

On my PC, timings are as follows:

• 1 known letter: 5 seconds
• 2 known letters: 2 minutes
• 3 known letters: 15 minutes
• 4 known letters: 2 hours
• 5 known letters: 36 hours
• 6 known letters: 1 month

Why is it so slow?

Generating RSA keys is slow by nature; and there is no way of knowing in advance what the ID will be.

Can I make it faster?

Yes, by running multiple instances in parallel.

Would it run faster in .NET / Python / Rust, or with OpenSSL / ssh-keygen, etc.?

Unlikely. The bottleneck is in generating the RSA key-pairs, and most of these tools use the same underlying operating system calls (e.g. the Win32 CryptGenKey function on Windows).

Once I've generated a PEM file, how do I then create a CRX file?

See project https://www.npmjs.com/package/crx

How can I submit this PEM file to the Chrome Web Store / Micosoft Edge Add-On Store?

You can't. These PEM files are only suitable for extensions distributed via Enterprise Policy or sideloaded via an installer.

How do you distribute an extension via Enterprise Policy?

See my other project https://github.com/andrewpmontgomery/chrome-extension-store

I have more questions

Raise an issue in Github, or email my GitHub username at gmail .com