Google Chrome is using alpha numeric hashes as identifiers for the Chrome extensions. For eg. \"ajpgkpeckebdhofmmjfgcjjiiejpodla\" is the identifier for XMarks Bookmark Sync
I made crx_appid gem to calculate appid easily.
https://rubygems.org/gems/crx_appid
$ gem install crx_appid $ crx_appid extension.pem