GitHub Keys gem allows you to fetch users keys in the simplest way. It uses web scraping because of GH API limits.

Add this line to your application's Gemfile:

gem 'ghkeys'

And then execute:

$ bundle

Or install it yourself as:

$ gem install ghkeys

require 'ghkeys'

GHKeys('axvm')
=> #array of strings

Each key will be wrapped into SSHKey class. It gives you ability to calculate md5\sha1\sha256 fingerprints. If key is corrupted or invalid, IncorrectOrCorruptedKey exception will be raised.

Bug reports and pull requests are welcome on GitHub at https://github.com/axvm/ghkeys.