This is the full ISO-7813 implementation, in ruby! This is battle tested, production ready. Use at will.
I recommend that you copy those files into your own project and not use this as a gem.
Add this line to your application's Gemfile:
gem 'iso7813'
And then execute:
$ bundle
Or install it yourself as:
$ gem install iso7813
Just include the modules into your classes.
Pretty please: don't ask me anything before reading the standard and the code. I'm either busy or drinking beer.