Ruby Entropy is an algorithm for evaluating the robustness of passphrases. The algorithm uses standard entropy to calculate a base passphrase strength and then reduces that strength based on repeatability patterns, keyboard patterns, and several weak passphrase tests.

There is a javascript version of the algorithm here.

##Install

$ gem install ruby-entropy

gem 'ruby-entropy', '~> 0.2.0'

##Require

require 'ruby-entropy'

##Use

example = RubyEntropy.new('correct horse battery staple')

example.passphrase

# => correct horse battery staple

example.strength

# => 77.27

###Blacklisted words and phrases (0.2.0+) Ruby Entropy maintains a short list of blacklisted words and phrases. If you want to add a blacklisted word or phrase e.g., your website name, you can add it like so:

RubyEntropy.blacklist_passphrase('correct')

example.strength

# => 57.95