Chao is a project mainly written in Ruby, it's free.
Ruby implementation of the chaocipher
A Ruby implementation of the Chaocipher. Not really intended for serious use, but it's somewhat strong, simple, and functional.
require 'chao'
key = Chao.generate_key # => ["RCGLKIWDAHSUVMFQZJPNBXTYEO", "ZIORTLCHJNWMDGQVAYBUXPKFSE"]
chao = Chao.new(*key) # => #<Chao:0x10187adc8>
chao.encipher 'Some text.' # => 'WSFPBXVV'
chao.encipher 'More text.' # => 'LVARDINW'
chao = Chao.new(*key)
chao.decipher 'WSFPBXVV' # => 'SOMETEXT'
chao.decipher 'LVARDINW' # => 'MORETEXT