i found one lib which is here
https://github.com/juggler/ruby-rc4/blob/master/lib/rc4.rb
But its not working for ruby 1.9.x
it throws an error
undefined method ^' for "\x1A":String__
is there any work around in ruby 1.9.x?
after googling i came to know that "In Ruby 1.9 string[index] returns character not code of the character (like it was in 1.8)." (https://rails.lighthouseapp.com/projects/8994/tickets/3144-undefined-method-for-string-ror-234)
Thanks in advance