RoR – MD5 generation

You can use Digest::MD5 from the Ruby standard library for this.

irb(main):001:0> require 'digest/md5'
=> true
irb(main):002:0> Digest::MD5.hexdigest('foobar')
=> "3858f62230ac3c915f300c664312c63f"

And one more thing: MD5 is a hash algorithm. You don’t “encrypt” anything with a hash algorithm.