mcrypt.rb

module MCrypt
   class Password
      def initialize(hashed_password)
         @hash = hashed_password
      end

      def self.create(plain_text_password)
         plain_text_password
         .reverse
         .split(//) * "*"
      end
   end
end

user.rb

# require_relative './mcrypt'

class User < ActiveRecord::Base
   # attr_writer :password

   include BCrypt
   # include MCrypt 

   def password
      @password ||= Password.new(password_hash) 
      p @password
   end

   def password=(new_password)
      @password = Password.create(new_password)
      self.password_hash = @password 
   end

end