gistfile1.rb

  def AES_encrypt(password)
    if not_encrypted?
      AES_crypt(password) { |c| c.encrypt }
      encrypt!
    end
  end
  
  def AES_decrypt(password)
    if encrypted?
      AES_crypt(password) { |c| c.decrypt }
      decrypt!
    end
  end
  
  private
    
    def set_file_attributes
      self.size = File.size(absolute_path)
    end
    
    def AES_crypt(password)
      c = OpenSSL::Cipher::Cipher.new("aes-256-cbc")
      yield c
      c.key = Digest::SHA1.hexdigest("abc" + password)
      c.iv = Digest::SHA1.hexdigest(password)
      output = Tempfile.new('slot', :external_encoding => Encoding::ASCII_8BIT)
      File.open(self.absolute_path,'r') do |file|
        while buf = file.read(4096)
          output.write(c.update(buf))
        end
        file.close
      end
      output.write(c.final)
      output.close
      File.unlink self.absolute_path
      FileUtils.move output.path, self.absolute_path
    end