# File lib/captcha/cipher.rb, line 29
    def self.decrypt(text)
      # Decode chr coded string
      encrypted = text.split('_').collect do |x|
        x.to_i.chr
      end
      encrypted = encrypted.join('')
      # Decrypt
      cipher = OpenSSL::Cipher::Cipher.new("aes-256-cbc")
      cipher.decrypt
      cipher.key = @@key
      cipher.iv = @@iv
      decrypted = cipher.update(encrypted)
      decrypted << cipher.final
    end