Encryption is the method of transforming readable data into unreadable data for the purposes of secrecy. Once encrypted, such data cannot be interpreted (either by humans or machines) until it is decrypted. Encryption is performed using an encryption algorithm and a secret value called a 'key'. Encrypted data generally cannot be decrypted without knowledge of the secret 'key' or substantial resources. Malware may use encryption to obfuscate its code (make its code unreadable), thus hoping to hinder its detection and removal from the affected computer. A common and simple encryption technique used by malware is XORing, in which the Exclusive Or (XOR) computational operation is applied to each bit according to a given key. Malware may use cryptors to encrypt their code.