Why Is XOR the Perfect Cipher?

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XOR is a simple bitwise operation that allows cryptographers to create strong encryption systems. It is the primary operation in the “add round key” step of AES-256(/cryptography/aes-256-cipher/). It is also used in the DES cipher. XOR, or “exclusive or” operates on binary data. It returns true if both of its inputs are opposites (one false and one true), otherwise, it returns false. The XOR cipher isn’t used in production because it is impractical to use keys that are the same length as the message body.