X

---

XML (Extensible Markup Language)

A system used to define specialized markup languages used to transmit formatted data. XML's name is misleading; although conceptually related to markup languages, it is actually a meta language, i.e. a language used to create other specialized languages.

XOR (eXclusive OR)

A fundamental binary operation frequently used in cryptographic algorithms. It operates on binary digits, bits, which take the value 0 or 1. For example, a XOR B is equal to 0 if and only if A = B, i.e. 0 XOR 0 = 0, 0 XOR 1 = 1, 1 XOR 0 = 1, 1 XOR 1 = 0. The usefulness becomes more apparent for wireless networking when you look at XOR as: plaintext XOR keystream = cipher-text. Thus, ciphertext XOR keystream = plaintext, which therefore implements a simple and robust reversible transformation of plaintext into ciphertext using a keystream—the fundamentals used in stream ciphers.

---