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The XOR cipher is often used in computer malware to make reverse engineering more difficult. If the key is random and is at least as long as the message, the XOR cipher is much more secure than when there is key repetition within a message. [4] When the keystream is generated by a pseudo-random number generator, the result is a stream cipher.
The xor–encrypt–xor (XEX) is a (tweakable) mode of operation of a block cipher. In tweaked-codebook mode with ciphertext stealing , it is one of the more popular modes of operation for whole-disk encryption. XEX is also a common form of key whitening, and part of some smart card proposals. [1] [2]
In cryptography, XOR is sometimes used as a simple, self-inverse mixing function, such as in one-time pad or Feistel network systems. [citation needed] XOR is also heavily used in block ciphers such as AES (Rijndael) or Serpent and in block cipher implementation (CBC, CFB, OFB or CTR).
The first block cipher to use a form of key whitening is DES-X, which simply uses two extra 64-bit keys for whitening, beyond the normal 56-bit key of DES. This is intended to increase the complexity of a brute force attack , increasing the effective size of the key without major changes in the algorithm.
The stream cipher produces a string of bits C(K) the same length as the messages. The encrypted versions of the messages then are: E(A) = A xor C E(B) = B xor C. where xor is performed bit by bit. Say an adversary has intercepted E(A) and E(B). They can easily compute: E(A) xor E(B)
BLAKE is a cryptographic hash function based on Daniel J. Bernstein's ChaCha stream cipher, but a permuted copy of the input block, XORed with round constants, is added before each ChaCha round.
XOR (exclusive or) is a logical operator whose negation is the logical biconditional. XOR may also refer to: XOR cipher, an encryption algorithm; XOR gate, a digital logic gate; bitwise XOR, an operator used in computer programming; XOR, a 1987 puzzle video game; XOR, an x200 instruction; Xor DDoS, a Linux Trojan malware
This reverses encryption step 2. X n−1 is the same as in the encryption process. P n−1 = X n−1 XOR C n−2. Exclusive-OR X n−1 with the previous ciphertext block, C n−2, to create P n−1. Finally, we reverse the XOR step from step 1 of the encryption process.