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In cryptography, the simple XOR cipher is a type of additive cipher, [1] an encryption algorithm that operates according to the principles: A ...
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).
In stream cipher encryption uniqueness is crucially important as plaintext may be trivially recovered otherwise. Example: Stream ciphers encrypt plaintext P to ciphertext C by deriving a key stream K from a given key and IV and computing C as C = P xor K. Assume that an attacker has observed two messages C 1 and C 2 both encrypted with the same ...
If the IV/nonce is random, then they can be combined with the counter using any invertible operation (concatenation, addition, or XOR) to produce the actual unique counter block for encryption. In case of a non-random nonce (such as a packet counter), the nonce and counter should be concatenated (e.g., storing the nonce in the upper 64 bits and ...
The most common form of key whitening is xor-encrypt-xor-- using a simple XOR before the first round and after the last round of encryption. 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 .
XOR gate (sometimes EOR, or EXOR and pronounced as Exclusive OR) is a digital logic gate that gives a true (1 or HIGH) output when the number of true inputs is odd. An XOR gate implements an exclusive or ( ↮ {\displaystyle \nleftrightarrow } ) from mathematical logic ; that is, a true output results if one, and only one, of the inputs to the ...
The processes for encryption and decryption are similar. IDEA derives much of its security by interleaving operations from different groups — modular addition and multiplication, and bitwise eXclusive OR (XOR) — which are algebraically "incompatible" in some sense. In more detail, these operators, which all deal with 16-bit quantities, are:
However, xor is commutative and has the property that X xor X = 0 (self-inverse) so: E(A) xor E(B) = (A xor C) xor (B xor C) = A xor B xor C xor C = A xor B If one message is longer than the other, our adversary just truncates the longer message to the size of the shorter and their attack will only reveal that portion of the longer message.