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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 ⊕ {\displaystyle \oplus } 0 = A, A ⊕ {\displaystyle \oplus } A = 0,
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]
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 .
On July 22, 1919, U.S. Patent 1,310,719 was issued to Gilbert Vernam for the XOR operation used for the encryption of a one-time pad. [7] Derived from his Vernam cipher, the system was a cipher that combined a message with a key read from a punched tape. In its original form, Vernam's system was vulnerable because the key tape was a loop, which ...
Say we send messages A and B of the same length, both encrypted using same key, K. 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 ...
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 FBI is warning phone users to encrypt their text messages, especially if you send messages between Apple and Android users. The FBI and the Cybersecurity and Infrastructure Security Agency ...
The zero padding of P in step 4 was important, because it makes the XOR operation's effect on the last B−M bits equivalent to copying the last B−M bits of E n−1 to the end of D n. These are the same bits that were stripped off of E n−1 in step 3 when C n was created. C n−1 = Encrypt (K, D n). Encrypt D n to create C n−1.