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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.
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 ...
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 combining function Vernam specified in U.S. patent 1,310,719, issued July 22, 1919, is the XOR operation, applied to the individual impulses or bits used to encode the characters in the Baudot code. Vernam did not use the term "XOR" in the patent, but he implemented that operation in relay logic.
The main idea is to choose the error-correcting bits such that the index-XOR (the XOR of all the bit positions containing a 1) is 0. We use positions 1, 10, 100, etc. (in binary) as the error-correcting bits, which guarantees it is possible to set the error-correcting bits so that the index-XOR of the whole message is 0.
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 .
The cast of “Friends” is well known for being besties, but that developed over time. During an appearance on Dax Shepard’s “Armchair Expert” podcast, “Friends” star Lisa Kudrow ...
Stream ciphers, in contrast to the 'block' type, create an arbitrarily long stream of key material, which is combined with the plaintext bit-by-bit or character-by-character, somewhat like the one-time pad. In a stream cipher, the output stream is created based on a hidden internal state that changes as the cipher operates.