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Since the affine cipher is still a monoalphabetic substitution cipher, it inherits the weaknesses of that class of ciphers. The Caesar cipher is an Affine cipher with a = 1 since the encrypting function simply reduces to a linear shift. The Atbash cipher uses a = −1. Considering the specific case of encrypting messages in English (i.e. m = 26 ...
Symmetric-key encryption can use either stream ciphers or block ciphers. [8] Stream ciphers encrypt the digits (typically bytes), or letters (in substitution ciphers) of a message one at a time. An example is ChaCha20. Substitution ciphers are well-known ciphers, but can be easily decrypted using a frequency table. [9]
The Atbash cipher can be seen as a special case of the affine cipher. Under the standard affine convention, an alphabet of m letters is mapped to the numbers 0, 1, ... , m − 1. (The Hebrew alphabet has m = 22, and the standard Latin alphabet has m = 26). The Atbash cipher may then be enciphered and deciphered using the encryption function for ...
Linear cryptanalysis. In cryptography, linear cryptanalysis is a general form of cryptanalysis based on finding affine approximations to the action of a cipher. Attacks have been developed for block ciphers and stream ciphers. Linear cryptanalysis is one of the two most widely used attacks on block ciphers; the other being differential ...
Unicity distance. In cryptography, unicity distance is the length of an original ciphertext needed to break the cipher by reducing the number of possible spurious keys to zero in a brute force attack. That is, after trying every possible key, there should be just one decipherment that makes sense, i.e. expected amount of ciphertext needed to ...
Definition. In affine arithmetic, each input or computed quantity x is represented by a formula where are known floating-point numbers, and are symbolic variables whose values are only known to lie in the range [-1,+1]. Thus, for example, a quantity X which is known to lie in the range [3,7] can be represented by the affine form , for some k.
A disk cipher device of the Jefferson type from the 2nd quarter of the 19th century in the National Cryptologic Museum. The Jefferson disk, also called the Bazeries cylinder or wheel cypher, [1] was a cipher system commonly attributed to Thomas Jefferson that uses a set of wheels or disks, each with letters of the alphabet arranged around their edge in an order, which is different for each ...
The CSA algorithm is composed of two distinct ciphers: a block cipher and a stream cipher. When used in encryption mode the data are first encrypted using the 64-bit block cipher in CBC mode, starting from packet end. The stream cipher is then applied from packet start. Block cipher. The block cipher process 64-bit blocks in 56 rounds.