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The affine cipher is a type of monoalphabetic substitution cipher, where each letter in an alphabet is mapped to its numeric equivalent, encrypted using a simple mathematical function, and converted back to a letter. The formula used means that each letter encrypts to one other letter, and back again, meaning the cipher is essentially a ...
The inverse S-box is simply the S-box run in reverse. For example, the inverse S-box of b8 16 is 9a 16.It is calculated by first calculating the inverse affine transformation of the input value, followed by the multiplicative inverse.
Suppose we have a non-linear function where the key is XOR'ed before evaluation and the values that allow the differential are {2,3} and {4,5}. If the attacker sends in the values of {6, 7} and observes the correct output difference it means the key is either 6 ⊕ K = 2, or 6 ⊕ K = 4, meaning the key K is either 2 or 4.
The GNU C library, a set of standard routines available for use in computer programming, contains a function—memfrob() [13] —which has a similar purpose to ROT13, although it is intended for use with arbitrary binary data. The function operates by combining each byte with the binary pattern 00101010 using the exclusive or (XOR
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 an affine cipher by setting a = b = (m − 1):
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 cryptanalysis.
Multivariate Quadratics involves a public and a private key. The private key consists of two affine transformations, S and T, and an easy to invert quadratic map ′:.We denote the matrix of the affine endomorphisms: by and the shift vector by and similarly for :.
By using the affine relations in (2) to replace the , with ,, the system of equations is linear in the and of degree 2 in the . Applying linear algebra it will give n {\displaystyle n} explicit equations, one for each y l {\displaystyle y_{l}} as polynomials of degree 2 in the x k {\displaystyle x_{k}} .