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Both the input and output are interpreted as polynomials over GF(2). First, the input is mapped to its multiplicative inverse in GF(2 8) = GF(2) [x]/(x 8 + x 4 + x 3 + x + 1), Rijndael's finite field. Zero, as the identity, is mapped to itself. This transformation is known as the Nyberg S-box after its inventor Kaisa Nyberg. [2]
Encryption is done in 2-word blocks. u = w/8 – The length of a word in bytes. b – The length of the key in bytes. K[] – The key, considered as an array of bytes (using 0-based indexing). c – The length of the key in words (or 1, if b = 0). L[] – A temporary working array used during key scheduling, initialized to the key in words.
The cipher illustrated here uses a left shift of 3, so that (for example) each occurrence of E in the plaintext becomes B in the ciphertext. In cryptography, a Caesar cipher, also known as Caesar's cipher, the shift cipher, Caesar's code, or Caesar shift, is one of the simplest and most widely known encryption techniques.
ISAAC (indirection, shift, accumulate, add, and count) is a cryptographically secure pseudorandom number generator and a stream cipher designed by Robert J. Jenkins Jr. in 1993. [1] The reference implementation source code was dedicated to the public domain. [2] "I developed (...) tests to break a generator, and I developed the generator to ...
To initialize the cipher, the key and IV are written into two of the shift registers, with the remaining bits starting in a fixed pattern; the cipher state is then updated 4 × 288 = 1152 times, so that every bit of the internal state depends on every bit of the key and of the IV in a complex nonlinear way.
An m×n S-box can be implemented as a lookup table with 2 m words of n bits each. Fixed tables are normally used, as in the Data Encryption Standard (DES), but in some ciphers the tables are generated dynamically from the key (e.g. the Blowfish and the Twofish encryption algorithms).
Salsa20 and the closely related ChaCha are stream ciphers developed by Daniel J. Bernstein.Salsa20, the original cipher, was designed in 2005, then later submitted to the eSTREAM European Union cryptographic validation process by Bernstein.
The Hasty Pudding cipher (HPC) is a variable-block-size block cipher designed by Richard Schroeppel, which was an unsuccessful candidate in the competition for selecting the U.S. Advanced Encryption Standard (AES). It has a number of unusual properties for a block cipher: its input block size and key length are variable, and it includes an ...