China
Africa
Explore chapters and articles related to this topic
Fundamentals of Multimedia Encryption Techniques
Published in Borko Furht, Darko Kirovski, Multimedia Encryption and Authentication Techniques and Applications, 2006
Borko Furht, Daniel Socek, Ahmet M. Eskicioglu
AES Key Schedule. In the AES algorithm, the initial input symmetric key is expanded to create a key schedule for each round. This procedure, given in Figure 3.2, generates a total of Nb(Nr+ 1) words that are used in the AddRoundKey () procedure. In this algorithm, SubWord() is a function that takes a 4-byte input word and applies the S-box to each of the 4 bytes to produce an output word. The function RotWord () takes a word [a0, a1, a2, a3] as input, performs a cyclic permutation, and returns the word [a1, a2, a3, a0]. The round constant word array, Rcon[i], contains the values given by [xi-1, {00}, {00}, {00}], with xi–1 being powers of x (x is denoted as {02}) in the field GF(28).
Practical Constructions of Symmetric-Key Primitives
Published in Jonathan Katz, Yehuda Lindell, Introduction to Modern Cryptography, 2020
Different sub-keys (or round keys) are used in each round. The actual key of the block cipher is sometimes called the master key. The round keys are derived from the master key according to a key schedule. The key schedule is often simple and may just use different subsets of the bits of the master key as the various sub-keys, though more complex key schedules can also be defined. An r-round SPN has r rounds of key mixing, S-box substitution, and application of a mixing permutation, followed by a final key-mixing step. (This means that an r-round SPN uses r + 1 sub-keys.)
Systems Management
Published in Paul J. Fortier, Handbook of Local Area Network Software, 1991
Enciphering and deciphering are performed with the same 64-bit key. The enciphering and deciphering processes are the reverse of one another. This is accomplished by revising the order of scheduling with which the key-dependent processing is performed. A block of data is subjected to an Initial Permutation (IP), then to a set of key-dependent computations, and then to the inverse permutation IP-1. The key-dependent computation can be defined in terms of a function of a Key Schedule (KS). The 64-bit block (LR) is divided into two equal blocks denoted as “L” for left and “R” for right.
A Review on Evolution of Symmetric Key Block Ciphers and Their Applications
Published in IETE Journal of Education, 2020
Block ciphers comprise of several rounds and each round has diffusion and confusion layers and uses a round key (see Figure 2). The round keys are derived from the master encryption key using key schedule algorithm (KSA). We usually formalize confusion layers realized by application of substitution boxes which are defined by lookup tables and diffusion layers as the application of MDS (maximum Distance separable) matrices and permutations.