November 2018
Intermediate to advanced
1440 pages
48h 29m
English
The two ciphers described in Chapter 10 are built upon iterations of functions both to encrypt and to generate keys. This appendix describes them in detail.
The DES (see section 10.2.3) takes as input a 64-bit plaintext message, and iterates through 16 rounds to generate a 64-bit ciphertext. Each round requires a 48-bit key, called a round key. A schedule of 16 round keys is generated from the 64-bit DES key. Section F.1.2 describes the generation of the round keys.
The input to the DES is 64 bits. The bits are permuted, and the resulting bits split into two halves. One half is given to a function, along with the round key for that round, and the output is combined with the other ...