14-10-2010, 11:32 AM
SEMINAR-THEORY.docx (Size: 24.46 KB / Downloads: 89)
Introduction
This algorithm is of interest for several reasons. It is designed for use in software. Unlike DES, or even IDEA, it does not divide the block into parts of which some parts affect others; instead, the plaintext is directly changed by going through S-boxes, which are replaced by their inverses for decryption.
Description of SAFER
SAFER uses eight rounds. The first step for a round is to apply the first subkey for the round to the eight bytes of the block. The operation by which each byte of the subkey is applied to each byte of the block depends on which byte is used: the sequence is
XOR, add, add, XOR, XOR, add, add, XOR
Then, the S-box is used. Those bytes to which the subkey was applied by an XOR go through the regular S-box; those bytes to which it was applied by addition go through the inverse S-box.