ARTICLE
Cryptography DES algorithm
In this article we will learn how DES algo work.
DES (Data Encryption standard) Algorithm
DES uses a 56-bit key. In fact, the 56-bit key is divided into eight 7-bit blocks and an 8th odd parity bit is added to each block (i.e., a "0" or "1" is added to the block). By using the 8 parity bits for rudimentary error detection, a DES key is actually 64 bits in length for computational purposes (although it only has 56 bits worth of randomness).
DES then acts on 64-bit blocks of the plaintext, invoking 16 rounds of permutations, swaps, and substitutes, as shown in Figure 6. The standard includes tables describing all of the selection, permutation, and expansion operations mentioned below; these aspects of the algorithm are not secrets
Consider this example with the given 56-bit key and input:
Key: 1100101 0100100 1001001 0011101 0110101 0101011 1101100 0011010
Input character string: GoGoogle
Input bit string: 11100010 11110110 10000010 11100110 11100110 10010110 10100110 11001110
Output bit string: 10011111 11110010 10000000 10000001 01011011 00101001 00000011 00101111
Output character string: UOU AO