Des and 3DES algorithms implemented in C language under Linux __.net

The Theory of DES algorithm

The DES algorithm belongs to symmetric encryption algorithm, which is widely used in some transactions with higher security requirements, such as payment industry. On the theory of DES algorithm, there are many articles on the Web have detailed explanation, write very well, I do not repeat here, here is a link: http://www.vckbase.com/document/viewdoc/?id=623, please friends to learn their own, My code is written based on the theory here.

II. implementation of the environment and documents

A, Environment: Redhat Linux + C

b, the implementation of the document: Des.h

Des.c

Makefile

Third, the Code

1, des.h documents

Function: To implement DES and 3DES encryption and decryption algorithm
Author: XXX
Date: 2008-9-23

#ifndef Des_h
#define Des_h

static int pc_1_table[56]={57,49,41,33,25,17, 9,
1,58,50,42,34,26,18,
10, 2,59,51,43,35,27,
19,11, 3,60,52,44,36,
63,55,47,39,31,23,15,
7,62,54,46,38,30,22,
14, 6,61,53,45,37,29,
21,13, 5,28,20,12, 4};

static int pc_2_table[48]={14,17,11,24, 1, 5,
3,28,15, 6,21,10,
23,19,12, 4, 26, 8,