DES算法C语言可运行源代码

代码转载自：

http://blog.csdn.net/zidane_2014/article/details/37988657

题外话1：

代码虽然不是我写的，但我还是针对评论区里的两个问题在代码里加了注释

(

gets_s函数“未定义”、

还一个

“什么玩意，忽悠人呢，不走那个解密函数直接输出还不是原来输入的明文？你这和直接输出明文有啥区别？”

)，

我请注意看

题外话2：

景中老师的《网络信息安全》课怎么样啊，2000字手写论文完成了吗（#滑稽）

我是14级的，当时多半都用我的报告呢~（报告你们自己写去吧，我不给，给你们几个攒报告的链接）：

https://blog.csdn.net/github_38140310/article/details/68955580

https://blog.csdn.net/haroroda/article/details/45769507

https://blog.csdn.net/lisonglisonglisong/article/details/41777413

下面就是能执行的代码了，也提一句8字节是4个汉字/8个数字或字母，验机时别露怯哦~

#include  
#include  
//#define gets_s gets   //出现[Error] 'gets_s' was not declared in this scope的话就加上这句，默认使用的gcc编译器的话会出现此错误，因为gets_s是vs提供的函数
int IP_Table[64] = {                                     //IP置换矩阵  
	58, 50, 42, 34, 26, 18, 10, 2, 60, 52, 44, 36, 28, 20, 12, 4,
	62, 54, 46, 38, 30, 22, 14, 6, 64, 56, 48, 40, 32, 24, 16, 8,
	57, 49, 41, 33, 25, 17,  9, 1, 59, 51, 43, 35, 27, 19, 11, 3,
	61, 53, 45, 37, 29, 21, 13, 5, 63, 55, 47, 39, 31, 23, 15, 7 };
int E_Table[48] = {                                    //扩展矩阵  
	32,  1,  2,  3,  4,  5,  4,  5,  6,  7,  8,  9,
	8,  9, 10, 11, 12, 13, 12, 13, 14, 15, 16, 17,
	16, 17, 18, 19, 20, 21, 20, 21, 22, 23, 24, 25,
	24, 25, 26, 27, 28, 29, 28, 29, 30, 31, 32,  1 };
int P_Table[32] = {                                             //  P 盒  
	16, 7, 20, 21, 29, 12, 28, 17, 1,  15, 23, 26, 5,  18, 31, 10,
	2,  8, 24, 14, 32, 27, 3,  9,  19, 13, 30, 6,  22, 11, 4,  25 };
int IPR_Table[64] = {                                    //逆IP置换矩阵  
	40, 8, 48, 16, 56, 24, 64, 32, 39, 7, 47, 15, 55, 23, 63, 31,
	38, 6, 46, 14, 54, 22, 62, 30, 37, 5, 45, 13, 53, 21, 61, 29,
	36, 4, 44, 12, 52, 20, 60, 28, 35, 3, 43, 11, 51, 19, 59, 27,
	34, 2, 42, 10, 50, 18, 58, 26, 33, 1, 41,  9, 49, 17, 57, 25 };
int PC1_Table[56] = {                               //密钥第一次置换矩阵  
	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 };
int PC2_Table[48] = {                          // 密钥第二次置换矩阵  
	14, 17, 11, 24,  1,  5,  3, 28, 15,  6, 21, 10,
	23, 19, 12,  4, 26,  8, 16,  7, 27, 20, 13,  2,
	41, 52, 31, 37, 47, 55, 30, 40, 51, 45, 33, 48,
	44, 49, 39, 56, 34, 53, 46, 42, 50, 36, 29, 32 };
int S_Box[8][4][16] = {                     //8个S盒   三维数组  
											// S1   
	14, 4,  13,  1,  2, 15, 11,  8,  3, 10,  6, 12,  5,  9,  0,  7,
	0, 15,  7,  4, 14,  2, 13,  1, 10,  6, 12, 11,  9,  5,  3,  8,
	4,  1, 14,  8, 13,  6,  2, 11, 15, 12,  9,  7,  3, 10,  5,  0,
	15, 12,  8,  2,  4,  9,  1,  7,  5, 11,  3, 14, 10,  0,  6, 13,
	// S2   
	15,  1,  8, 14,  6, 11,  3,  4,  9,  7,  2, 13, 12,  0,  5, 10,
	3, 13,  4,  7, 15,  2,  8, 14, 12,  0,  1, 10,  6,  9, 11,  5,
	0, 14,  7, 11, 10,  4, 13,  1,  5,  8, 12,  6,  9,  3,  2, 15,
	13,  8, 10,  1,  3, 15,  4,  2, 11,  6,  7, 12,  0,  5, 14,  9,
	// S3   
	10,  0,  9, 14,  6,  3, 15,  5,  1, 13, 12,  7, 11,  4,  2,  8,
	13,  7,  0,  9,  3,  4,  6, 10,  2,  8,  5, 14, 12, 11, 15,  1,
	13,  6,  4,  9,  8, 15,  3,  0, 11,  1,  2, 12,  5, 10, 14,  7,
	1, 10, 13,  0,  6,  9,  8,  7,  4, 15, 14,  3, 11,  5,  2, 12,
	// S4   
	7, 13, 14,  3,  0,  6,  9, 10,  1,  2,  8,  5, 11, 12,  4, 15,
	13,  8, 11,  5,  6, 15,  0,  3,  4,  7,  2, 12,  1, 10, 14,  9,
	10,  6,  9,  0, 12, 11,  7, 13, 15,  1,  3, 14,  5,  2,  8,  4,
	3, 15,  0,  6, 10,  1, 13,  8,  9,  4,  5, 11, 12,  7,  2, 14,
	// S5   
	2, 12,  4,  1,  7, 10, 11,  6,  8,  5,  3, 15, 13,  0, 14,  9,
	14, 11,  2, 12,  4,  7, 13,  1,  5,  0, 15, 10,  3,  9,  8,  6,
	4,  2,  1, 11, 10, 13,  7,  8, 15,  9, 12,  5,  6,  3,  0, 14,
	11,  8, 12,  7,  1, 14,  2, 13,  6, 15,  0,  9, 10,  4,  5,  3,
	// S6   
	12,  1, 10, 15,  9,  2,  6,  8,  0, 13,  3,  4, 14,  7,  5, 11,
	10, 15,  4,  2,  7, 12,  9,  5,  6,  1, 13, 14,  0, 11,  3,  8,
	9, 14, 15,  5,  2,  8, 12,  3,  7,  0,  4, 10,  1, 13, 11,  6,
	4,  3,  2, 12,  9,  5, 15, 10, 11, 14,  1,  7,  6,  0,  8, 13,
	// S7   
	4, 11,  2, 14, 15,  0,  8, 13,  3, 12,  9,  7,  5, 10,  6,  1,
	13,  0, 11,  7,  4,  9,  1, 10, 14,  3,  5, 12,  2, 15,  8,  6,
	1,  4, 11, 13, 12,  3,  7, 14, 10, 15,  6,  8,  0,  5,  9,  2,
	6, 11, 13,  8,  1,  4, 10,  7,  9,  5,  0, 15, 14,  2,  3, 12,
	// S8   
	13,  2,  8,  4,  6, 15, 11,  1, 10,  9,  3, 14,  5,  0, 12,  7,
	1, 15, 13,  8, 10,  3,  7,  4, 12,  5,  6, 11,  0, 14,  9,  2,
	7, 11,  4,  1,  9, 12, 14,  2,  0,  6, 10, 13, 15,  3,  5,  8,
	2,  1, 14,  7,  4, 10,  8, 13, 15, 12,  9,  0,  3,  5,  6, 11
};
static void CharToBit(const char input[], int output[], int bits)//把CHAR转换为INT  
{
	int i, j;
	for (j = 0; j<8; j++)
	{
		for (i = 0; i<8; i++)
		{
			output[7 * (j + 1) - i + j] = (input[j] >> i) & 1;
		}
	}
};
static void BitToChar(const int intput[], char output[], int bits)//把INT转换为CHAR  
{
	int i, j;
	for (j = 0; j<8; j++)
	{
		for (i = 0; i<8; i++)
		{
			output[j] = output[j] * 2 + intput[i + 8 * j];
		}
	}
};
static void Xor(int *INA, int *INB, int len)//异或操作  
{
	int i;
	for (i = 0; i> i) & 1;
		}
	}
};
static void F_func(int input[32], int output[32], int subkey[48])//完成DES算法轮变换  
{
	int len = 48;
	int temp[48] = { 0 };
	int temp_1[32] = { 0 };
	E(input, temp, E_Table);
	Xor(temp, subkey, len);
	S(temp, temp_1, S_Box);
	P(temp_1, output, P_Table);
};
static void RotateL(const int input[28], int output[28], int leftCount)//秘钥循环左移  
{
	int i;
	int len = 28;
	for (i = 0; i