一．实验目的
DES加密解密算法的实现。
二．实验内容
选用C++语言，效率高。
#include "stdio.h" #include "iostream.h" #include "memory.h" static void F_func(bool In[32], const bool Ki[48]);// F 函数 static void S_func(bool Out[32], const bool In[48]);// S 盒代替 static void Transform(bool *Out, bool *In, const char *Table, int len); static void Xor(bool *InA, const bool *InB, int len);// 异或 static void RotateL(bool *In, int len, int loop);// 循环左移 static void ByteToBit(bool *Out, const char *In, int bits); static void BitToByte(char *Out, const bool *In, int bits); // 初始变换 const static char IP[64] = { 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 }; // 末置换 const static char IPR[64] = { 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 }; // 扩展置换 static const char E[48] = { 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 }; // 作用在S盒的32位输出结果上的P变换
const static char P[32] = { 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, 2 5 }; // 密钥初始置换 const static char PC1[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 }; // 密钥压缩变换 PC-2 const static char PC2[48] = { 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 }; // 每圈移位次数 const static char LOOP[16] = { 1,1,2,2,2,2,2,2,1,2,2,2,2,2,2,1 }; // S盒 const static char S_Box[8][4][16] = { // 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 bool SubKey[16][48];// 16圈子密钥 void Des_Run(char Out[8], char In[8],int i) { static bool M[64], Tmp[32], *Li = &M[0], *Ri = &M[32]; ByteToBit(M, In, 64);// 字节组转换成位组 Transform(M, M, IP, 64);// 初始变换 if( i == 0 ){ //加密 for(int i=0; i<16; i++) { memcpy(Tmp, Ri, 32); F_func(Ri, SubKey[i]); Xor(Ri, Li, 32); memcpy(Li, Tmp, 32); } }else{ //解密 for(int i=15; i>=0; i--) { memcpy(Tmp, Li, 32); F_func(Li, SubKey[i]); Xor(Li, Ri, 32); memcpy(Ri, Tmp, 32); } } Transform(M, M, IPR, 64); BitToByte(Out, M, 64); } void Des_SetKey(const char Key[8]) //设置密钥 { static bool K[64], *KL = &K[0], *KR = &K[28]; ByteToBit(K, Key, 64);// 字节组转换成位组 Transform(K, K, PC1, 56);// 密钥变换 PC-1 for(int i=0; i<16; i++) { RotateL(KL, 28, LOOP[i]); RotateL(KR, 28, LOOP[i]); Transform(SubKey[i], K, PC2, 48);// 密钥压缩变换 PC-2 } } // F 函数 void F_func(bool In[32], const bool Ki[48]) { static bool MR[48]; Transform(MR, In, E, 48); Xor(MR, Ki, 48); S_func(In, MR); Transform(In, In, P, 32); } // S 盒置换 void S_func(bool Out[32], const bool In[48]) { for(char i=0,j,k; i<8; i++,In+=6,Out+=4) { j = (In[0]<<1) + In[5]; k = (In[1]<<3) + (In[2]<<2) + (In[3]<<1) + In[4]; ByteToBit(Out, &S_Box[i][j][k], 4); } } // 通用置换函数 void Transform(bool *Out, bool *In, const char *Table, int len) { static bool Tmp[256]; for(int i=0; i
>(i%8)) & 1; } // 位转换成字节 void BitToByte(char *Out, const bool *In, int bits) { memset(Out, 0, (bits+7)/8); for(int i=0; i>message; puts("Before encrypting"); puts(message); Des_SetKey(key); Des_Run(message, message, 0); puts("After encrypting"); puts(message); puts("After decrypting"); Des_Run(message, message, 1); puts(message); }
三． 实验总结通过这两次上机实验，使我了解了DES算法的原理。
