DES加密解密算法-C语言实现

#include "stdio.h" #include "memory.h" #include "stdlib.h" #include "des.h" static int ip_table[64] = { 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, 56,48,40,32,24,16,8,0, 58,50,42,34,26,18,10,2, 60,52,44,36,28,20,12,4, 62,54,46,38,30,22,14,6}; static int ip1_table[64] = {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, 32,0,40,8,48,16,56,24}; static int ex_table[48] = {31, 0, 1, 2, 3, 4, 3, 4, 5, 6, 7, 8, 7, 8,9,10,11,12, 11,12,13,14,15,16, 15,16,17,18,19,20, 19,20,21,22,23,24, 23,24,25,26,27,28, 27,28,29,30,31, 0}; static int p_table[32] = {15,6,19,20,28,11,27,16, 0,14,22,25,4,17,30,9, 1,7,23,13,31,26,2,8, 18,12,29,5,21,10,3,24}; static int s_table[8][4][16] = {{{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}}, {{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}}, {{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}}, {{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}}, {{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}}, {{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}}, {{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}}, {{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 int pc_table[56] = {56,48,40,32,24,16,8, 0,57,49,41,33,25,17, 9,1,58,50,42,34,26, 18,10,2,59,51,43,35, 62,54,46,38,30,22,14, 6,61,53,45,37,29,21, 13,5,60,52,44,36,28, 20,12,4,27,19,11,3}; static int pc1_table[48] = {13,16,10,23,0,4,2,27, 14,5,20,9,22,18,11,3, 25,7,15,6,26,19,12,1, 40,51,30,36,46,54,29,39, 50,44,32,46,43,48,38,55, 33,52,45,41,49,35,28,31}; static int move_times[16] = {1,1,2,2,2,2,2,2,1,2,2,2,2,2,2,1}; static void convert_bits(char *data,char* buffer) { int i = 0,j = 0,cnt = 0; for(i = 0 ;i < 8 ;i++){ for(j = 0 ;j < 8 ;j++){ buffer[cnt++] = ( data[i] >> j) & 0x1; } } } static void re_convert_bits(char *data,char* buffer) { int i = 0,j = 0,cnt = 0; memset(buffer,0x0,8*sizeof(char)); for(i = 0 ;i < 8 ;i++){ for(j = 0 ;j < 8 ;j++){ buffer[i] |= data[cnt++] << j; } } } static void LeftShift(char* data, int shift){ static char temp[56]; memcpy(temp,data,shift); memcpy(&temp[shift],&data[28],shift); memcpy(data,&data[shift],28-shift); memcpy(&data[28-shift],temp,shift); memcpy(&data[28],&data[28+shift],28-shift); memcpy(&data[56-shift],&temp[shift],shift); } static void pc1_transform(char* key, char* dst){ int i; for(i = 0; i < 56; i++){ dst[i] = key[pc_table[i]]; } } static void pc2_transform(char* key, char* dst){ int i; for(i = 0; i < 48; i++){ dst[i] = key[pc1_table[i]]; } } static void ip_transform(char* data){ int i; static char temp[64]; for(i = 0; i < 64; i++){ temp[i] = data[ip_table[i]]; } memcpy(data,temp,64); } static void e_transform(char* data){ int i; static char temp[48]; for(i = 0; i < 48; i++){ temp[i] = data[ex_table[i]]; } memcpy(data,temp,48); } static void p_transform(char* data){ int i; static char temp[32]; for(i = 0; i < 32; i++){ temp[i] = data[p_table[i]]; } memcpy(data,temp,32); } static void ip1_transform(char* data){ int i; static char temp[64]; for(i = 0; i < 64; i++){ temp[i] = data[ip1_table[i]]; } memcpy(data,temp,64); } static void block_xor(char* R, char* L ,int count){ int i; for(i = 0; i < count; i++){ R[i] ^= L[i]; } } static void sbos(char* data){ int i; int line,row,output; int cur1,cur2; for(i = 0; i < 8; i++){ cur1 = i*6; cur2 = i<<2; line = (data[cur1]<<1) + data[cur1+5]; row = (data[cur1+1]<<3) + (data[cur1+2]<<2)+ (data[cur1+3]<<1) + data[cur1+4]; output = s_table[i][line][row]; data[cur2++] = (output&0X08)>>3; data[cur2++] = (output&0X04)>>2; data[cur2++] = (output&0X02)>>1; data[cur2] = output&0x01; } } static void block_swap(char* left, char* right){ static char temp[32]; memcpy(temp,left,32); memcpy(left,right,32); memcpy(right,temp,32); } /************************************************************************/ /* functions:DES_GetKey,DES_Encrypt,DES_Decrypt */ /************************************************************************/ DES_KEY DES_GetKey(char* key_str) { static DES_KEY key; static char temp[56]; int i; static char key_bits[64]; convert_bits(key_str,key_bits); pc1_transform(key_bits,temp); for(i = 0; i < 16; i++){ LeftShift(temp,move_times[i]); pc2_transform(temp,key.keys[i]); } return key; } void DES_Encrypt(DES_KEY* key,char* data,char* dst) { static char bits[64]; static char right[48]; int i; convert_bits(data,bits); ip_transform(bits); for(i = 0; i < 16; i++){ memcpy(right,&bits[32],32); e_transform(right); block_xor(right,key->keys[i],48); sbos(right); p_transform(right); block_xor(bits,right,32); if(i != 15){ block_swap(bits,&bits[32]); } } ip1_transform(bits); re_convert_bits(bits,dst); } void DES_Decrypt(DES_KEY* key,char* data,char* dst) { static char bits[64]; static char right[48]; int i; convert_bits(data,bits); ip_transform(bits); for(i = 15; i >= 0; i--){ memcpy(right,&bits[32],32); e_transform(right); block_xor(right,key->keys[i],48); sbos(right); p_transform(right); block_xor(bits,right,32); if(i != 0){ block_swap(bits,&bits[32]); } } ip1_transform(bits); re_convert_bits(bits,dst); }