DES加解密算法是一个挺老的算法了，现在给出它的C语言版。
des.h
1 #ifdef __cplusplus 2 extern "C" { 3 #endif 4 5 void setKey(const char key[8]); 6 char* des(const char datas[]); 7 char * dedes(const char datas[]); 8 9 #ifdef __cplusplus 10 } 11 #endif
des_tables.h
1 char table_IP[] /* 初始置换表 IP */ 2 = { 3 58, 50, 42, 34, 26, 18, 10, 2, 60, 52, 44, 36, 28, 20, 12, 4, 4 62, 54, 46, 38, 30, 22, 14, 6, 64, 56, 48, 40, 32, 24, 16, 8, 5 57, 49, 41, 33, 25, 17, 9, 1, 59, 51, 43, 35, 27, 19, 11, 3, 6 61, 53, 45, 37, 29, 21, 13, 5, 63, 55, 47, 39, 31, 23, 15, 7 7 }; 8 9 const static char table_FP[] /* 末置换表 */ 10 = { 11 40, 8, 48, 16, 56, 24, 64, 32, 39, 7, 47, 15, 55, 23, 63, 31, 12 38, 6, 46, 14, 54, 22, 62, 30, 37, 5, 45, 13, 53, 21, 61, 29, 13 36, 4, 44, 12, 52, 20, 60, 28, 35, 3, 43, 11, 51, 19, 59, 27, 14 34, 2, 42, 10, 50, 18, 58, 26, 33, 1, 41, 9, 49, 17, 57, 25 15 }; 16 17 //= { 18 // 40, 8, 48, 16, 56, 24, 64, 32, 39, 7, 47, 15, 55, 23, 63, 31, 19 // 38, 6, 46, 14, 54, 22, 62, 30, 37, 5, 45, 13, 53, 21, 61, 29, 20 // 36, 4, 44, 12, 52, 20, 60, 28, 35, 3, 43, 11, 51, 19, 59, 27, 21 // 34, 2, 42, 10, 50, 18, 58, 26, 33, 1, 41, 9, 49, 17, 57, 25 22 //}; 23 24 char table_PC_1[] /* 密钥置换表PC_1 */ 25 = { 26 57, 49, 41, 33, 25, 17, 9, 1, 58, 50, 42, 34, 26, 18, 27 10, 2, 59, 51, 43, 35, 27, 19, 11, 3, 60, 52, 44, 36, 28 63, 55, 47, 39, 31, 23, 15, 7, 62, 54, 46, 38, 30, 22, 29 14, 6, 61, 53, 45, 37, 29, 21, 13, 5, 28, 20, 12, 4 30 }; 31 32 33 char table_PC_2[] /* 压缩置换表 PC_2 */ 34 = { 35 14, 17, 11, 24, 1, 5, 3, 28, 15, 6, 21, 10, 36 23, 19, 12, 4, 26, 8, 16, 7, 27, 20, 13, 2, 37 41, 52, 31, 37, 47, 55, 30, 40, 51, 45, 33, 48, 38 44, 49, 39, 56, 34, 53, 46, 42, 50, 36, 29, 32 39 }; 40 41 42 43 char table_S[8][64] /* 48->32 bit compression tables*/ 44 = { /* S[1] */ 45 14, 4, 13, 1, 2, 15, 11, 8, 3, 10, 6, 12, 5, 9, 0, 7, 46 0, 15, 7, 4, 14, 2, 13, 1, 10, 6, 12, 11, 9, 5, 3, 8, 47 4, 1, 14, 8, 13, 6, 2, 11, 15, 12, 9, 7, 3, 10, 5, 0, 48 15, 12, 8, 2, 4, 9, 1, 7, 5, 11, 3, 14, 10, 0, 6, 13, 49 /* S[2] */ 50 15, 1, 8, 14, 6, 11, 3, 4, 9, 7, 2, 13, 12, 0, 5, 10, 51 3, 13, 4, 7, 15, 2, 8, 14, 12, 0, 1, 10, 6, 9, 11, 5, 52 0, 14, 7, 11, 10, 4, 13, 1, 5, 8, 12, 6, 9, 3, 2, 15, 53 13, 8, 10, 1, 3, 15, 4, 2, 11, 6, 7, 12, 0, 5, 14, 9, 54 /* S[3] */ 55 10, 0, 9, 14, 6, 3, 15, 5, 1, 13, 12, 7, 11, 4, 2, 8, 56 13, 7, 0, 9, 3, 4, 6, 10, 2, 8, 5, 14, 12, 11, 15, 1, 57 13, 6, 4, 9, 8, 15, 3, 0, 11, 1, 2, 12, 5, 10, 14, 7, 58 1, 10, 13, 0, 6, 9, 8, 7, 4, 15, 14, 3, 11, 5, 2, 12, 59 /* S[4] */ 60 7, 13, 14, 3, 0, 6, 9, 10, 1, 2, 8, 5, 11, 12, 4, 15, 61 13, 8, 11, 5, 6, 15, 0, 3, 4, 7, 2, 12, 1, 10, 14, 9, 62 10, 6, 9, 0, 12, 11, 7, 13, 15, 1, 3, 14, 5, 2, 8, 4, 63 3, 15, 0, 6, 10, 1, 13, 8, 9, 4, 5, 11, 12, 7, 2, 14, 64 /* S[5] */ 65 2, 12, 4, 1, 7, 10, 11, 6, 8, 5, 3, 15, 13, 0, 14, 9, 66 14, 11, 2, 12, 4, 7, 13, 1, 5, 0, 15, 10, 3, 9, 8, 6, 67 4, 2, 1, 11, 10, 13, 7, 8, 15, 9, 12, 5, 6, 3, 0, 14, 68 11, 8, 12, 7, 1, 14, 2, 13, 6, 15, 0, 9, 10, 4, 5, 3, 69 /* S[6] */ 70 12, 1, 10, 15, 9, 2, 6, 8, 0, 13, 3, 4, 14, 7, 5, 11, 71 10, 15, 4, 2, 7, 12, 9, 5, 6, 1, 13, 14, 0, 11, 3, 8, 72 9, 14, 15, 5, 2, 8, 12, 3, 7, 0, 4, 10, 1, 13, 11, 6, 73 4, 3, 2, 12, 9, 5, 15, 10, 11, 14, 1, 7, 6, 0, 8, 13, 74 /* S[7] */ 75 4, 11, 2, 14, 15, 0, 8, 13, 3, 12, 9, 7, 5, 10, 6, 1, 76 13, 0, 11, 7, 4, 9, 1, 10, 14, 3, 5, 12, 2, 15, 8, 6, 77 1, 4, 11, 13, 12, 3, 7, 14, 10, 15, 6, 8, 0, 5, 9, 2, 78 6, 11, 13, 8, 1, 4, 10, 7, 9, 5, 0, 15, 14, 2, 3, 12, 79 /* S[8] */ 80 13, 2, 8, 4, 6, 15, 11, 1, 10, 9, 3, 14, 5, 0, 12, 7, 81 1, 15, 13, 8, 10, 3, 7, 4, 12, 5, 6, 11, 0, 14, 9, 2, 82 7, 11, 4, 1, 9, 12, 14, 2, 0, 6, 10, 13, 15, 3, 5, 8, 83 2, 1, 14, 7, 4, 10, 8, 13, 15, 12, 9, 0, 3, 5, 6, 11 84 }; 85 86 char table_P[] /* P 盒置换 */ 87 = { 16, 7, 20, 21, 29, 12, 28, 17, 1, 15, 23, 26, 5, 18, 31, 10, 88 2, 8, 24, 14, 32, 27, 3, 9, 19, 13, 30, 6, 22, 11, 4, 25 89 }; 90 91 char table_E[] 92 = { 93 32, 1, 2, 3, 4, 5, 4, 5, 6, 7, 8, 9, 94 8, 9, 10, 11, 12, 13, 12, 13, 14, 15, 16, 17, 95 16, 17, 18, 19, 20, 21, 20, 21, 22, 23, 24, 25, 96 24, 25, 26, 27, 28, 29, 28, 29, 30, 31, 32, 1 97 }; 98 99 char table_move[] 100 ={ 101 1,1,2,2, 102 2,2,2,2, 103 1,2,2,2, 104 2,2,2,1 105 };
des.c
1 #include<stdio.h> 2 #include<string.h> 3 #include"des_tables.h" 4 #include"des.h" 5 6 //保存这16轮的加密密钥<64位> 7 char keys[17][8]; 8 //存着经过压缩置换后的 key 9 char key_48[16][6]; 10 11 char data[16]; 12 //s盒置换结果缓冲区 13 char data_32[4]; 14 char *data_left; 15 char *data_right; 16 17 18 //密钥置换 19 void fun_InitReplacementKey(){ 20 register int i,j,l=0; 21 register unsigned int k; 22 register char *to_pos = keys[16]; 23 memset(to_pos,0,8); 24 for(i=0,l=0;i<8;i++){ 25 for(j=7;j>0;j--){ 26 k = table_PC_1[l++]-1; 27 *to_pos = (*to_pos)| (( (*(keys[0]+(k>>3)) >>(7 - (k&0x07) ))&0x01 )<<j); 28 } 29 30 to_pos++; 31 } 32 } 33 34 //对密钥进行移位,并存在接下来下面的字节中 35 void fun_MoveKey(int len , char*offset, char *dist){ 36 ///////////////////////// 37 ///错误了!!!! 是分两块进行循环移位 !!!!!!! 38 ///< 已修改 ! 需要分左右部分 > 39 40 register int i = len; 41 unsigned char firstBit; 42 static unsigned char *tmp; 43 tmp =(unsigned char*)dist; 44 memcpy(tmp,offset,8); 45 firstBit =(unsigned char)tmp[0]; 46 firstBit = firstBit>>(8-len); 47 48 //左边部分循环左移 49 for(i=0;i< 3;i++){ 50 tmp[i] = (tmp[i]&0xfe) <<len ; 51 tmp[i] = tmp[i]|((tmp[i+1]>>(7-len))&0xff); 52 tmp[i] = tmp[i]&0xfe; 53 } 54 55 tmp[i] = (tmp[i] &0xfe)<<len; 56 tmp[i] = tmp[i]|(firstBit<<1); 57 tmp[i] = tmp[i]&0xfe; 58 59 firstBit =(unsigned char)tmp[++i]; 60 firstBit = firstBit>>(8-len); 61 62 //右边部分循环左移 63 for(i;i<7;i++){ 64 tmp[i] = (tmp[i]&0xfe) <<len ; 65 tmp[i] = tmp[i]|((tmp[i+1]>>(7-len))&0xff); 66 tmp[i] = tmp[i]&0xfe; 67 } 68 tmp[i] = (tmp[i] &0xfe)<<len; 69 tmp[i] = tmp[i]|(firstBit<<1); 70 tmp[i] = tmp[i]&0xfe; 71 72 } 73 74 //对密钥进行压缩置换并保存到指定位置 75 void fun_ReplacementCompressKey(char* offset,char *dist){ 76 //压缩置换是在 0-56位进行.需要先对64位密钥进行压缩为56位在进行48位选择 77 register int i,j,k,l; 78 register char dt; 79 register unsigned char* tmp = (unsigned char*)offset; 80 char mid_tmp[7]; 81 82 for(i=0;i<7;i++){ 83 mid_tmp[i] = (tmp[i]<<(i)) | ((tmp[i+1])>>(7-i)); 84 } 85 86 memset(dist,0,7); 87 //进行置换 88 for(i=0,l=0;i<6;i++){ 89 for(dt =0,j=7;j>=0;j--){ 90 k = table_PC_2[l++]-1; 91 dt = dt|(( (*(mid_tmp+(k>>3)) >>(7 - k&0x07 ))&0x01 )<<j); 92 if(j==0) 93 break; 94 } 95 dist[i] = dt; 96 } 97 } 98 99 /**********************************************/ 100 101 102 /**********************************************/ 103 //加密过程 104 105 //初始置换 ip 106 //从offset位置开始将数据置换到 data[8-15]字节 ,然后重新复制到data[0-7]中 107 void fun_initReplacement(const char *offset){ 108 register int i,j,l; 109 register unsigned char k,*tmp,*to; 110 //将数据块区域重置为 0 111 tmp = (unsigned char*)offset; 112 to = (unsigned char* )(data+8); 113 memset(to,0,8); 114 for(i=0,l=0;i<8;i++){ 115 for(j=7;j>=0;j--){ 116 k = table_IP[l++]-1; 117 to[i] = to[i] | ((( *(tmp+(k>>3))>>(7- (k &0x07)))&0x01)<<j); 118 if(j==0) 119 break; 120 } 121 } 122 memcpy(data,data+8,8); 123 //初始化指针 124 data_left = data; 125 data_right = data+4; 126 } 127 128 //末置换 fp 129 void fun_finalReplacement(){ 130 //数据块存在 data[0]-data[7]中 ! 131 //置换临时空间 data[8]-data[15] 132 register int i,j,l; 133 register unsigned char k,*tmp,*to; 134 //将数据块区域重置为 0 135 tmp = (unsigned char*)data; 136 to = (unsigned char*)(data+8); 137 for(i=0,l=0;i<8;i++){ 138 for(j=7;j>=0;j--){ 139 k = table_FP[l++]-1; 140 to[i] = to[i] | ((( *(tmp+(k>>3))>>(7- (k &0x07)))&0x01)<<j); 141 if(j==0) 142 break; 143 } 144 } 145 memcpy(data,to,8); 146 147 } 148 149 //扩展置换 150 void fun_expandReplacement_32To48(){ 151 //////////将右边的数据扩展至 48 位 ! 152 register int i,j; 153 register unsigned char k,l,*tmp,*to_pos; 154 tmp = (unsigned char *)data_right; 155 to_pos = (unsigned char*)(data+8); 156 memset(to_pos,0,8); 157 //printf(" ---------- 扩展置换 --------- "); 158 for(i=0,l=0;i<6;i++){ 159 for(j=7 ,k=0;j>=0;j--){ 160 k = table_E[l++]-1; 161 *to_pos = (*to_pos)| (((*(tmp+(k>>3)) >>(7 - (k&0x07) ))&0x01)<<j); 162 //printf("%d %d %x ",l,k,((*(tmp+(k>>3)) >>(7 - (k&0x07) ))&0x01)); 163 if(j==0) 164 break; 165 } 166 to_pos++; 167 } 168 } 169 170 //加 密钥 异或 171 void fun_xor_48(char *ktmp){ 172 register int i; 173 char *dtmp = data+8; 174 for(i=0;i<6;i++){ 175 dtmp[i] = dtmp[i]^ktmp[i]; 176 177 } 178 } 179 180 // s盒置换 181 void fun_S_Replacement(){ 182 // s盒工作原理 : 48位 分成8组.每组6位 0位和5位组成行定位, 1-4位组成列定位. 183 // 定位出来的数据即为替换后的 4 位数据 184 register unsigned char row,col,ctmp,index,i; 185 register char *dtmp; 186 static char tmp[4]; 187 dtmp = data+8; 188 memset(tmp,0,4); 189 //((*(tmp+(k>>3)) >>(7 - (k&0x07) ))&0x01) 190 for(index =0,ctmp=0,i=0;i< 8 ;i++){ 191 // row 为:index 接下来第零位和第五位 192 row = (((*(dtmp+((index)>>3))>>((7-((index)&0x07))))&0x01)<<1); //第0位 193 row|=(((*(dtmp+((index+5)>>3))>>((7-((index+5)&0x07))))&0x01))&0x03;//第5位 194 195 col =(((*(dtmp+((index+1)>>3))>>((7-((index+1)&0x07))))&0x01)<<3); //第1位 196 col|= (((*(dtmp+((index+2)>>3))>>((7-((index+2)&0x07))))&0x01)<<2); //第2位 197 col|= (((*(dtmp+((index+3)>>3))>>((7-((index+3)&0x07))))&0x01)<<1); //第3位 198 col|= (((*(dtmp+((index+4)>>3))>>((7-((index+4)&0x07))))&0x01))&0x0f;//第4位 199 ctmp = table_S[i][(row<<4)+col]; 200 201 //写入4位 202 tmp[i>>1] = tmp[i>>1] | ((ctmp&0xf)<<(((~i)&0x01)<<2)); 203 index+=6; 204 } 205 memcpy(data+8,tmp,4); 206 } 207 208 209 //P盒置换 210 void fun_P_Replacement(){ 211 register unsigned char i,k,l; 212 static char tmp[4],j; 213 register char *offset =data + 8; 214 memset(tmp,0,4); 215 for(i=0,l=0;i<4;i++){ 216 for(k=0,j=7;j>=0;j--){ 217 k = table_P[l++]-1; 218 tmp[i] = tmp[i] |((( * (offset+(k>>3)))>>(7 - (k&0x07))&0x01)<<j); 219 if(j==0) 220 break; 221 } 222 } 223 memcpy(data+8,tmp,4); 224 } 225 226 //左右域异或 227 void fun_xor_32(){ 228 register char i; 229 for(i=0;i<4;i++){ 230 data_left[i] = data_left[i]^data[8+i]; 231 } 232 } 233 234 235 //设置 密码 <生成过程所有密码> 236 void setKey(const char key[8]){ 237 register int i; 238 register char*offset,*to,*ct; 239 memcpy(keys[0],key,8); 240 fun_InitReplacementKey(); 241 offset = keys[16]; 242 to = keys[0]; 243 ct = key_48[0]; 244 //16轮迭代算出需要的 <key> 245 for(i=0;i<16;i++){ 246 fun_MoveKey(table_move[i],offset,to); 247 fun_ReplacementCompressKey(to,ct); 248 offset = to; 249 ct+=6; 250 to+=8; 251 } 252 } 253 254 255 //加密 256 char* des(const char datas[]){ 257 int i=0; 258 static char *swapeTmp; 259 fun_initReplacement(datas); 260 for(i=0;i<15;i++){ 261 fun_expandReplacement_32To48(); 262 fun_xor_48(key_48[i]); 263 fun_S_Replacement(); 264 fun_P_Replacement(); 265 fun_xor_32(); 266 swapeTmp = data_left; 267 data_left =data_right; 268 data_right =swapeTmp; 269 }//经检验前 15 轮可以正确运算... 270 {//第16轮 271 fun_expandReplacement_32To48(); 272 fun_xor_48(key_48[i]); 273 fun_S_Replacement(); 274 fun_P_Replacement(); 275 fun_xor_32(); 276 //printf(" ---- 16 轮----- Data: %x Left: %x Right: %x ",data,data_left,data_right); 277 //现在状况是 data<right,left>需要将 left 和right的数据块调换过来!!!!!! 278 memcpy(data+8,data,4); 279 memcpy(data,data+4,4); 280 memcpy(data+4,data+8,4); 281 memset(data+8,0,8); 282 } 283 //末置换! 284 fun_finalReplacement(); 285 return data; 286 } 287 288 //解密算法 289 char * dedes(const char datas[]){ 290 int i=0; 291 static char *swapeTmp; 292 fun_initReplacement(datas); 293 for(i=15;i>0;i--){ 294 fun_expandReplacement_32To48(); 295 fun_xor_48(key_48[i]); 296 fun_S_Replacement(); 297 fun_P_Replacement(); 298 fun_xor_32(); 299 swapeTmp = data_left; 300 data_left =data_right; 301 data_right =swapeTmp; 302 }//经检验前 15 轮可以正确运算... 303 {//第16轮 304 fun_expandReplacement_32To48(); 305 fun_xor_48(key_48[i]); 306 fun_S_Replacement(); 307 fun_P_Replacement(); 308 fun_xor_32(); 309 //现在状况是 data<right,left>需要将 left 和right的数据块调换过来!!!!!! 310 memcpy(data+8,data,4); 311 memcpy(data,data+4,4); 312 memcpy(data+4,data+8,4); 313 memset(data+8,0,8); 314 } 315 //末置换! 316 fun_finalReplacement(); 317 data[8]=' '; 318 return data; 319 }