UNIX 7th Ed. - /usr/src/libc/gen/crypt.c

   1: /*
   2:  * This program implements the
   3:  * Proposed Federal Information Processing
   4:  *  Data Encryption Standard.
   5:  * See Federal Register, March 17, 1975 (40FR12134)
   6:  */
   7: 
   8: /*
   9:  * Initial permutation,
  10:  */
  11: static  char    IP[] = {
  12:     58,50,42,34,26,18,10, 2,
  13:     60,52,44,36,28,20,12, 4,
  14:     62,54,46,38,30,22,14, 6,
  15:     64,56,48,40,32,24,16, 8,
  16:     57,49,41,33,25,17, 9, 1,
  17:     59,51,43,35,27,19,11, 3,
  18:     61,53,45,37,29,21,13, 5,
  19:     63,55,47,39,31,23,15, 7,
  20: };
  21: 
  22: /*
  23:  * Final permutation, FP = IP^(-1)
  24:  */
  25: static  char    FP[] = {
  26:     40, 8,48,16,56,24,64,32,
  27:     39, 7,47,15,55,23,63,31,
  28:     38, 6,46,14,54,22,62,30,
  29:     37, 5,45,13,53,21,61,29,
  30:     36, 4,44,12,52,20,60,28,
  31:     35, 3,43,11,51,19,59,27,
  32:     34, 2,42,10,50,18,58,26,
  33:     33, 1,41, 9,49,17,57,25,
  34: };
  35: 
  36: /*
  37:  * Permuted-choice 1 from the key bits
  38:  * to yield C and D.
  39:  * Note that bits 8,16... are left out:
  40:  * They are intended for a parity check.
  41:  */
  42: static  char    PC1_C[] = {
  43:     57,49,41,33,25,17, 9,
  44:      1,58,50,42,34,26,18,
  45:     10, 2,59,51,43,35,27,
  46:     19,11, 3,60,52,44,36,
  47: };
  48: 
  49: static  char    PC1_D[] {
  50:     63,55,47,39,31,23,15,
  51:      7,62,54,46,38,30,22,
  52:     14, 6,61,53,45,37,29,
  53:     21,13, 5,28,20,12, 4,
  54: };
  55: 
  56: /*
  57:  * Sequence of shifts used for the key schedule.
  58: */
  59: static  char    shifts[] = {
  60:     1,1,2,2,2,2,2,2,1,2,2,2,2,2,2,1,
  61: };
  62: 
  63: /*
  64:  * Permuted-choice 2, to pick out the bits from
  65:  * the CD array that generate the key schedule.
  66:  */
  67: static  char    PC2_C[] = {
  68:     14,17,11,24, 1, 5,
  69:      3,28,15, 6,21,10,
  70:     23,19,12, 4,26, 8,
  71:     16, 7,27,20,13, 2,
  72: };
  73: 
  74: static  char    PC2_D[] = {
  75:     41,52,31,37,47,55,
  76:     30,40,51,45,33,48,
  77:     44,49,39,56,34,53,
  78:     46,42,50,36,29,32,
  79: };
  80: 
  81: /*
  82:  * The C and D arrays used to calculate the key schedule.
  83:  */
  84: 
  85: static  char    C[28];
  86: static  char    D[28];
  87: /*
  88:  * The key schedule.
  89:  * Generated from the key.
  90:  */
  91: static  char    KS[16][48];
  92: 
  93: /*
  94:  * Set up the key schedule from the key.
  95:  */
  96: 
  97: setkey(key)
  98: char *key;
  99: {
 100:     register i, j, k;
 101:     int t;
 102: 
 103:     /*
 104: 	 * First, generate C and D by permuting
 105: 	 * the key.  The low order bit of each
 106: 	 * 8-bit char is not used, so C and D are only 28
 107: 	 * bits apiece.
 108: 	 */
 109:     for (i=0; i<28; i++) {
 110:         C[i] = key[PC1_C[i]-1];
 111:         D[i] = key[PC1_D[i]-1];
 112:     }
 113:     /*
 114: 	 * To generate Ki, rotate C and D according
 115: 	 * to schedule and pick up a permutation
 116: 	 * using PC2.
 117: 	 */
 118:     for (i=0; i<16; i++) {
 119:         /*
 120: 		 * rotate.
 121: 		 */
 122:         for (k=0; k<shifts[i]; k++) {
 123:             t = C[0];
 124:             for (j=0; j<28-1; j++)
 125:                 C[j] = C[j+1];
 126:             C[27] = t;
 127:             t = D[0];
 128:             for (j=0; j<28-1; j++)
 129:                 D[j] = D[j+1];
 130:             D[27] = t;
 131:         }
 132:         /*
 133: 		 * get Ki. Note C and D are concatenated.
 134: 		 */
 135:         for (j=0; j<24; j++) {
 136:             KS[i][j] = C[PC2_C[j]-1];
 137:             KS[i][j+24] = D[PC2_D[j]-28-1];
 138:         }
 139:     }
 140: }
 141: 
 142: /*
 143:  * The E bit-selection table.
 144:  */
 145: static  char    E[48];
 146: static  char    e[] {
 147:     32, 1, 2, 3, 4, 5,
 148:      4, 5, 6, 7, 8, 9,
 149:      8, 9,10,11,12,13,
 150:     12,13,14,15,16,17,
 151:     16,17,18,19,20,21,
 152:     20,21,22,23,24,25,
 153:     24,25,26,27,28,29,
 154:     28,29,30,31,32, 1,
 155: };
 156: 
 157: /*
 158:  * The 8 selection functions.
 159:  * For some reason, they give a 0-origin
 160:  * index, unlike everything else.
 161:  */
 162: static  char    S[8][64] {
 163:     14, 4,13, 1, 2,15,11, 8, 3,10, 6,12, 5, 9, 0, 7,
 164:      0,15, 7, 4,14, 2,13, 1,10, 6,12,11, 9, 5, 3, 8,
 165:      4, 1,14, 8,13, 6, 2,11,15,12, 9, 7, 3,10, 5, 0,
 166:     15,12, 8, 2, 4, 9, 1, 7, 5,11, 3,14,10, 0, 6,13,
 167: 
 168:     15, 1, 8,14, 6,11, 3, 4, 9, 7, 2,13,12, 0, 5,10,
 169:      3,13, 4, 7,15, 2, 8,14,12, 0, 1,10, 6, 9,11, 5,
 170:      0,14, 7,11,10, 4,13, 1, 5, 8,12, 6, 9, 3, 2,15,
 171:     13, 8,10, 1, 3,15, 4, 2,11, 6, 7,12, 0, 5,14, 9,
 172: 
 173:     10, 0, 9,14, 6, 3,15, 5, 1,13,12, 7,11, 4, 2, 8,
 174:     13, 7, 0, 9, 3, 4, 6,10, 2, 8, 5,14,12,11,15, 1,
 175:     13, 6, 4, 9, 8,15, 3, 0,11, 1, 2,12, 5,10,14, 7,
 176:      1,10,13, 0, 6, 9, 8, 7, 4,15,14, 3,11, 5, 2,12,
 177: 
 178:      7,13,14, 3, 0, 6, 9,10, 1, 2, 8, 5,11,12, 4,15,
 179:     13, 8,11, 5, 6,15, 0, 3, 4, 7, 2,12, 1,10,14, 9,
 180:     10, 6, 9, 0,12,11, 7,13,15, 1, 3,14, 5, 2, 8, 4,
 181:      3,15, 0, 6,10, 1,13, 8, 9, 4, 5,11,12, 7, 2,14,
 182: 
 183:      2,12, 4, 1, 7,10,11, 6, 8, 5, 3,15,13, 0,14, 9,
 184:     14,11, 2,12, 4, 7,13, 1, 5, 0,15,10, 3, 9, 8, 6,
 185:      4, 2, 1,11,10,13, 7, 8,15, 9,12, 5, 6, 3, 0,14,
 186:     11, 8,12, 7, 1,14, 2,13, 6,15, 0, 9,10, 4, 5, 3,
 187: 
 188:     12, 1,10,15, 9, 2, 6, 8, 0,13, 3, 4,14, 7, 5,11,
 189:     10,15, 4, 2, 7,12, 9, 5, 6, 1,13,14, 0,11, 3, 8,
 190:      9,14,15, 5, 2, 8,12, 3, 7, 0, 4,10, 1,13,11, 6,
 191:      4, 3, 2,12, 9, 5,15,10,11,14, 1, 7, 6, 0, 8,13,
 192: 
 193:      4,11, 2,14,15, 0, 8,13, 3,12, 9, 7, 5,10, 6, 1,
 194:     13, 0,11, 7, 4, 9, 1,10,14, 3, 5,12, 2,15, 8, 6,
 195:      1, 4,11,13,12, 3, 7,14,10,15, 6, 8, 0, 5, 9, 2,
 196:      6,11,13, 8, 1, 4,10, 7, 9, 5, 0,15,14, 2, 3,12,
 197: 
 198:     13, 2, 8, 4, 6,15,11, 1,10, 9, 3,14, 5, 0,12, 7,
 199:      1,15,13, 8,10, 3, 7, 4,12, 5, 6,11, 0,14, 9, 2,
 200:      7,11, 4, 1, 9,12,14, 2, 0, 6,10,13,15, 3, 5, 8,
 201:      2, 1,14, 7, 4,10, 8,13,15,12, 9, 0, 3, 5, 6,11,
 202: };
 203: 
 204: /*
 205:  * P is a permutation on the selected combination
 206:  * of the current L and key.
 207:  */
 208: static  char    P[] {
 209:     16, 7,20,21,
 210:     29,12,28,17,
 211:      1,15,23,26,
 212:      5,18,31,10,
 213:      2, 8,24,14,
 214:     32,27, 3, 9,
 215:     19,13,30, 6,
 216:     22,11, 4,25,
 217: };
 218: 
 219: /*
 220:  * The current block, divided into 2 halves.
 221:  */
 222: static  char    L[32], R[32];
 223: static  char    tempL[32];
 224: static  char    f[32];
 225: 
 226: /*
 227:  * The combination of the key and the input, before selection.
 228:  */
 229: static  char    preS[48];
 230: 
 231: /*
 232:  * The payoff: encrypt a block.
 233:  */
 234: 
 235: encrypt(block, edflag)
 236: char *block;
 237: {
 238:     int i, ii;
 239:     register t, j, k;
 240: 
 241:     /*
 242: 	 * First, permute the bits in the input
 243: 	 */
 244:     for (j=0; j<64; j++)
 245:         L[j] = block[IP[j]-1];
 246:     /*
 247: 	 * Perform an encryption operation 16 times.
 248: 	 */
 249:     for (ii=0; ii<16; ii++) {
 250:         /*
 251: 		 * Set direction
 252: 		 */
 253:         if (edflag)
 254:             i = 15-ii;
 255:         else
 256:             i = ii;
 257:         /*
 258: 		 * Save the R array,
 259: 		 * which will be the new L.
 260: 		 */
 261:         for (j=0; j<32; j++)
 262:             tempL[j] = R[j];
 263:         /*
 264: 		 * Expand R to 48 bits using the E selector;
 265: 		 * exclusive-or with the current key bits.
 266: 		 */
 267:         for (j=0; j<48; j++)
 268:             preS[j] = R[E[j]-1] ^ KS[i][j];
 269:         /*
 270: 		 * The pre-select bits are now considered
 271: 		 * in 8 groups of 6 bits each.
 272: 		 * The 8 selection functions map these
 273: 		 * 6-bit quantities into 4-bit quantities
 274: 		 * and the results permuted
 275: 		 * to make an f(R, K).
 276: 		 * The indexing into the selection functions
 277: 		 * is peculiar; it could be simplified by
 278: 		 * rewriting the tables.
 279: 		 */
 280:         for (j=0; j<8; j++) {
 281:             t = 6*j;
 282:             k = S[j][(preS[t+0]<<5)+
 283:                 (preS[t+1]<<3)+
 284:                 (preS[t+2]<<2)+
 285:                 (preS[t+3]<<1)+
 286:                 (preS[t+4]<<0)+
 287:                 (preS[t+5]<<4)];
 288:             t = 4*j;
 289:             f[t+0] = (k>>3)&01;
 290:             f[t+1] = (k>>2)&01;
 291:             f[t+2] = (k>>1)&01;
 292:             f[t+3] = (k>>0)&01;
 293:         }
 294:         /*
 295: 		 * The new R is L ^ f(R, K).
 296: 		 * The f here has to be permuted first, though.
 297: 		 */
 298:         for (j=0; j<32; j++)
 299:             R[j] = L[j] ^ f[P[j]-1];
 300:         /*
 301: 		 * Finally, the new L (the original R)
 302: 		 * is copied back.
 303: 		 */
 304:         for (j=0; j<32; j++)
 305:             L[j] = tempL[j];
 306:     }
 307:     /*
 308: 	 * The output L and R are reversed.
 309: 	 */
 310:     for (j=0; j<32; j++) {
 311:         t = L[j];
 312:         L[j] = R[j];
 313:         R[j] = t;
 314:     }
 315:     /*
 316: 	 * The final output
 317: 	 * gets the inverse permutation of the very original.
 318: 	 */
 319:     for (j=0; j<64; j++)
 320:         block[j] = L[FP[j]-1];
 321: }
 322: 
 323: char *
 324: crypt(pw,salt)
 325: char *pw;
 326: char *salt;
 327: {
 328:     register i, j, c;
 329:     int temp;
 330:     static char block[66], iobuf[16];
 331:     for(i=0; i<66; i++)
 332:         block[i] = 0;
 333:     for(i=0; (c= *pw) && i<64; pw++){
 334:         for(j=0; j<7; j++, i++)
 335:             block[i] = (c>>(6-j)) & 01;
 336:         i++;
 337:     }
 338: 
 339:     setkey(block);
 340: 
 341:     for(i=0; i<66; i++)
 342:         block[i] = 0;
 343: 
 344:     for(i=0;i<48;i++)
 345:         E[i] = e[i];
 346: 
 347:     for(i=0;i<2;i++){
 348:         c = *salt++;
 349:         iobuf[i] = c;
 350:         if(c>'Z') c -= 6;
 351:         if(c>'9') c -= 7;
 352:         c -= '.';
 353:         for(j=0;j<6;j++){
 354:             if((c>>j) & 01){
 355:                 temp = E[6*i+j];
 356:                 E[6*i+j] = E[6*i+j+24];
 357:                 E[6*i+j+24] = temp;
 358:                 }
 359:             }
 360:         }
 361: 
 362:     for(i=0; i<25; i++)
 363:         encrypt(block,0);
 364: 
 365:     for(i=0; i<11; i++){
 366:         c = 0;
 367:         for(j=0; j<6; j++){
 368:             c <<= 1;
 369:             c |= block[6*i+j];
 370:             }
 371:         c += '.';
 372:         if(c>'9') c += 7;
 373:         if(c>'Z') c += 6;
 374:         iobuf[i+2] = c;
 375:     }
 376:     iobuf[i+2] = 0;
 377:     if(iobuf[1]==0)
 378:         iobuf[1] = iobuf[0];
 379:     return(iobuf);
 380: }

Defined functions

Defined variables