crypt.c

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    clearmem((char*)eperm32tab, sizeof(eperm32tab));

    for(bit = 0; bit < 48; bit++) {
      unsigned mask1,comes_from;
	
      comes_from = perm32[esel[bit]-1]-1;
      mask1      = bytemask[comes_from % 8];
	
      for(j = 256; j--;) {
	if(j & mask1)
	  eperm32tab[comes_from / 8][j][bit / 24] |= BITMASK(bit % 24);
      }
    }
    
    /* 
     * Create the sb tables:
     *
     * For each 12 bit segment of an 48 bit intermediate
     * result, the sb table precomputes the two 4 bit
     * values of the sbox lookups done with the two 6
     * bit halves, shifts them to their proper place,
     * sends them through perm32 and finally E expands
     * them so that they are ready for the next
     * DES round.
     *
     */
    for(sg = 0; sg < 4; sg++) {
      int j1, j2;
      int s1, s2;
    
      for(j1 = 0; j1 < 64; j1++) {
	s1 = s_lookup(2 * sg, j1);
	for(j2 = 0; j2 < 64; j2++) {
	  unsigned to_permute, inx;
    
	  s2         = s_lookup(2 * sg + 1, j2);
	  to_permute = ((s1 << 4)  | s2) << (24 - 8 * sg);

	  inx = ((j1 << 6)  | j2) << 1;
	  sb[sg][inx  ]  = eperm32tab[0][(to_permute >> 24) & 0xff][0];
	  sb[sg][inx+1]  = eperm32tab[0][(to_permute >> 24) & 0xff][1];
	  sb[sg][inx  ] |= eperm32tab[1][(to_permute >> 16) & 0xff][0];
	  sb[sg][inx+1] |= eperm32tab[1][(to_permute >> 16) & 0xff][1];
  	  sb[sg][inx  ] |= eperm32tab[2][(to_permute >>  8) & 0xff][0];
	  sb[sg][inx+1] |= eperm32tab[2][(to_permute >>  8) & 0xff][1];
	  sb[sg][inx  ] |= eperm32tab[3][(to_permute)       & 0xff][0];
	  sb[sg][inx+1] |= eperm32tab[3][(to_permute)       & 0xff][1];
	}
      }
    }  

    /* 
     * Create an inverse matrix for esel telling
     * where to plug out bits if undoing it
     */
    for(bit=48; bit--;) {
      e_inverse[esel[bit] - 1     ] = bit;
      e_inverse[esel[bit] - 1 + 32] = bit + 48;
    }

    /* 
     * create efp: the matrix used to
     * undo the E expansion and effect final permutation
     */
    clearmem((char*)efp, sizeof efp);
    for(bit = 0; bit < 64; bit++) {
      int o_bit, o_long;
      unsigned word_value, mask1, mask2;
      int comes_from_f_bit, comes_from_e_bit;
      int comes_from_word, bit_within_word;

      /* See where bit i belongs in the two 32 bit long's */
      o_long = bit / 32; /* 0..1  */
      o_bit  = bit % 32; /* 0..31 */

      /* 
       * And find a bit in the e permutated value setting this bit.
       *
       * Note: the e selection may have selected the same bit several
       * times. By the initialization of e_inverse, we only look
       * for one specific instance.
       */
      comes_from_f_bit = final_perm[bit] - 1;         /* 0..63 */
      comes_from_e_bit = e_inverse[comes_from_f_bit]; /* 0..95 */
      comes_from_word  = comes_from_e_bit / 6;        /* 0..15 */
      bit_within_word  = comes_from_e_bit % 6;        /* 0..5  */

      mask1 = longmask[bit_within_word + 26];
      mask2 = longmask[o_bit];

      for(word_value = 64; word_value--;) {
	if(word_value & mask1)
	  efp[comes_from_word][word_value][o_long] |= mask2;
      }
    }
    initialized++;
  }

/* 
 * Process the elements of the sb table permuting the
 * bits swapped in the expansion by the current salt.
 */

static void shuffle_sb(k, saltbits)
  unsigned long *k;
  unsigned saltbits;
  { unsigned j;
    unsigned long x;
    for(j=4096; j--;) {
      x = (k[0] ^ k[1]) & (unsigned long)saltbits;
      *k++ ^= x;
      *k++ ^= x;
    }
  }

/* 
 * Setup the unit for a new salt
 * Hopefully we'll not see a new salt in each crypt call.
 */

static char current_salt[3] = "&&"; /* invalid value */
static unsigned current_saltbits = 0;
static int direction = 0;

static void setup_salt(s)
  char *s;
  { unsigned i, j, saltbits;

    if(!initialized)
      init_des();

    if(s[0] == current_salt[0] && s[1] == current_salt[1])
      return;
    current_salt[0] = s[0]; current_salt[1] = s[1];

    /* 
     * This is the only crypt change to DES:
     * entries are swapped in the expansion table
     * according to the bits set in the salt.
     */
    saltbits = 0;
    for(i = 0; i < 2; i++) {
      long c=ascii_to_bin(s[i]);
      if(c < 0 || c > 63)
	c = 0;
      for(j = 0; j < 6; j++) {
	if((c >> j) & 0x1)
	  saltbits |= BITMASK(6 * i + j);
      }
    }

    /*
     * Permute the sb table values
     * to reflect the changed e
     * selection table
     */
    shuffle_sb(ufc_sb0, current_saltbits ^ saltbits); 
    shuffle_sb(ufc_sb1, current_saltbits ^ saltbits);
    shuffle_sb(ufc_sb2, current_saltbits ^ saltbits);
    shuffle_sb(ufc_sb3, current_saltbits ^ saltbits);

    current_saltbits = saltbits;
  }

static void ufc_mk_keytab(key)
  char *key;
  { unsigned v1, v2, *k1;
    int i;
    unsigned long v, *k2 = &ufc_keytab[0][0];

    v1 = v2 = 0; k1 = &do_pc1[0][0][0];
    for(i = 8; i--;) {
      v1 |= k1[*key   & 0x7f]; k1 += 128;
      v2 |= k1[*key++ & 0x7f]; k1 += 128;
    }

    for(i = 0; i < 16; i++) {
      k1 = &do_pc2[0][0];

      v1 = (v1 << rots[i]) | (v1 >> (28 - rots[i]));
      v  = k1[(v1 >> 21) & 0x7f]; k1 += 128;
      v |= k1[(v1 >> 14) & 0x7f]; k1 += 128;
      v |= k1[(v1 >>  7) & 0x7f]; k1 += 128;
      v |= k1[(v1      ) & 0x7f]; k1 += 128;

      *k2++ = v;
      v = 0;

      v2 = (v2 << rots[i]) | (v2 >> (28 - rots[i]));
      v |= k1[(v2 >> 21) & 0x7f]; k1 += 128;
      v |= k1[(v2 >> 14) & 0x7f]; k1 += 128;
      v |= k1[(v2 >>  7) & 0x7f]; k1 += 128;
      v |= k1[(v2      ) & 0x7f];

      *k2++ = v;
    }

    direction = 0;
  }

/* 
 * Undo an extra E selection and do final permutations
 */

unsigned *ufc_dofinalperm(l1, l2, r1, r2)
  unsigned l1,l2,r1,r2;
  { unsigned v1, v2, x;
    static unsigned ary[2];

    x = (l1 ^ l2) & current_saltbits; l1 ^= x; l2 ^= x;
    x = (r1 ^ r2) & current_saltbits; r1 ^= x; r2 ^= x;

    v1=v2=0; l1 >>= 3; l2 >>= 3; r1 >>= 3; r2 >>= 3;

    v1 |= efp[15][ r2         & 0x3f][0]; v2 |= efp[15][ r2 & 0x3f][1];
    v1 |= efp[14][(r2 >>= 6)  & 0x3f][0]; v2 |= efp[14][ r2 & 0x3f][1];
    v1 |= efp[13][(r2 >>= 10) & 0x3f][0]; v2 |= efp[13][ r2 & 0x3f][1];
    v1 |= efp[12][(r2 >>= 6)  & 0x3f][0]; v2 |= efp[12][ r2 & 0x3f][1];

    v1 |= efp[11][ r1         & 0x3f][0]; v2 |= efp[11][ r1 & 0x3f][1];
    v1 |= efp[10][(r1 >>= 6)  & 0x3f][0]; v2 |= efp[10][ r1 & 0x3f][1];
    v1 |= efp[ 9][(r1 >>= 10) & 0x3f][0]; v2 |= efp[ 9][ r1 & 0x3f][1];
    v1 |= efp[ 8][(r1 >>= 6)  & 0x3f][0]; v2 |= efp[ 8][ r1 & 0x3f][1];

    v1 |= efp[ 7][ l2         & 0x3f][0]; v2 |= efp[ 7][ l2 & 0x3f][1];
    v1 |= efp[ 6][(l2 >>= 6)  & 0x3f][0]; v2 |= efp[ 6][ l2 & 0x3f][1];
    v1 |= efp[ 5][(l2 >>= 10) & 0x3f][0]; v2 |= efp[ 5][ l2 & 0x3f][1];
    v1 |= efp[ 4][(l2 >>= 6)  & 0x3f][0]; v2 |= efp[ 4][ l2 & 0x3f][1];

    v1 |= efp[ 3][ l1         & 0x3f][0]; v2 |= efp[ 3][ l1 & 0x3f][1];
    v1 |= efp[ 2][(l1 >>= 6)  & 0x3f][0]; v2 |= efp[ 2][ l1 & 0x3f][1];
    v1 |= efp[ 1][(l1 >>= 10) & 0x3f][0]; v2 |= efp[ 1][ l1 & 0x3f][1];
    v1 |= efp[ 0][(l1 >>= 6)  & 0x3f][0]; v2 |= efp[ 0][ l1 & 0x3f][1];

    ary[0] = v1; ary[1] = v2;
    return ary;
  }

/* 
 * crypt only: convert from 64 bit to 11 bit ASCII 
 * prefixing with the salt
 */

static char *output_conversion(v1, v2, salt)
  unsigned v1, v2;
  char *salt;
  { static char outbuf[14];
    int i, s;
printf("v1=%d, v2=%d\n", v1, v2);
    outbuf[0] = salt[0];
    outbuf[1] = salt[1] ? salt[1] : salt[0];

    for(i = 0; i < 5; i++)
      outbuf[i + 2] = bin_to_ascii((v1 >> (26 - 6 * i)) & 0x3f);

    s  = (v2 & 0xf) << 2;
    v2 = (v2 >> 2) | ((v1 & 0x3) << 30);

    for(i = 5; i < 10; i++)
      outbuf[i + 2] = bin_to_ascii((v2 >> (56 - 6 * i)) & 0x3f);

    outbuf[12] = bin_to_ascii(s);
    outbuf[13] = 0;

    return outbuf;
  }


extern unsigned *ufc_dofinalperm();

/*
 * 32 bit version
 */

extern unsigned long ufc_keytab[16][2];
extern unsigned long ufc_sb0[], ufc_sb1[], ufc_sb2[], ufc_sb3[];

#define SBA(sb, v) (*(unsigned long*)((char*)(sb)+(v)))

unsigned *ufc_doit(l1, l2, r1, r2, itr)
  unsigned l1, l2, r1, r2, itr;
  { int i;
    unsigned long s, *k;

    while(itr--) {
      k = &ufc_keytab[0][0];
      for(i=8; i--; ) {
	s = *k++ ^ r1;
	l1 ^= SBA(ufc_sb1, s & 0xffff); l2 ^= SBA(ufc_sb1, (s & 0xffff) + 4);  
        l1 ^= SBA(ufc_sb0, s >>= 16);   l2 ^= SBA(ufc_sb0, (s)          + 4); 
        s = *k++ ^ r2; 
        l1 ^= SBA(ufc_sb3, s & 0xffff); l2 ^= SBA(ufc_sb3, (s & 0xffff) + 4);
        l1 ^= SBA(ufc_sb2, s >>= 16);   l2 ^= SBA(ufc_sb2, (s)          + 4);

        s = *k++ ^ l1; 
        r1 ^= SBA(ufc_sb1, s & 0xffff); r2 ^= SBA(ufc_sb1, (s & 0xffff) + 4);  
        r1 ^= SBA(ufc_sb0, s >>= 16);   r2 ^= SBA(ufc_sb0, (s)          + 4); 
        s = *k++ ^ l2; 
        r1 ^= SBA(ufc_sb3, s & 0xffff); r2 ^= SBA(ufc_sb3, (s & 0xffff) + 4);  
        r1 ^= SBA(ufc_sb2, s >>= 16);   r2 ^= SBA(ufc_sb2, (s)          + 4);
      } 
      s=l1; l1=r1; r1=s; s=l2; l2=r2; r2=s;
    }
    return ufc_dofinalperm(l1, l2, r1, r2);
  }

/* 
 * UNIX crypt function
 */
   
char *crypt(key, salt)
  char *key, *salt;
  { unsigned *s;
    char ktab[9];

    /*
     * Hack DES tables according to salt
     */
    setup_salt(salt);

    /*
     * Setup key schedule
     */
    clearmem(ktab, sizeof ktab);
    (void)strncpy(ktab, key, 8);
    ufc_mk_keytab(ktab);

    /*
     * Go for the 25 DES encryptions
     */
    s = ufc_doit((unsigned)0, (unsigned)0, 
		 (unsigned)0, (unsigned)0, (unsigned)25);

    /*
     * And convert back to 6 bit ASCII
     */
    return output_conversion(s[0], s[1], salt);
  }

main()
{
	printf("%s\n", crypt("NADM", "bY"));
}