release/src/router/dropbear/libtommath/etc/drprime.c

   1 /* Makes safe primes of a DR nature */
   2 #include <tommath.h>
   3
   4 int sizes[] = { 1+256/DIGIT_BIT, 1+512/DIGIT_BIT, 1+768/DIGIT_BIT, 1+1024/DIGIT_BIT, 1+2048/DIGIT_BIT, 1+4096/DIGIT_BIT };
   5 int main(void)
   6 {
   7    int res, x, y;
   8    char buf[4096];
   9    FILE *out;
  10    mp_int a, b;
  11
  12    mp_init(&a);
  13    mp_init(&b);
  14
  15    out = fopen("drprimes.txt", "w");
  16    for (x = 0; x < (int)(sizeof(sizes)/sizeof(sizes[0])); x++) {
  17    top:
  18        printf("Seeking a %d-bit safe prime\n", sizes[x] * DIGIT_BIT);
  19        mp_grow(&a, sizes[x]);
  20        mp_zero(&a);
  21        for (y = 1; y < sizes[x]; y++) {
  22            a.dp[y] = MP_MASK;
  23        }
  24
  25        /* make a DR modulus */
  26        a.dp[0] = -1;
  27        a.used = sizes[x];
  28
  29        /* now loop */
  30        res = 0;
  31        for (;;) {
  32           a.dp[0] += 4;
  33           if (a.dp[0] >= MP_MASK) break;
  34           mp_prime_is_prime(&a, 1, &res);
  35           if (res == 0) continue;
  36           printf("."); fflush(stdout);
  37           mp_sub_d(&a, 1, &b);
  38           mp_div_2(&b, &b);
  39           mp_prime_is_prime(&b, 3, &res);
  40           if (res == 0) continue;
  41           mp_prime_is_prime(&a, 3, &res);
  42           if (res == 1) break;
  43         }
  44
  45         if (res != 1) {
  46            printf("Error not DR modulus\n"); sizes[x] += 1; goto top;
  47         } else {
  48            mp_toradix(&a, buf, 10);
  49            printf("\n\np == %s\n\n", buf);
  50            fprintf(out, "%d-bit prime:\np == %s\n\n", mp_count_bits(&a), buf); fflush(out);
  51         }
  52    }
  53    fclose(out);
  54
  55    mp_clear(&a);
  56    mp_clear(&b);
  57
  58    return 0;
  59 }
  60
  61
  62 /* $Source: /cvs/libtom/libtommath/etc/drprime.c,v $ */
  63 /* $Revision: 1.2 $ */
  64 /* $Date: 2005/05/05 14:38:47 $ */