tommath/etc/drprime.c

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2003-03-22 10:10:20 -05:00
/* Makes safe primes of a DR nature */
#include <tommath.h>
const int sizes[] = { 8, 19, 28, 37, 55, 74, 110, 147 };
int main(void)
{
int res, x, y;
char buf[4096];
FILE *out;
mp_int a, b;
mp_init(&a);
mp_init(&b);
out = fopen("drprimes.txt", "w");
for (x = 0; x < (int)(sizeof(sizes)/sizeof(sizes[0])); x++) {
printf("Seeking a %d-bit safe prime\n", sizes[x] * DIGIT_BIT);
mp_grow(&a, sizes[x]);
mp_zero(&a);
for (y = 1; y < sizes[x]; y++) {
a.dp[y] = MP_MASK;
}
/* make a DR modulus */
a.dp[0] = 1;
a.used = sizes[x];
/* now loop */
do {
fflush(stdout);
mp_prime_next_prime(&a, 3);
printf(".");
mp_sub_d(&a, 1, &b);
mp_div_2(&b, &b);
mp_prime_is_prime(&b, 3, &res);
} while (res == 0);
if (mp_dr_is_modulus(&a) != 1) {
printf("Error not DR modulus\n");
} else {
mp_toradix(&a, buf, 10);
printf("\n\np == %s\n\n", buf);
fprintf(out, "%d-bit prime:\np == %s\n\n", mp_count_bits(&a), buf); fflush(out);
}
}
fclose(out);
mp_clear(&a);
mp_clear(&b);
return 0;
}