### view libtommath/etc/drprime.c @ 1514:6c16a05023aa

rename some options and move some to sysoptions.h
author Matt Johnston Sun, 18 Feb 2018 00:29:17 +0800 8bba51a55704
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```/* Makes safe primes of a DR nature */
#include <tommath.h>

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 };
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++) {
top:
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++) {
}

/* make a DR modulus */
a.dp[0] = -1;
a.used = sizes[x];

/* now loop */
res = 0;
for (;;) {
a.dp[0] += 4;
mp_prime_is_prime(&a, 1, &res);
if (res == 0) continue;
printf("."); fflush(stdout);
mp_sub_d(&a, 1, &b);
mp_div_2(&b, &b);
mp_prime_is_prime(&b, 3, &res);
if (res == 0) continue;
mp_prime_is_prime(&a, 3, &res);
if (res == 1) break;
}

if (res != 1) {
printf("Error not DR modulus\n"); sizes[x] += 1; goto top;
} else {
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;
}

/* ref:         \$Format:%D\$ */
/* git commit:  \$Format:%H\$ */
/* commit time: \$Format:%ai\$ */
```