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Use cryptographic RNG
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@czurnieden @sjaeckel
czurnieden authored and sjaeckel committed Mar 11, 2024
1 parent 782cda7 commit 942b8b4
Showing 1 changed file with 54 additions and 37 deletions.
91 changes: 54 additions & 37 deletions etc/pprime.c
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Original file line number Diff line number Diff line change
Expand Up @@ -8,20 +8,29 @@
#include <time.h>
#include "../tommath_private.h"

static mp_digit prime_digit(void)
static void mp_print(const char *s, const mp_int *a, int radix, FILE *stream)
{
mp_err err;
fputs(s, stream);
err = mp_fwrite(a, radix, stream);
if (err != MP_OKAY) {
fprintf(stderr,"mp_fwrite in mp_print failed. error = %s\n", mp_error_to_string(err));
exit(EXIT_FAILURE);
}
fputc('\n',stream);
}

static mp_digit prime_digit(int bits)
{
int n;
mp_digit d = 0;
mp_int a;
mp_err err;

n = abs(rand()) % MP_MASK;
if ((err = mp_init_ul(&a, (unsigned long)n)) != MP_OKAY) goto LTM_ERR;
if ((err = mp_prime_next_prime(&a, -1, false)) != MP_OKAY) goto LTM_ERR;
while (a.used > 1) {
if ((err = mp_div_2(&a, &a)) != MP_OKAY) goto LTM_ERR;
if ((err = mp_prime_next_prime(&a, -1, false)) != MP_OKAY) goto LTM_ERR;
if ((err = mp_init(&a)) != MP_OKAY) {
return 0;
}

if ((err = mp_prime_rand(&a, 1, bits, false)) != MP_OKAY) goto LTM_ERR;
d = a.dp[0];

LTM_ERR:
Expand All @@ -35,12 +44,14 @@ static mp_err pprime(int k, int li, mp_int *p, mp_int *q)
{
mp_int a, b, c, n, x, y, z, v;
mp_err err = MP_OKAY;
int ii;
static const mp_digit bases[] = { 2, 3, 5, 7, 11, 13, 17, 19 };
int ii, bits;

/* single digit ? */
if (k <= (int) MP_DIGIT_BIT) {
mp_set(p, prime_digit());
if (k < (int) MP_DIGIT_BIT) {
mp_set(p, prime_digit(k));
if (mp_iszero(p)) {
return MP_VAL;
}
return MP_OKAY;
}

Expand All @@ -54,14 +65,27 @@ static mp_err pprime(int k, int li, mp_int *p, mp_int *q)
}

/* set the prime */
mp_set(&a, prime_digit());
mp_set(&a, prime_digit(MP_DIGIT_BIT));
if (mp_iszero(&a)) {
err = MP_VAL;
goto LTM_ERR;
}

/* now loop making the single digit */
while (mp_count_bits(&a) < k) {
fprintf(stderr, "prime has %4d bits left\r", k - mp_count_bits(&a));
bits = k - mp_count_bits(&a);
fprintf(stderr, "prime has %4d bits left\r", bits);
fflush(stderr);
top:
mp_set(&b, prime_digit());
if (bits < MP_DIGIT_BIT) {
mp_set(&b, prime_digit(bits));
} else {
mp_set(&b, prime_digit(MP_DIGIT_BIT));
}
if (mp_iszero(&b)) {
err = MP_VAL;
goto LTM_ERR;
}

/* now compute z = a * b * 2 */
/* z = a * b */
Expand All @@ -78,10 +102,10 @@ static mp_err pprime(int k, int li, mp_int *p, mp_int *q)
if (mp_cmp_d(&y, 1uL) != MP_EQ) {
goto top;
}

mp_set(&x, 2u);
/* now try base x=bases[ii] */
for (ii = 0; ii < li; ii++) {
mp_set(&x, bases[ii]);
if ((err = mp_prime_next_prime(&x, -1, false)) != MP_OKAY) goto LTM_ERR;

/* compute x^a mod n; y = x^a mod n */
if ((err = mp_exptmod(&x, &a, &n, &y)) != MP_OKAY) goto LTM_ERR;
Expand Down Expand Up @@ -132,17 +156,11 @@ static mp_err pprime(int k, int li, mp_int *p, mp_int *q)
goto top;
}

{
char buf[4096];

if ((err = mp_to_decimal(&n, buf, sizeof(buf))) != MP_OKAY) goto LTM_ERR;
printf("Certificate of primality for:\n%s\n\n", buf);
if ((err = mp_to_decimal(&a, buf, sizeof(buf))) != MP_OKAY) goto LTM_ERR;
printf("A == \n%s\n\n", buf);
if ((err = mp_to_decimal(&b, buf, sizeof(buf))) != MP_OKAY) goto LTM_ERR;
printf("B == \n%s\n\nG == %lu\n", buf, bases[ii]);
printf("----------------------------------------------------------------\n");
}
mp_print("Certificate of primality for:\n ", &n, 10, stdout);
mp_print("A == ", &a, 10, stdout);
mp_print("B == ", &b, 10, stdout);
mp_print("G == ", &x, 10, stdout);
printf("----------------------------------------------------------------\n");

/* a = n */
if ((err = mp_copy(&n, &a)) != MP_OKAY) goto LTM_ERR;
Expand Down Expand Up @@ -170,29 +188,28 @@ int main(void)
int k, li;
clock_t t1;

srand(time(NULL));

printf("Enter # of bits: \n");
fgets(buf, sizeof(buf), stdin);
sscanf(buf, "%d", &k);

printf("Enter number of bases to try (1 to 8):\n");
printf("Enter number of bases to try\n");
fgets(buf, sizeof(buf), stdin);
sscanf(buf, "%d", &li);


if ((err = mp_init_multi(&p, &q, NULL)) != MP_OKAY) goto LTM_ERR;
if ((err = mp_init_multi(&p, &q, NULL)) != MP_OKAY) goto LTM_ERR;

t1 = clock();
pprime(k, li, &p, &q);
if ((err = pprime(k, li, &p, &q)) != MP_OKAY) {
fprintf(stderr, "Something went wrong in function pprime: %s\n", mp_error_to_string(err));
goto LTM_ERR;
}
t1 = clock() - t1;

printf("\n\nTook %lu ticks, %d bits\n", t1, mp_count_bits(&p));

if ((err = mp_to_decimal(&p, buf, sizeof(buf))) != MP_OKAY) goto LTM_ERR;
printf("P == %s\n", buf);
if ((err = mp_to_decimal(&q, buf, sizeof(buf))) != MP_OKAY) goto LTM_ERR;
printf("Q == %s\n", buf);
mp_print("P == ", &p, 10, stdout);
mp_print("Q == ", &q, 10, stdout);

mp_clear_multi(&p, &q, NULL);
exit(EXIT_SUCCESS);
Expand Down

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