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czurniedensjaeckel
czurnieden
authored and
sjaeckel
committed
Use cryptographic RNG
1 parent 782cda7 commit 942b8b4

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1 file changed

+54
-37
lines changed

1 file changed

+54
-37
lines changed

‎etc/pprime.c‎

Lines changed: 54 additions & 37 deletions
Original file line numberDiff line numberDiff line change
@@ -8,20 +8,29 @@
88
#include <time.h>
99
#include "../tommath_private.h"
1010

11-
static mp_digit prime_digit(void)
11+
static void mp_print(const char *s, const mp_int *a, int radix, FILE *stream)
12+
{
13+
mp_err err;
14+
fputs(s, stream);
15+
err = mp_fwrite(a, radix, stream);
16+
if (err != MP_OKAY) {
17+
fprintf(stderr,"mp_fwrite in mp_print failed. error = %s\n", mp_error_to_string(err));
18+
exit(EXIT_FAILURE);
19+
}
20+
fputc('\n',stream);
21+
}
22+
23+
static mp_digit prime_digit(int bits)
1224
{
13-
int n;
1425
mp_digit d = 0;
1526
mp_int a;
1627
mp_err err;
1728

18-
n = abs(rand()) % MP_MASK;
19-
if ((err = mp_init_ul(&a, (unsigned long)n)) != MP_OKAY) goto LTM_ERR;
20-
if ((err = mp_prime_next_prime(&a, -1, false)) != MP_OKAY) goto LTM_ERR;
21-
while (a.used > 1) {
22-
if ((err = mp_div_2(&a, &a)) != MP_OKAY) goto LTM_ERR;
23-
if ((err = mp_prime_next_prime(&a, -1, false)) != MP_OKAY) goto LTM_ERR;
29+
if ((err = mp_init(&a)) != MP_OKAY) {
30+
return 0;
2431
}
32+
33+
if ((err = mp_prime_rand(&a, 1, bits, false)) != MP_OKAY) goto LTM_ERR;
2534
d = a.dp[0];
2635

2736
LTM_ERR:
@@ -35,12 +44,14 @@ static mp_err pprime(int k, int li, mp_int *p, mp_int *q)
3544
{
3645
mp_int a, b, c, n, x, y, z, v;
3746
mp_err err = MP_OKAY;
38-
int ii;
39-
static const mp_digit bases[] = { 2, 3, 5, 7, 11, 13, 17, 19 };
47+
int ii, bits;
4048

4149
/* single digit ? */
42-
if (k <= (int) MP_DIGIT_BIT) {
43-
mp_set(p, prime_digit());
50+
if (k < (int) MP_DIGIT_BIT) {
51+
mp_set(p, prime_digit(k));
52+
if (mp_iszero(p)) {
53+
return MP_VAL;
54+
}
4455
return MP_OKAY;
4556
}
4657

@@ -54,14 +65,27 @@ static mp_err pprime(int k, int li, mp_int *p, mp_int *q)
5465
}
5566

5667
/* set the prime */
57-
mp_set(&a, prime_digit());
68+
mp_set(&a, prime_digit(MP_DIGIT_BIT));
69+
if (mp_iszero(&a)) {
70+
err = MP_VAL;
71+
goto LTM_ERR;
72+
}
5873

5974
/* now loop making the single digit */
6075
while (mp_count_bits(&a) < k) {
61-
fprintf(stderr, "prime has %4d bits left\r", k - mp_count_bits(&a));
76+
bits = k - mp_count_bits(&a);
77+
fprintf(stderr, "prime has %4d bits left\r", bits);
6278
fflush(stderr);
6379
top:
64-
mp_set(&b, prime_digit());
80+
if (bits < MP_DIGIT_BIT) {
81+
mp_set(&b, prime_digit(bits));
82+
} else {
83+
mp_set(&b, prime_digit(MP_DIGIT_BIT));
84+
}
85+
if (mp_iszero(&b)) {
86+
err = MP_VAL;
87+
goto LTM_ERR;
88+
}
6589

6690
/* now compute z = a * b * 2 */
6791
/* z = a * b */
@@ -78,10 +102,10 @@ static mp_err pprime(int k, int li, mp_int *p, mp_int *q)
78102
if (mp_cmp_d(&y, 1uL) != MP_EQ) {
79103
goto top;
80104
}
81-
105+
mp_set(&x, 2u);
82106
/* now try base x=bases[ii] */
83107
for (ii = 0; ii < li; ii++) {
84-
mp_set(&x, bases[ii]);
108+
if ((err = mp_prime_next_prime(&x, -1, false)) != MP_OKAY) goto LTM_ERR;
85109

86110
/* compute x^a mod n; y = x^a mod n */
87111
if ((err = mp_exptmod(&x, &a, &n, &y)) != MP_OKAY) goto LTM_ERR;
@@ -132,17 +156,11 @@ static mp_err pprime(int k, int li, mp_int *p, mp_int *q)
132156
goto top;
133157
}
134158

135-
{
136-
char buf[4096];
137-
138-
if ((err = mp_to_decimal(&n, buf, sizeof(buf))) != MP_OKAY) goto LTM_ERR;
139-
printf("Certificate of primality for:\n%s\n\n", buf);
140-
if ((err = mp_to_decimal(&a, buf, sizeof(buf))) != MP_OKAY) goto LTM_ERR;
141-
printf("A == \n%s\n\n", buf);
142-
if ((err = mp_to_decimal(&b, buf, sizeof(buf))) != MP_OKAY) goto LTM_ERR;
143-
printf("B == \n%s\n\nG == %lu\n", buf, bases[ii]);
144-
printf("----------------------------------------------------------------\n");
145-
}
159+
mp_print("Certificate of primality for:\n ", &n, 10, stdout);
160+
mp_print("A == ", &a, 10, stdout);
161+
mp_print("B == ", &b, 10, stdout);
162+
mp_print("G == ", &x, 10, stdout);
163+
printf("----------------------------------------------------------------\n");
146164

147165
/* a = n */
148166
if ((err = mp_copy(&n, &a)) != MP_OKAY) goto LTM_ERR;
@@ -170,29 +188,28 @@ int main(void)
170188
int k, li;
171189
clock_t t1;
172190

173-
srand(time(NULL));
174-
175191
printf("Enter # of bits: \n");
176192
fgets(buf, sizeof(buf), stdin);
177193
sscanf(buf, "%d", &k);
178194

179-
printf("Enter number of bases to try (1 to 8):\n");
195+
printf("Enter number of bases to try\n");
180196
fgets(buf, sizeof(buf), stdin);
181197
sscanf(buf, "%d", &li);
182198

183199

184-
if ((err = mp_init_multi(&p, &q, NULL)) != MP_OKAY) goto LTM_ERR;
200+
if ((err = mp_init_multi(&p, &q, NULL)) != MP_OKAY) goto LTM_ERR;
185201

186202
t1 = clock();
187-
pprime(k, li, &p, &q);
203+
if ((err = pprime(k, li, &p, &q)) != MP_OKAY) {
204+
fprintf(stderr, "Something went wrong in function pprime: %s\n", mp_error_to_string(err));
205+
goto LTM_ERR;
206+
}
188207
t1 = clock() - t1;
189208

190209
printf("\n\nTook %lu ticks, %d bits\n", t1, mp_count_bits(&p));
191210

192-
if ((err = mp_to_decimal(&p, buf, sizeof(buf))) != MP_OKAY) goto LTM_ERR;
193-
printf("P == %s\n", buf);
194-
if ((err = mp_to_decimal(&q, buf, sizeof(buf))) != MP_OKAY) goto LTM_ERR;
195-
printf("Q == %s\n", buf);
211+
mp_print("P == ", &p, 10, stdout);
212+
mp_print("Q == ", &q, 10, stdout);
196213

197214
mp_clear_multi(&p, &q, NULL);
198215
exit(EXIT_SUCCESS);

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