/* gcd */
static int gcd(void *a, void *b, void *c) {
LTC_ARGCHK(a != NULL);
LTC_ARGCHK(b != NULL);
LTC_ARGCHK(c != NULL);
fp_gcd(a, b, c);
return CRYPT_OK;
}
/* c = [a, b] */
void fp_lcm(fp_int *a, fp_int *b, fp_int *c)
{
fp_int t1, t2;
fp_init(&t1);
fp_init(&t2);
fp_gcd(a, b, &t1);
if (fp_cmp_mag(a, b) == FP_GT) {
fp_div(a, &t1, &t2, NULL);
fp_mul(b, &t2, c);
} else {
fp_div(b, &t1, &t2, NULL);
fp_mul(a, &t2, c);
}
}
static int
tfm_rsa_generate_key(RSA *rsa, int bits, BIGNUM *e, BN_GENCB *cb)
{
fp_int el, p, q, n, d, dmp1, dmq1, iqmp, t1, t2, t3;
int counter, ret, bitsp;
if (bits < 789)
return -1;
bitsp = (bits + 1) / 2;
ret = -1;
fp_init_multi(&el, &p, &q, &n, &n, &d, &dmp1, &dmq1, &iqmp, &t1, &t2, &t3, NULL);
BN2mpz(&el, e);
/* generate p and q so that p != q and bits(pq) ~ bits */
counter = 0;
do {
BN_GENCB_call(cb, 2, counter++);
CHECK(random_num(&p, bitsp), 0);
CHECK(fp_find_prime(&p), FP_YES);
fp_sub_d(&p, 1, &t1);
fp_gcd(&t1, &el, &t2);
} while(fp_cmp_d(&t2, 1) != 0);
BN_GENCB_call(cb, 3, 0);
counter = 0;
do {
BN_GENCB_call(cb, 2, counter++);
CHECK(random_num(&q, bits - bitsp), 0);
CHECK(fp_find_prime(&q), FP_YES);
if (fp_cmp(&p, &q) == 0) /* don't let p and q be the same */
continue;
fp_sub_d(&q, 1, &t1);
fp_gcd(&t1, &el, &t2);
} while(fp_cmp_d(&t2, 1) != 0);
/* make p > q */
if (fp_cmp(&p, &q) < 0) {
fp_int c;
fp_copy(&p, &c);
fp_copy(&q, &p);
fp_copy(&c, &q);
}
BN_GENCB_call(cb, 3, 1);
/* calculate n, n = p * q */
fp_mul(&p, &q, &n);
/* calculate d, d = 1/e mod (p - 1)(q - 1) */
fp_sub_d(&p, 1, &t1);
fp_sub_d(&q, 1, &t2);
fp_mul(&t1, &t2, &t3);
fp_invmod(&el, &t3, &d);
/* calculate dmp1 dmp1 = d mod (p-1) */
fp_mod(&d, &t1, &dmp1);
/* calculate dmq1 dmq1 = d mod (q-1) */
fp_mod(&d, &t2, &dmq1);
/* calculate iqmp iqmp = 1/q mod p */
fp_invmod(&q, &p, &iqmp);
/* fill in RSA key */
rsa->e = mpz2BN(&el);
rsa->p = mpz2BN(&p);
rsa->q = mpz2BN(&q);
rsa->n = mpz2BN(&n);
rsa->d = mpz2BN(&d);
rsa->dmp1 = mpz2BN(&dmp1);
rsa->dmq1 = mpz2BN(&dmq1);
rsa->iqmp = mpz2BN(&iqmp);
ret = 1;
out:
fp_zero_multi(&el, &p, &q, &n, &d, &dmp1,
&dmq1, &iqmp, &t1, &t2, &t3, NULL);
return ret;
}
