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tuning DSA key generation

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Karel Miko 2014-01-12 21:50:56 +01:00 committed by Steffen Jaeckel
parent e271b9fdbe
commit 3908c70d68
1 changed files with 5 additions and 8 deletions
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13
src/pk/dsa/dsa_make_key.c
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@ -29,7 +29,7 @@
int dsa_make_key(prng_state *prng, int wprng, int group_size, int modulus_size, dsa_key *key) int dsa_make_key(prng_state *prng, int wprng, int group_size, int modulus_size, dsa_key *key)
{ {
void *tmp, *tmp2; void *tmp, *tmp2;
int err, res, q_size; int err, res, qbits;
unsigned char *buf; unsigned char *buf;
LTC_ARGCHK(key != NULL); LTC_ARGCHK(key != NULL);
@ -104,14 +104,11 @@ int dsa_make_key(prng_state *prng, int wprng, int group_size, int modulus_size,
/* so now we have our DH structure, generator g, order q, modulus p /* so now we have our DH structure, generator g, order q, modulus p
Now we need a random exponent [mod q] and it's power g^x mod p Now we need a random exponent [mod q] and it's power g^x mod p
*/ */
q_size = mp_unsigned_bin_size(key->q); qbits = mp_count_bits(key->q);
do { do {
if (prng_descriptor[wprng].read(buf, q_size, prng) != (unsigned long)q_size) { if ((err = rand_bn_bits(key->x, qbits, prng, wprng)) != CRYPT_OK) { goto error; }
err = CRYPT_ERROR_READPRNG; /* private key x should be from range: 1 <= x <= q-1 */
goto error; } while (mp_cmp_d(key->x, 0) != LTC_MP_GT || mp_cmp(key->x, key->q) != LTC_MP_LT);
}
if ((err = mp_read_unsigned_bin(key->x, buf, q_size)) != CRYPT_OK) { goto error; }
} while (mp_cmp_d(key->x, 1) != LTC_MP_GT || mp_cmp(key->x, key->q) != LTC_MP_LT);
if ((err = mp_exptmod(key->g, key->x, key->p, key->y)) != CRYPT_OK) { goto error; } if ((err = mp_exptmod(key->g, key->x, key->p, key->y)) != CRYPT_OK) { goto error; }
key->type = PK_PRIVATE; key->type = PK_PRIVATE;