Merge pull request #230 from libtom/math/miller-rabin

Fix number of Miller-Rabin rounds
This commit is contained in:
Steffen Jaeckel 2017-06-22 12:44:33 +02:00 committed by GitHub
commit 5e71ac27e2
6 changed files with 29 additions and 9 deletions

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@ -24,6 +24,12 @@
typedef void rsa_key;
#endif
#ifndef LTC_MILLER_RABIN_REPS
/* Number of rounds of the Miller-Rabin test
* "Reasonable values of reps are between 15 and 50." c.f. gmp doc of mpz_probab_prime_p() */
#define LTC_MILLER_RABIN_REPS 35
#endif
/** math descriptor */
typedef struct {
/** Name of the math provider */
@ -345,7 +351,7 @@ typedef struct {
/** Primality testing
@param a The integer to test
@param b The number of tests that shall be executed
@param b The number of Miller-Rabin tests that shall be executed
@param c The destination of the result (FP_YES if prime)
@return CRYPT_OK on success
*/
@ -472,13 +478,13 @@ typedef struct {
int (*submod)(void *a, void *b, void *c, void *d);
/* ---- misc stuff ---- */
/** Make a pseudo-random mpi
@param a The mpi to make random
@param size The desired length
@return CRYPT_OK on success
*/
int (*rand)(void *a, int size);
} ltc_math_descriptor;
extern ltc_math_descriptor ltc_mp;

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@ -446,7 +446,7 @@ static int isprime(void *a, int b, int *c)
LTC_ARGCHK(a != NULL);
LTC_ARGCHK(c != NULL);
if (b == 0) {
b = 8;
b = LTC_MILLER_RABIN_REPS;
} /* if */
*c = mpz_probab_prime_p(a, b) > 0 ? LTC_MP_YES : LTC_MP_NO;
return CRYPT_OK;

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@ -404,7 +404,7 @@ static int isprime(void *a, int b, int *c)
LTC_ARGCHK(a != NULL);
LTC_ARGCHK(c != NULL);
if (b == 0) {
b = 8;
b = LTC_MILLER_RABIN_REPS;
} /* if */
err = mpi_to_ltc_error(mp_prime_is_prime(a, b, c));
*c = (*c == MP_YES) ? LTC_MP_YES : LTC_MP_NO;

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@ -66,7 +66,7 @@ int rand_prime(void *N, long len, prng_state *prng, int wprng)
}
/* test */
if ((err = mp_prime_is_prime(N, 8, &res)) != CRYPT_OK) {
if ((err = mp_prime_is_prime(N, LTC_MILLER_RABIN_REPS, &res)) != CRYPT_OK) {
XFREE(buf);
return err;
}

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@ -415,8 +415,10 @@ static int isprime(void *a, int b, int *c)
{
LTC_ARGCHK(a != NULL);
LTC_ARGCHK(c != NULL);
(void)b;
*c = (fp_isprime(a) == FP_YES) ? LTC_MP_YES : LTC_MP_NO;
if (b == 0) {
b = LTC_MILLER_RABIN_REPS;
} /* if */
*c = (fp_isprime_ex(a, b) == FP_YES) ? LTC_MP_YES : LTC_MP_NO;
return CRYPT_OK;
}

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@ -75,11 +75,23 @@ static int dsa_make_params(prng_state *prng, int wprng, int group_size, int modu
L = modulus_size * 8;
N = group_size * 8;
/* XXX-TODO no Lucas test */
#ifdef LTC_MPI_HAS_LUCAS_TEST
/* M-R tests (when followed by one Lucas test) according FIPS-186-4 - Appendix C.3 - table C.1 */
mr_tests_p = (L <= 2048) ? 3 : 2;
if (N <= 160) { mr_tests_q = 19; }
else if (N <= 224) { mr_tests_q = 24; }
else { mr_tests_q = 27; }
#else
/* M-R tests (without Lucas test) according FIPS-186-4 - Appendix C.3 - table C.1 */
if (L <= 1024) { mr_tests_p = 40; }
else if (L <= 2048) { mr_tests_p = 56; }
else { mr_tests_p = 64; }
if (N <= 160) { mr_tests_q = 40; }
else if (N <= 224) { mr_tests_q = 56; }
else { mr_tests_q = 64; }
#endif
if (N <= 256) {
hash = register_hash(&sha256_desc);
@ -122,7 +134,7 @@ static int dsa_make_params(prng_state *prng, int wprng, int group_size, int modu
if ((err = mp_mod(U, t2N1, U)) != CRYPT_OK) { goto cleanup; }
if ((err = mp_add(t2N1, U, q)) != CRYPT_OK) { goto cleanup; }
if (!mp_isodd(q)) mp_add_d(q, 1, q);
if ((err = mp_prime_is_prime(q, mr_tests_q, &res)) != CRYPT_OK) { goto cleanup; } /* XXX-TODO rounds are ignored; no Lucas test */
if ((err = mp_prime_is_prime(q, mr_tests_q, &res)) != CRYPT_OK) { goto cleanup; }
if (res == LTC_MP_YES) found_q = 1;
}
@ -149,7 +161,7 @@ static int dsa_make_params(prng_state *prng, int wprng, int group_size, int modu
if ((err = mp_sub(X, p, p)) != CRYPT_OK) { goto cleanup; }
if (mp_cmp(p, t2L1) != LTC_MP_LT) {
/* p >= 2^(L-1) */
if ((err = mp_prime_is_prime(p, mr_tests_p, &res)) != CRYPT_OK) { goto cleanup; } /* XXX-TODO rounds are ignored; no Lucas test */
if ((err = mp_prime_is_prime(p, mr_tests_p, &res)) != CRYPT_OK) { goto cleanup; }
if (res == LTC_MP_YES) {
found_p = 1;
}