generic-library/openssl
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Add a method to generate a prime that is guaranteed not to be divisible by 3 or 5.

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Possibly some reduction in bias, but no speed gains.
This commit is contained in:
Felix Laurie von Massenbach 2014-05-27 00:37:03 +01:00 committed by Ben Laurie
parent b359642ffd
commit b0513819e0
3 changed files with 80 additions and 29 deletions
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23
apps/speed.c
View File

@ -2041,6 +2041,29 @@ int MAIN(int argc, char **argv)
BN_free(rnd);
}
if (prime_doit[D_PRIME_COPRIME])
{
BIGNUM *rnd = BN_new();
BIGNUM *add = BN_new();
BN_CTX *ctx = BN_CTX_new();
BN_set_word(add, 2);
prime_print_message(prime_names[D_PRIME_COPRIME],
prime_c[D_PRIME_COPRIME]);
Time_F(START);
for (count=0, run=1; COND(prime_c[D_PRIME_COPRIME]); count++)
bn_probable_prime_dh_coprime(rnd, 1024, add, NULL, ctx);
d=Time_F(STOP);
prime_print_result(D_PRIME_COPRIME, count, d);
BN_CTX_free(ctx);
BN_free(add);
BN_free(rnd);
}
RAND_pseudo_bytes(buf,36);
#ifndef OPENSSL_NO_RSA

2
crypto/bn/bn_lcl.h
View File

@ -536,6 +536,8 @@ BIGNUM *int_bn_mod_inverse(BIGNUM *in,
int bn_probable_prime_dh(BIGNUM *rnd, int bits,
const BIGNUM *add, const BIGNUM *rem, BN_CTX *ctx);
int bn_probable_prime_dh_coprime(BIGNUM *rnd, int bits,
const BIGNUM *add, const BIGNUM *rem, BN_CTX *ctx);
#ifdef __cplusplus
}

84
crypto/bn/bn_prime.c
View File

@ -129,9 +129,13 @@
static int witness(BIGNUM *w, const BIGNUM *a, const BIGNUM *a1,
const BIGNUM *a1_odd, int k, BN_CTX *ctx, BN_MONT_CTX *mont);
static int probable_prime(BIGNUM *rnd, int bits);
static int probable_prime_dh(BIGNUM *rnd, const BIGNUM *add,
const BIGNUM *rem, BN_CTX *ctx, int first_prime_index);
static int probable_prime_dh_safe(BIGNUM *rnd, int bits,
const BIGNUM *add, const BIGNUM *rem, BN_CTX *ctx);
static int prime_offsets[8] = { 7, 11, 13, 17, 19, 23, 29, 31 };
int BN_GENCB_call(BN_GENCB *cb, int a, int b)
{
/* No callback means continue */
@ -363,40 +367,25 @@ err:
int bn_probable_prime_dh(BIGNUM *rnd, int bits,
const BIGNUM *add, const BIGNUM *rem, BN_CTX *ctx)
{
int i,ret=0;
BIGNUM *t1;
if (!BN_rand(rnd, bits, 0, 1)) return(0);
BN_CTX_start(ctx);
if ((t1 = BN_CTX_get(ctx)) == NULL) goto err;
return(probable_prime_dh(rnd, add, rem, ctx, 1));
}
if (!BN_rand(rnd,bits,0,1)) goto err;
int bn_probable_prime_dh_coprime(BIGNUM *rnd, int bits,
const BIGNUM *add, const BIGNUM *rem, BN_CTX *ctx)
{
BIGNUM *offset_index = BN_new();
/* we need ((rnd-rem) % add) == 0 */
if (!BN_rand(rnd, bits, 0, 1)) return(0);
if (!BN_rand(offset_index, 3, -1, -1)) return(0);
if (!BN_mod(t1,rnd,add,ctx)) goto err;
if (!BN_sub(rnd,rnd,t1)) goto err;
if (rem == NULL)
{ if (!BN_add_word(rnd,1)) goto err; }
else
{ if (!BN_add(rnd,rnd,rem)) goto err; }
BN_mul_word(rnd, 30);
BN_add_word(rnd, prime_offsets[BN_get_word(offset_index)]);
BN_free(offset_index);
/* we now have a random number 'rand' to test. */
loop:
for (i=1; i<NUMPRIMES; i++)
{
/* check that rnd is a prime */
if (BN_mod_word(rnd,(BN_ULONG)primes[i]) <= 1)
{
if (!BN_add(rnd,rnd,add)) goto err;
goto loop;
}
}
ret=1;
err:
BN_CTX_end(ctx);
bn_check_top(rnd);
return(ret);
return(probable_prime_dh(rnd, add, rem, ctx, 3));
}
static int witness(BIGNUM *w, const BIGNUM *a, const BIGNUM *a1,
@ -491,6 +480,43 @@ loop:
return(1);
}
static int probable_prime_dh(BIGNUM *rnd, const BIGNUM *add,
const BIGNUM *rem, BN_CTX *ctx, int first_prime_index)
{
int i,ret=0;
BIGNUM *t1;
BN_CTX_start(ctx);
if ((t1 = BN_CTX_get(ctx)) == NULL) goto err;
/* we need ((rnd-rem) % add) == 0 */
if (!BN_mod(t1,rnd,add,ctx)) goto err;
if (!BN_sub(rnd,rnd,t1)) goto err;
if (rem == NULL)
{ if (!BN_add_word(rnd,1)) goto err; }
else
{ if (!BN_add(rnd,rnd,rem)) goto err; }
/* we now have a random number 'rand' to test. */
loop:
for (i=first_prime_index; i<NUMPRIMES; i++)
{
/* check that rnd is a prime */
if (BN_mod_word(rnd,(BN_ULONG)primes[i]) <= 1)
{
if (!BN_add(rnd,rnd,add)) goto err;
goto loop;
}
}
ret=1;
err:
BN_CTX_end(ctx);
bn_check_top(rnd);
return(ret);
}
static int probable_prime_dh_safe(BIGNUM *p, int bits, const BIGNUM *padd,
const BIGNUM *rem, BN_CTX *ctx)
{