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Merge probable_prime_dh_safe with bn_probable_prime_dh

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This should avoid half of the trial divisions in probable_prime_dh_safe
and avoid bn_probable_prime_dh generating primes with special properties.

Reviewed-by: Paul Dale <paul.dale@oracle.com>
(Merged from https://github.com/openssl/openssl/pull/9309)
This commit is contained in:
Bernd Edlinger 2019-07-05 11:55:56 +02:00
parent 3ce0566dab
commit 28b4880b8b
2 changed files with 39 additions and 90 deletions
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5
crypto/bn/bn_lcl.h
View file

@ -1,5 +1,5 @@
/*
* Copyright 1995-2018 The OpenSSL Project Authors. All Rights Reserved.
* Copyright 1995-2019 The OpenSSL Project Authors. All Rights Reserved.
*
* Licensed under the Apache License 2.0 (the "License"). You may not use
* this file except in compliance with the License. You can obtain a copy
@ -654,9 +654,6 @@ BIGNUM *int_bn_mod_inverse(BIGNUM *in,
const BIGNUM *a, const BIGNUM *n, BN_CTX *ctx,
int *noinv);
int bn_probable_prime_dh(BIGNUM *rnd, int bits,
const BIGNUM *add, const BIGNUM *rem, BN_CTX *ctx);
static ossl_inline BIGNUM *bn_expand(BIGNUM *a, int bits)
{
if (bits > (INT_MAX - BN_BITS2 + 1))

124
crypto/bn/bn_prime.c
View file

@ -21,9 +21,9 @@
static int probable_prime(BIGNUM *rnd, int bits, int safe, prime_t *mods,
BN_CTX *ctx);
static int probable_prime_dh_safe(BIGNUM *rnd, int bits,
const BIGNUM *add, const BIGNUM *rem,
BN_CTX *ctx);
static int probable_prime_dh(BIGNUM *rnd, int bits, int safe, prime_t *mods,
const BIGNUM *add, const BIGNUM *rem,
BN_CTX *ctx);
#define square(x) ((BN_ULONG)(x) * (BN_ULONG)(x))
@ -125,13 +125,8 @@ int BN_generate_prime_ex2(BIGNUM *ret, int bits, int safe,
if (!probable_prime(ret, bits, safe, mods, ctx))
goto err;
} else {
if (safe) {
if (!probable_prime_dh_safe(ret, bits, add, rem, ctx))
goto err;
} else {
if (!bn_probable_prime_dh(ret, bits, add, rem, ctx))
goto err;
}
if (!probable_prime_dh(ret, bits, safe, mods, add, rem, ctx))
goto err;
}
if (!BN_GENCB_call(cb, 0, c1++))
@ -452,16 +447,23 @@ static int probable_prime(BIGNUM *rnd, int bits, int safe, prime_t *mods,
return 1;
}
int bn_probable_prime_dh(BIGNUM *rnd, int bits,
const BIGNUM *add, const BIGNUM *rem, BN_CTX *ctx)
static int probable_prime_dh(BIGNUM *rnd, int bits, int safe, prime_t *mods,
const BIGNUM *add, const BIGNUM *rem,
BN_CTX *ctx)
{
int i, ret = 0;
BIGNUM *t1;
BN_ULONG delta;
BN_ULONG maxdelta = BN_MASK2 - primes[NUMPRIMES - 1];
BN_CTX_start(ctx);
if ((t1 = BN_CTX_get(ctx)) == NULL)
goto err;
if (maxdelta > BN_MASK2 - BN_get_word(add))
maxdelta = BN_MASK2 - BN_get_word(add);
again:
if (!BN_rand_ex(rnd, bits, BN_RAND_TOP_ONE, BN_RAND_BOTTOM_ODD, ctx))
goto err;
@ -472,27 +474,44 @@ int bn_probable_prime_dh(BIGNUM *rnd, int bits,
if (!BN_sub(rnd, rnd, t1))
goto err;
if (rem == NULL) {
if (!BN_add_word(rnd, 1))
if (!BN_add_word(rnd, safe ? 3u : 1u))
goto err;
} else {
if (!BN_add(rnd, rnd, rem))
goto err;
}
/* we now have a random number 'rand' to test. */
if (BN_num_bits(rnd) < bits
|| BN_get_word(rnd) < (safe ? 5u : 3u)) {
if (!BN_add(rnd, rnd, add))
goto err;
}
loop:
/* we now have a random number 'rnd' to test. */
for (i = 1; i < NUMPRIMES; i++) {
/* check that rnd is a prime */
BN_ULONG mod = BN_mod_word(rnd, (BN_ULONG)primes[i]);
if (mod == (BN_ULONG)-1)
goto err;
if (mod <= 1) {
if (!BN_add(rnd, rnd, add))
goto err;
mods[i] = (prime_t) mod;
}
delta = 0;
loop:
for (i = 1; i < NUMPRIMES; i++) {
/* check that rnd is a prime */
if (bits <= 31 && delta <= 0x7fffffff
&& square(primes[i]) > BN_get_word(rnd) + delta)
break;
/* rnd mod p == 1 implies q = (rnd-1)/2 is divisible by p */
if (safe ? (mods[i] + delta) % primes[i] <= 1
: (mods[i] + delta) % primes[i] == 0) {
delta += BN_get_word(add);
if (delta > maxdelta)
goto again;
goto loop;
}
}
if (!BN_add_word(rnd, delta))
goto err;
ret = 1;
err:
@ -500,70 +519,3 @@ int bn_probable_prime_dh(BIGNUM *rnd, int bits,
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)
{
int i, ret = 0;
BIGNUM *t1, *qadd, *q;
bits--;
BN_CTX_start(ctx);
t1 = BN_CTX_get(ctx);
q = BN_CTX_get(ctx);
qadd = BN_CTX_get(ctx);
if (qadd == NULL)
goto err;
if (!BN_rshift1(qadd, padd))
goto err;
if (!BN_rand_ex(q, bits, BN_RAND_TOP_ONE, BN_RAND_BOTTOM_ODD, ctx))
goto err;
/* we need ((rnd-rem) % add) == 0 */
if (!BN_mod(t1, q, qadd, ctx))
goto err;
if (!BN_sub(q, q, t1))
goto err;
if (rem == NULL) {
if (!BN_add_word(q, 1))
goto err;
} else {
if (!BN_rshift1(t1, rem))
goto err;
if (!BN_add(q, q, t1))
goto err;
}
/* we now have a random number 'rand' to test. */
if (!BN_lshift1(p, q))
goto err;
if (!BN_add_word(p, 1))
goto err;
loop:
for (i = 1; i < NUMPRIMES; i++) {
/* check that p and q are prime */
/*
* check that for p and q gcd(p-1,primes) == 1 (except for 2)
*/
BN_ULONG pmod = BN_mod_word(p, (BN_ULONG)primes[i]);
BN_ULONG qmod = BN_mod_word(q, (BN_ULONG)primes[i]);
if (pmod == (BN_ULONG)-1 || qmod == (BN_ULONG)-1)
goto err;
if (pmod == 0 || qmod == 0) {
if (!BN_add(p, p, padd))
goto err;
if (!BN_add(q, q, qadd))
goto err;
goto loop;
}
}
ret = 1;
err:
BN_CTX_end(ctx);
bn_check_top(p);
return ret;
}