openssl/crypto/ffc/ffc_key_generate.c
Shane Lontis 55f02cb684 Change DH_get_nid() to set the value of q if it is not already set
Fixes #11108.

It only sets q if a valid named group is found.
The function signature was recently changed to pass a non const DH pointer
in order to allow the nid to be cached internally. As an extension of this
the value of q can now also be set as q is always known for named groups.
The length field is also set if q is set.

Reviewed-by: Tomas Mraz <tmraz@fedoraproject.org>
(Merged from https://github.com/openssl/openssl/pull/11114)
2020-03-07 07:47:58 +10:00

75 lines
2.2 KiB
C

/*
* Copyright 2019-2020 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
* in the file LICENSE in the source distribution or at
* https://www.openssl.org/source/license.html
*/
#include "internal/ffc.h"
/*
* SP800-56Ar3 5.6.1.1.4 Key pair generation by testing candidates.
* Generates a private key in the interval [1, min(2 ^ N - 1, q - 1)].
*
* ctx must be set up with a libctx (for fips mode).
* params contains the FFC domain parameters p, q and g (for DH or DSA).
* N is the maximum bit length of the generated private key,
* s is the security strength.
* priv_key is the returned private key,
*/
int ffc_generate_private_key(BN_CTX *ctx, const FFC_PARAMS *params,
int N, int s, BIGNUM *priv)
{
#ifdef FIPS_MODE
return ffc_generate_private_key_fips(ctx, params, N, s, priv);
#else
do {
if (!BN_priv_rand_range_ex(priv, params->q, ctx))
return 0;
} while (BN_is_zero(priv) || BN_is_one(priv));
return 1;
#endif /* FIPS_MODE */
}
int ffc_generate_private_key_fips(BN_CTX *ctx, const FFC_PARAMS *params,
int N, int s, BIGNUM *priv)
{
int ret = 0, qbits = BN_num_bits(params->q);
BIGNUM *m, *two_powN = NULL;
/* Step (2) : check range of N */
if (N < 2 * s || N > qbits)
return 0;
/* Deal with the edge case where the value of N is not set */
if (N == 0) {
N = qbits;
s = N / 2;
}
two_powN = BN_new();
/* 2^N */
if (two_powN == NULL || !BN_lshift(two_powN, BN_value_one(), N))
goto err;
/* Step (5) : M = min(2 ^ N, q) */
m = (BN_cmp(two_powN, params->q) > 0) ? params->q : two_powN;
do {
/* Steps (3, 4 & 7) : c + 1 = 1 + random[0..2^N - 1] */
if (!BN_priv_rand_range_ex(priv, two_powN, ctx)
|| !BN_add_word(priv, 1))
goto err;
/* Step (6) : loop if c > M - 2 (i.e. c + 1 >= M) */
if (BN_cmp(priv, m) < 0)
break;
} while (1);
ret = 1;
err:
BN_free(two_powN);
return ret;
}