openssl/crypto/dh/dh_check.c
Pauli ada66e78ef Deprecate the low level Diffie-Hellman functions.
Use of the low level DH functions has been informally discouraged for a
long time.  We now formally deprecate them.

Reviewed-by: Richard Levitte <levitte@openssl.org>
(Merged from https://github.com/openssl/openssl/pull/11024)
2020-02-20 19:04:57 +10:00

313 lines
8.5 KiB
C

/*
* 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
* in the file LICENSE in the source distribution or at
* https://www.openssl.org/source/license.html
*/
/*
* DH low level APIs are deprecated for public use, but still ok for
* internal use.
*/
#include "internal/deprecated.h"
#include <stdio.h>
#include "internal/cryptlib.h"
#include <openssl/bn.h>
#include "dh_local.h"
#include "crypto/dh.h"
/*-
* Check that p and g are suitable enough
*
* p is odd
* 1 < g < p - 1
*/
int DH_check_params_ex(const DH *dh)
{
int errflags = 0;
if (!DH_check_params(dh, &errflags))
return 0;
if ((errflags & DH_CHECK_P_NOT_PRIME) != 0)
DHerr(DH_F_DH_CHECK_PARAMS_EX, DH_R_CHECK_P_NOT_PRIME);
if ((errflags & DH_NOT_SUITABLE_GENERATOR) != 0)
DHerr(DH_F_DH_CHECK_PARAMS_EX, DH_R_NOT_SUITABLE_GENERATOR);
if ((errflags & DH_MODULUS_TOO_SMALL) != 0)
DHerr(DH_F_DH_CHECK_PARAMS_EX, DH_R_MODULUS_TOO_SMALL);
if ((errflags & DH_MODULUS_TOO_LARGE) != 0)
DHerr(DH_F_DH_CHECK_PARAMS_EX, DH_R_MODULUS_TOO_LARGE);
return errflags == 0;
}
#ifdef FIPS_MODE
int DH_check_params(const DH *dh, int *ret)
{
int nid;
*ret = 0;
/*
* SP800-56A R3 Section 5.5.2 Assurances of Domain Parameter Validity
* (1a) The domain parameters correspond to any approved safe prime group.
*/
nid = DH_get_nid((DH *)dh);
if (nid != NID_undef)
return 1;
/*
* OR
* (2b) FFC domain params conform to FIPS-186-4 explicit domain param
* validity tests.
*/
return ffc_params_FIPS186_4_validate(&dh->params, FFC_PARAM_TYPE_DH, NULL,
FFC_PARAMS_VALIDATE_ALL, ret, NULL);
}
#else
int DH_check_params(const DH *dh, int *ret)
{
int ok = 0;
BIGNUM *tmp = NULL;
BN_CTX *ctx = NULL;
*ret = 0;
ctx = BN_CTX_new();
if (ctx == NULL)
goto err;
BN_CTX_start(ctx);
tmp = BN_CTX_get(ctx);
if (tmp == NULL)
goto err;
if (!BN_is_odd(dh->params.p))
*ret |= DH_CHECK_P_NOT_PRIME;
if (BN_is_negative(dh->params.g)
|| BN_is_zero(dh->params.g)
|| BN_is_one(dh->params.g))
*ret |= DH_NOT_SUITABLE_GENERATOR;
if (BN_copy(tmp, dh->params.p) == NULL || !BN_sub_word(tmp, 1))
goto err;
if (BN_cmp(dh->params.g, tmp) >= 0)
*ret |= DH_NOT_SUITABLE_GENERATOR;
if (BN_num_bits(dh->params.p) < DH_MIN_MODULUS_BITS)
*ret |= DH_MODULUS_TOO_SMALL;
if (BN_num_bits(dh->params.p) > OPENSSL_DH_MAX_MODULUS_BITS)
*ret |= DH_MODULUS_TOO_LARGE;
ok = 1;
err:
BN_CTX_end(ctx);
BN_CTX_free(ctx);
return ok;
}
#endif /* FIPS_MODE */
/*-
* Check that p is a safe prime and
* g is a suitable generator.
*/
int DH_check_ex(const DH *dh)
{
int errflags = 0;
if (!DH_check(dh, &errflags))
return 0;
if ((errflags & DH_NOT_SUITABLE_GENERATOR) != 0)
DHerr(DH_F_DH_CHECK_EX, DH_R_NOT_SUITABLE_GENERATOR);
if ((errflags & DH_CHECK_Q_NOT_PRIME) != 0)
DHerr(DH_F_DH_CHECK_EX, DH_R_CHECK_Q_NOT_PRIME);
if ((errflags & DH_CHECK_INVALID_Q_VALUE) != 0)
DHerr(DH_F_DH_CHECK_EX, DH_R_CHECK_INVALID_Q_VALUE);
if ((errflags & DH_CHECK_INVALID_J_VALUE) != 0)
DHerr(DH_F_DH_CHECK_EX, DH_R_CHECK_INVALID_J_VALUE);
if ((errflags & DH_UNABLE_TO_CHECK_GENERATOR) != 0)
DHerr(DH_F_DH_CHECK_EX, DH_R_UNABLE_TO_CHECK_GENERATOR);
if ((errflags & DH_CHECK_P_NOT_PRIME) != 0)
DHerr(DH_F_DH_CHECK_EX, DH_R_CHECK_P_NOT_PRIME);
if ((errflags & DH_CHECK_P_NOT_SAFE_PRIME) != 0)
DHerr(DH_F_DH_CHECK_EX, DH_R_CHECK_P_NOT_SAFE_PRIME);
if ((errflags & DH_MODULUS_TOO_SMALL) != 0)
DHerr(DH_F_DH_CHECK_EX, DH_R_MODULUS_TOO_SMALL);
if ((errflags & DH_MODULUS_TOO_LARGE) != 0)
DHerr(DH_F_DH_CHECK_EX, DH_R_MODULUS_TOO_LARGE);
return errflags == 0;
}
/* Note: according to documentation - this only checks the params */
int DH_check(const DH *dh, int *ret)
{
#ifdef FIPS_MODE
return DH_check_params(dh, ret);
#else
int ok = 0, r;
BN_CTX *ctx = NULL;
BIGNUM *t1 = NULL, *t2 = NULL;
int nid = DH_get_nid((DH *)dh);
*ret = 0;
if (nid != NID_undef)
return 1;
if (!DH_check_params(dh, ret))
return 0;
ctx = BN_CTX_new();
if (ctx == NULL)
goto err;
BN_CTX_start(ctx);
t1 = BN_CTX_get(ctx);
t2 = BN_CTX_get(ctx);
if (t2 == NULL)
goto err;
if (dh->params.q != NULL) {
if (BN_cmp(dh->params.g, BN_value_one()) <= 0)
*ret |= DH_NOT_SUITABLE_GENERATOR;
else if (BN_cmp(dh->params.g, dh->params.p) >= 0)
*ret |= DH_NOT_SUITABLE_GENERATOR;
else {
/* Check g^q == 1 mod p */
if (!BN_mod_exp(t1, dh->params.g, dh->params.q, dh->params.p, ctx))
goto err;
if (!BN_is_one(t1))
*ret |= DH_NOT_SUITABLE_GENERATOR;
}
r = BN_check_prime(dh->params.q, ctx, NULL);
if (r < 0)
goto err;
if (!r)
*ret |= DH_CHECK_Q_NOT_PRIME;
/* Check p == 1 mod q i.e. q divides p - 1 */
if (!BN_div(t1, t2, dh->params.p, dh->params.q, ctx))
goto err;
if (!BN_is_one(t2))
*ret |= DH_CHECK_INVALID_Q_VALUE;
if (dh->params.j != NULL
&& BN_cmp(dh->params.j, t1))
*ret |= DH_CHECK_INVALID_J_VALUE;
}
r = BN_check_prime(dh->params.p, ctx, NULL);
if (r < 0)
goto err;
if (!r)
*ret |= DH_CHECK_P_NOT_PRIME;
else if (dh->params.q == NULL) {
if (!BN_rshift1(t1, dh->params.p))
goto err;
r = BN_check_prime(t1, ctx, NULL);
if (r < 0)
goto err;
if (!r)
*ret |= DH_CHECK_P_NOT_SAFE_PRIME;
}
ok = 1;
err:
BN_CTX_end(ctx);
BN_CTX_free(ctx);
return ok;
#endif /* FIPS_MODE */
}
int DH_check_pub_key_ex(const DH *dh, const BIGNUM *pub_key)
{
int errflags = 0;
if (!DH_check_pub_key(dh, pub_key, &errflags))
return 0;
if ((errflags & DH_CHECK_PUBKEY_TOO_SMALL) != 0)
DHerr(DH_F_DH_CHECK_PUB_KEY_EX, DH_R_CHECK_PUBKEY_TOO_SMALL);
if ((errflags & DH_CHECK_PUBKEY_TOO_LARGE) != 0)
DHerr(DH_F_DH_CHECK_PUB_KEY_EX, DH_R_CHECK_PUBKEY_TOO_LARGE);
if ((errflags & DH_CHECK_PUBKEY_INVALID) != 0)
DHerr(DH_F_DH_CHECK_PUB_KEY_EX, DH_R_CHECK_PUBKEY_INVALID);
return errflags == 0;
}
/*
* See SP800-56Ar3 Section 5.6.2.3.1 : FFC Full public key validation.
*/
int DH_check_pub_key(const DH *dh, const BIGNUM *pub_key, int *ret)
{
return ffc_validate_public_key(&dh->params, pub_key, ret);
}
/*
* See SP800-56Ar3 Section 5.6.2.3.1 : FFC Partial public key validation.
* To only be used with ephemeral FFC public keys generated using the approved
* safe-prime groups.
*/
int dh_check_pub_key_partial(const DH *dh, const BIGNUM *pub_key, int *ret)
{
return ffc_validate_public_key_partial(&dh->params, pub_key, ret);
}
int dh_check_priv_key(const DH *dh, const BIGNUM *priv_key, int *ret)
{
int ok = 0;
BIGNUM *two_powN = NULL, *upper;
*ret = 0;
two_powN = BN_new();
if (two_powN == NULL)
return 0;
if (dh->params.q == NULL)
goto err;
upper = dh->params.q;
/* Is it from an approved Safe prime group ?*/
if (DH_get_nid((DH *)dh) != NID_undef) {
if (!BN_lshift(two_powN, BN_value_one(), dh->length))
goto err;
if (BN_cmp(two_powN, dh->params.q) < 0)
upper = two_powN;
}
if (!ffc_validate_private_key(upper, priv_key, ret))
goto err;
ok = 1;
err:
BN_free(two_powN);
return ok;
}
/*
* FFC pairwise check from SP800-56A R3.
* Section 5.6.2.1.4 Owner Assurance of Pair-wise Consistency
*/
int dh_check_pairwise(DH *dh)
{
int ret = 0;
BN_CTX *ctx = NULL;
BIGNUM *pub_key = NULL;
if (dh->params.p == NULL
|| dh->params.g == NULL
|| dh->priv_key == NULL
|| dh->pub_key == NULL)
return 0;
ctx = BN_CTX_new_ex(dh->libctx);
if (ctx == NULL)
goto err;
pub_key = BN_new();
if (pub_key == NULL)
goto err;
/* recalculate the public key = (g ^ priv) mod p */
if (!dh_generate_public_key(ctx, dh, dh->priv_key, pub_key))
goto err;
/* check it matches the existing pubic_key */
ret = BN_cmp(pub_key, dh->pub_key) == 0;
err:
BN_free(pub_key);
BN_CTX_free(ctx);
return ret;
}