361 lines
10 KiB
C
361 lines
10 KiB
C
/*
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* Copyright 1995-2023 The OpenSSL Project Authors. All Rights Reserved.
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*
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* Licensed under the Apache License 2.0 (the "License"). You may not use
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* this file except in compliance with the License. You can obtain a copy
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* in the file LICENSE in the source distribution or at
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* https://www.openssl.org/source/license.html
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*/
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/*
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* DH low level APIs are deprecated for public use, but still ok for
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* internal use.
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*/
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#include "internal/deprecated.h"
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#include <stdio.h>
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#include "internal/cryptlib.h"
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#include <openssl/bn.h>
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#include "dh_local.h"
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#include "crypto/dh.h"
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/*-
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* Check that p and g are suitable enough
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*
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* p is odd
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* 1 < g < p - 1
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*/
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int DH_check_params_ex(const DH *dh)
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{
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int errflags = 0;
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if (!DH_check_params(dh, &errflags))
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return 0;
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if ((errflags & DH_CHECK_P_NOT_PRIME) != 0)
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ERR_raise(ERR_LIB_DH, DH_R_CHECK_P_NOT_PRIME);
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if ((errflags & DH_NOT_SUITABLE_GENERATOR) != 0)
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ERR_raise(ERR_LIB_DH, DH_R_NOT_SUITABLE_GENERATOR);
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if ((errflags & DH_MODULUS_TOO_SMALL) != 0)
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ERR_raise(ERR_LIB_DH, DH_R_MODULUS_TOO_SMALL);
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if ((errflags & DH_MODULUS_TOO_LARGE) != 0)
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ERR_raise(ERR_LIB_DH, DH_R_MODULUS_TOO_LARGE);
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return errflags == 0;
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}
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#ifdef FIPS_MODULE
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int DH_check_params(const DH *dh, int *ret)
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{
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int nid;
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*ret = 0;
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/*
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* SP800-56A R3 Section 5.5.2 Assurances of Domain Parameter Validity
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* (1a) The domain parameters correspond to any approved safe prime group.
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*/
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nid = DH_get_nid((DH *)dh);
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if (nid != NID_undef)
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return 1;
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/*
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* OR
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* (2b) FFC domain params conform to FIPS-186-4 explicit domain param
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* validity tests.
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*/
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return ossl_ffc_params_FIPS186_4_validate(dh->libctx, &dh->params,
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FFC_PARAM_TYPE_DH, ret, NULL);
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}
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#else
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int DH_check_params(const DH *dh, int *ret)
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{
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int ok = 0;
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BIGNUM *tmp = NULL;
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BN_CTX *ctx = NULL;
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*ret = 0;
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ctx = BN_CTX_new_ex(dh->libctx);
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if (ctx == NULL)
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goto err;
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BN_CTX_start(ctx);
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tmp = BN_CTX_get(ctx);
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if (tmp == NULL)
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goto err;
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if (!BN_is_odd(dh->params.p))
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*ret |= DH_CHECK_P_NOT_PRIME;
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if (BN_is_negative(dh->params.g)
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|| BN_is_zero(dh->params.g)
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|| BN_is_one(dh->params.g))
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*ret |= DH_NOT_SUITABLE_GENERATOR;
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if (BN_copy(tmp, dh->params.p) == NULL || !BN_sub_word(tmp, 1))
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goto err;
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if (BN_cmp(dh->params.g, tmp) >= 0)
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*ret |= DH_NOT_SUITABLE_GENERATOR;
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if (BN_num_bits(dh->params.p) < DH_MIN_MODULUS_BITS)
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*ret |= DH_MODULUS_TOO_SMALL;
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if (BN_num_bits(dh->params.p) > OPENSSL_DH_MAX_MODULUS_BITS)
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*ret |= DH_MODULUS_TOO_LARGE;
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ok = 1;
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err:
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BN_CTX_end(ctx);
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BN_CTX_free(ctx);
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return ok;
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}
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#endif /* FIPS_MODULE */
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/*-
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* Check that p is a safe prime and
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* g is a suitable generator.
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*/
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int DH_check_ex(const DH *dh)
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{
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int errflags = 0;
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if (!DH_check(dh, &errflags))
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return 0;
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if ((errflags & DH_NOT_SUITABLE_GENERATOR) != 0)
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ERR_raise(ERR_LIB_DH, DH_R_NOT_SUITABLE_GENERATOR);
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if ((errflags & DH_CHECK_Q_NOT_PRIME) != 0)
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ERR_raise(ERR_LIB_DH, DH_R_CHECK_Q_NOT_PRIME);
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if ((errflags & DH_CHECK_INVALID_Q_VALUE) != 0)
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ERR_raise(ERR_LIB_DH, DH_R_CHECK_INVALID_Q_VALUE);
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if ((errflags & DH_CHECK_INVALID_J_VALUE) != 0)
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ERR_raise(ERR_LIB_DH, DH_R_CHECK_INVALID_J_VALUE);
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if ((errflags & DH_UNABLE_TO_CHECK_GENERATOR) != 0)
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ERR_raise(ERR_LIB_DH, DH_R_UNABLE_TO_CHECK_GENERATOR);
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if ((errflags & DH_CHECK_P_NOT_PRIME) != 0)
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ERR_raise(ERR_LIB_DH, DH_R_CHECK_P_NOT_PRIME);
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if ((errflags & DH_CHECK_P_NOT_SAFE_PRIME) != 0)
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ERR_raise(ERR_LIB_DH, DH_R_CHECK_P_NOT_SAFE_PRIME);
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if ((errflags & DH_MODULUS_TOO_SMALL) != 0)
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ERR_raise(ERR_LIB_DH, DH_R_MODULUS_TOO_SMALL);
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if ((errflags & DH_MODULUS_TOO_LARGE) != 0)
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ERR_raise(ERR_LIB_DH, DH_R_MODULUS_TOO_LARGE);
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return errflags == 0;
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}
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/* Note: according to documentation - this only checks the params */
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int DH_check(const DH *dh, int *ret)
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{
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#ifdef FIPS_MODULE
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return DH_check_params(dh, ret);
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#else
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int ok = 0, r, q_good = 0;
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BN_CTX *ctx = NULL;
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BIGNUM *t1 = NULL, *t2 = NULL;
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int nid = DH_get_nid((DH *)dh);
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*ret = 0;
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if (nid != NID_undef)
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return 1;
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/* Don't do any checks at all with an excessively large modulus */
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if (BN_num_bits(dh->params.p) > OPENSSL_DH_CHECK_MAX_MODULUS_BITS) {
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ERR_raise(ERR_LIB_DH, DH_R_MODULUS_TOO_LARGE);
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*ret = DH_MODULUS_TOO_LARGE | DH_CHECK_P_NOT_PRIME;
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return 0;
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}
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if (!DH_check_params(dh, ret))
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return 0;
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ctx = BN_CTX_new_ex(dh->libctx);
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if (ctx == NULL)
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goto err;
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BN_CTX_start(ctx);
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t1 = BN_CTX_get(ctx);
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t2 = BN_CTX_get(ctx);
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if (t2 == NULL)
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goto err;
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if (dh->params.q != NULL) {
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if (BN_ucmp(dh->params.p, dh->params.q) > 0)
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q_good = 1;
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else
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*ret |= DH_CHECK_INVALID_Q_VALUE;
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}
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if (q_good) {
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if (BN_cmp(dh->params.g, BN_value_one()) <= 0)
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*ret |= DH_NOT_SUITABLE_GENERATOR;
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else if (BN_cmp(dh->params.g, dh->params.p) >= 0)
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*ret |= DH_NOT_SUITABLE_GENERATOR;
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else {
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/* Check g^q == 1 mod p */
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if (!BN_mod_exp(t1, dh->params.g, dh->params.q, dh->params.p, ctx))
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goto err;
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if (!BN_is_one(t1))
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*ret |= DH_NOT_SUITABLE_GENERATOR;
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}
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r = BN_check_prime(dh->params.q, ctx, NULL);
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if (r < 0)
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goto err;
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if (!r)
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*ret |= DH_CHECK_Q_NOT_PRIME;
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/* Check p == 1 mod q i.e. q divides p - 1 */
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if (!BN_div(t1, t2, dh->params.p, dh->params.q, ctx))
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goto err;
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if (!BN_is_one(t2))
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*ret |= DH_CHECK_INVALID_Q_VALUE;
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if (dh->params.j != NULL
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&& BN_cmp(dh->params.j, t1))
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*ret |= DH_CHECK_INVALID_J_VALUE;
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}
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r = BN_check_prime(dh->params.p, ctx, NULL);
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if (r < 0)
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goto err;
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if (!r)
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*ret |= DH_CHECK_P_NOT_PRIME;
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else if (dh->params.q == NULL) {
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if (!BN_rshift1(t1, dh->params.p))
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goto err;
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r = BN_check_prime(t1, ctx, NULL);
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if (r < 0)
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goto err;
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if (!r)
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*ret |= DH_CHECK_P_NOT_SAFE_PRIME;
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}
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ok = 1;
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err:
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BN_CTX_end(ctx);
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BN_CTX_free(ctx);
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return ok;
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#endif /* FIPS_MODULE */
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}
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int DH_check_pub_key_ex(const DH *dh, const BIGNUM *pub_key)
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{
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int errflags = 0;
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if (!DH_check_pub_key(dh, pub_key, &errflags))
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return 0;
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if ((errflags & DH_CHECK_PUBKEY_TOO_SMALL) != 0)
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ERR_raise(ERR_LIB_DH, DH_R_CHECK_PUBKEY_TOO_SMALL);
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if ((errflags & DH_CHECK_PUBKEY_TOO_LARGE) != 0)
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ERR_raise(ERR_LIB_DH, DH_R_CHECK_PUBKEY_TOO_LARGE);
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if ((errflags & DH_CHECK_PUBKEY_INVALID) != 0)
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ERR_raise(ERR_LIB_DH, DH_R_CHECK_PUBKEY_INVALID);
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return errflags == 0;
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}
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/*
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* See SP800-56Ar3 Section 5.6.2.3.1 : FFC Full public key validation.
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*/
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int DH_check_pub_key(const DH *dh, const BIGNUM *pub_key, int *ret)
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{
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/* Don't do any checks at all with an excessively large modulus */
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if (BN_num_bits(dh->params.p) > OPENSSL_DH_CHECK_MAX_MODULUS_BITS) {
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ERR_raise(ERR_LIB_DH, DH_R_MODULUS_TOO_LARGE);
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*ret = DH_MODULUS_TOO_LARGE | DH_CHECK_PUBKEY_INVALID;
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return 0;
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}
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if (dh->params.q != NULL && BN_ucmp(dh->params.p, dh->params.q) < 0) {
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*ret |= DH_CHECK_INVALID_Q_VALUE | DH_CHECK_PUBKEY_INVALID;
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return 1;
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}
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return ossl_ffc_validate_public_key(&dh->params, pub_key, ret);
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}
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/*
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* See SP800-56Ar3 Section 5.6.2.3.1 : FFC Partial public key validation.
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* To only be used with ephemeral FFC public keys generated using the approved
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* safe-prime groups.
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*/
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int ossl_dh_check_pub_key_partial(const DH *dh, const BIGNUM *pub_key, int *ret)
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{
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return ossl_ffc_validate_public_key_partial(&dh->params, pub_key, ret)
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&& *ret == 0;
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}
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int ossl_dh_check_priv_key(const DH *dh, const BIGNUM *priv_key, int *ret)
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{
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int ok = 0;
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BIGNUM *two_powN = NULL, *upper;
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*ret = 0;
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two_powN = BN_new();
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if (two_powN == NULL)
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return 0;
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if (dh->params.q != NULL) {
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upper = dh->params.q;
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#ifndef FIPS_MODULE
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} else if (dh->params.p != NULL) {
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/*
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* We do not have q so we just check the key is within some
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* reasonable range, or the number of bits is equal to dh->length.
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*/
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int length = dh->length;
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if (length == 0) {
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length = BN_num_bits(dh->params.p) - 1;
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if (BN_num_bits(priv_key) <= length
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&& BN_num_bits(priv_key) > 1)
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ok = 1;
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} else if (BN_num_bits(priv_key) == length) {
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ok = 1;
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}
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goto end;
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#endif
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} else {
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goto end;
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}
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/* Is it from an approved Safe prime group ?*/
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if (DH_get_nid((DH *)dh) != NID_undef && dh->length != 0) {
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if (!BN_lshift(two_powN, BN_value_one(), dh->length))
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goto end;
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if (BN_cmp(two_powN, dh->params.q) < 0)
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upper = two_powN;
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}
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if (!ossl_ffc_validate_private_key(upper, priv_key, ret))
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goto end;
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ok = 1;
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end:
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BN_free(two_powN);
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return ok;
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}
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/*
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* FFC pairwise check from SP800-56A R3.
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* Section 5.6.2.1.4 Owner Assurance of Pair-wise Consistency
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*/
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int ossl_dh_check_pairwise(const DH *dh)
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{
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int ret = 0;
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BN_CTX *ctx = NULL;
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BIGNUM *pub_key = NULL;
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if (dh->params.p == NULL
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|| dh->params.g == NULL
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|| dh->priv_key == NULL
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|| dh->pub_key == NULL)
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return 0;
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ctx = BN_CTX_new_ex(dh->libctx);
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if (ctx == NULL)
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goto err;
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pub_key = BN_new();
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if (pub_key == NULL)
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goto err;
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/* recalculate the public key = (g ^ priv) mod p */
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if (!ossl_dh_generate_public_key(ctx, dh, dh->priv_key, pub_key))
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goto err;
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/* check it matches the existing pubic_key */
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ret = BN_cmp(pub_key, dh->pub_key) == 0;
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err:
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BN_free(pub_key);
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BN_CTX_free(ctx);
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return ret;
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}
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