dh_key.c
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上传日期:2020-08-09
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- /* crypto/dh/dh_key.c */
- /* Copyright (C) 1995-1998 Eric Young (eay@cryptsoft.com)
- * All rights reserved.
- *
- * This package is an SSL implementation written
- * by Eric Young (eay@cryptsoft.com).
- * The implementation was written so as to conform with Netscapes SSL.
- *
- * This library is free for commercial and non-commercial use as long as
- * the following conditions are aheared to. The following conditions
- * apply to all code found in this distribution, be it the RC4, RSA,
- * lhash, DES, etc., code; not just the SSL code. The SSL documentation
- * included with this distribution is covered by the same copyright terms
- * except that the holder is Tim Hudson (tjh@cryptsoft.com).
- *
- * Copyright remains Eric Young's, and as such any Copyright notices in
- * the code are not to be removed.
- * If this package is used in a product, Eric Young should be given attribution
- * as the author of the parts of the library used.
- * This can be in the form of a textual message at program startup or
- * in documentation (online or textual) provided with the package.
- *
- * Redistribution and use in source and binary forms, with or without
- * modification, are permitted provided that the following conditions
- * are met:
- * 1. Redistributions of source code must retain the copyright
- * notice, this list of conditions and the following disclaimer.
- * 2. Redistributions in binary form must reproduce the above copyright
- * notice, this list of conditions and the following disclaimer in the
- * documentation and/or other materials provided with the distribution.
- * 3. All advertising materials mentioning features or use of this software
- * must display the following acknowledgement:
- * "This product includes cryptographic software written by
- * Eric Young (eay@cryptsoft.com)"
- * The word 'cryptographic' can be left out if the rouines from the library
- * being used are not cryptographic related :-).
- * 4. If you include any Windows specific code (or a derivative thereof) from
- * the apps directory (application code) you must include an acknowledgement:
- * "This product includes software written by Tim Hudson (tjh@cryptsoft.com)"
- *
- * THIS SOFTWARE IS PROVIDED BY ERIC YOUNG ``AS IS'' AND
- * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
- * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
- * ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
- * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
- * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
- * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
- * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
- * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
- * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
- * SUCH DAMAGE.
- *
- * The licence and distribution terms for any publically available version or
- * derivative of this code cannot be changed. i.e. this code cannot simply be
- * copied and put under another distribution licence
- * [including the GNU Public Licence.]
- */
- #include <stdio.h>
- #include "cryptlib.h"
- #include <openssl/bn.h>
- #include <openssl/rand.h>
- #include <openssl/dh.h>
- static int generate_key(DH *dh);
- static int compute_key(unsigned char *key, const BIGNUM *pub_key, DH *dh);
- static int dh_bn_mod_exp(const DH *dh, BIGNUM *r,
- const BIGNUM *a, const BIGNUM *p,
- const BIGNUM *m, BN_CTX *ctx,
- BN_MONT_CTX *m_ctx);
- static int dh_init(DH *dh);
- static int dh_finish(DH *dh);
- int DH_generate_key(DH *dh)
- {
- return dh->meth->generate_key(dh);
- }
- int DH_compute_key(unsigned char *key, const BIGNUM *pub_key, DH *dh)
- {
- return dh->meth->compute_key(key, pub_key, dh);
- }
- static DH_METHOD dh_ossl = {
- "OpenSSL DH Method",
- generate_key,
- compute_key,
- dh_bn_mod_exp,
- dh_init,
- dh_finish,
- 0,
- NULL,
- NULL
- };
- const DH_METHOD *DH_OpenSSL(void)
- {
- return &dh_ossl;
- }
- static int generate_key(DH *dh)
- {
- int ok=0;
- int generate_new_key=0;
- unsigned l;
- BN_CTX *ctx;
- BN_MONT_CTX *mont=NULL;
- BIGNUM *pub_key=NULL,*priv_key=NULL;
- ctx = BN_CTX_new();
- if (ctx == NULL) goto err;
- if (dh->priv_key == NULL)
- {
- priv_key=BN_new();
- if (priv_key == NULL) goto err;
- generate_new_key=1;
- }
- else
- priv_key=dh->priv_key;
- if (dh->pub_key == NULL)
- {
- pub_key=BN_new();
- if (pub_key == NULL) goto err;
- }
- else
- pub_key=dh->pub_key;
- if (dh->flags & DH_FLAG_CACHE_MONT_P)
- {
- mont = BN_MONT_CTX_set_locked(&dh->method_mont_p,
- CRYPTO_LOCK_DH, dh->p, ctx);
- if (!mont)
- goto err;
- }
- if (generate_new_key)
- {
- l = dh->length ? dh->length : BN_num_bits(dh->p)-1; /* secret exponent length */
- if (!BN_rand(priv_key, l, 0, 0)) goto err;
- }
- {
- BIGNUM local_prk;
- BIGNUM *prk;
- if ((dh->flags & DH_FLAG_NO_EXP_CONSTTIME) == 0)
- {
- BN_init(&local_prk);
- prk = &local_prk;
- BN_with_flags(prk, priv_key, BN_FLG_EXP_CONSTTIME);
- }
- else
- prk = priv_key;
- if (!dh->meth->bn_mod_exp(dh, pub_key, dh->g, prk, dh->p, ctx, mont)) goto err;
- }
-
- dh->pub_key=pub_key;
- dh->priv_key=priv_key;
- ok=1;
- err:
- if (ok != 1)
- DHerr(DH_F_GENERATE_KEY,ERR_R_BN_LIB);
- if ((pub_key != NULL) && (dh->pub_key == NULL)) BN_free(pub_key);
- if ((priv_key != NULL) && (dh->priv_key == NULL)) BN_free(priv_key);
- BN_CTX_free(ctx);
- return(ok);
- }
- static int compute_key(unsigned char *key, const BIGNUM *pub_key, DH *dh)
- {
- BN_CTX *ctx;
- BN_MONT_CTX *mont=NULL;
- BIGNUM *tmp;
- int ret= -1;
- int check_result;
- ctx = BN_CTX_new();
- if (ctx == NULL) goto err;
- BN_CTX_start(ctx);
- tmp = BN_CTX_get(ctx);
-
- if (dh->priv_key == NULL)
- {
- DHerr(DH_F_COMPUTE_KEY,DH_R_NO_PRIVATE_VALUE);
- goto err;
- }
- if (dh->flags & DH_FLAG_CACHE_MONT_P)
- {
- mont = BN_MONT_CTX_set_locked(&dh->method_mont_p,
- CRYPTO_LOCK_DH, dh->p, ctx);
- if ((dh->flags & DH_FLAG_NO_EXP_CONSTTIME) == 0)
- {
- /* XXX */
- BN_set_flags(dh->priv_key, BN_FLG_EXP_CONSTTIME);
- }
- if (!mont)
- goto err;
- }
- if (!DH_check_pub_key(dh, pub_key, &check_result) || check_result)
- {
- DHerr(DH_F_COMPUTE_KEY,DH_R_INVALID_PUBKEY);
- goto err;
- }
- if (!dh->meth->bn_mod_exp(dh, tmp, pub_key, dh->priv_key,dh->p,ctx,mont))
- {
- DHerr(DH_F_COMPUTE_KEY,ERR_R_BN_LIB);
- goto err;
- }
- ret=BN_bn2bin(tmp,key);
- err:
- if (ctx != NULL)
- {
- BN_CTX_end(ctx);
- BN_CTX_free(ctx);
- }
- return(ret);
- }
- static int dh_bn_mod_exp(const DH *dh, BIGNUM *r,
- const BIGNUM *a, const BIGNUM *p,
- const BIGNUM *m, BN_CTX *ctx,
- BN_MONT_CTX *m_ctx)
- {
- /* If a is only one word long and constant time is false, use the faster
- * exponenentiation function.
- */
- if (a->top == 1 && ((dh->flags & DH_FLAG_NO_EXP_CONSTTIME) != 0))
- {
- BN_ULONG A = a->d[0];
- return BN_mod_exp_mont_word(r,A,p,m,ctx,m_ctx);
- }
- else
- return BN_mod_exp_mont(r,a,p,m,ctx,m_ctx);
- }
- static int dh_init(DH *dh)
- {
- dh->flags |= DH_FLAG_CACHE_MONT_P;
- return(1);
- }
- static int dh_finish(DH *dh)
- {
- if(dh->method_mont_p)
- BN_MONT_CTX_free(dh->method_mont_p);
- return(1);
- }