1 /* crypto/dh/dh_key.c */
2 /* Copyright (C) 1995-1998 Eric Young (eay@cryptsoft.com)
5 * This package is an SSL implementation written
6 * by Eric Young (eay@cryptsoft.com).
7 * The implementation was written so as to conform with Netscapes SSL.
9 * This library is free for commercial and non-commercial use as long as
10 * the following conditions are aheared to. The following conditions
11 * apply to all code found in this distribution, be it the RC4, RSA,
12 * lhash, DES, etc., code; not just the SSL code. The SSL documentation
13 * included with this distribution is covered by the same copyright terms
14 * except that the holder is Tim Hudson (tjh@cryptsoft.com).
16 * Copyright remains Eric Young's, and as such any Copyright notices in
17 * the code are not to be removed.
18 * If this package is used in a product, Eric Young should be given attribution
19 * as the author of the parts of the library used.
20 * This can be in the form of a textual message at program startup or
21 * in documentation (online or textual) provided with the package.
23 * Redistribution and use in source and binary forms, with or without
24 * modification, are permitted provided that the following conditions
26 * 1. Redistributions of source code must retain the copyright
27 * notice, this list of conditions and the following disclaimer.
28 * 2. Redistributions in binary form must reproduce the above copyright
29 * notice, this list of conditions and the following disclaimer in the
30 * documentation and/or other materials provided with the distribution.
31 * 3. All advertising materials mentioning features or use of this software
32 * must display the following acknowledgement:
33 * "This product includes cryptographic software written by
34 * Eric Young (eay@cryptsoft.com)"
35 * The word 'cryptographic' can be left out if the rouines from the library
36 * being used are not cryptographic related :-).
37 * 4. If you include any Windows specific code (or a derivative thereof) from
38 * the apps directory (application code) you must include an acknowledgement:
39 * "This product includes software written by Tim Hudson (tjh@cryptsoft.com)"
41 * THIS SOFTWARE IS PROVIDED BY ERIC YOUNG ``AS IS'' AND
42 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
43 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
44 * ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
45 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
46 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
47 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
48 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
49 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
50 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
53 * The licence and distribution terms for any publically available version or
54 * derivative of this code cannot be changed. i.e. this code cannot simply be
55 * copied and put under another distribution licence
56 * [including the GNU Public Licence.]
61 #include <openssl/bn.h>
62 #include <openssl/rand.h>
63 #include <openssl/dh.h>
65 static int generate_key(DH
*dh
);
66 static int compute_key(unsigned char *key
, const BIGNUM
*pub_key
, DH
*dh
);
67 static int dh_bn_mod_exp(const DH
*dh
, BIGNUM
*r
,
68 const BIGNUM
*a
, const BIGNUM
*p
,
69 const BIGNUM
*m
, BN_CTX
*ctx
,
71 static int dh_init(DH
*dh
);
72 static int dh_finish(DH
*dh
);
74 int DH_generate_key(DH
*dh
)
76 return dh
->meth
->generate_key(dh
);
79 int DH_compute_key(unsigned char *key
, const BIGNUM
*pub_key
, DH
*dh
)
81 return dh
->meth
->compute_key(key
, pub_key
, dh
);
84 static DH_METHOD dh_ossl
= {
96 const DH_METHOD
*DH_OpenSSL(void)
101 static int generate_key(DH
*dh
)
104 int generate_new_key
=0;
107 BN_MONT_CTX
*mont
=NULL
;
108 BIGNUM
*pub_key
=NULL
,*priv_key
=NULL
;
111 if (ctx
== NULL
) goto err
;
113 if (dh
->priv_key
== NULL
)
116 if (priv_key
== NULL
) goto err
;
120 priv_key
=dh
->priv_key
;
122 if (dh
->pub_key
== NULL
)
125 if (pub_key
== NULL
) goto err
;
131 if (dh
->flags
& DH_FLAG_CACHE_MONT_P
)
133 mont
= BN_MONT_CTX_set_locked(&dh
->method_mont_p
,
134 CRYPTO_LOCK_DH
, dh
->p
, ctx
);
139 if (generate_new_key
)
141 l
= dh
->length
? dh
->length
: BN_num_bits(dh
->p
)-1; /* secret exponent length */
142 if (!BN_rand(priv_key
, l
, 0, 0)) goto err
;
149 if ((dh
->flags
& DH_FLAG_NO_EXP_CONSTTIME
) == 0)
153 BN_with_flags(prk
, priv_key
, BN_FLG_CONSTTIME
);
158 if (!dh
->meth
->bn_mod_exp(dh
, pub_key
, dh
->g
, prk
, dh
->p
, ctx
, mont
)) goto err
;
162 dh
->priv_key
=priv_key
;
166 DHerr(DH_F_GENERATE_KEY
,ERR_R_BN_LIB
);
168 if ((pub_key
!= NULL
) && (dh
->pub_key
== NULL
)) BN_free(pub_key
);
169 if ((priv_key
!= NULL
) && (dh
->priv_key
== NULL
)) BN_free(priv_key
);
174 static int compute_key(unsigned char *key
, const BIGNUM
*pub_key
, DH
*dh
)
177 BN_MONT_CTX
*mont
=NULL
;
182 if (BN_num_bits(dh
->p
) > OPENSSL_DH_MAX_MODULUS_BITS
)
184 DHerr(DH_F_COMPUTE_KEY
,DH_R_MODULUS_TOO_LARGE
);
189 if (ctx
== NULL
) goto err
;
191 tmp
= BN_CTX_get(ctx
);
193 if (dh
->priv_key
== NULL
)
195 DHerr(DH_F_COMPUTE_KEY
,DH_R_NO_PRIVATE_VALUE
);
199 if (dh
->flags
& DH_FLAG_CACHE_MONT_P
)
201 mont
= BN_MONT_CTX_set_locked(&dh
->method_mont_p
,
202 CRYPTO_LOCK_DH
, dh
->p
, ctx
);
203 if ((dh
->flags
& DH_FLAG_NO_EXP_CONSTTIME
) == 0)
206 BN_set_flags(dh
->priv_key
, BN_FLG_CONSTTIME
);
212 if (!DH_check_pub_key(dh
, pub_key
, &check_result
) || check_result
)
214 DHerr(DH_F_COMPUTE_KEY
,DH_R_INVALID_PUBKEY
);
218 if (!dh
->meth
->bn_mod_exp(dh
, tmp
, pub_key
, dh
->priv_key
,dh
->p
,ctx
,mont
))
220 DHerr(DH_F_COMPUTE_KEY
,ERR_R_BN_LIB
);
224 ret
=BN_bn2bin(tmp
,key
);
234 static int dh_bn_mod_exp(const DH
*dh
, BIGNUM
*r
,
235 const BIGNUM
*a
, const BIGNUM
*p
,
236 const BIGNUM
*m
, BN_CTX
*ctx
,
239 /* If a is only one word long and constant time is false, use the faster
240 * exponenentiation function.
242 if (a
->top
== 1 && ((dh
->flags
& DH_FLAG_NO_EXP_CONSTTIME
) != 0))
244 BN_ULONG A
= a
->d
[0];
245 return BN_mod_exp_mont_word(r
,A
,p
,m
,ctx
,m_ctx
);
248 return BN_mod_exp_mont(r
,a
,p
,m
,ctx
,m_ctx
);
252 static int dh_init(DH
*dh
)
254 dh
->flags
|= DH_FLAG_CACHE_MONT_P
;
258 static int dh_finish(DH
*dh
)
260 if(dh
->method_mont_p
)
261 BN_MONT_CTX_free(dh
->method_mont_p
);