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1 | /* crypto/dh/dh_key.c */ |
2 | /* Copyright (C) 1995-1997 Eric Young (eay@cryptsoft.com) | |
3 | * All rights reserved. | |
4 | * | |
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. | |
8 | * | |
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). | |
15 | * | |
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. | |
22 | * | |
23 | * Redistribution and use in source and binary forms, with or without | |
24 | * modification, are permitted provided that the following conditions | |
25 | * are met: | |
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)" | |
40 | * | |
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 | |
51 | * SUCH DAMAGE. | |
52 | * | |
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.] | |
57 | */ | |
58 | ||
59 | #include <stdio.h> | |
60 | #include "cryptlib.h" | |
61 | #include "bn.h" | |
62 | #include "rand.h" | |
63 | #include "dh.h" | |
64 | ||
65 | int DH_generate_key(dh) | |
66 | DH *dh; | |
67 | { | |
68 | int ok=0; | |
69 | unsigned int i; | |
70 | BN_CTX *ctx=NULL; | |
71 | BIGNUM *pub_key=NULL,*priv_key=NULL; | |
72 | ||
73 | ctx=BN_CTX_new(); | |
74 | if (ctx == NULL) goto err; | |
75 | ||
76 | if (dh->priv_key == NULL) | |
77 | { | |
78 | i=dh->length; | |
79 | if (i == 0) | |
80 | { | |
81 | /* Make the number p-1 bits long */ | |
82 | i=BN_num_bits(dh->p)-1; | |
83 | } | |
84 | priv_key=BN_new(); | |
85 | if (priv_key == NULL) goto err; | |
86 | if (!BN_rand(priv_key,i,0,0)) goto err; | |
87 | } | |
88 | else | |
89 | priv_key=dh->priv_key; | |
90 | ||
91 | if (dh->pub_key == NULL) | |
92 | { | |
93 | pub_key=BN_new(); | |
94 | if (pub_key == NULL) goto err; | |
95 | } | |
96 | else | |
97 | pub_key=dh->pub_key; | |
98 | ||
99 | if (!BN_mod_exp(pub_key,dh->g,priv_key,dh->p,ctx)) goto err; | |
100 | ||
101 | dh->pub_key=pub_key; | |
102 | dh->priv_key=priv_key; | |
103 | ok=1; | |
104 | err: | |
105 | if (ok != 1) | |
106 | DHerr(DH_F_DH_GENERATE_KEY,ERR_R_BN_LIB); | |
107 | ||
108 | if ((pub_key != NULL) && (dh->pub_key == NULL)) BN_free(pub_key); | |
109 | if ((priv_key != NULL) && (dh->priv_key == NULL)) BN_free(priv_key); | |
110 | if (ctx != NULL) BN_CTX_free(ctx); | |
111 | return(ok); | |
112 | } | |
113 | ||
114 | int DH_compute_key(key,pub_key,dh) | |
115 | unsigned char *key; | |
116 | BIGNUM *pub_key; | |
117 | DH *dh; | |
118 | { | |
119 | BN_CTX *ctx; | |
120 | BIGNUM *tmp; | |
121 | int ret= -1; | |
122 | ||
123 | ctx=BN_CTX_new(); | |
124 | if (ctx == NULL) goto err; | |
125 | tmp=ctx->bn[ctx->tos++]; | |
126 | ||
127 | if (dh->priv_key == NULL) | |
128 | { | |
129 | DHerr(DH_F_DH_COMPUTE_KEY,DH_R_NO_PRIVATE_VALUE); | |
130 | goto err; | |
131 | } | |
132 | if (!BN_mod_exp(tmp,pub_key,dh->priv_key,dh->p,ctx)) | |
133 | { | |
134 | DHerr(DH_F_DH_COMPUTE_KEY,ERR_R_BN_LIB); | |
135 | goto err; | |
136 | } | |
137 | ||
138 | ret=BN_bn2bin(tmp,key); | |
139 | err: | |
140 | if (ctx != NULL) BN_CTX_free(ctx); | |
141 | return(ret); | |
142 | } |