cipher-3des1.c revision 126274 
1/*
2 * Copyright (c) 2003 Markus Friedl.  All rights reserved.
3 *
4 * Redistribution and use in source and binary forms, with or without
5 * modification, are permitted provided that the following conditions
6 * are met:
7 * 1. Redistributions of source code must retain the above copyright
8 *    notice, this list of conditions and the following disclaimer.
9 * 2. Redistributions in binary form must reproduce the above copyright
10 *    notice, this list of conditions and the following disclaimer in the
11 *    documentation and/or other materials provided with the distribution.
12 *
13 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
14 * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
15 * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
16 * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
17 * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
18 * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
19 * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
20 * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
21 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
22 * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
23 */
24
25#include "includes.h"
26RCSID("$OpenBSD: cipher-3des1.c,v 1.2 2003/12/22 20:29:55 markus Exp $");
27
28#include <openssl/evp.h>
29#include "xmalloc.h"
30#include "log.h"
31
32#if OPENSSL_VERSION_NUMBER < 0x00906000L
33#define SSH_OLD_EVP
34#endif
35
36/*
37 * This is used by SSH1:
38 *
39 * What kind of triple DES are these 2 routines?
40 *
41 * Why is there a redundant initialization vector?
42 *
43 * If only iv3 was used, then, this would till effect have been
44 * outer-cbc. However, there is also a private iv1 == iv2 which
45 * perhaps makes differential analysis easier. On the other hand, the
46 * private iv1 probably makes the CRC-32 attack ineffective. This is a
47 * result of that there is no longer any known iv1 to use when
48 * choosing the X block.
49 */
50struct ssh1_3des_ctx
51{
52	EVP_CIPHER_CTX	k1, k2, k3;
53};
54
55const EVP_CIPHER * evp_ssh1_3des(void);
56void ssh1_3des_iv(EVP_CIPHER_CTX *, int, u_char *, int);
57
58static int
59ssh1_3des_init(EVP_CIPHER_CTX *ctx, const u_char *key, const u_char *iv,
60    int enc)
61{
62	struct ssh1_3des_ctx *c;
63	u_char *k1, *k2, *k3;
64
65	if ((c = EVP_CIPHER_CTX_get_app_data(ctx)) == NULL) {
66		c = xmalloc(sizeof(*c));
67		EVP_CIPHER_CTX_set_app_data(ctx, c);
68	}
69	if (key == NULL)
70		return (1);
71	if (enc == -1)
72		enc = ctx->encrypt;
73	k1 = k2 = k3 = (u_char *) key;
74	k2 += 8;
75	if (EVP_CIPHER_CTX_key_length(ctx) >= 16+8) {
76		if (enc)
77			k3 += 16;
78		else
79			k1 += 16;
80	}
81	EVP_CIPHER_CTX_init(&c->k1);
82	EVP_CIPHER_CTX_init(&c->k2);
83	EVP_CIPHER_CTX_init(&c->k3);
84#ifdef SSH_OLD_EVP
85	EVP_CipherInit(&c->k1, EVP_des_cbc(), k1, NULL, enc);
86	EVP_CipherInit(&c->k2, EVP_des_cbc(), k2, NULL, !enc);
87	EVP_CipherInit(&c->k3, EVP_des_cbc(), k3, NULL, enc);
88#else
89	if (EVP_CipherInit(&c->k1, EVP_des_cbc(), k1, NULL, enc) == 0 ||
90	    EVP_CipherInit(&c->k2, EVP_des_cbc(), k2, NULL, !enc) == 0 ||
91	    EVP_CipherInit(&c->k3, EVP_des_cbc(), k3, NULL, enc) == 0) {
92		memset(c, 0, sizeof(*c));
93		xfree(c);
94		EVP_CIPHER_CTX_set_app_data(ctx, NULL);
95		return (0);
96	}
97#endif
98	return (1);
99}
100
101static int
102ssh1_3des_cbc(EVP_CIPHER_CTX *ctx, u_char *dest, const u_char *src, u_int len)
103{
104	struct ssh1_3des_ctx *c;
105
106	if ((c = EVP_CIPHER_CTX_get_app_data(ctx)) == NULL) {
107		error("ssh1_3des_cbc: no context");
108		return (0);
109	}
110#ifdef SSH_OLD_EVP
111	EVP_Cipher(&c->k1, dest, (u_char *)src, len);
112	EVP_Cipher(&c->k2, dest, dest, len);
113	EVP_Cipher(&c->k3, dest, dest, len);
114#else
115	if (EVP_Cipher(&c->k1, dest, (u_char *)src, len) == 0 ||
116	    EVP_Cipher(&c->k2, dest, dest, len) == 0 ||
117	    EVP_Cipher(&c->k3, dest, dest, len) == 0)
118		return (0);
119#endif
120	return (1);
121}
122
123static int
124ssh1_3des_cleanup(EVP_CIPHER_CTX *ctx)
125{
126	struct ssh1_3des_ctx *c;
127
128	if ((c = EVP_CIPHER_CTX_get_app_data(ctx)) != NULL) {
129		EVP_CIPHER_CTX_cleanup(&c->k1);
130		EVP_CIPHER_CTX_cleanup(&c->k2);
131		EVP_CIPHER_CTX_cleanup(&c->k3);
132		memset(c, 0, sizeof(*c));
133		xfree(c);
134		EVP_CIPHER_CTX_set_app_data(ctx, NULL);
135	}
136	return (1);
137}
138
139void
140ssh1_3des_iv(EVP_CIPHER_CTX *evp, int doset, u_char *iv, int len)
141{
142	struct ssh1_3des_ctx *c;
143
144	if (len != 24)
145		fatal("%s: bad 3des iv length: %d", __func__, len);
146	if ((c = EVP_CIPHER_CTX_get_app_data(evp)) == NULL)
147		fatal("%s: no 3des context", __func__);
148	if (doset) {
149		debug3("%s: Installed 3DES IV", __func__);
150		memcpy(c->k1.iv, iv, 8);
151		memcpy(c->k2.iv, iv + 8, 8);
152		memcpy(c->k3.iv, iv + 16, 8);
153	} else {
154		debug3("%s: Copying 3DES IV", __func__);
155		memcpy(iv, c->k1.iv, 8);
156		memcpy(iv + 8, c->k2.iv, 8);
157		memcpy(iv + 16, c->k3.iv, 8);
158	}
159}
160
161const EVP_CIPHER *
162evp_ssh1_3des(void)
163{
164	static EVP_CIPHER ssh1_3des;
165
166	memset(&ssh1_3des, 0, sizeof(EVP_CIPHER));
167	ssh1_3des.nid = NID_undef;
168	ssh1_3des.block_size = 8;
169	ssh1_3des.iv_len = 0;
170	ssh1_3des.key_len = 16;
171	ssh1_3des.init = ssh1_3des_init;
172	ssh1_3des.cleanup = ssh1_3des_cleanup;
173	ssh1_3des.do_cipher = ssh1_3des_cbc;
174#ifndef SSH_OLD_EVP
175	ssh1_3des.flags = EVP_CIPH_CBC_MODE | EVP_CIPH_VARIABLE_LENGTH;
176#endif
177	return (&ssh1_3des);
178}
179