cipher-3des1.c revision 162853 
1/* $OpenBSD: cipher-3des1.c,v 1.6 2006/08/03 03:34:42 deraadt Exp $ */
2/*
3 * Copyright (c) 2003 Markus Friedl.  All rights reserved.
4 *
5 * Redistribution and use in source and binary forms, with or without
6 * modification, are permitted provided that the following conditions
7 * are met:
8 * 1. Redistributions of source code must retain the above copyright
9 *    notice, this list of conditions and the following disclaimer.
10 * 2. Redistributions in binary form must reproduce the above copyright
11 *    notice, this list of conditions and the following disclaimer in the
12 *    documentation and/or other materials provided with the distribution.
13 *
14 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
15 * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
16 * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
17 * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
18 * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
19 * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
20 * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
21 * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
22 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
23 * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
24 */
25
26#include "includes.h"
27
28#include <sys/types.h>
29
30#include <openssl/evp.h>
31
32#include <stdarg.h>
33#include <string.h>
34
35#include "xmalloc.h"
36#include "log.h"
37
38#if OPENSSL_VERSION_NUMBER < 0x00906000L
39#define SSH_OLD_EVP
40#endif
41
42/*
43 * This is used by SSH1:
44 *
45 * What kind of triple DES are these 2 routines?
46 *
47 * Why is there a redundant initialization vector?
48 *
49 * If only iv3 was used, then, this would till effect have been
50 * outer-cbc. However, there is also a private iv1 == iv2 which
51 * perhaps makes differential analysis easier. On the other hand, the
52 * private iv1 probably makes the CRC-32 attack ineffective. This is a
53 * result of that there is no longer any known iv1 to use when
54 * choosing the X block.
55 */
56struct ssh1_3des_ctx
57{
58	EVP_CIPHER_CTX	k1, k2, k3;
59};
60
61const EVP_CIPHER * evp_ssh1_3des(void);
62void ssh1_3des_iv(EVP_CIPHER_CTX *, int, u_char *, int);
63
64static int
65ssh1_3des_init(EVP_CIPHER_CTX *ctx, const u_char *key, const u_char *iv,
66    int enc)
67{
68	struct ssh1_3des_ctx *c;
69	u_char *k1, *k2, *k3;
70
71	if ((c = EVP_CIPHER_CTX_get_app_data(ctx)) == NULL) {
72		c = xmalloc(sizeof(*c));
73		EVP_CIPHER_CTX_set_app_data(ctx, c);
74	}
75	if (key == NULL)
76		return (1);
77	if (enc == -1)
78		enc = ctx->encrypt;
79	k1 = k2 = k3 = (u_char *) key;
80	k2 += 8;
81	if (EVP_CIPHER_CTX_key_length(ctx) >= 16+8) {
82		if (enc)
83			k3 += 16;
84		else
85			k1 += 16;
86	}
87	EVP_CIPHER_CTX_init(&c->k1);
88	EVP_CIPHER_CTX_init(&c->k2);
89	EVP_CIPHER_CTX_init(&c->k3);
90#ifdef SSH_OLD_EVP
91	EVP_CipherInit(&c->k1, EVP_des_cbc(), k1, NULL, enc);
92	EVP_CipherInit(&c->k2, EVP_des_cbc(), k2, NULL, !enc);
93	EVP_CipherInit(&c->k3, EVP_des_cbc(), k3, NULL, enc);
94#else
95	if (EVP_CipherInit(&c->k1, EVP_des_cbc(), k1, NULL, enc) == 0 ||
96	    EVP_CipherInit(&c->k2, EVP_des_cbc(), k2, NULL, !enc) == 0 ||
97	    EVP_CipherInit(&c->k3, EVP_des_cbc(), k3, NULL, enc) == 0) {
98		memset(c, 0, sizeof(*c));
99		xfree(c);
100		EVP_CIPHER_CTX_set_app_data(ctx, NULL);
101		return (0);
102	}
103#endif
104	return (1);
105}
106
107static int
108ssh1_3des_cbc(EVP_CIPHER_CTX *ctx, u_char *dest, const u_char *src, u_int len)
109{
110	struct ssh1_3des_ctx *c;
111
112	if ((c = EVP_CIPHER_CTX_get_app_data(ctx)) == NULL) {
113		error("ssh1_3des_cbc: no context");
114		return (0);
115	}
116#ifdef SSH_OLD_EVP
117	EVP_Cipher(&c->k1, dest, (u_char *)src, len);
118	EVP_Cipher(&c->k2, dest, dest, len);
119	EVP_Cipher(&c->k3, dest, dest, len);
120#else
121	if (EVP_Cipher(&c->k1, dest, (u_char *)src, len) == 0 ||
122	    EVP_Cipher(&c->k2, dest, dest, len) == 0 ||
123	    EVP_Cipher(&c->k3, dest, dest, len) == 0)
124		return (0);
125#endif
126	return (1);
127}
128
129static int
130ssh1_3des_cleanup(EVP_CIPHER_CTX *ctx)
131{
132	struct ssh1_3des_ctx *c;
133
134	if ((c = EVP_CIPHER_CTX_get_app_data(ctx)) != NULL) {
135		EVP_CIPHER_CTX_cleanup(&c->k1);
136		EVP_CIPHER_CTX_cleanup(&c->k2);
137		EVP_CIPHER_CTX_cleanup(&c->k3);
138		memset(c, 0, sizeof(*c));
139		xfree(c);
140		EVP_CIPHER_CTX_set_app_data(ctx, NULL);
141	}
142	return (1);
143}
144
145void
146ssh1_3des_iv(EVP_CIPHER_CTX *evp, int doset, u_char *iv, int len)
147{
148	struct ssh1_3des_ctx *c;
149
150	if (len != 24)
151		fatal("%s: bad 3des iv length: %d", __func__, len);
152	if ((c = EVP_CIPHER_CTX_get_app_data(evp)) == NULL)
153		fatal("%s: no 3des context", __func__);
154	if (doset) {
155		debug3("%s: Installed 3DES IV", __func__);
156		memcpy(c->k1.iv, iv, 8);
157		memcpy(c->k2.iv, iv + 8, 8);
158		memcpy(c->k3.iv, iv + 16, 8);
159	} else {
160		debug3("%s: Copying 3DES IV", __func__);
161		memcpy(iv, c->k1.iv, 8);
162		memcpy(iv + 8, c->k2.iv, 8);
163		memcpy(iv + 16, c->k3.iv, 8);
164	}
165}
166
167const EVP_CIPHER *
168evp_ssh1_3des(void)
169{
170	static EVP_CIPHER ssh1_3des;
171
172	memset(&ssh1_3des, 0, sizeof(EVP_CIPHER));
173	ssh1_3des.nid = NID_undef;
174	ssh1_3des.block_size = 8;
175	ssh1_3des.iv_len = 0;
176	ssh1_3des.key_len = 16;
177	ssh1_3des.init = ssh1_3des_init;
178	ssh1_3des.cleanup = ssh1_3des_cleanup;
179	ssh1_3des.do_cipher = ssh1_3des_cbc;
180#ifndef SSH_OLD_EVP
181	ssh1_3des.flags = EVP_CIPH_CBC_MODE | EVP_CIPH_VARIABLE_LENGTH;
182#endif
183	return (&ssh1_3des);
184}
185