cipher-3des1.c revision 295367 
1/* $OpenBSD: cipher-3des1.c,v 1.12 2015/01/14 10:24:42 markus Exp $ */
2/*
3 * Copyright (c) 2003 Markus Friedl.  All rights reserved.
4 *
5 * Permission to use, copy, modify, and distribute this software for any
6 * purpose with or without fee is hereby granted, provided that the above
7 * copyright notice and this permission notice appear in all copies.
8 *
9 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
10 * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
11 * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
12 * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
13 * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
14 * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
15 * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
16 * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
17 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
18 * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
19 */
20
21#include "includes.h"
22
23#include <sys/types.h>
24#include <string.h>
25#include <openssl/evp.h>
26
27#include "ssherr.h"
28
29/*
30 * This is used by SSH1:
31 *
32 * What kind of triple DES are these 2 routines?
33 *
34 * Why is there a redundant initialization vector?
35 *
36 * If only iv3 was used, then, this would till effect have been
37 * outer-cbc. However, there is also a private iv1 == iv2 which
38 * perhaps makes differential analysis easier. On the other hand, the
39 * private iv1 probably makes the CRC-32 attack ineffective. This is a
40 * result of that there is no longer any known iv1 to use when
41 * choosing the X block.
42 */
43struct ssh1_3des_ctx
44{
45	EVP_CIPHER_CTX	k1, k2, k3;
46};
47
48const EVP_CIPHER * evp_ssh1_3des(void);
49int ssh1_3des_iv(EVP_CIPHER_CTX *, int, u_char *, int);
50
51static int
52ssh1_3des_init(EVP_CIPHER_CTX *ctx, const u_char *key, const u_char *iv,
53    int enc)
54{
55	struct ssh1_3des_ctx *c;
56	u_char *k1, *k2, *k3;
57
58	if ((c = EVP_CIPHER_CTX_get_app_data(ctx)) == NULL) {
59		if ((c = calloc(1, sizeof(*c))) == NULL)
60			return 0;
61		EVP_CIPHER_CTX_set_app_data(ctx, c);
62	}
63	if (key == NULL)
64		return 1;
65	if (enc == -1)
66		enc = ctx->encrypt;
67	k1 = k2 = k3 = (u_char *) key;
68	k2 += 8;
69	if (EVP_CIPHER_CTX_key_length(ctx) >= 16+8) {
70		if (enc)
71			k3 += 16;
72		else
73			k1 += 16;
74	}
75	EVP_CIPHER_CTX_init(&c->k1);
76	EVP_CIPHER_CTX_init(&c->k2);
77	EVP_CIPHER_CTX_init(&c->k3);
78	if (EVP_CipherInit(&c->k1, EVP_des_cbc(), k1, NULL, enc) == 0 ||
79	    EVP_CipherInit(&c->k2, EVP_des_cbc(), k2, NULL, !enc) == 0 ||
80	    EVP_CipherInit(&c->k3, EVP_des_cbc(), k3, NULL, enc) == 0) {
81		explicit_bzero(c, sizeof(*c));
82		free(c);
83		EVP_CIPHER_CTX_set_app_data(ctx, NULL);
84		return 0;
85	}
86	return 1;
87}
88
89static int
90ssh1_3des_cbc(EVP_CIPHER_CTX *ctx, u_char *dest, const u_char *src, size_t len)
91{
92	struct ssh1_3des_ctx *c;
93
94	if ((c = EVP_CIPHER_CTX_get_app_data(ctx)) == NULL)
95		return 0;
96	if (EVP_Cipher(&c->k1, dest, (u_char *)src, len) == 0 ||
97	    EVP_Cipher(&c->k2, dest, dest, len) == 0 ||
98	    EVP_Cipher(&c->k3, dest, dest, len) == 0)
99		return 0;
100	return 1;
101}
102
103static int
104ssh1_3des_cleanup(EVP_CIPHER_CTX *ctx)
105{
106	struct ssh1_3des_ctx *c;
107
108	if ((c = EVP_CIPHER_CTX_get_app_data(ctx)) != NULL) {
109		EVP_CIPHER_CTX_cleanup(&c->k1);
110		EVP_CIPHER_CTX_cleanup(&c->k2);
111		EVP_CIPHER_CTX_cleanup(&c->k3);
112		explicit_bzero(c, sizeof(*c));
113		free(c);
114		EVP_CIPHER_CTX_set_app_data(ctx, NULL);
115	}
116	return 1;
117}
118
119int
120ssh1_3des_iv(EVP_CIPHER_CTX *evp, int doset, u_char *iv, int len)
121{
122	struct ssh1_3des_ctx *c;
123
124	if (len != 24)
125		return SSH_ERR_INVALID_ARGUMENT;
126	if ((c = EVP_CIPHER_CTX_get_app_data(evp)) == NULL)
127		return SSH_ERR_INTERNAL_ERROR;
128	if (doset) {
129		memcpy(c->k1.iv, iv, 8);
130		memcpy(c->k2.iv, iv + 8, 8);
131		memcpy(c->k3.iv, iv + 16, 8);
132	} else {
133		memcpy(iv, c->k1.iv, 8);
134		memcpy(iv + 8, c->k2.iv, 8);
135		memcpy(iv + 16, c->k3.iv, 8);
136	}
137	return 0;
138}
139
140const EVP_CIPHER *
141evp_ssh1_3des(void)
142{
143	static EVP_CIPHER ssh1_3des;
144
145	memset(&ssh1_3des, 0, sizeof(ssh1_3des));
146	ssh1_3des.nid = NID_undef;
147	ssh1_3des.block_size = 8;
148	ssh1_3des.iv_len = 0;
149	ssh1_3des.key_len = 16;
150	ssh1_3des.init = ssh1_3des_init;
151	ssh1_3des.cleanup = ssh1_3des_cleanup;
152	ssh1_3des.do_cipher = ssh1_3des_cbc;
153	ssh1_3des.flags = EVP_CIPH_CBC_MODE | EVP_CIPH_VARIABLE_LENGTH;
154	return &ssh1_3des;
155}
156