cipher-3des1.c

   1 /* $OpenBSD: cipher-3des1.c,v 1.5 2006/07/22 20:48:22 stevesk 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 <openssl/evp.h>
  29
  30 #include <string.h>
  31
  32 #include "xmalloc.h"
  33 #include "log.h"
  34
  35 #if OPENSSL_VERSION_NUMBER < 0x00906000L
  36 #define SSH_OLD_EVP
  37 #endif
  38
  39 /*
  40  * This is used by SSH1:
  41  *
  42  * What kind of triple DES are these 2 routines?
  43  *
  44  * Why is there a redundant initialization vector?
  45  *
  46  * If only iv3 was used, then, this would till effect have been
  47  * outer-cbc. However, there is also a private iv1 == iv2 which
  48  * perhaps makes differential analysis easier. On the other hand, the
  49  * private iv1 probably makes the CRC-32 attack ineffective. This is a
  50  * result of that there is no longer any known iv1 to use when
  51  * choosing the X block.
  52  */
  53 struct ssh1_3des_ctx
  54 {
  55         EVP_CIPHER_CTX  k1, k2, k3;
  56 };
  57
  58 const EVP_CIPHER * evp_ssh1_3des(void);
  59 void ssh1_3des_iv(EVP_CIPHER_CTX *, int, u_char *, int);
  60
  61 static int
  62 ssh1_3des_init(EVP_CIPHER_CTX *ctx, const u_char *key, const u_char *iv,
  63     int enc)
  64 {
  65         struct ssh1_3des_ctx *c;
  66         u_char *k1, *k2, *k3;
  67
  68         if ((c = EVP_CIPHER_CTX_get_app_data(ctx)) == NULL) {
  69                 c = xmalloc(sizeof(*c));
  70                 EVP_CIPHER_CTX_set_app_data(ctx, c);
  71         }
  72         if (key == NULL)
  73                 return (1);
  74         if (enc == -1)
  75                 enc = ctx->encrypt;
  76         k1 = k2 = k3 = (u_char *) key;
  77         k2 += 8;
  78         if (EVP_CIPHER_CTX_key_length(ctx) >= 16+8) {
  79                 if (enc)
  80                         k3 += 16;
  81                 else
  82                         k1 += 16;
  83         }
  84         EVP_CIPHER_CTX_init(&c->k1);
  85         EVP_CIPHER_CTX_init(&c->k2);
  86         EVP_CIPHER_CTX_init(&c->k3);
  87 #ifdef SSH_OLD_EVP
  88         EVP_CipherInit(&c->k1, EVP_des_cbc(), k1, NULL, enc);
  89         EVP_CipherInit(&c->k2, EVP_des_cbc(), k2, NULL, !enc);
  90         EVP_CipherInit(&c->k3, EVP_des_cbc(), k3, NULL, enc);
  91 #else
  92         if (EVP_CipherInit(&c->k1, EVP_des_cbc(), k1, NULL, enc) == 0 ||
  93             EVP_CipherInit(&c->k2, EVP_des_cbc(), k2, NULL, !enc) == 0 ||
  94             EVP_CipherInit(&c->k3, EVP_des_cbc(), k3, NULL, enc) == 0) {
  95                 memset(c, 0, sizeof(*c));
  96                 xfree(c);
  97                 EVP_CIPHER_CTX_set_app_data(ctx, NULL);
  98                 return (0);
  99         }
 100 #endif
 101         return (1);
 102 }
 103
 104 static int
 105 ssh1_3des_cbc(EVP_CIPHER_CTX *ctx, u_char *dest, const u_char *src, u_int len)
 106 {
 107         struct ssh1_3des_ctx *c;
 108
 109         if ((c = EVP_CIPHER_CTX_get_app_data(ctx)) == NULL) {
 110                 error("ssh1_3des_cbc: no context");
 111                 return (0);
 112         }
 113 #ifdef SSH_OLD_EVP
 114         EVP_Cipher(&c->k1, dest, (u_char *)src, len);
 115         EVP_Cipher(&c->k2, dest, dest, len);
 116         EVP_Cipher(&c->k3, dest, dest, len);
 117 #else
 118         if (EVP_Cipher(&c->k1, dest, (u_char *)src, len) == 0 ||
 119             EVP_Cipher(&c->k2, dest, dest, len) == 0 ||
 120             EVP_Cipher(&c->k3, dest, dest, len) == 0)
 121                 return (0);
 122 #endif
 123         return (1);
 124 }
 125
 126 static int
 127 ssh1_3des_cleanup(EVP_CIPHER_CTX *ctx)
 128 {
 129         struct ssh1_3des_ctx *c;
 130
 131         if ((c = EVP_CIPHER_CTX_get_app_data(ctx)) != NULL) {
 132                 EVP_CIPHER_CTX_cleanup(&c->k1);
 133                 EVP_CIPHER_CTX_cleanup(&c->k2);
 134                 EVP_CIPHER_CTX_cleanup(&c->k3);
 135                 memset(c, 0, sizeof(*c));
 136                 xfree(c);
 137                 EVP_CIPHER_CTX_set_app_data(ctx, NULL);
 138         }
 139         return (1);
 140 }
 141
 142 void
 143 ssh1_3des_iv(EVP_CIPHER_CTX *evp, int doset, u_char *iv, int len)
 144 {
 145         struct ssh1_3des_ctx *c;
 146
 147         if (len != 24)
 148                 fatal("%s: bad 3des iv length: %d", __func__, len);
 149         if ((c = EVP_CIPHER_CTX_get_app_data(evp)) == NULL)
 150                 fatal("%s: no 3des context", __func__);
 151         if (doset) {
 152                 debug3("%s: Installed 3DES IV", __func__);
 153                 memcpy(c->k1.iv, iv, 8);
 154                 memcpy(c->k2.iv, iv + 8, 8);
 155                 memcpy(c->k3.iv, iv + 16, 8);
 156         } else {
 157                 debug3("%s: Copying 3DES IV", __func__);
 158                 memcpy(iv, c->k1.iv, 8);
 159                 memcpy(iv + 8, c->k2.iv, 8);
 160                 memcpy(iv + 16, c->k3.iv, 8);
 161         }
 162 }
 163
 164 const EVP_CIPHER *
 165 evp_ssh1_3des(void)
 166 {
 167         static EVP_CIPHER ssh1_3des;
 168
 169         memset(&ssh1_3des, 0, sizeof(EVP_CIPHER));
 170         ssh1_3des.nid = NID_undef;
 171         ssh1_3des.block_size = 8;
 172         ssh1_3des.iv_len = 0;
 173         ssh1_3des.key_len = 16;
 174         ssh1_3des.init = ssh1_3des_init;
 175         ssh1_3des.cleanup = ssh1_3des_cleanup;
 176         ssh1_3des.do_cipher = ssh1_3des_cbc;
 177 #ifndef SSH_OLD_EVP
 178         ssh1_3des.flags = EVP_CIPH_CBC_MODE | EVP_CIPH_VARIABLE_LENGTH;
 179 #endif
 180         return (&ssh1_3des);
 181 }