cipher-3des1.c

   1 /* $OpenBSD: cipher-3des1.c,v 1.4 2006/03/25 13:17:01 djm 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 #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  */
  50 struct ssh1_3des_ctx
  51 {
  52         EVP_CIPHER_CTX  k1, k2, k3;
  53 };
  54
  55 const EVP_CIPHER * evp_ssh1_3des(void);
  56 void ssh1_3des_iv(EVP_CIPHER_CTX *, int, u_char *, int);
  57
  58 static int
  59 ssh1_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
 101 static int
 102 ssh1_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
 123 static int
 124 ssh1_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
 139 void
 140 ssh1_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
 161 const EVP_CIPHER *
 162 evp_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 }