crypto/openssh/cipher-3des1.c

   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  */
  43 struct ssh1_3des_ctx
  44 {
  45         EVP_CIPHER_CTX  k1, k2, k3;
  46 };
  47
  48 const EVP_CIPHER * evp_ssh1_3des(void);
  49 int ssh1_3des_iv(EVP_CIPHER_CTX *, int, u_char *, int);
  50
  51 static int
  52 ssh1_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
  89 static int
  90 ssh1_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
 103 static int
 104 ssh1_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
 119 int
 120 ssh1_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
 140 const EVP_CIPHER *
 141 evp_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 }