cipher-bf1.c

   1 /* $OpenBSD: cipher-bf1.c,v 1.5 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 <string.h>
  33
  34 #include "xmalloc.h"
  35 #include "log.h"
  36
  37 #if OPENSSL_VERSION_NUMBER < 0x00906000L
  38 #define SSH_OLD_EVP
  39 #endif
  40
  41 /*
  42  * SSH1 uses a variation on Blowfish, all bytes must be swapped before
  43  * and after encryption/decryption. Thus the swap_bytes stuff (yuk).
  44  */
  45
  46 const EVP_CIPHER * evp_ssh1_bf(void);
  47
  48 static void
  49 swap_bytes(const u_char *src, u_char *dst, int n)
  50 {
  51         u_char c[4];
  52
  53         /* Process 4 bytes every lap. */
  54         for (n = n / 4; n > 0; n--) {
  55                 c[3] = *src++;
  56                 c[2] = *src++;
  57                 c[1] = *src++;
  58                 c[0] = *src++;
  59
  60                 *dst++ = c[0];
  61                 *dst++ = c[1];
  62                 *dst++ = c[2];
  63                 *dst++ = c[3];
  64         }
  65 }
  66
  67 #ifdef SSH_OLD_EVP
  68 static void bf_ssh1_init (EVP_CIPHER_CTX * ctx, const unsigned char *key,
  69                           const unsigned char *iv, int enc)
  70 {
  71         if (iv != NULL)
  72                 memcpy (&(ctx->oiv[0]), iv, 8);
  73         memcpy (&(ctx->iv[0]), &(ctx->oiv[0]), 8);
  74         if (key != NULL)
  75                 BF_set_key (&(ctx->c.bf_ks), EVP_CIPHER_CTX_key_length (ctx),
  76                             key);
  77 }
  78 #endif
  79
  80 static int (*orig_bf)(EVP_CIPHER_CTX *, u_char *, const u_char *, u_int) = NULL;
  81
  82 static int
  83 bf_ssh1_cipher(EVP_CIPHER_CTX *ctx, u_char *out, const u_char *in, u_int len)
  84 {
  85         int ret;
  86
  87         swap_bytes(in, out, len);
  88         ret = (*orig_bf)(ctx, out, out, len);
  89         swap_bytes(out, out, len);
  90         return (ret);
  91 }
  92
  93 const EVP_CIPHER *
  94 evp_ssh1_bf(void)
  95 {
  96         static EVP_CIPHER ssh1_bf;
  97
  98         memcpy(&ssh1_bf, EVP_bf_cbc(), sizeof(EVP_CIPHER));
  99         orig_bf = ssh1_bf.do_cipher;
 100         ssh1_bf.nid = NID_undef;
 101 #ifdef SSH_OLD_EVP
 102         ssh1_bf.init = bf_ssh1_init;
 103 #endif
 104         ssh1_bf.do_cipher = bf_ssh1_cipher;
 105         ssh1_bf.key_len = 32;
 106         return (&ssh1_bf);
 107 }