cipher-aes.c

   1 /*
   2  * Copyright (c) 2003 Markus Friedl.  All rights reserved.
   3  *
   4  * Redistribution and use in source and binary forms, with or without
   5  * modification, are permitted provided that the following conditions
   6  * are met:
   7  * 1. Redistributions of source code must retain the above copyright
   8  *    notice, this list of conditions and the following disclaimer.
   9  * 2. Redistributions in binary form must reproduce the above copyright
  10  *    notice, this list of conditions and the following disclaimer in the
  11  *    documentation and/or other materials provided with the distribution.
  12  *
  13  * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
  14  * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
  15  * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
  16  * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
  17  * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
  18  * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
  19  * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
  20  * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
  21  * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
  22  * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
  23  */
  24
  25 #include "includes.h"
  26
  27 /* compatibility with old or broken OpenSSL versions */
  28 #include "openbsd-compat/openssl-compat.h"
  29
  30 #ifdef USE_BUILTIN_RIJNDAEL
  31
  32 #include <openssl/evp.h>
  33 #include "rijndael.h"
  34 #include "xmalloc.h"
  35 #include "log.h"
  36
  37 #define RIJNDAEL_BLOCKSIZE 16
  38 struct ssh_rijndael_ctx
  39 {
  40         rijndael_ctx    r_ctx;
  41         u_char          r_iv[RIJNDAEL_BLOCKSIZE];
  42 };
  43
  44 const EVP_CIPHER * evp_rijndael(void);
  45 void ssh_rijndael_iv(EVP_CIPHER_CTX *, int, u_char *, u_int);
  46
  47 static int
  48 ssh_rijndael_init(EVP_CIPHER_CTX *ctx, const u_char *key, const u_char *iv,
  49     int enc)
  50 {
  51         struct ssh_rijndael_ctx *c;
  52
  53         if ((c = EVP_CIPHER_CTX_get_app_data(ctx)) == NULL) {
  54                 c = xmalloc(sizeof(*c));
  55                 EVP_CIPHER_CTX_set_app_data(ctx, c);
  56         }
  57         if (key != NULL) {
  58                 if (enc == -1)
  59                         enc = ctx->encrypt;
  60                 rijndael_set_key(&c->r_ctx, (u_char *)key,
  61                     8*EVP_CIPHER_CTX_key_length(ctx), enc);
  62         }
  63         if (iv != NULL)
  64                 memcpy(c->r_iv, iv, RIJNDAEL_BLOCKSIZE);
  65         return (1);
  66 }
  67
  68 static int
  69 ssh_rijndael_cbc(EVP_CIPHER_CTX *ctx, u_char *dest, const u_char *src,
  70     u_int len)
  71 {
  72         struct ssh_rijndael_ctx *c;
  73         u_char buf[RIJNDAEL_BLOCKSIZE];
  74         u_char *cprev, *cnow, *plain, *ivp;
  75         int i, j, blocks = len / RIJNDAEL_BLOCKSIZE;
  76
  77         if (len == 0)
  78                 return (1);
  79         if (len % RIJNDAEL_BLOCKSIZE)
  80                 fatal("ssh_rijndael_cbc: bad len %d", len);
  81         if ((c = EVP_CIPHER_CTX_get_app_data(ctx)) == NULL) {
  82                 error("ssh_rijndael_cbc: no context");
  83                 return (0);
  84         }
  85         if (ctx->encrypt) {
  86                 cnow  = dest;
  87                 plain = (u_char *)src;
  88                 cprev = c->r_iv;
  89                 for (i = 0; i < blocks; i++, plain+=RIJNDAEL_BLOCKSIZE,
  90                     cnow+=RIJNDAEL_BLOCKSIZE) {
  91                         for (j = 0; j < RIJNDAEL_BLOCKSIZE; j++)
  92                                 buf[j] = plain[j] ^ cprev[j];
  93                         rijndael_encrypt(&c->r_ctx, buf, cnow);
  94                         cprev = cnow;
  95                 }
  96                 memcpy(c->r_iv, cprev, RIJNDAEL_BLOCKSIZE);
  97         } else {
  98                 cnow  = (u_char *) (src+len-RIJNDAEL_BLOCKSIZE);
  99                 plain = dest+len-RIJNDAEL_BLOCKSIZE;
 100
 101                 memcpy(buf, cnow, RIJNDAEL_BLOCKSIZE);
 102                 for (i = blocks; i > 0; i--, cnow-=RIJNDAEL_BLOCKSIZE,
 103                     plain-=RIJNDAEL_BLOCKSIZE) {
 104                         rijndael_decrypt(&c->r_ctx, cnow, plain);
 105                         ivp = (i == 1) ? c->r_iv : cnow-RIJNDAEL_BLOCKSIZE;
 106                         for (j = 0; j < RIJNDAEL_BLOCKSIZE; j++)
 107                                 plain[j] ^= ivp[j];
 108                 }
 109                 memcpy(c->r_iv, buf, RIJNDAEL_BLOCKSIZE);
 110         }
 111         return (1);
 112 }
 113
 114 static int
 115 ssh_rijndael_cleanup(EVP_CIPHER_CTX *ctx)
 116 {
 117         struct ssh_rijndael_ctx *c;
 118
 119         if ((c = EVP_CIPHER_CTX_get_app_data(ctx)) != NULL) {
 120                 memset(c, 0, sizeof(*c));
 121                 xfree(c);
 122                 EVP_CIPHER_CTX_set_app_data(ctx, NULL);
 123         }
 124         return (1);
 125 }
 126
 127 void
 128 ssh_rijndael_iv(EVP_CIPHER_CTX *evp, int doset, u_char * iv, u_int len)
 129 {
 130         struct ssh_rijndael_ctx *c;
 131
 132         if ((c = EVP_CIPHER_CTX_get_app_data(evp)) == NULL)
 133                 fatal("ssh_rijndael_iv: no context");
 134         if (doset)
 135                 memcpy(c->r_iv, iv, len);
 136         else
 137                 memcpy(iv, c->r_iv, len);
 138 }
 139
 140 const EVP_CIPHER *
 141 evp_rijndael(void)
 142 {
 143         static EVP_CIPHER rijndal_cbc;
 144
 145         memset(&rijndal_cbc, 0, sizeof(EVP_CIPHER));
 146         rijndal_cbc.nid = NID_undef;
 147         rijndal_cbc.block_size = RIJNDAEL_BLOCKSIZE;
 148         rijndal_cbc.iv_len = RIJNDAEL_BLOCKSIZE;
 149         rijndal_cbc.key_len = 16;
 150         rijndal_cbc.init = ssh_rijndael_init;
 151         rijndal_cbc.cleanup = ssh_rijndael_cleanup;
 152         rijndal_cbc.do_cipher = ssh_rijndael_cbc;
 153 #ifndef SSH_OLD_EVP
 154         rijndal_cbc.flags = EVP_CIPH_CBC_MODE | EVP_CIPH_VARIABLE_LENGTH |
 155             EVP_CIPH_ALWAYS_CALL_INIT | EVP_CIPH_CUSTOM_IV;
 156 #endif
 157         return (&rijndal_cbc);
 158 }
 159 #endif /* USE_BUILTIN_RIJNDAEL */