This is a multi-part message in MIME format...

------------=_1182413375-53767-1
Content-Type: text/plain; charset="utf-8"
Content-Transfer-Encoding: quoted-printable

openssl:

I have been playing with the AES encryption code that I have "cut out"=20
of the sources and I recently tried using the AES_cbc_encrypt()=20
routine (defined in aes_cbc.c) - comparing it to some "know results" in=20
the WiMedia specifications. I found that the encryption operation was OK=
,=20
but the decryption operation gave the wrong result!! In either=20
case, (encryption/decryption) the routine is also doing something that=20
would appear to be wrong: it is overwriting the IV input string. I have=20
included "my" version of this file (that appears to work correctly in my=20
tests).

The details:

1. Testing done using VC++ v6.0 in Windows, but I believe this is not=20
relevant.
2. file: aes_cbc.c (same version in 0.9.8d and 0.9.8e)

-Bruce

------------=_1182413375-53767-1
Content-Type: text/plain; charset="us-ascii"; name="aes_cbc.c"
Content-Disposition: inline; filename="aes_cbc.c"
Content-Transfer-Encoding: 7bit
RT-Attachment: 1548/16851/6859

/* crypto/aes/aes_cbc.c -*- mode:C; c-file-style: "eay" -*- */
/* ================================================== ==================
* Copyright (c) 1998-2002 The OpenSSL Project. All rights reserved.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions
* are met:
*
* 1. Redistributions of source code must retain the above copyright
* notice, this list of conditions and the following disclaimer.
*
* 2. Redistributions in binary form must reproduce the above copyright
* notice, this list of conditions and the following disclaimer in
* the documentation and/or other materials provided with the
* distribution.
*
* 3. All advertising materials mentioning features or use of this
* software must display the following acknowledgment:
* "This product includes software developed by the OpenSSL Project
* for use in the OpenSSL Toolkit. (http://www.openssl.org/)"
*
* 4. The names "OpenSSL Toolkit" and "OpenSSL Project" must not be used to
* endorse or promote products derived from this software without
* prior written permission. For written permission, please contact
* openssl-core@openssl.org.
*
* 5. Products derived from this software may not be called "OpenSSL"
* nor may "OpenSSL" appear in their names without prior written
* permission of the OpenSSL Project.
*
* 6. Redistributions of any form whatsoever must retain the following
* acknowledgment:
* "This product includes software developed by the OpenSSL Project
* for use in the OpenSSL Toolkit (http://www.openssl.org/)"
*
* THIS SOFTWARE IS PROVIDED BY THE OpenSSL PROJECT ``AS IS'' AND ANY
* EXPRESSED OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
* PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE OpenSSL PROJECT OR
* ITS CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
* SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
* NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
* LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
* HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT,
* STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
* ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED
* OF THE POSSIBILITY OF SUCH DAMAGE.
* ================================================== ==================
*
*/

#ifndef AES_DEBUG
# ifndef NDEBUG
# define NDEBUG
# endif
#endif
#include

#include
#include "aes_locl.h"

/* --- do AES CBC encryption/decryption ---

06/19/07 BRK 1. fixed bug, it was writing back to IV
2. fixed bug, the decryption operation was wrong if in = out
*/
void AES_cbc_encrypt(const unsigned char *in, unsigned char *out,
const unsigned long length, const AES_KEY *key,
unsigned char *ivec, const int enc) {

unsigned long n;
unsigned long len = length;
unsigned char tmp[AES_BLOCK_SIZE];
unsigned char tmp1[AES_BLOCK_SIZE];
const unsigned char *iv = ivec;

assert(in && out && key && ivec);
assert((AES_ENCRYPT == enc)||(AES_DECRYPT == enc));

if (AES_ENCRYPT == enc)
{
while (len >= AES_BLOCK_SIZE)
{
for(n=0; n < AES_BLOCK_SIZE; ++n)
out[n] = in[n] ^ iv[n];
AES_encrypt(out, out, key);
iv = out;
len -= AES_BLOCK_SIZE;
in += AES_BLOCK_SIZE;
out += AES_BLOCK_SIZE;
}
if (len)
{
for(n=0; n < len; ++n)
out[n] = in[n] ^ iv[n];
for(n=len; n < AES_BLOCK_SIZE; ++n)
out[n] = iv[n];
AES_encrypt(out, out, key);
iv = out;
}
}
else /* do DECRYPT case */
if (in != out)
{
while (len >= AES_BLOCK_SIZE)
{
AES_decrypt(in, out, key);
for(n=0; n < AES_BLOCK_SIZE; ++n)
out[n] ^= iv[n];
iv = in;
len -= AES_BLOCK_SIZE;
in += AES_BLOCK_SIZE;
out += AES_BLOCK_SIZE;
}
if (len)
{
AES_decrypt(in,tmp,key);
for(n=0; n < len; ++n)
out[n] = tmp[n] ^ iv[n];
iv = in;
}
}
else
{
while (len >= AES_BLOCK_SIZE)
{
AES_decrypt(in, tmp1, key);
for(n=0; n < AES_BLOCK_SIZE; ++n)
tmp1[n] ^= iv[n];
memcpy(tmp, in, AES_BLOCK_SIZE);
memcpy(out, tmp1, AES_BLOCK_SIZE);
len -= AES_BLOCK_SIZE;
in += AES_BLOCK_SIZE;
out += AES_BLOCK_SIZE;
iv = tmp;
}
if (len)
{
AES_decrypt(in, tmp1, key);
for(n=0; n < len; ++n)
out[n] = tmp1[n] ^ iv[n];
for(n=len; n < AES_BLOCK_SIZE; ++n)
out[n] = iv[n];
}
}
} /* AES_cbc_encrypt */

------------=_1182413375-53767-1--
__________________________________________________ ____________________
OpenSSL Project http://www.openssl.org
Development Mailing List openssl-dev@openssl.org
Automated List Manager majordomo@openssl.org