92 lines
2.7 KiB
C
92 lines
2.7 KiB
C
/**
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* airpdcap_rijndael.c
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*
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* @version 3.0 (December 2000)
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*
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* Optimised ANSI C code for the Rijndael cipher (now AES)
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*
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* @author Vincent Rijmen <vincent.rijmen@esat.kuleuven.ac.be>
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* @author Antoon Bosselaers <antoon.bosselaers@esat.kuleuven.ac.be>
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* @author Paulo Barreto <paulo.barreto@terra.com.br>
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*
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* This code is hereby placed in the public domain.
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*
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* THIS SOFTWARE IS PROVIDED BY THE AUTHORS ''AS IS'' AND ANY EXPRESS
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* OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED
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* WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
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* ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHORS OR CONTRIBUTORS BE
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* LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
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* CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
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* SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR
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* BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY,
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* WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE
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* OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE,
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* EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
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*/
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#include "airpdcap_rijndael.h"
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#include "airpdcap_debug.h"
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#include <glib.h>
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#include <wsutil/aes.h>
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/* Based on RFC 3394 and NIST AES Key Wrap Specification pseudo-code.
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This function is used to unwrap an encrypted AES key. One example of its use is
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in the WPA-2 protocol to get the group key.
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*/
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UCHAR *
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AES_unwrap(UCHAR *kek, UINT16 key_len, UCHAR *cipher_text, UINT16 cipher_len)
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{
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UCHAR *output;
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UCHAR a[8], b[16];
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UCHAR *r;
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gint16 i, j, n;
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rijndael_ctx ctx;
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if (kek == NULL || cipher_len < 16 || cipher_text == NULL) {
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return NULL; /* "should not happen" */
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}
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/* Allocate buffer for the unwrapped key */
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output = (guint8 *) g_malloc0(cipher_len);
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/* Initialize variables */
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n = (cipher_len/8)-1; /* the algorithm works on 64-bits at a time */
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memcpy(a, cipher_text, 8);
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r = output;
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memcpy(r, cipher_text+8, cipher_len - 8);
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/* Compute intermediate values */
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for (j=5; j >= 0; --j){
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r = output + (n - 1) * 8;
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/* DEBUG_DUMP("r1", (r-8), 8); */
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/* DEBUG_DUMP("r2", r, 8); */
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for (i = n; i >= 1; --i){
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UINT16 t = (n*j) + i;
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/* DEBUG_DUMP("a", a, 8); */
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memcpy(b, a, 8);
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b[7] ^= t;
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/* DEBUG_DUMP("a plus t", b, 8); */
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memcpy(b+8, r, 8);
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rijndael_set_key(&ctx, kek, key_len*8 /*bits*/);
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rijndael_decrypt(&ctx, b, b); /* NOTE: we are using the same src and dst buffer. It's ok. */
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/* DEBUG_DUMP("aes decrypt", b, 16) */
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memcpy(a,b,8);
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memcpy(r, b+8, 8);
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r -= 8;
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}
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}
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/* DEBUG_DUMP("a", a, 8); */
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/* DEBUG_DUMP("output", output, cipher_len - 8); */
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return output;
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}
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/* */
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/******************************************************************************/
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