Line data    Source code

       1             : /*      $OpenBSD: michael.c,v 1.2 2008/07/21 19:52:45 damien Exp $      */
       2             : 
       3             : /*
       4             :  * Copyright (c) 2005, 2006 Reyk Floeter <reyk@openbsd.org>
       5             :  *
       6             :  * Permission to use, copy, modify, and distribute this software for any
       7             :  * purpose with or without fee is hereby granted, provided that the above
       8             :  * copyright notice and this permission notice appear in all copies.
       9             :  *
      10             :  * THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
      11             :  * WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
      12             :  * MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
      13             :  * ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
      14             :  * WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
      15             :  * ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
      16             :  * OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
      17             :  */
      18             : 
      19             : /*
      20             :  * Implementation of the Michael MIC as defined in IEEE 802.11i for TKIP.
      21             :  * The MIC generates a 64bit digest, which shouldn't be used for any other
      22             :  * applications except TKIP.
      23             :  */
      24             : 
      25             : #include <sys/param.h>
      26             : #include <sys/systm.h>
      27             : 
      28             : #include <crypto/michael.h>
      29             : 
      30             : #define ROL(n, x)       (((x) << (n)) | ((x) >> (32 - (n))))
      31             : #define ROR(n, x)       (((x) >> (n)) | ((x) << (32 - (n))))
      32             : #define XSWAP(x)        (((x) & 0xff00ff00UL) >> 8 | ((x) & 0x00ff00ffUL) << 8)
      33             : 
      34             : #if defined(__STRICT_ALIGNMENT) || _BYTE_ORDER != _LITTLE_ENDIAN
      35             : #define GETLE32(x)      ((x)[0] | (x)[1] << 8 | (x)[2] << 16 | (x)[3] << 24)
      36             : #define PUTLE32(x, v)   ((x)[0] = (u_int8_t)(v),                        \
      37             :                          (x)[1] = (u_int8_t)((v) >> 8),                   \
      38             :                          (x)[2] = (u_int8_t)((v) >> 16),          \
      39             :                          (x)[3] = (u_int8_t)((v) >> 24))
      40             : #else
      41             : #define GETLE32(x)      (*((u_int32_t *)(x)))
      42             : #define PUTLE32(x, v)   (*((u_int32_t *)(x)) = (v))
      43             : #endif
      44             : 
      45             : #define MICHAEL_BLOCK(l, r) do {                                        \
      46             :         r ^= ROL(17, l);                                                \
      47             :         l += r;                                                         \
      48             :         r ^= XSWAP(l);                                                  \
      49             :         l += r;                                                         \
      50             :         r ^= ROL(3, l);                                                 \
      51             :         l += r;                                                         \
      52             :         r ^= ROR(2, l);                                                 \
      53             :         l += r;                                                         \
      54             : } while (0)
      55             : 
      56             : void
      57           0 : michael_init(MICHAEL_CTX *ctx)
      58             : {
      59           0 :         bzero(ctx, sizeof(MICHAEL_CTX));
      60           0 : }
      61             : 
      62             : void
      63           0 : michael_update(MICHAEL_CTX *ctx, const u_int8_t *data, u_int len)
      64             : {
      65             :         int i;
      66             : 
      67           0 :         for (i = 0; i < len; i++) {
      68           0 :                 ctx->michael_state |= data[i] << (ctx->michael_count << 3);
      69           0 :                 ctx->michael_count++;
      70             : 
      71           0 :                 if (ctx->michael_count >= MICHAEL_RAW_BLOCK_LENGTH) {
      72           0 :                         ctx->michael_l ^= ctx->michael_state;
      73           0 :                         MICHAEL_BLOCK(ctx->michael_l, ctx->michael_r);
      74           0 :                         ctx->michael_state = ctx->michael_count = 0;
      75           0 :                 }
      76             :         }
      77           0 : }
      78             : 
      79             : void
      80           0 : michael_final(u_int8_t digest[MICHAEL_DIGEST_LENGTH], MICHAEL_CTX *ctx)
      81             : {
      82             :         static const u_int8_t pad[] =
      83             :             { 0x5a, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00 };
      84             : 
      85           0 :         michael_update(ctx, pad, sizeof(pad));
      86             : 
      87           0 :         PUTLE32(digest, ctx->michael_l);
      88           0 :         PUTLE32(digest + MICHAEL_RAW_BLOCK_LENGTH, ctx->michael_r);
      89           0 : }
      90             : 
      91             : void
      92           0 : michael_key(const u_int8_t *key, MICHAEL_CTX *ctx)
      93             : {
      94           0 :         ctx->michael_l = ctx->michael_key[0] =
      95           0 :             GETLE32(key);
      96           0 :         ctx->michael_r = ctx->michael_key[1] =
      97           0 :             GETLE32(key + MICHAEL_RAW_BLOCK_LENGTH);
      98           0 : }