crypto/michael_mic.c

   1 /*
   2  * Cryptographic API
   3  *
   4  * Michael MIC (IEEE 802.11i/TKIP) keyed digest
   5  *
   6  * Copyright (c) 2004 Jouni Malinen <j@w1.fi>
   7  *
   8  * This program is free software; you can redistribute it and/or modify
   9  * it under the terms of the GNU General Public License version 2 as
  10  * published by the Free Software Foundation.
  11  */
  12
  13 #include <asm/byteorder.h>
  14 #include <linux/init.h>
  15 #include <linux/module.h>
  16 #include <linux/string.h>
  17 #include <linux/crypto.h>
  18 #include <linux/types.h>
  19
  20
  21 struct michael_mic_ctx {
  22         u8 pending[4];
  23         size_t pending_len;
  24
  25         u32 l, r;
  26 };
  27
  28
  29 static inline u32 xswap(u32 val)
  30 {
  31         return ((val & 0x00ff00ff) << 8) | ((val & 0xff00ff00) >> 8);
  32 }
  33
  34
  35 #define michael_block(l, r)     \
  36 do {                            \
  37         r ^= rol32(l, 17);      \
  38         l += r;                 \
  39         r ^= xswap(l);          \
  40         l += r;                 \
  41         r ^= rol32(l, 3);       \
  42         l += r;                 \
  43         r ^= ror32(l, 2);       \
  44         l += r;                 \
  45 } while (0)
  46
  47
  48 static void michael_init(struct crypto_tfm *tfm)
  49 {
  50         struct michael_mic_ctx *mctx = crypto_tfm_ctx(tfm);
  51         mctx->pending_len = 0;
  52 }
  53
  54
  55 static void michael_update(struct crypto_tfm *tfm, const u8 *data,
  56                            unsigned int len)
  57 {
  58         struct michael_mic_ctx *mctx = crypto_tfm_ctx(tfm);
  59         const __le32 *src;
  60
  61         if (mctx->pending_len) {
  62                 int flen = 4 - mctx->pending_len;
  63                 if (flen > len)
  64                         flen = len;
  65                 memcpy(&mctx->pending[mctx->pending_len], data, flen);
  66                 mctx->pending_len += flen;
  67                 data += flen;
  68                 len -= flen;
  69
  70                 if (mctx->pending_len < 4)
  71                         return;
  72
  73                 src = (const __le32 *)mctx->pending;
  74                 mctx->l ^= le32_to_cpup(src);
  75                 michael_block(mctx->l, mctx->r);
  76                 mctx->pending_len = 0;
  77         }
  78
  79         src = (const __le32 *)data;
  80
  81         while (len >= 4) {
  82                 mctx->l ^= le32_to_cpup(src++);
  83                 michael_block(mctx->l, mctx->r);
  84                 len -= 4;
  85         }
  86
  87         if (len > 0) {
  88                 mctx->pending_len = len;
  89                 memcpy(mctx->pending, src, len);
  90         }
  91 }
  92
  93
  94 static void michael_final(struct crypto_tfm *tfm, u8 *out)
  95 {
  96         struct michael_mic_ctx *mctx = crypto_tfm_ctx(tfm);
  97         u8 *data = mctx->pending;
  98         __le32 *dst = (__le32 *)out;
  99
 100         /* Last block and padding (0x5a, 4..7 x 0) */
 101         switch (mctx->pending_len) {
 102         case 0:
 103                 mctx->l ^= 0x5a;
 104                 break;
 105         case 1:
 106                 mctx->l ^= data[0] | 0x5a00;
 107                 break;
 108         case 2:
 109                 mctx->l ^= data[0] | (data[1] << 8) | 0x5a0000;
 110                 break;
 111         case 3:
 112                 mctx->l ^= data[0] | (data[1] << 8) | (data[2] << 16) |
 113                         0x5a000000;
 114                 break;
 115         }
 116         michael_block(mctx->l, mctx->r);
 117         /* l ^= 0; */
 118         michael_block(mctx->l, mctx->r);
 119
 120         dst[0] = cpu_to_le32(mctx->l);
 121         dst[1] = cpu_to_le32(mctx->r);
 122 }
 123
 124
 125 static int michael_setkey(struct crypto_tfm *tfm, const u8 *key,
 126                           unsigned int keylen)
 127 {
 128         struct michael_mic_ctx *mctx = crypto_tfm_ctx(tfm);
 129         const __le32 *data = (const __le32 *)key;
 130
 131         if (keylen != 8) {
 132                 tfm->crt_flags |= CRYPTO_TFM_RES_BAD_KEY_LEN;
 133                 return -EINVAL;
 134         }
 135
 136         mctx->l = le32_to_cpu(data[0]);
 137         mctx->r = le32_to_cpu(data[1]);
 138         return 0;
 139 }
 140
 141
 142 static struct crypto_alg michael_mic_alg = {
 143         .cra_name       = "michael_mic",
 144         .cra_flags      = CRYPTO_ALG_TYPE_DIGEST,
 145         .cra_blocksize  = 8,
 146         .cra_ctxsize    = sizeof(struct michael_mic_ctx),
 147         .cra_module     = THIS_MODULE,
 148         .cra_alignmask  = 3,
 149         .cra_list       = LIST_HEAD_INIT(michael_mic_alg.cra_list),
 150         .cra_u          = { .digest = {
 151         .dia_digestsize = 8,
 152         .dia_init       = michael_init,
 153         .dia_update     = michael_update,
 154         .dia_final      = michael_final,
 155         .dia_setkey     = michael_setkey } }
 156 };
 157
 158
 159 static int __init michael_mic_init(void)
 160 {
 161         return crypto_register_alg(&michael_mic_alg);
 162 }
 163
 164
 165 static void __exit michael_mic_exit(void)
 166 {
 167         crypto_unregister_alg(&michael_mic_alg);
 168 }
 169
 170
 171 module_init(michael_mic_init);
 172 module_exit(michael_mic_exit);
 173
 174 MODULE_LICENSE("GPL v2");
 175 MODULE_DESCRIPTION("Michael MIC");
 176 MODULE_AUTHOR("Jouni Malinen <j@w1.fi>");