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 #include <crypto/internal/hash.h>
  13 #include <asm/byteorder.h>
  14 #include <linux/init.h>
  15 #include <linux/module.h>
  16 #include <linux/string.h>
  17 #include <linux/types.h>
  18
  19
  20 struct michael_mic_ctx {
  21         u32 l, r;
  22 };
  23
  24 struct michael_mic_desc_ctx {
  25         u8 pending[4];
  26         size_t pending_len;
  27
  28         u32 l, r;
  29 };
  30
  31 static inline u32 xswap(u32 val)
  32 {
  33         return ((val & 0x00ff00ff) << 8) | ((val & 0xff00ff00) >> 8);
  34 }
  35
  36
  37 #define michael_block(l, r)     \
  38 do {                            \
  39         r ^= rol32(l, 17);      \
  40         l += r;                 \
  41         r ^= xswap(l);          \
  42         l += r;                 \
  43         r ^= rol32(l, 3);       \
  44         l += r;                 \
  45         r ^= ror32(l, 2);       \
  46         l += r;                 \
  47 } while (0)
  48
  49
  50 static int michael_init(struct shash_desc *desc)
  51 {
  52         struct michael_mic_desc_ctx *mctx = shash_desc_ctx(desc);
  53         struct michael_mic_ctx *ctx = crypto_shash_ctx(desc->tfm);
  54         mctx->pending_len = 0;
  55         mctx->l = ctx->l;
  56         mctx->r = ctx->r;
  57
  58         return 0;
  59 }
  60
  61
  62 static int michael_update(struct shash_desc *desc, const u8 *data,
  63                            unsigned int len)
  64 {
  65         struct michael_mic_desc_ctx *mctx = shash_desc_ctx(desc);
  66         const __le32 *src;
  67
  68         if (mctx->pending_len) {
  69                 int flen = 4 - mctx->pending_len;
  70                 if (flen > len)
  71                         flen = len;
  72                 memcpy(&mctx->pending[mctx->pending_len], data, flen);
  73                 mctx->pending_len += flen;
  74                 data += flen;
  75                 len -= flen;
  76
  77                 if (mctx->pending_len < 4)
  78                         return 0;
  79
  80                 src = (const __le32 *)mctx->pending;
  81                 mctx->l ^= le32_to_cpup(src);
  82                 michael_block(mctx->l, mctx->r);
  83                 mctx->pending_len = 0;
  84         }
  85
  86         src = (const __le32 *)data;
  87
  88         while (len >= 4) {
  89                 mctx->l ^= le32_to_cpup(src++);
  90                 michael_block(mctx->l, mctx->r);
  91                 len -= 4;
  92         }
  93
  94         if (len > 0) {
  95                 mctx->pending_len = len;
  96                 memcpy(mctx->pending, src, len);
  97         }
  98
  99         return 0;
 100 }
 101
 102
 103 static int michael_final(struct shash_desc *desc, u8 *out)
 104 {
 105         struct michael_mic_desc_ctx *mctx = shash_desc_ctx(desc);
 106         u8 *data = mctx->pending;
 107         __le32 *dst = (__le32 *)out;
 108
 109         /* Last block and padding (0x5a, 4..7 x 0) */
 110         switch (mctx->pending_len) {
 111         case 0:
 112                 mctx->l ^= 0x5a;
 113                 break;
 114         case 1:
 115                 mctx->l ^= data[0] | 0x5a00;
 116                 break;
 117         case 2:
 118                 mctx->l ^= data[0] | (data[1] << 8) | 0x5a0000;
 119                 break;
 120         case 3:
 121                 mctx->l ^= data[0] | (data[1] << 8) | (data[2] << 16) |
 122                         0x5a000000;
 123                 break;
 124         }
 125         michael_block(mctx->l, mctx->r);
 126         /* l ^= 0; */
 127         michael_block(mctx->l, mctx->r);
 128
 129         dst[0] = cpu_to_le32(mctx->l);
 130         dst[1] = cpu_to_le32(mctx->r);
 131
 132         return 0;
 133 }
 134
 135
 136 static int michael_setkey(struct crypto_shash *tfm, const u8 *key,
 137                           unsigned int keylen)
 138 {
 139         struct michael_mic_ctx *mctx = crypto_shash_ctx(tfm);
 140
 141         const __le32 *data = (const __le32 *)key;
 142
 143         if (keylen != 8) {
 144                 crypto_shash_set_flags(tfm, CRYPTO_TFM_RES_BAD_KEY_LEN);
 145                 return -EINVAL;
 146         }
 147
 148         mctx->l = le32_to_cpu(data[0]);
 149         mctx->r = le32_to_cpu(data[1]);
 150         return 0;
 151 }
 152
 153 static struct shash_alg alg = {
 154         .digestsize             =       8,
 155         .setkey                 =       michael_setkey,
 156         .init                   =       michael_init,
 157         .update                 =       michael_update,
 158         .final                  =       michael_final,
 159         .descsize               =       sizeof(struct michael_mic_desc_ctx),
 160         .base                   =       {
 161                 .cra_name               =       "michael_mic",
 162                 .cra_blocksize          =       8,
 163                 .cra_alignmask          =       3,
 164                 .cra_ctxsize            =       sizeof(struct michael_mic_ctx),
 165                 .cra_module             =       THIS_MODULE,
 166         }
 167 };
 168
 169 static int __init michael_mic_init(void)
 170 {
 171         return crypto_register_shash(&alg);
 172 }
 173
 174
 175 static void __exit michael_mic_exit(void)
 176 {
 177         crypto_unregister_shash(&alg);
 178 }
 179
 180
 181 subsys_initcall(michael_mic_init);
 182 module_exit(michael_mic_exit);
 183
 184 MODULE_LICENSE("GPL v2");
 185 MODULE_DESCRIPTION("Michael MIC");
 186 MODULE_AUTHOR("Jouni Malinen <j@w1.fi>");
 187 MODULE_ALIAS_CRYPTO("michael_mic");