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 <jkmaline@cc.hut.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 <linux/init.h>
  14 #include <linux/module.h>
  15 #include <linux/string.h>
  16 #include <linux/crypto.h>
  17
  18
  19 struct michael_mic_ctx {
  20         u8 pending[4];
  21         size_t pending_len;
  22
  23         u32 l, r;
  24 };
  25
  26
  27 static inline u32 xswap(u32 val)
  28 {
  29         return ((val & 0x00ff00ff) << 8) | ((val & 0xff00ff00) >> 8);
  30 }
  31
  32
  33 #define michael_block(l, r)     \
  34 do {                            \
  35         r ^= rol32(l, 17);      \
  36         l += r;                 \
  37         r ^= xswap(l);          \
  38         l += r;                 \
  39         r ^= rol32(l, 3);       \
  40         l += r;                 \
  41         r ^= ror32(l, 2);       \
  42         l += r;                 \
  43 } while (0)
  44
  45
  46 static inline u32 get_le32(const u8 *p)
  47 {
  48         return p[0] | (p[1] << 8) | (p[2] << 16) | (p[3] << 24);
  49 }
  50
  51
  52 static inline void put_le32(u8 *p, u32 v)
  53 {
  54         p[0] = v;
  55         p[1] = v >> 8;
  56         p[2] = v >> 16;
  57         p[3] = v >> 24;
  58 }
  59
  60
  61 static void michael_init(void *ctx)
  62 {
  63         struct michael_mic_ctx *mctx = ctx;
  64         mctx->pending_len = 0;
  65 }
  66
  67
  68 static void michael_update(void *ctx, const u8 *data, unsigned int len)
  69 {
  70         struct michael_mic_ctx *mctx = ctx;
  71
  72         if (mctx->pending_len) {
  73                 int flen = 4 - mctx->pending_len;
  74                 if (flen > len)
  75                         flen = len;
  76                 memcpy(&mctx->pending[mctx->pending_len], data, flen);
  77                 mctx->pending_len += flen;
  78                 data += flen;
  79                 len -= flen;
  80
  81                 if (mctx->pending_len < 4)
  82                         return;
  83
  84                 mctx->l ^= get_le32(mctx->pending);
  85                 michael_block(mctx->l, mctx->r);
  86                 mctx->pending_len = 0;
  87         }
  88
  89         while (len >= 4) {
  90                 mctx->l ^= get_le32(data);
  91                 michael_block(mctx->l, mctx->r);
  92                 data += 4;
  93                 len -= 4;
  94         }
  95
  96         if (len > 0) {
  97                 mctx->pending_len = len;
  98                 memcpy(mctx->pending, data, len);
  99         }
 100 }
 101
 102
 103 static void michael_final(void *ctx, u8 *out)
 104 {
 105         struct michael_mic_ctx *mctx = ctx;
 106         u8 *data = mctx->pending;
 107
 108         /* Last block and padding (0x5a, 4..7 x 0) */
 109         switch (mctx->pending_len) {
 110         case 0:
 111                 mctx->l ^= 0x5a;
 112                 break;
 113         case 1:
 114                 mctx->l ^= data[0] | 0x5a00;
 115                 break;
 116         case 2:
 117                 mctx->l ^= data[0] | (data[1] << 8) | 0x5a0000;
 118                 break;
 119         case 3:
 120                 mctx->l ^= data[0] | (data[1] << 8) | (data[2] << 16) |
 121                         0x5a000000;
 122                 break;
 123         }
 124         michael_block(mctx->l, mctx->r);
 125         /* l ^= 0; */
 126         michael_block(mctx->l, mctx->r);
 127
 128         put_le32(out, mctx->l);
 129         put_le32(out + 4, mctx->r);
 130 }
 131
 132
 133 static int michael_setkey(void *ctx, const u8 *key, unsigned int keylen,
 134                           u32 *flags)
 135 {
 136         struct michael_mic_ctx *mctx = ctx;
 137         if (keylen != 8) {
 138                 if (flags)
 139                         *flags = CRYPTO_TFM_RES_BAD_KEY_LEN;
 140                 return -EINVAL;
 141         }
 142         mctx->l = get_le32(key);
 143         mctx->r = get_le32(key + 4);
 144         return 0;
 145 }
 146
 147
 148 static struct crypto_alg michael_mic_alg = {
 149         .cra_name       = "michael_mic",
 150         .cra_flags      = CRYPTO_ALG_TYPE_DIGEST,
 151         .cra_blocksize  = 8,
 152         .cra_ctxsize    = sizeof(struct michael_mic_ctx),
 153         .cra_module     = THIS_MODULE,
 154         .cra_list       = LIST_HEAD_INIT(michael_mic_alg.cra_list),
 155         .cra_u          = { .digest = {
 156         .dia_digestsize = 8,
 157         .dia_init       = michael_init,
 158         .dia_update     = michael_update,
 159         .dia_final      = michael_final,
 160         .dia_setkey     = michael_setkey } }
 161 };
 162
 163
 164 static int __init michael_mic_init(void)
 165 {
 166         return crypto_register_alg(&michael_mic_alg);
 167 }
 168
 169
 170 static void __exit michael_mic_exit(void)
 171 {
 172         crypto_unregister_alg(&michael_mic_alg);
 173 }
 174
 175
 176 module_init(michael_mic_init);
 177 module_exit(michael_mic_exit);
 178
 179 MODULE_LICENSE("GPL v2");
 180 MODULE_DESCRIPTION("Michael MIC");
 181 MODULE_AUTHOR("Jouni Malinen <jkmaline@cc.hut.fi>");