LXR linux-bk/crypto/michael

   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
  19struct michael_mic_ctx {
  20        u8 pending[4];
  21        size_t pending_len;
  22
  23        u32 l, r;
  24};
  25
  26
  27static inline u32 rotl(u32 val, int bits)
  28{
  29        return (val << bits) | (val >> (32 - bits));
  30}
  31
  32
  33static inline u32 rotr(u32 val, int bits)
  34{
  35        return (val >> bits) | (val << (32 - bits));
  36}
  37
  38
  39static inline u32 xswap(u32 val)
  40{
  41        return ((val & 0x00ff00ff) << 8) | ((val & 0xff00ff00) >> 8);
  42}
  43
  44
  45#define michael_block(l, r)     \
  46do {                            \
  47        r ^= rotl(l, 17);       \
  48        l += r;                 \
  49        r ^= xswap(l);          \
  50        l += r;                 \
  51        r ^= rotl(l, 3);        \
  52        l += r;                 \
  53        r ^= rotr(l, 2);        \
  54        l += r;                 \
  55} while (0)
  56
  57
  58static inline u32 get_le32(const u8 *p)
  59{
  60        return p[0] | (p[1] << 8) | (p[2] << 16) | (p[3] << 24);
  61}
  62
  63
  64static inline void put_le32(u8 *p, u32 v)
  65{
  66        p[0] = v;
  67        p[1] = v >> 8;
  68        p[2] = v >> 16;
  69        p[3] = v >> 24;
  70}
  71
  72
  73static void michael_init(void *ctx)
  74{
  75        struct michael_mic_ctx *mctx = ctx;
  76        mctx->pending_len = 0;
  77}
  78
  79
  80static void michael_update(void *ctx, const u8 *data, unsigned int len)
  81{
  82        struct michael_mic_ctx *mctx = ctx;
  83
  84        if (mctx->pending_len) {
  85                int flen = 4 - mctx->pending_len;
  86                if (flen > len)
  87                        flen = len;
  88                memcpy(&mctx->pending[mctx->pending_len], data, flen);
  89                mctx->pending_len += flen;
  90                data += flen;
  91                len -= flen;
  92
  93                if (mctx->pending_len < 4)
  94                        return;
  95
  96                mctx->l ^= get_le32(mctx->pending);
  97                michael_block(mctx->l, mctx->r);
  98                mctx->pending_len = 0;
  99        }
 100
 101        while (len >= 4) {
 102                mctx->l ^= get_le32(data);
 103                michael_block(mctx->l, mctx->r);
 104                data += 4;
 105                len -= 4;
 106        }
 107
 108        if (len > 0) {
 109                mctx->pending_len = len;
 110                memcpy(mctx->pending, data, len);
 111        }
 112}
 113
 114
 115static void michael_final(void *ctx, u8 *out)
 116{
 117        struct michael_mic_ctx *mctx = ctx;
 118        u8 *data = mctx->pending;
 119
 120        /* Last block and padding (0x5a, 4..7 x 0) */
 121        switch (mctx->pending_len) {
 122        case 0:
 123                mctx->l ^= 0x5a;
 124                break;
 125        case 1:
 126                mctx->l ^= data[0] | 0x5a00;
 127                break;
 128        case 2:
 129                mctx->l ^= data[0] | (data[1] << 8) | 0x5a0000;
 130                break;
 131        case 3:
 132                mctx->l ^= data[0] | (data[1] << 8) | (data[2] << 16) |
 133                        0x5a000000;
 134                break;
 135        }
 136        michael_block(mctx->l, mctx->r);
 137        /* l ^= 0; */
 138        michael_block(mctx->l, mctx->r);
 139
 140        put_le32(out, mctx->l);
 141        put_le32(out + 4, mctx->r);
 142}
 143
 144
 145static int michael_setkey(void *ctx, const u8 *key, unsigned int keylen,
 146                          u32 *flags)
 147{
 148        struct michael_mic_ctx *mctx = ctx;
 149        if (keylen != 8) {
 150                if (flags)
 151                        *flags = CRYPTO_TFM_RES_BAD_KEY_LEN;
 152                return -EINVAL;
 153        }
 154        mctx->l = get_le32(key);
 155        mctx->r = get_le32(key + 4);
 156        return 0;
 157}
 158
 159
 160static struct crypto_alg michael_mic_alg = {
 161        .cra_name       = "michael_mic",
 162        .cra_flags      = CRYPTO_ALG_TYPE_DIGEST,
 163        .cra_blocksize  = 8,
 164        .cra_ctxsize    = sizeof(struct michael_mic_ctx),
 165        .cra_module     = THIS_MODULE,
 166        .cra_list       = LIST_HEAD_INIT(michael_mic_alg.cra_list),
 167        .cra_u          = { .digest = {
 168        .dia_digestsize = 8,
 169        .dia_init       = michael_init,
 170        .dia_update     = michael_update,
 171        .dia_final      = michael_final,
 172        .dia_setkey     = michael_setkey } }
 173};
 174
 175
 176static int __init michael_mic_init(void)
 177{
 178        return crypto_register_alg(&michael_mic_alg);
 179}
 180
 181
 182static void __exit michael_mic_exit(void)
 183{
 184        crypto_unregister_alg(&michael_mic_alg);
 185}
 186
 187
 188module_init(michael_mic_init);
 189module_exit(michael_mic_exit);
 190
 191MODULE_LICENSE("GPL v2");
 192MODULE_DESCRIPTION("Michael MIC");
 193MODULE_AUTHOR("Jouni Malinen <jkmaline@cc.hut.fi>");
 194