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/*
* Cryptographic API
*
* Michael MIC (IEEE 802.11i/TKIP) keyed digest
*
* Copyright (c) 2004 Jouni Malinen <jkmaline@cc.hut.fi>
*
* This program is free software; you can redistribute it and/or modify
* it under the terms of the GNU General Public License version 2 as
* published by the Free Software Foundation.
*/
#include <asm/byteorder.h>
#include <linux/init.h>
#include <linux/module.h>
#include <linux/string.h>
#include <linux/crypto.h>
#include <linux/types.h>
struct michael_mic_ctx {
u8 pending[4];
size_t pending_len;
u32 l, r;
};
static inline u32 xswap(u32 val)
{
return ((val & 0x00ff00ff) << 8) | ((val & 0xff00ff00) >> 8);
}
#define michael_block(l, r) \
do { \
r ^= rol32(l, 17); \
l += r; \
r ^= xswap(l); \
l += r; \
r ^= rol32(l, 3); \
l += r; \
r ^= ror32(l, 2); \
l += r; \
} while (0)
static void michael_init(struct crypto_tfm *tfm)
{
struct michael_mic_ctx *mctx = crypto_tfm_ctx(tfm);
mctx->pending_len = 0;
}
static void michael_update(struct crypto_tfm *tfm, const u8 *data,
unsigned int len)
{
struct michael_mic_ctx *mctx = crypto_tfm_ctx(tfm);
const __le32 *src;
if (mctx->pending_len) {
int flen = 4 - mctx->pending_len;
if (flen > len)
flen = len;
memcpy(&mctx->pending[mctx->pending_len], data, flen);
mctx->pending_len += flen;
data += flen;
len -= flen;
if (mctx->pending_len < 4)
return;
src = (const __le32 *)mctx->pending;
mctx->l ^= le32_to_cpup(src);
michael_block(mctx->l, mctx->r);
mctx->pending_len = 0;
}
src = (const __le32 *)data;
while (len >= 4) {
mctx->l ^= le32_to_cpup(src++);
michael_block(mctx->l, mctx->r);
len -= 4;
}
if (len > 0) {
mctx->pending_len = len;
memcpy(mctx->pending, src, len);
}
}
static void michael_final(struct crypto_tfm *tfm, u8 *out)
{
struct michael_mic_ctx *mctx = crypto_tfm_ctx(tfm);
u8 *data = mctx->pending;
__le32 *dst = (__le32 *)out;
/* Last block and padding (0x5a, 4..7 x 0) */
switch (mctx->pending_len) {
case 0:
mctx->l ^= 0x5a;
break;
case 1:
mctx->l ^= data[0] | 0x5a00;
break;
case 2:
mctx->l ^= data[0] | (data[1] << 8) | 0x5a0000;
break;
case 3:
mctx->l ^= data[0] | (data[1] << 8) | (data[2] << 16) |
0x5a000000;
break;
}
michael_block(mctx->l, mctx->r);
/* l ^= 0; */
michael_block(mctx->l, mctx->r);
dst[0] = cpu_to_le32(mctx->l);
dst[1] = cpu_to_le32(mctx->r);
}
static int michael_setkey(struct crypto_tfm *tfm, const u8 *key,
unsigned int keylen)
{
struct michael_mic_ctx *mctx = crypto_tfm_ctx(tfm);
const __le32 *data = (const __le32 *)key;
if (keylen != 8) {
tfm->crt_flags |= CRYPTO_TFM_RES_BAD_KEY_LEN;
return -EINVAL;
}
mctx->l = le32_to_cpu(data[0]);
mctx->r = le32_to_cpu(data[1]);
return 0;
}
static struct crypto_alg michael_mic_alg = {
.cra_name = "michael_mic",
.cra_flags = CRYPTO_ALG_TYPE_DIGEST,
.cra_blocksize = 8,
.cra_ctxsize = sizeof(struct michael_mic_ctx),
.cra_module = THIS_MODULE,
.cra_alignmask = 3,
.cra_list = LIST_HEAD_INIT(michael_mic_alg.cra_list),
.cra_u = { .digest = {
.dia_digestsize = 8,
.dia_init = michael_init,
.dia_update = michael_update,
.dia_final = michael_final,
.dia_setkey = michael_setkey } }
};
static int __init michael_mic_init(void)
{
return crypto_register_alg(&michael_mic_alg);
}
static void __exit michael_mic_exit(void)
{
crypto_unregister_alg(&michael_mic_alg);
}
module_init(michael_mic_init);
module_exit(michael_mic_exit);
MODULE_LICENSE("GPL v2");
MODULE_DESCRIPTION("Michael MIC");
MODULE_AUTHOR("Jouni Malinen <jkmaline@cc.hut.fi>");
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