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/*
* Cryptographic API
*
* Michael MIC (IEEE 802.11i/TKIP) keyed digest
*
* Copyright (c) 2004 Jouni Malinen <j@w1.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 <crypto/internal/hash.h>
#include <asm/byteorder.h>
#include <linux/init.h>
#include <linux/module.h>
#include <linux/string.h>
#include <linux/types.h>
struct michael_mic_ctx {
u32 l, r;
};
struct michael_mic_desc_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 int michael_init(struct shash_desc *desc)
{
struct michael_mic_desc_ctx *mctx = shash_desc_ctx(desc);
struct michael_mic_ctx *ctx = crypto_shash_ctx(desc->tfm);
mctx->pending_len = 0;
mctx->l = ctx->l;
mctx->r = ctx->r;
return 0;
}
static int michael_update(struct shash_desc *desc, const u8 *data,
unsigned int len)
{
struct michael_mic_desc_ctx *mctx = shash_desc_ctx(desc);
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 0;
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);
}
return 0;
}
static int michael_final(struct shash_desc *desc, u8 *out)
{
struct michael_mic_desc_ctx *mctx = shash_desc_ctx(desc);
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);
return 0;
}
static int michael_setkey(struct crypto_shash *tfm, const u8 *key,
unsigned int keylen)
{
struct michael_mic_ctx *mctx = crypto_shash_ctx(tfm);
const __le32 *data = (const __le32 *)key;
if (keylen != 8) {
crypto_shash_set_flags(tfm, 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 shash_alg alg = {
.digestsize = 8,
.setkey = michael_setkey,
.init = michael_init,
.update = michael_update,
.final = michael_final,
.descsize = sizeof(struct michael_mic_desc_ctx),
.base = {
.cra_name = "michael_mic",
.cra_blocksize = 8,
.cra_alignmask = 3,
.cra_ctxsize = sizeof(struct michael_mic_ctx),
.cra_module = THIS_MODULE,
}
};
static int __init michael_mic_init(void)
{
return crypto_register_shash(&alg);
}
static void __exit michael_mic_exit(void)
{
crypto_unregister_shash(&alg);
}
module_init(michael_mic_init);
module_exit(michael_mic_exit);
MODULE_LICENSE("GPL v2");
MODULE_DESCRIPTION("Michael MIC");
MODULE_AUTHOR("Jouni Malinen <j@w1.fi>");
MODULE_ALIAS_CRYPTO("michael_mic");
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