linux/net/mac80211/aes_cmac.c

/*
 * AES-128-CMAC with TLen 16 for IEEE 802.11w BIP
 * Copyright 2008, 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 <linux/kernel.h>
#include <linux/types.h>
#include <linux/crypto.h>
#include <linux/export.h>
#include <linux/err.h>
#include <crypto/aes.h>

#include <net/mac80211.h>
#include "key.h"
#include "aes_cmac.h"

#define CMAC_TLEN 8 /* CMAC TLen = 64 bits (8 octets) */
#define CMAC_TLEN_256 16 /* CMAC TLen = 128 bits (16 octets) */
#define AAD_LEN 20

static const u8 zero[CMAC_TLEN_256];

void ieee80211_aes_cmac(struct crypto_shash *tfm, const u8 *aad,
			const u8 *data, size_t data_len, u8 *mic)
{
	SHASH_DESC_ON_STACK(desc, tfm);
	u8 out[AES_BLOCK_SIZE];

	desc->tfm = tfm;

	crypto_shash_init(desc);
	crypto_shash_update(desc, aad, AAD_LEN);
	crypto_shash_update(desc, data, data_len - CMAC_TLEN);
	crypto_shash_finup(desc, zero, CMAC_TLEN, out);

	memcpy(mic, out, CMAC_TLEN);
}

void ieee80211_aes_cmac_256(struct crypto_shash *tfm, const u8 *aad,
			    const u8 *data, size_t data_len, u8 *mic)
{
	SHASH_DESC_ON_STACK(desc, tfm);

	desc->tfm = tfm;

	crypto_shash_init(desc);
	crypto_shash_update(desc, aad, AAD_LEN);
	crypto_shash_update(desc, data, data_len - CMAC_TLEN_256);
	crypto_shash_finup(desc, zero, CMAC_TLEN_256, mic);
}

struct crypto_shash *ieee80211_aes_cmac_key_setup(const u8 key[],
						  size_t key_len)
{
	struct crypto_shash *tfm;

	tfm = crypto_alloc_shash("cmac(aes)", 0, 0);
	if (!IS_ERR(tfm))
		crypto_shash_setkey(tfm, key, key_len);

	return tfm;
}

void ieee80211_aes_cmac_key_free(struct crypto_shash *tfm)
{
	crypto_free_shash(tfm);
}