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/*
* AES-128 EAX
*
* Copyright (c) 2003-2007, 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.
*
* Alternatively, this software may be distributed under the terms of BSD
* license.
*
* See README and COPYING for more details.
*/
#include "includes.h"
#include "common.h"
#include "aes.h"
#include "aes_wrap.h"
/**
* aes_128_eax_encrypt - AES-128 EAX mode encryption
* @key: Key for encryption (16 bytes)
* @nonce: Nonce for counter mode
* @nonce_len: Nonce length in bytes
* @hdr: Header data to be authenticity protected
* @hdr_len: Length of the header data bytes
* @data: Data to encrypt in-place
* @data_len: Length of data in bytes
* @tag: 16-byte tag value
* Returns: 0 on success, -1 on failure
*/
int aes_128_eax_encrypt(const u8 *key, const u8 *nonce, size_t nonce_len,
const u8 *hdr, size_t hdr_len,
u8 *data, size_t data_len, u8 *tag)
{
u8 *buf;
size_t buf_len;
u8 nonce_mac[AES_BLOCK_SIZE], hdr_mac[AES_BLOCK_SIZE],
data_mac[AES_BLOCK_SIZE];
int i, ret = -1;
if (nonce_len > data_len)
buf_len = nonce_len;
else
buf_len = data_len;
if (hdr_len > buf_len)
buf_len = hdr_len;
buf_len += 16;
buf = os_malloc(buf_len);
if (buf == NULL)
return -1;
os_memset(buf, 0, 15);
buf[15] = 0;
os_memcpy(buf + 16, nonce, nonce_len);
if (omac1_aes_128(key, buf, 16 + nonce_len, nonce_mac))
goto fail;
buf[15] = 1;
os_memcpy(buf + 16, hdr, hdr_len);
if (omac1_aes_128(key, buf, 16 + hdr_len, hdr_mac))
goto fail;
if (aes_128_ctr_encrypt(key, nonce_mac, data, data_len))
goto fail;
buf[15] = 2;
os_memcpy(buf + 16, data, data_len);
if (omac1_aes_128(key, buf, 16 + data_len, data_mac))
goto fail;
for (i = 0; i < AES_BLOCK_SIZE; i++)
tag[i] = nonce_mac[i] ^ data_mac[i] ^ hdr_mac[i];
ret = 0;
fail:
os_free(buf);
return ret;
}
/**
* aes_128_eax_decrypt - AES-128 EAX mode decryption
* @key: Key for decryption (16 bytes)
* @nonce: Nonce for counter mode
* @nonce_len: Nonce length in bytes
* @hdr: Header data to be authenticity protected
* @hdr_len: Length of the header data bytes
* @data: Data to encrypt in-place
* @data_len: Length of data in bytes
* @tag: 16-byte tag value
* Returns: 0 on success, -1 on failure, -2 if tag does not match
*/
int aes_128_eax_decrypt(const u8 *key, const u8 *nonce, size_t nonce_len,
const u8 *hdr, size_t hdr_len,
u8 *data, size_t data_len, const u8 *tag)
{
u8 *buf;
size_t buf_len;
u8 nonce_mac[AES_BLOCK_SIZE], hdr_mac[AES_BLOCK_SIZE],
data_mac[AES_BLOCK_SIZE];
int i;
if (nonce_len > data_len)
buf_len = nonce_len;
else
buf_len = data_len;
if (hdr_len > buf_len)
buf_len = hdr_len;
buf_len += 16;
buf = os_malloc(buf_len);
if (buf == NULL)
return -1;
os_memset(buf, 0, 15);
buf[15] = 0;
os_memcpy(buf + 16, nonce, nonce_len);
if (omac1_aes_128(key, buf, 16 + nonce_len, nonce_mac)) {
os_free(buf);
return -1;
}
buf[15] = 1;
os_memcpy(buf + 16, hdr, hdr_len);
if (omac1_aes_128(key, buf, 16 + hdr_len, hdr_mac)) {
os_free(buf);
return -1;
}
buf[15] = 2;
os_memcpy(buf + 16, data, data_len);
if (omac1_aes_128(key, buf, 16 + data_len, data_mac)) {
os_free(buf);
return -1;
}
os_free(buf);
for (i = 0; i < AES_BLOCK_SIZE; i++) {
if (tag[i] != (nonce_mac[i] ^ data_mac[i] ^ hdr_mac[i]))
return -2;
}
return aes_128_ctr_encrypt(key, nonce_mac, data, data_len);
}
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