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/* Copyright (C) 2022 Dinglan Peng
*
* This is free software; you can redistribute it and/or modify
* it under the terms of the GNU General Public License as published by
* the Free Software Foundation; either version 2 of the License, or
* (at your option) any later version.
*
* This software is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU General Public License for more details.
*
* You should have received a copy of the GNU General Public License
* along with this software; if not, write to the Free Software
* Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307,
* USA.
*/
#ifdef HAVE_CONFIG_H
#include <config.h>
#endif
#include <assert.h>
#include <rdr/AESInStream.h>
#include <rdr/Exception.h>
#ifdef HAVE_NETTLE
using namespace rdr;
AESInStream::AESInStream(InStream* _in, const uint8_t* key,
int _keySize)
: keySize(_keySize), in(_in), counter()
{
if (keySize == 128)
EAX_SET_KEY(&eaxCtx128, aes128_set_encrypt_key, aes128_encrypt, key);
else if (keySize == 256)
EAX_SET_KEY(&eaxCtx256, aes256_set_encrypt_key, aes256_encrypt, key);
else
assert(!"incorrect key size");
}
AESInStream::~AESInStream() {}
bool AESInStream::fillBuffer()
{
if (!in->hasData(2))
return false;
const uint8_t* ptr = in->getptr(2);
size_t length = ((int)ptr[0] << 8) | (int)ptr[1];
if (!in->hasData(2 + length + 16))
return false;
ensureSpace(length);
ptr = in->getptr(2 + length + 16);
const uint8_t* ad = ptr;
const uint8_t* data = ptr + 2;
const uint8_t* mac = ptr + 2 + length;
uint8_t macComputed[16];
if (keySize == 128) {
EAX_SET_NONCE(&eaxCtx128, aes128_encrypt, 16, counter);
EAX_UPDATE(&eaxCtx128, aes128_encrypt, 2, ad);
EAX_DECRYPT(&eaxCtx128, aes128_encrypt, length, (uint8_t*)end, data);
EAX_DIGEST(&eaxCtx128, aes128_encrypt, 16, macComputed);
} else {
EAX_SET_NONCE(&eaxCtx256, aes256_encrypt, 16, counter);
EAX_UPDATE(&eaxCtx256, aes256_encrypt, 2, ad);
EAX_DECRYPT(&eaxCtx256, aes256_encrypt, length, (uint8_t*)end, data);
EAX_DIGEST(&eaxCtx256, aes256_encrypt, 16, macComputed);
}
if (memcmp(mac, macComputed, 16) != 0)
throw Exception("AESInStream: failed to authenticate message");
in->setptr(2 + length + 16);
end += length;
// Update nonce by incrementing the counter as a
// 128bit little endian unsigned integer
for (int i = 0; i < 16; ++i) {
// increment until there is no carry
if (++counter[i] != 0) {
break;
}
}
return true;
}
#endif
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