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/*
* anytun
*
* The secure anycast tunneling protocol (satp) defines a protocol used
* for communication between any combination of unicast and anycast
* tunnel endpoints. It has less protocol overhead than IPSec in Tunnel
* mode and allows tunneling of every ETHER TYPE protocol (e.g.
* ethernet, ip, arp ...). satp directly includes cryptography and
* message authentication based on the methodes used by SRTP. It is
* intended to deliver a generic, scaleable and secure solution for
* tunneling and relaying of packets of any protocol.
*
*
* Copyright (C) 2007 anytun.org <satp@wirdorange.org>
*
* 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.
*
* This program 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 program (see the file COPYING included with this
* distribution); if not, write to the Free Software Foundation, Inc.,
* 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
*/
#include "log.h"
#include "keyDerivation.h"
#include "mpi.h"
#include "threadUtils.hpp"
#include <stdexcept>
#include <iostream>
#include <string>
#include <gcrypt.h>
void KeyDerivation::init(Buffer key, Buffer salt)
{
Lock lock(mutex_);
gcry_error_t err;
// TODO: hardcoded keysize!
err = gcry_cipher_open( &cipher_, GCRY_CIPHER_AES128, GCRY_CIPHER_MODE_CTR, 0 );
if( err ) {
cLog.msg(Log::PRIO_ERR) << "KeyDerivation::init: Failed to open cipher: " << gpg_strerror( err );
return;
}
salt_ = SyncBuffer(salt);
key_ = SyncBuffer(key);
updateKey();
}
void KeyDerivation::updateKey()
{
gcry_error_t err;
err = gcry_cipher_setkey( cipher_, key_.getBuf(), key_.getLength() );
if( err )
cLog.msg(Log::PRIO_ERR) << "KeyDerivation::init: Failed to set cipher key: " << gpg_strerror( err );
}
KeyDerivation::~KeyDerivation()
{
Lock lock(mutex_);
gcry_cipher_close( cipher_ );
}
void KeyDerivation::setLogKDRate(const uint8_t log_rate)
{
Lock lock(mutex_);
if( log_rate < 49 )
ld_kdr_ = log_rate;
}
void KeyDerivation::generate(satp_prf_label label, seq_nr_t seq_nr, Buffer& key, u_int32_t length)
{
////Lock lock(mutex_);
gcry_error_t err;
Mpi r;
Mpi key_id(128);
Mpi iv(128);
// see at: http://tools.ietf.org/html/rfc3711#section-4.3
// * Let r = index DIV key_derivation_rate (with DIV as defined above).
// * Let key_id = <label> || r.
// * Let x = key_id XOR master_salt, where key_id and master_salt are
// aligned so that their least significant bits agree (right-
// alignment).
//
if( ld_kdr_ == -1 ) // means key_derivation_rate = 0
r = 0;
else
// TODO: kdr can be greater than 2^32 (= 2^48)
r = static_cast<long unsigned int>(seq_nr / ( 0x01 << ld_kdr_ ));
r = r.mul2exp(8);
key_id = r + static_cast<long unsigned int>(label);
Mpi salt = Mpi(salt_.getBuf(), salt_.getLength());
iv = key_id ^ salt;
err = gcry_cipher_reset( cipher_ );
if( err )
cLog.msg(Log::PRIO_ERR) << "KeyDerivation::generate: Failed to reset cipher: " << gpg_strerror( err );
u_int8_t *iv_buf = iv.getNewBuf(16);
err = gcry_cipher_setiv( cipher_ , iv_buf, 16);
delete[] iv_buf;
if( err )
cLog.msg(Log::PRIO_ERR) << "KeyDerivation::generate: Failed to set IV: " << gpg_strerror( err );
err = gcry_cipher_encrypt( cipher_, key, length, 0, 0 );
if( err )
cLog.msg(Log::PRIO_ERR) << "KeyDerivation::generate: Failed to generate cipher bitstream: " << gpg_strerror( err );
}
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