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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) 2007-2008 Othmar Gsenger, Erwin Nindl,
* Christian Pointner <satp@wirdorange.org>
*
* This file is part of Anytun.
*
* Anytun is free software: you can redistribute it and/or modify
* it under the terms of the GNU General Public License version 3 as
* published by the Free Software Foundation.
*
* Anytun 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 anytun. If not, see <http://www.gnu.org/licenses/>.
*/
#include "authAlgo.h"
#include "log.h"
#include "buffer.h"
#include "encryptedPacket.h"
#include <iostream>
#include <cstring>
#include <gcrypt.h>
//****** NullAuthAlgo ******
void NullAuthAlgo::generate(EncryptedPacket& packet)
{
}
bool NullAuthAlgo::checkTag(EncryptedPacket& packet)
{
return true;
}
u_int32_t NullAuthAlgo::getMaxLength()
{
return MAX_LENGTH_;
}
//****** Sha1AuthAlgo ******
Sha1AuthAlgo::Sha1AuthAlgo() : ctx_(NULL)
{
gcry_error_t err = gcry_md_open( &ctx_, GCRY_MD_SHA1, GCRY_MD_FLAG_HMAC );
if( err )
cLog.msg(Log::PRIO_CRIT) << "Sha1AuthAlgo::Sha1AuthAlgo: Failed to open message digest algo";
}
Sha1AuthAlgo::~Sha1AuthAlgo()
{
if(ctx_)
gcry_md_close( ctx_ );
}
void Sha1AuthAlgo::setKey(Buffer& key)
{
if(!ctx_)
return;
gcry_error_t err = gcry_md_setkey( ctx_, key.getBuf(), key.getLength() );
if( err ) {
char buf[STERROR_TEXT_MAX];
buf[0] = 0;
cLog.msg(Log::PRIO_ERR) << "Sha1AuthAlgo::setKey: Failed to set cipher key: " << gpg_strerror_r(err, buf, STERROR_TEXT_MAX);
}
}
void Sha1AuthAlgo::generate(EncryptedPacket& packet)
{
if(!packet.getAuthTagLength())
return;
gcry_md_reset( ctx_ );
gcry_md_write( ctx_, packet.getAuthenticatedPortion(), packet.getAuthenticatedPortionLength() );
gcry_md_final( ctx_ );
u_int8_t* tag = packet.getAuthTag();
if(packet.getAuthTagLength() > MAX_LENGTH_)
std::memset(tag, 0, (packet.getAuthTagLength() - MAX_LENGTH_));
u_int8_t* hmac = gcry_md_read(ctx_, 0);
u_int32_t length = (packet.getAuthTagLength() < MAX_LENGTH_) ? packet.getAuthTagLength() : MAX_LENGTH_;
std::memcpy(&tag[packet.getAuthTagLength() - length], &hmac[MAX_LENGTH_ - length], length);
}
bool Sha1AuthAlgo::checkTag(EncryptedPacket& packet)
{
if(!packet.getAuthTagLength())
return true;
gcry_md_reset( ctx_ );
gcry_md_write( ctx_, packet.getAuthenticatedPortion(), packet.getAuthenticatedPortionLength() );
gcry_md_final( ctx_ );
u_int8_t* tag = packet.getAuthTag();
if(packet.getAuthTagLength() > MAX_LENGTH_)
for(u_int32_t i=0; i < (packet.getAuthTagLength() - MAX_LENGTH_); ++i)
if(tag[i]) return false;
u_int8_t* hmac = gcry_md_read(ctx_, 0);
u_int32_t length = (packet.getAuthTagLength() < MAX_LENGTH_) ? packet.getAuthTagLength() : MAX_LENGTH_;
if(std::memcmp(&tag[packet.getAuthTagLength() - length], &hmac[MAX_LENGTH_ - length], length))
return false;
return true;
}
u_int32_t Sha1AuthAlgo::getMaxLength()
{
return MAX_LENGTH_;
}
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