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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 "anytunError.h"
#include "buffer.h"
#include "encryptedPacket.h"
#include <iostream>
#include <cstring>
//****** NullAuthAlgo ******
void NullAuthAlgo::generate(KeyDerivation& kd, EncryptedPacket& packet)
{
}
bool NullAuthAlgo::checkTag(KeyDerivation& kd, EncryptedPacket& packet)
{
return true;
}
#ifndef NO_CRYPT
//****** Sha1AuthAlgo ******
Sha1AuthAlgo::Sha1AuthAlgo(kd_dir_t d) : AuthAlgo(d), key_(DIGEST_LENGTH)
{
#ifndef USE_SSL_CRYPTO
gcry_error_t err = gcry_md_open(&handle_, GCRY_MD_SHA1, GCRY_MD_FLAG_HMAC);
if(err) {
cLog.msg(Log::PRIO_CRIT) << "Sha1AuthAlgo::Sha1AuthAlgo: Failed to open message digest algo";
return;
}
#else
HMAC_CTX_init(&ctx_);
HMAC_Init_ex(&ctx_, NULL, 0, EVP_sha1(), NULL);
#endif
}
Sha1AuthAlgo::~Sha1AuthAlgo()
{
#ifndef USE_SSL_CRYPTO
if(handle_)
gcry_md_close(handle_);
#else
HMAC_CTX_cleanup(&ctx_);
#endif
}
void Sha1AuthAlgo::generate(KeyDerivation& kd, EncryptedPacket& packet)
{
#ifndef USE_SSL_CRYPTO
if(!handle_)
return;
#endif
packet.addAuthTag();
if(!packet.getAuthTagLength())
return;
kd.generate(dir_, LABEL_SATP_MSG_AUTH, packet.getSeqNr(), key_);
#ifndef USE_SSL_CRYPTO
gcry_error_t err = gcry_md_setkey(handle_, key_.getBuf(), key_.getLength());
if(err) {
cLog.msg(Log::PRIO_ERR) << "Sha1AuthAlgo::setKey: Failed to set hmac key: " << AnytunGpgError(err);
return;
}
gcry_md_reset(handle_);
gcry_md_write(handle_, packet.getAuthenticatedPortion(), packet.getAuthenticatedPortionLength());
gcry_md_final(handle_);
u_int8_t* hmac = gcry_md_read(handle_, 0);
#else
HMAC_Init_ex(&ctx_, key_.getBuf(), key_.getLength(), EVP_sha1(), NULL);
u_int8_t hmac[DIGEST_LENGTH];
HMAC_Update(&ctx_, packet.getAuthenticatedPortion(), packet.getAuthenticatedPortionLength());
HMAC_Final(&ctx_, hmac, NULL);
#endif
u_int8_t* tag = packet.getAuthTag();
u_int32_t length = (packet.getAuthTagLength() < DIGEST_LENGTH) ? packet.getAuthTagLength() : DIGEST_LENGTH;
if(length > DIGEST_LENGTH)
std::memset(tag, 0, packet.getAuthTagLength());
std::memcpy(&tag[packet.getAuthTagLength() - length], &hmac[DIGEST_LENGTH - length], length);
}
bool Sha1AuthAlgo::checkTag(KeyDerivation& kd, EncryptedPacket& packet)
{
#ifndef USE_SSL_CRYPTO
if(!handle_)
return false;
#endif
packet.withAuthTag(true);
if(!packet.getAuthTagLength())
return true;
kd.generate(dir_, LABEL_SATP_MSG_AUTH, packet.getSeqNr(), key_);
#ifndef USE_SSL_CRYPTO
gcry_error_t err = gcry_md_setkey(handle_, key_.getBuf(), key_.getLength());
if(err) {
cLog.msg(Log::PRIO_ERR) << "Sha1AuthAlgo::setKey: Failed to set hmac key: " << AnytunGpgError(err);
return false;
}
gcry_md_reset(handle_);
gcry_md_write(handle_, packet.getAuthenticatedPortion(), packet.getAuthenticatedPortionLength());
gcry_md_final(handle_);
u_int8_t* hmac = gcry_md_read(handle_, 0);
#else
HMAC_Init_ex(&ctx_, key_.getBuf(), key_.getLength(), EVP_sha1(), NULL);
u_int8_t hmac[DIGEST_LENGTH];
HMAC_Update(&ctx_, packet.getAuthenticatedPortion(), packet.getAuthenticatedPortionLength());
HMAC_Final(&ctx_, hmac, NULL);
#endif
u_int8_t* tag = packet.getAuthTag();
u_int32_t length = (packet.getAuthTagLength() < DIGEST_LENGTH) ? packet.getAuthTagLength() : DIGEST_LENGTH;
if(length > DIGEST_LENGTH)
for(u_int32_t i=0; i < (packet.getAuthTagLength() - DIGEST_LENGTH); ++i)
if(tag[i]) return false;
int ret = std::memcmp(&tag[packet.getAuthTagLength() - length], &hmac[DIGEST_LENGTH - length], length);
packet.removeAuthTag();
if(ret)
return false;
return true;
}
#endif
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