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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 <stdexcept>
#include <iostream>
#include <string>
#include <cstdio>
#include <gcrypt.h>
#include "cipher.h"
#include "mpi.h"
#include "log.h"
// TODO: in should be const but does not work with getBuf() :(
void Cipher::encrypt(PlainPacket & in, EncryptedPacket & out, seq_nr_t seq_nr, sender_id_t sender_id, mux_t mux)
{
u_int32_t len = cipher(in, in.getLength(), out.getPayload(), out.getPayloadLength(), seq_nr, sender_id, mux);
out.setSenderId(sender_id);
out.setSeqNr(seq_nr);
out.setMux(mux);
out.setPayloadLength(len);
}
// TODO: in should be const but does not work with getBuf() :(
void Cipher::decrypt(EncryptedPacket & in, PlainPacket & out)
{
u_int32_t len = decipher(in.getPayload() , in.getPayloadLength(), out, out.getLength(), in.getSeqNr(), in.getSenderId(), in.getMux());
out.setLength(len);
}
//******* NullCipher *******
u_int32_t NullCipher::cipher(u_int8_t* in, u_int32_t ilen, u_int8_t* out, u_int32_t olen, seq_nr_t seq_nr, sender_id_t sender_id, mux_t mux)
{
std::memcpy(out, in, (ilen < olen) ? ilen : olen);
return (ilen < olen) ? ilen : olen;
}
u_int32_t NullCipher::decipher(u_int8_t* in, u_int32_t ilen, u_int8_t* out, u_int32_t olen, seq_nr_t seq_nr, sender_id_t sender_id, mux_t mux)
{
std::memcpy(out, in, (ilen < olen) ? ilen : olen);
return (ilen < olen) ? ilen : olen;
}
//****** AesIcmCipher ******
AesIcmCipher::AesIcmCipher() : cipher_(NULL)
{
// TODO: hardcoded keysize
gcry_error_t err = gcry_cipher_open( &cipher_, GCRY_CIPHER_AES128, GCRY_CIPHER_MODE_CTR, 0 );
if( err )
cLog.msg(Log::PRIO_CRIT) << "AesIcmCipher::AesIcmCipher: Failed to open cipher";
}
AesIcmCipher::~AesIcmCipher()
{
if(cipher_)
gcry_cipher_close( cipher_ );
}
void AesIcmCipher::setKey(Buffer& key)
{
if(!cipher_)
return;
gcry_error_t err = gcry_cipher_setkey( cipher_, key.getBuf(), key.getLength() );
if( err )
cLog.msg(Log::PRIO_ERR) << "AesIcmCipher::setKey: Failed to set cipher key: " << gpg_strerror( err );
}
void AesIcmCipher::setSalt(Buffer& salt)
{
salt_ = salt;
if(!salt_[u_int32_t(0)])
salt_[u_int32_t(0)] = 1; // TODO: this is a outstandingly ugly workaround
}
u_int32_t AesIcmCipher::cipher(u_int8_t* in, u_int32_t ilen, u_int8_t* out, u_int32_t olen, seq_nr_t seq_nr, sender_id_t sender_id, mux_t mux)
{
calc(in, ilen, out, olen, seq_nr, sender_id, mux);
return (ilen < olen) ? ilen : olen;
}
u_int32_t AesIcmCipher::decipher(u_int8_t* in, u_int32_t ilen, u_int8_t* out, u_int32_t olen, seq_nr_t seq_nr, sender_id_t sender_id, mux_t mux)
{
calc(in, ilen, out, olen, seq_nr, sender_id, mux);
return (ilen < olen) ? ilen : olen;
}
void AesIcmCipher::calc(u_int8_t* in, u_int32_t ilen, u_int8_t* out, u_int32_t olen, seq_nr_t seq_nr, sender_id_t sender_id, mux_t mux)
{
if(!cipher_)
return;
gcry_error_t err = gcry_cipher_reset( cipher_ );
if( err ) {
cLog.msg(Log::PRIO_ERR) << "AesIcmCipher: Failed to reset cipher: " << gpg_strerror( err );
return;
}
// set the IV ( = CTR)
//==========================================================================
// // where the 128-bit integer value IV SHALL be defined by the SSRC, the
// // SRTP packet index i, and the SRTP session salting key k_s, as below.
// //
// // IV = (k_s * 2^16) XOR (SSRC * 2^64) XOR (i * 2^16)
// // sizeof(k_s) = 112 bit, random
Mpi ctr(128); // TODO: hardcoded size
Mpi salt(salt_.getBuf(), salt_.getLength());
Mpi sid_mux(32);
sid_mux = sender_id;
Mpi mux_mpi(32);
mux_mpi = mux;
sid_mux = sid_mux ^ mux_mpi.mul2exp(16);
Mpi seq(32);
seq = seq_nr;
ctr = salt.mul2exp(16) ^ sid_mux.mul2exp(64) ^ seq.mul2exp(16); // TODO: hardcoded size
size_t written;
u_int8_t *ctr_buf = ctr.getNewBuf(&written); // TODO: hardcoded size
err = gcry_cipher_setctr( cipher_, ctr_buf, written ); // TODO: hardcoded size
delete[] ctr_buf;
if( err ) {
cLog.msg(Log::PRIO_ERR) << "AesIcmCipher: Failed to set cipher CTR: " << gpg_strerror( err );
return;
}
err = gcry_cipher_encrypt( cipher_, out, olen, in, ilen );
if( err ) {
cLog.msg(Log::PRIO_ERR) << "AesIcmCipher: Failed to generate cipher bitstream: " << gpg_strerror( err );
return;
}
}
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