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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 "cypher.h"
#include "mpi.h"
#include "log.h"
void Cypher::encrypt(const PlainPacket & in,EncryptedPacket & out, seq_nr_t seq_nr, sender_id_t sender_id)
{
cypher(out.payload_, in.complete_payload_ , in.complete_payload_length_, seq_nr, sender_id);
out.setSenderId(sender_id);
out.setSeqNr(seq_nr);
out.setPayloadLength(in.complete_payload_length_);
}
void Cypher::decrypt(const EncryptedPacket & in,PlainPacket & out)
{
cypher(out.complete_payload_, in.payload_ , in.payload_length_, in.getSeqNr(), in.getSenderId());
out.setCompletePayloadLength(in.payload_length_);
}
void NullCypher::cypher(u_int8_t * out, u_int8_t * in, u_int32_t length, seq_nr_t seq_nr, sender_id_t sender_id)
{
std::memcpy(out, in, length );
}
const char* AesIcmCypher::MIN_GCRYPT_VERSION = "1.2.3";
AesIcmCypher::AesIcmCypher() : salt_(Buffer(14))
{
gcry_error_t err;
// No other library has already initialized libgcrypt.
if( !gcry_control(GCRYCTL_ANY_INITIALIZATION_P) )
{
if( !gcry_check_version( MIN_GCRYPT_VERSION ) ) {
cLog.msg(Log::PRIO_ERR) << "AesIcmCypher::AesIcmCypher: Invalid Version of libgcrypt, should be >= " << MIN_GCRYPT_VERSION;
return;
}
/* Allocate a pool of secure memory. This also drops priviliges
on some systems. */
err = gcry_control(GCRYCTL_INIT_SECMEM, GCRYPT_SEC_MEM, 0);
if( err ) {
cLog.msg(Log::PRIO_ERR) << "Failed to allocate " << GCRYPT_SEC_MEM << "bytes of secure memory: " << gpg_strerror( err );
return;
}
/* Tell Libgcrypt that initialization has completed. */
err = gcry_control(GCRYCTL_INITIALIZATION_FINISHED);
if( err ) {
cLog.msg(Log::PRIO_CRIT) << "AesIcmCypher::AesIcmCypher: Failed to finish the initialization of libgcrypt: " << gpg_strerror( err );
return;
} else {
cLog.msg(Log::PRIO_DEBUG) << "AesIcmCypher::AesIcmCypher: libgcrypt init finished";
}
}
err = gcry_cipher_open( &cipher_, GCRY_CIPHER_AES128, GCRY_CIPHER_MODE_CTR, 0 );
if( err )
cLog.msg(Log::PRIO_CRIT) << "AesIcmCypher::AesIcmCypher: Failed to open cypher";
}
AesIcmCypher::~AesIcmCypher()
{
gcry_cipher_close( cipher_ );
cLog.msg(Log::PRIO_DEBUG) << "AesIcmCypher::~AesIcmCypher: closed cipher";
}
void AesIcmCypher::setKey(Buffer key)
{
gcry_error_t err;
// FIXXME: hardcoded keysize
err = gcry_cipher_setkey( cipher_, key.getBuf(), 16 );
if( err )
cLog.msg(Log::PRIO_ERR) << "AesIcmCypher::setKey: Failed to set cipher key: " << gpg_strerror( err );
}
void AesIcmCypher::setSalt(Buffer salt)
{
salt_ = salt;
}
void AesIcmCypher::cypher(u_int8_t * out, u_int8_t * in, u_int32_t length, seq_nr_t seq_nr, sender_id_t sender_id)
{
gcry_error_t err;
// set the IV
//==========================================================================
// // 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 iv(128);
Mpi salt = Mpi(salt_.getBuf(), salt_.getLength());
Mpi sid = sender_id;
Mpi seq = seq_nr;
iv = salt.mul2exp(16) ^ sid.mul2exp(64) ^ seq.mul2exp(16);
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) << "AesIcmCypher: Failed to set cipher IV: " << gpg_strerror( err );
return;
}
err = gcry_cipher_reset( cipher_ );
if( err ) {
cLog.msg(Log::PRIO_ERR) << "AesIcmCypher: Failed to reset cipher: " << gpg_strerror( err );
return;
}
err = gcry_cipher_encrypt( cipher_, out, length, in, length );
if( err ) {
cLog.msg(Log::PRIO_ERR) << "AesIcmCypher: Failed to generate cipher bitstream: " << gpg_strerror( err );
return;
}
}
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