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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 "keyDerivation.h"
extern "C" {
#include <srtp/crypto_kernel.h>
}
err_status_t KeyDerivation::init(const uint8_t key[30], const uint8_t salt[14])
{
aes_icm_context_init(&kdf_, key);
for(uint8_t i = 0; i < 14; i++)
salt_[i] = salt[i];
return err_status_ok;
}
err_status_t KeyDerivation::setLogKDRate(const uint8_t log_rate)
{
if( log_rate < 49 )
{
ld_kdr_ = log_rate;
return err_status_ok;
}
return err_status_bad_param;
}
err_status_t KeyDerivation::generate(satp_prf_label label, seq_nr_t seq_nr, uint8_t *key, int length)
{
v128_t iv, salt, key_id;
uint8_t r = 0;
v128_set_to_zero(&iv);
v128_set_to_zero(&salt);
v128_set_to_zero(&key_id);
// look at: http://tools.ietf.org/html/rfc3711#section-4.3
if( ld_kdr_ == -1 ) // means key_derivation_rate = 0
r = 0;
else
// FIXXME: kdr can be greater than 2^32 (= 2^48)
r = seq_nr / ( 0x01 << ld_kdr_ );
key_id.v32[0] = (label << 8);
key_id.v32[0] += r;
v128_copy_octet_string(&salt, salt_);
v128_xor(&iv, &salt, &key_id);
aes_icm_set_iv(&kdf_, &iv);
/* generate keystream output */
aes_icm_output(&kdf_, key, length);
return err_status_ok;
}
err_status_t KeyDerivation::clear()
{
/* zeroize aes context */
v128_set_to_zero(&kdf_.counter);
v128_set_to_zero(&kdf_.offset);
v128_set_to_zero(&kdf_.keystream_buffer);
for(uint8_t i = 0; i < 11; i++)
{
v128_set_to_zero(&kdf_.expanded_key[i]);
}
kdf_.bytes_in_buffer = 0;
return err_status_ok;
}
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