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/* <!-- copyright */
/*
* aria2 - The high speed download utility
*
* Copyright (C) 2013 Nils Maier
*
* This program is free software; you can redistribute it and/or modify
* it under the terms of the GNU General Public License as published by
* the Free Software Foundation; either version 2 of the License, or
* (at your option) any later version.
*
* 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; if not, write to the Free Software
* Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
*
* In addition, as a special exception, the copyright holders give
* permission to link the code of portions of this program with the
* OpenSSL library under certain conditions as described in each
* individual source file, and distribute linked combinations
* including the two.
* You must obey the GNU General Public License in all respects
* for all of the code used other than OpenSSL. If you modify
* file(s) with this exception, you may extend this exception to your
* version of the file(s), but you are not obligated to do so. If you
* do not wish to do so, delete this exception statement from your
* version. If you delete this exception statement from all source
* files in the program, then also delete it here.
*/
/* copyright --> */
#include "InternalDHKeyExchange.h"
#include <cstring>
#include "DlAbortEx.h"
#include "LogFactory.h"
#include "fmt.h"
#include "util.h"
namespace aria2 {
void DHKeyExchange::init(const unsigned char* prime, size_t primeBits,
const unsigned char* generator, size_t privateKeyBits)
{
std::string pr = reinterpret_cast<const char*>(prime);
if (pr.length() % 2) {
pr = "0" + pr;
}
pr = util::fromHex(pr.begin(), pr.end());
if (pr.empty()) {
throw DL_ABORT_EX("No valid prime supplied");
}
prime_ = n(pr.c_str(), pr.length());
std::string gen = reinterpret_cast<const char*>(generator);
if (gen.length() % 2) {
gen = "0" + gen;
}
gen = util::fromHex(gen.begin(), gen.end());
if (gen.empty()) {
throw DL_ABORT_EX("No valid generator supplied");
}
generator_ = n(gen.c_str(), gen.length());
size_t pbytes = (privateKeyBits + 7) / 8;
unsigned char buf[pbytes];
util::generateRandomData(buf, pbytes);
privateKey_ = n(reinterpret_cast<char*>(buf), pbytes);
keyLength_ = (primeBits + 7) / 8;
}
void DHKeyExchange::generatePublicKey()
{
publicKey_ = generator_.mul_mod(privateKey_, prime_);
}
size_t DHKeyExchange::getPublicKey(unsigned char* out, size_t outLength) const
{
if (outLength < keyLength_) {
throw DL_ABORT_EX(fmt("Insufficient buffer for public key. expect:%lu, actual:%lu",
static_cast<unsigned long>(keyLength_),
static_cast<unsigned long>(outLength)));
}
publicKey_.binary(reinterpret_cast<char*>(out), outLength);
return keyLength_;
}
void DHKeyExchange::generateNonce(unsigned char* out, size_t outLength) const
{
util::generateRandomData(out, outLength);
}
size_t DHKeyExchange::computeSecret(unsigned char* out, size_t outLength,
const unsigned char* peerPublicKeyData,
size_t peerPublicKeyLength) const
{
if (outLength < keyLength_) {
throw DL_ABORT_EX(fmt("Insufficient buffer for secret. expect:%lu, actual:%lu",
static_cast<unsigned long>(keyLength_),
static_cast<unsigned long>(outLength)));
}
if (prime_.length() < peerPublicKeyLength) {
throw DL_ABORT_EX(fmt("peer public key overflows bignum. max:%lu, actual:%lu",
static_cast<unsigned long>(prime_.length()),
static_cast<unsigned long>(peerPublicKeyLength)));
}
n peerKey(reinterpret_cast<const char*>(peerPublicKeyData), peerPublicKeyLength);
n secret = peerKey.mul_mod(privateKey_, prime_);
secret.binary(reinterpret_cast<char*>(out), outLength);
return outLength;
}
} // namespace aria2
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