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* aria2 - The high speed download utility
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* Copyright (C) 2011 Tatsuhiro Tsujikawa
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* This program is free software; you can redistribute it and/or modify
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* it under the terms of the GNU General Public License as published by
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* the Free Software Foundation; either version 2 of the License, or
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* (at your option) any later version.
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* This program is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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* GNU General Public License for more details.
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* You should have received a copy of the GNU General Public License
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* along with this program; if not, write to the Free Software
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* Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
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* In addition, as a special exception, the copyright holders give
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* permission to link the code of portions of this program with the
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* OpenSSL library under certain conditions as described in each
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* individual source file, and distribute linked combinations
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* You must obey the GNU General Public License in all respects
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* for all of the code used other than OpenSSL. If you modify
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* file(s) with this exception, you may extend this exception to your
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* version of the file(s), but you are not obligated to do so. If you
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* do not wish to do so, delete this exception statement from your
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* version. If you delete this exception statement from all source
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* files in the program, then also delete it here.
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#include "LibgmpDHKeyExchange.h"
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#include "DlAbortEx.h"
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void handleError(int err)
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(fmt("Exception in libgmp routine(DHKeyExchange class): code%d", err));
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DHKeyExchange::DHKeyExchange()
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mpz_init(privateKey_);
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DHKeyExchange::~DHKeyExchange()
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mpz_clear(generator_);
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mpz_clear(privateKey_);
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mpz_clear(publicKey_);
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void DHKeyExchange::init
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(const unsigned char* prime, size_t primeBits,
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const unsigned char* generator,
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size_t privateKeyBits)
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if(mpz_set_str(prime_, reinterpret_cast<const char*>(prime), 16) == -1) {
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(generator_, reinterpret_cast<const char*>(generator), 16) == -1) {
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mpz_urandomb(privateKey_, global::gmpRandstate, privateKeyBits);
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keyLength_ = (primeBits+7)/8;
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void DHKeyExchange::generatePublicKey()
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mpz_powm(publicKey_, generator_, privateKey_, prime_);
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size_t DHKeyExchange::getPublicKey(unsigned char* out, size_t outLength) const
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if(outLength < keyLength_) {
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(fmt("Insufficient buffer for public key. expect:%lu, actual:%lu",
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static_cast<unsigned long>(keyLength_),
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static_cast<unsigned long>(outLength)));
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memset(out, 0, outLength);
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size_t publicKeyBytes = (mpz_sizeinbase(publicKey_, 2)+7)/8;
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size_t offset = keyLength_-publicKeyBytes;
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mpz_export(out+offset, &nwritten, 1, 1, 1, 0, publicKey_);
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void DHKeyExchange::generateNonce(unsigned char* out, size_t outLength) const
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util::generateRandomData(out, outLength);
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size_t DHKeyExchange::computeSecret
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(unsigned char* out, size_t outLength,
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const unsigned char* peerPublicKeyData,
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size_t peerPublicKeyLength) const
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if(outLength < keyLength_) {
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(fmt("Insufficient buffer for secret. expect:%lu, actual:%lu",
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static_cast<unsigned long>(keyLength_),
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static_cast<unsigned long>(outLength)));
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mpz_init(peerPublicKey);
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mpz_import(peerPublicKey, peerPublicKeyLength, 1, 1, 1, 0, peerPublicKeyData);
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mpz_powm(secret, peerPublicKey, privateKey_, prime_);
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mpz_clear(peerPublicKey);
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memset(out, 0, outLength);
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size_t secretBytes = (mpz_sizeinbase(secret, 2)+7)/8;
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size_t offset = keyLength_-secretBytes;
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mpz_export(out+offset, &nwritten, 1, 1, 1, 0, secret);