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// libTorrent - BitTorrent library
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// Copyright (C) 2005-2007, Jari Sundell
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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., 59 Temple Place, Suite 330, Boston, MA 02111-1307 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 for
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// all of the code used other than OpenSSL. If you modify file(s)
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// with this exception, you may extend this exception to your version
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// of the file(s), but you are not obligated to do so. If you do not
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// wish to do so, delete this exception statement from your version.
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// If you delete this exception statement from all source files in the
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// program, then also delete it here.
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// Contact: Jari Sundell <jaris@ifi.uio.no>
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// 3185 Skoppum, NORWAY
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#include <openssl/bn.h>
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#include "diffie_hellman.h"
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#include "torrent/exceptions.h"
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DiffieHellman::DiffieHellman(const unsigned char *prime, int primeLength,
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const unsigned char *generator, int generatorLength) :
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m_dh->p = BN_bin2bn(prime, primeLength, NULL);
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m_dh->g = BN_bin2bn(generator, generatorLength, NULL);
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DH_generate_key(m_dh);
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throw internal_error("Compiled without encryption support.");
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DiffieHellman::~DiffieHellman() {
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DiffieHellman::compute_secret(const unsigned char *pubkey, unsigned int length) {
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BIGNUM* k = BN_bin2bn(pubkey, length, NULL);
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m_secret = new char[DH_size(m_dh)];
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m_size = DH_compute_key((unsigned char*)m_secret, k, m_dh);
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DiffieHellman::store_pub_key(unsigned char* dest, unsigned int length) {
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std::memset(dest, 0, length);
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if ((int)length >= BN_num_bytes(m_dh->pub_key))
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BN_bn2bin(m_dh->pub_key, dest + length - BN_num_bytes(m_dh->pub_key));