306 lines
8.2 KiB
C++
306 lines
8.2 KiB
C++
/*
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Copyright (c) 2007-2012, Un Shyam & Arvid Norberg
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All rights reserved.
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Redistribution and use in source and binary forms, with or without
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modification, are permitted provided that the following conditions
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are met:
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* Redistributions of source code must retain the above copyright
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notice, this list of conditions and the following disclaimer.
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* Redistributions in binary form must reproduce the above copyright
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notice, this list of conditions and the following disclaimer in
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the documentation and/or other materials provided with the distribution.
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* Neither the name of the author nor the names of its
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contributors may be used to endorse or promote products derived
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from this software without specific prior written permission.
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THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
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AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
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IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
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ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR CONTRIBUTORS BE
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LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
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CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
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SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
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INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
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CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
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ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
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POSSIBILITY OF SUCH DAMAGE.
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*/
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#ifndef TORRENT_DISABLE_ENCRYPTION
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#ifndef TORRENT_PE_CRYPTO_HPP_INCLUDED
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#define TORRENT_PE_CRYPTO_HPP_INCLUDED
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#include "libtorrent/config.hpp"
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#ifdef TORRENT_USE_GCRYPT
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#include <gcrypt.h>
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#elif defined TORRENT_USE_OPENSSL
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#include <openssl/rc4.h>
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#include <openssl/evp.h>
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#include <openssl/aes.h>
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#else
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// RC4 state from libtomcrypt
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struct rc4 {
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int x, y;
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unsigned char buf[256];
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};
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void TORRENT_EXTRA_EXPORT rc4_init(const unsigned char* in, unsigned long len, rc4 *state);
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unsigned long TORRENT_EXTRA_EXPORT rc4_encrypt(unsigned char *out, unsigned long outlen, rc4 *state);
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#endif
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#include "libtorrent/peer_id.hpp" // For sha1_hash
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#include "libtorrent/assert.hpp"
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namespace libtorrent
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{
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class TORRENT_EXTRA_EXPORT dh_key_exchange
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{
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public:
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dh_key_exchange();
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bool good() const { return true; }
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// Get local public key, always 96 bytes
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char const* get_local_key() const;
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// read remote_pubkey, generate and store shared secret in
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// m_dh_shared_secret.
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int compute_secret(const char* remote_pubkey);
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char const* get_secret() const { return m_dh_shared_secret; }
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sha1_hash const& get_hash_xor_mask() const { return m_xor_mask; }
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private:
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int get_local_key_size() const
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{ return sizeof(m_dh_local_key); }
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char m_dh_local_key[96];
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char m_dh_local_secret[96];
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char m_dh_shared_secret[96];
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sha1_hash m_xor_mask;
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};
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struct encryption_handler
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{
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virtual void set_incoming_key(unsigned char const* key, int len) = 0;
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virtual void set_outgoing_key(unsigned char const* key, int len) = 0;
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virtual void encrypt(char* pos, int len) = 0;
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virtual void decrypt(char* pos, int len) = 0;
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virtual ~encryption_handler() {}
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};
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struct rc4_handler : encryption_handler
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{
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public:
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// Input longkeys must be 20 bytes
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rc4_handler()
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: m_encrypt(false)
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, m_decrypt(false)
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{
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#ifdef TORRENT_USE_GCRYPT
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gcry_cipher_open(&m_rc4_incoming, GCRY_CIPHER_ARCFOUR, GCRY_CIPHER_MODE_STREAM, 0);
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gcry_cipher_open(&m_rc4_outgoing, GCRY_CIPHER_ARCFOUR, GCRY_CIPHER_MODE_STREAM, 0);
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#endif
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};
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void set_incoming_key(unsigned char const* key, int len)
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{
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m_decrypt = true;
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#ifdef TORRENT_USE_GCRYPT
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gcry_cipher_close(m_rc4_incoming);
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gcry_cipher_open(&m_rc4_incoming, GCRY_CIPHER_ARCFOUR, GCRY_CIPHER_MODE_STREAM, 0);
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gcry_cipher_setkey(m_rc4_incoming, key, len);
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#elif defined TORRENT_USE_OPENSSL
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RC4_set_key(&m_remote_key, len, key);
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#else
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rc4_init(key, len, &m_rc4_incoming);
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#endif
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// Discard first 1024 bytes
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char buf[1024];
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decrypt(buf, 1024);
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}
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void set_outgoing_key(unsigned char const* key, int len)
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{
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m_encrypt = true;
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#ifdef TORRENT_USE_GCRYPT
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gcry_cipher_close(m_rc4_outgoing);
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gcry_cipher_open(&m_rc4_outgoing, GCRY_CIPHER_ARCFOUR, GCRY_CIPHER_MODE_STREAM, 0);
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gcry_cipher_setkey(m_rc4_outgoing, key, len);
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#elif defined TORRENT_USE_OPENSSL
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RC4_set_key(&m_local_key, len, key);
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#else
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rc4_init(key, len, &m_rc4_outgoing);
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#endif
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// Discard first 1024 bytes
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char buf[1024];
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encrypt(buf, 1024);
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}
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~rc4_handler()
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{
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#ifdef TORRENT_USE_GCRYPT
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gcry_cipher_close(m_rc4_incoming);
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gcry_cipher_close(m_rc4_outgoing);
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#endif
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};
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void encrypt(char* pos, int len)
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{
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if (!m_encrypt) return;
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TORRENT_ASSERT(len >= 0);
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TORRENT_ASSERT(pos);
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#ifdef TORRENT_USE_GCRYPT
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gcry_cipher_encrypt(m_rc4_outgoing, pos, len, 0, 0);
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#elif defined TORRENT_USE_OPENSSL
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RC4(&m_local_key, len, (const unsigned char*)pos, (unsigned char*)pos);
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#else
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rc4_encrypt((unsigned char*)pos, len, &m_rc4_outgoing);
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#endif
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}
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void decrypt(char* pos, int len)
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{
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if (!m_decrypt) return;
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TORRENT_ASSERT(len >= 0);
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TORRENT_ASSERT(pos);
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#ifdef TORRENT_USE_GCRYPT
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gcry_cipher_decrypt(m_rc4_incoming, pos, len, 0, 0);
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#elif defined TORRENT_USE_OPENSSL
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RC4(&m_remote_key, len, (const unsigned char*)pos, (unsigned char*)pos);
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#else
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rc4_encrypt((unsigned char*)pos, len, &m_rc4_incoming);
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#endif
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}
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private:
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#ifdef TORRENT_USE_GCRYPT
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gcry_cipher_hd_t m_rc4_incoming;
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gcry_cipher_hd_t m_rc4_outgoing;
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#elif defined TORRENT_USE_OPENSSL
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RC4_KEY m_local_key; // Key to encrypt outgoing data
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RC4_KEY m_remote_key; // Key to decrypt incoming data
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#else
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rc4 m_rc4_incoming;
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rc4 m_rc4_outgoing;
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#endif
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// determines whether or not encryption and decryption is enabled
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bool m_encrypt;
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bool m_decrypt;
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};
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#ifdef TORRENT_USE_OPENSSL
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struct aes256_handler : encryption_handler
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{
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aes256_handler() : m_enc_pos(0), m_dec_pos(0)
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{
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EVP_CIPHER_CTX_init(&m_enc);
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EVP_CIPHER_CTX_init(&m_dec);
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}
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~aes256_handler()
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{
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EVP_CIPHER_CTX_cleanup(&m_enc);
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EVP_CIPHER_CTX_cleanup(&m_dec);
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}
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void set_incoming_key(unsigned char const* in_key, int len)
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{
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const int nrounds = 5;
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boost::uint8_t salt[8] = { 0xf1, 0x03, 0x46, 0xe2, 0xb1, 0xa8, 0x29, 0x63 };
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boost::uint8_t key[32];
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boost::uint8_t iv[32];
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EVP_BytesToKey(EVP_aes_256_cbc(), EVP_sha1(), salt, in_key, len, nrounds, key, iv);
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TORRENT_ASSERT(len == 32);
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EVP_EncryptInit_ex(&m_enc, EVP_aes_256_cbc(), NULL, key, iv);
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// since we're using the AES as a stream cipher, both the encrypt and
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// decrypt context will in fact only _encrypt_ stuff, so initializing
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// this as encrypt is not a typo
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EVP_EncryptInit_ex(&m_dec, EVP_aes_256_cbc(), NULL, key, iv);
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m_enc_pos = 0;
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m_dec_pos = 0;
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std::memcpy(m_enc_state, iv, sizeof(m_enc_state));
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std::memcpy(m_dec_state, iv, sizeof(m_enc_state));
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}
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void set_outgoing_key(unsigned char const* key, int len) { /* no-op */ }
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void encrypt(char* pos, int len)
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{
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while (len > 0)
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{
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while (m_enc_pos < AES_BLOCK_SIZE && len > 0)
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{
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*pos ^= m_enc_state[m_enc_pos];
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++m_enc_pos;
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++pos;
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--len;
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}
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if (m_enc_pos == AES_BLOCK_SIZE)
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{
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next_block(&m_enc, m_enc_state);
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m_enc_pos = 0;
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}
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}
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}
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void decrypt(char* pos, int len)
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{
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while (len > 0)
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{
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while (m_dec_pos < AES_BLOCK_SIZE && len > 0)
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{
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*pos ^= m_dec_state[m_dec_pos];
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++m_dec_pos;
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++pos;
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--len;
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}
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if (m_dec_pos == AES_BLOCK_SIZE)
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{
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next_block(&m_dec, m_dec_state);
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m_dec_pos = 0;
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}
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}
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}
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private:
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// we're turning the AES block-cipher into a stream cipher. This
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// function will produce the next block in the sequence of
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// block-sized buffers. We're using "Output feedback" (OFB) mode.
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void next_block(EVP_CIPHER_CTX* ctx, boost::uint8_t* pad)
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{
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int outlen = AES_BLOCK_SIZE;
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EVP_EncryptUpdate(ctx, pad, &outlen, pad, AES_BLOCK_SIZE);
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TORRENT_ASSERT(outlen == AES_BLOCK_SIZE);
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}
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EVP_CIPHER_CTX m_enc;
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EVP_CIPHER_CTX m_dec;
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boost::uint8_t m_enc_state[AES_BLOCK_SIZE];
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boost::uint8_t m_dec_state[AES_BLOCK_SIZE];
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int m_enc_pos;
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int m_dec_pos;
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};
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#endif // TORRENT_USE_OPENSSL
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} // namespace libtorrent
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#endif // TORRENT_PE_CRYPTO_HPP_INCLUDED
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#endif // TORRENT_DISABLE_ENCRYPTION
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