mirror of
https://github.com/transmission/transmission
synced 2024-12-26 17:47:37 +00:00
424 lines
10 KiB
C
424 lines
10 KiB
C
/* * This file Copyright (C) 2007-2010 Mnemosyne LLC
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*
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* This file is licensed by the GPL version 2. Works owned by the
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* Transmission project are granted a special exemption to clause 2(b)
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* so that the bulk of its code can remain under the MIT license.
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* This exemption does not extend to derived works not owned by
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* the Transmission project.
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*
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* $Id$
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*/
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#include <assert.h>
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#include <inttypes.h> /* uint8_t */
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#include <limits.h> /* for INT_MAX */
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#include <stdarg.h>
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#include <stdlib.h> /* for abs() */
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#include <string.h> /* memcpy */
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#include <openssl/bn.h>
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#include <openssl/dh.h>
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#include <openssl/err.h>
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#include <openssl/rc4.h>
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#include <openssl/sha.h>
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#include <openssl/rand.h>
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#include "transmission.h"
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#include "crypto.h"
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#include "utils.h"
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#define MY_NAME "tr_crypto"
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/**
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***
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**/
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void
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tr_sha1( uint8_t * setme,
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const void * content1,
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int content1_len,
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... )
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{
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va_list vl;
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SHA_CTX sha;
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SHA1_Init( &sha );
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SHA1_Update( &sha, content1, content1_len );
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va_start( vl, content1_len );
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for( ; ; )
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{
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const void * content = (const void*) va_arg( vl, const void* );
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const int content_len = content ? (int) va_arg( vl, int ) : -1;
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if( content == NULL || content_len < 1 )
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break;
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SHA1_Update( &sha, content, content_len );
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}
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va_end( vl );
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SHA1_Final( setme, &sha );
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}
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/**
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***
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**/
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#define KEY_LEN 96
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#define PRIME_LEN 96
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#define DH_PRIVKEY_LEN_MIN 16
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#define DH_PRIVKEY_LEN 20
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static const uint8_t dh_P[PRIME_LEN] =
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{
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0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xC9, 0x0F, 0xDA, 0xA2,
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0x21, 0x68, 0xC2, 0x34, 0xC4, 0xC6, 0x62, 0x8B, 0x80, 0xDC, 0x1C, 0xD1,
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0x29, 0x02, 0x4E, 0x08, 0x8A, 0x67, 0xCC, 0x74, 0x02, 0x0B, 0xBE, 0xA6,
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0x3B, 0x13, 0x9B, 0x22, 0x51, 0x4A, 0x08, 0x79, 0x8E, 0x34, 0x04, 0xDD,
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0xEF, 0x95, 0x19, 0xB3, 0xCD, 0x3A, 0x43, 0x1B, 0x30, 0x2B, 0x0A, 0x6D,
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0xF2, 0x5F, 0x14, 0x37, 0x4F, 0xE1, 0x35, 0x6D, 0x6D, 0x51, 0xC2, 0x45,
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0xE4, 0x85, 0xB5, 0x76, 0x62, 0x5E, 0x7E, 0xC6, 0xF4, 0x4C, 0x42, 0xE9,
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0xA6, 0x3A, 0x36, 0x21, 0x00, 0x00, 0x00, 0x00, 0x00, 0x09, 0x05, 0x63,
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};
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static const uint8_t dh_G[] = { 2 };
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/** @brief Holds state information for encrypted peer communications */
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struct tr_crypto
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{
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RC4_KEY dec_key;
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RC4_KEY enc_key;
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uint8_t torrentHash[SHA_DIGEST_LENGTH];
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tr_bool isIncoming;
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tr_bool torrentHashIsSet;
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tr_bool mySecretIsSet;
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uint8_t myPublicKey[KEY_LEN];
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uint8_t mySecret[KEY_LEN];
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DH * dh;
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};
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/**
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***
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**/
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#define logErrorFromSSL( ... ) \
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do { \
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if( tr_msgLoggingIsActive( TR_MSG_ERR ) ) { \
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char buf[512]; \
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ERR_error_string_n( ERR_get_error( ), buf, sizeof( buf ) ); \
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tr_msg( __FILE__, __LINE__, TR_MSG_ERR, MY_NAME, "%s", buf ); \
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} \
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} while( 0 )
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static void
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ensureKeyExists( tr_crypto * crypto)
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{
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if( crypto->dh == NULL )
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{
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int len, offset;
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DH * dh = DH_new( );
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dh->p = BN_bin2bn( dh_P, sizeof( dh_P ), NULL );
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if( dh->p == NULL )
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logErrorFromSSL( );
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dh->g = BN_bin2bn( dh_G, sizeof( dh_G ), NULL );
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if( dh->g == NULL )
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logErrorFromSSL( );
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/* private DH value: strong random BN of DH_PRIVKEY_LEN*8 bits */
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dh->priv_key = BN_new( );
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do {
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if( BN_rand( dh->priv_key, DH_PRIVKEY_LEN * 8, -1, 0 ) != 1 )
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logErrorFromSSL( );
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} while ( BN_num_bits( dh->priv_key ) < DH_PRIVKEY_LEN_MIN * 8 );
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if( !DH_generate_key( dh ) )
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logErrorFromSSL( );
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/* DH can generate key sizes that are smaller than the size of
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P with exponentially decreasing probability, in which case
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the msb's of myPublicKey need to be zeroed appropriately. */
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len = BN_num_bytes( dh->pub_key );
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offset = KEY_LEN - len;
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assert( len <= KEY_LEN );
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memset( crypto->myPublicKey, 0, offset );
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BN_bn2bin( dh->pub_key, crypto->myPublicKey + offset );
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crypto->dh = dh;
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}
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}
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tr_crypto *
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tr_cryptoNew( const uint8_t * torrentHash,
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int isIncoming )
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{
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tr_crypto * crypto;
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crypto = tr_new0( tr_crypto, 1 );
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crypto->isIncoming = isIncoming ? 1 : 0;
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tr_cryptoSetTorrentHash( crypto, torrentHash );
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crypto->dh = NULL;
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return crypto;
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}
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void
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tr_cryptoFree( tr_crypto * crypto )
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{
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if( crypto->dh != NULL )
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DH_free( crypto->dh );
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tr_free( crypto );
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}
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/**
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***
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**/
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const uint8_t*
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tr_cryptoComputeSecret( tr_crypto * crypto,
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const uint8_t * peerPublicKey )
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{
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int len;
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uint8_t secret[KEY_LEN];
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BIGNUM * bn = BN_bin2bn( peerPublicKey, KEY_LEN, NULL );
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DH * dh;
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ensureKeyExists( crypto );
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dh = crypto->dh;
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assert( DH_size( dh ) == KEY_LEN );
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len = DH_compute_key( secret, bn, dh );
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if( len == -1 )
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logErrorFromSSL( );
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else {
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int offset;
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assert( len <= KEY_LEN );
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offset = KEY_LEN - len;
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memset( crypto->mySecret, 0, offset );
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memcpy( crypto->mySecret + offset, secret, len );
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crypto->mySecretIsSet = 1;
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}
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BN_free( bn );
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return crypto->mySecret;
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}
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const uint8_t*
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tr_cryptoGetMyPublicKey( const tr_crypto * crypto,
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int * setme_len )
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{
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ensureKeyExists( (tr_crypto *) crypto );
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*setme_len = KEY_LEN;
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return crypto->myPublicKey;
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}
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/**
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***
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**/
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static void
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initRC4( tr_crypto * crypto,
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RC4_KEY * setme,
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const char * key )
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{
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SHA_CTX sha;
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uint8_t buf[SHA_DIGEST_LENGTH];
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assert( crypto->torrentHashIsSet );
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assert( crypto->mySecretIsSet );
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if( SHA1_Init( &sha )
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&& SHA1_Update( &sha, key, 4 )
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&& SHA1_Update( &sha, crypto->mySecret, KEY_LEN )
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&& SHA1_Update( &sha, crypto->torrentHash, SHA_DIGEST_LENGTH )
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&& SHA1_Final( buf, &sha ) )
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{
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RC4_set_key( setme, SHA_DIGEST_LENGTH, buf );
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}
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else
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{
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logErrorFromSSL( );
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}
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}
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void
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tr_cryptoDecryptInit( tr_crypto * crypto )
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{
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unsigned char discard[1024];
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const char * txt = crypto->isIncoming ? "keyA" : "keyB";
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initRC4( crypto, &crypto->dec_key, txt );
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RC4( &crypto->dec_key, sizeof( discard ), discard, discard );
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}
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void
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tr_cryptoDecrypt( tr_crypto * crypto,
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size_t buf_len,
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const void * buf_in,
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void * buf_out )
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{
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RC4( &crypto->dec_key, buf_len,
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(const unsigned char*)buf_in,
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(unsigned char*)buf_out );
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}
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void
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tr_cryptoEncryptInit( tr_crypto * crypto )
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{
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unsigned char discard[1024];
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const char * txt = crypto->isIncoming ? "keyB" : "keyA";
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initRC4( crypto, &crypto->enc_key, txt );
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RC4( &crypto->enc_key, sizeof( discard ), discard, discard );
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}
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void
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tr_cryptoEncrypt( tr_crypto * crypto,
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size_t buf_len,
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const void * buf_in,
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void * buf_out )
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{
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RC4( &crypto->enc_key, buf_len,
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(const unsigned char*)buf_in,
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(unsigned char*)buf_out );
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}
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/**
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***
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**/
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void
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tr_cryptoSetTorrentHash( tr_crypto * crypto,
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const uint8_t * hash )
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{
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crypto->torrentHashIsSet = hash ? 1 : 0;
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if( hash )
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memcpy( crypto->torrentHash, hash, SHA_DIGEST_LENGTH );
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else
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memset( crypto->torrentHash, 0, SHA_DIGEST_LENGTH );
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}
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const uint8_t*
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tr_cryptoGetTorrentHash( const tr_crypto * crypto )
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{
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assert( crypto );
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assert( crypto->torrentHashIsSet );
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return crypto->torrentHash;
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}
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int
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tr_cryptoHasTorrentHash( const tr_crypto * crypto )
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{
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assert( crypto );
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return crypto->torrentHashIsSet ? 1 : 0;
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}
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int
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tr_cryptoRandInt( int upperBound )
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{
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int noise;
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int val;
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assert( upperBound > 0 );
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if( RAND_pseudo_bytes ( (unsigned char *) &noise, sizeof noise ) >= 0 )
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{
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val = abs( noise ) % upperBound;
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}
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else /* fall back to a weaker implementation... */
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{
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val = tr_cryptoWeakRandInt( upperBound );
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}
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return val;
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}
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int
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tr_cryptoWeakRandInt( int upperBound )
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{
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static tr_bool init = FALSE;
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assert( upperBound > 0 );
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if( !init )
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{
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srand( tr_time_msec( ) );
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init = TRUE;
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}
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return rand( ) % upperBound;
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}
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void
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tr_cryptoRandBuf( void * buf, size_t len )
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{
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if( RAND_pseudo_bytes ( (unsigned char*)buf, len ) != 1 )
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logErrorFromSSL( );
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}
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/***
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****
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***/
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char*
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tr_ssha1( const void * plaintext )
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{
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enum { saltval_len = 8,
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salter_len = 64 };
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static const char * salter = "0123456789"
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"abcdefghijklmnopqrstuvwxyz"
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"ABCDEFGHIJKLMNOPQRSTUVWXYZ"
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"./";
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size_t i;
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char salt[saltval_len];
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uint8_t sha[SHA_DIGEST_LENGTH];
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char buf[2*SHA_DIGEST_LENGTH + saltval_len + 2];
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for( i=0; i<saltval_len; ++i )
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salt[i] = salter[ tr_cryptoRandInt( salter_len ) ];
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tr_sha1( sha, plaintext, strlen( plaintext ), salt, saltval_len, NULL );
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tr_sha1_to_hex( &buf[1], sha );
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memcpy( &buf[1+2*SHA_DIGEST_LENGTH], &salt, saltval_len );
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buf[1+2*SHA_DIGEST_LENGTH + saltval_len] = '\0';
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buf[0] = '{'; /* signal that this is a hash. this makes saving/restoring
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easier */
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return tr_strdup( &buf );
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}
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tr_bool
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tr_ssha1_matches( const char * source, const char * pass )
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{
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char * salt;
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size_t saltlen;
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char * hashed;
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uint8_t buf[SHA_DIGEST_LENGTH];
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tr_bool result;
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/* extract the salt */
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saltlen = strlen( source ) - 2*SHA_DIGEST_LENGTH-1;
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salt = tr_malloc( saltlen );
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memcpy( salt, source + 2*SHA_DIGEST_LENGTH+1, saltlen );
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/* hash pass + salt */
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hashed = tr_malloc( 2*SHA_DIGEST_LENGTH + saltlen + 2 );
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tr_sha1( buf, pass, strlen( pass ), salt, saltlen, NULL );
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tr_sha1_to_hex( &hashed[1], buf );
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memcpy( hashed + 1+2*SHA_DIGEST_LENGTH, salt, saltlen );
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hashed[1+2*SHA_DIGEST_LENGTH + saltlen] = '\0';
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hashed[0] = '{';
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result = strcmp( source, hashed ) == 0 ? TRUE : FALSE;
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tr_free( hashed );
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tr_free( salt );
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return result;
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}
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