transmission/libtransmission/crypto.c

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/*
* This file Copyright (C) 2007-2014 Mnemosyne LLC
*
* It may be used under the GNU GPL versions 2 or 3
* or any future license endorsed by Mnemosyne LLC.
*
* $Id$
*/
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#include <assert.h>
#include <string.h> /* memcpy (), memmove (), memset () */
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#include "transmission.h"
#include "crypto.h"
#include "crypto-utils.h"
#include "utils.h"
/**
***
**/
#define PRIME_LEN 96
#define DH_PRIVKEY_LEN 20
static const uint8_t dh_P[PRIME_LEN] =
{
0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xC9, 0x0F, 0xDA, 0xA2,
0x21, 0x68, 0xC2, 0x34, 0xC4, 0xC6, 0x62, 0x8B, 0x80, 0xDC, 0x1C, 0xD1,
0x29, 0x02, 0x4E, 0x08, 0x8A, 0x67, 0xCC, 0x74, 0x02, 0x0B, 0xBE, 0xA6,
0x3B, 0x13, 0x9B, 0x22, 0x51, 0x4A, 0x08, 0x79, 0x8E, 0x34, 0x04, 0xDD,
0xEF, 0x95, 0x19, 0xB3, 0xCD, 0x3A, 0x43, 0x1B, 0x30, 0x2B, 0x0A, 0x6D,
0xF2, 0x5F, 0x14, 0x37, 0x4F, 0xE1, 0x35, 0x6D, 0x6D, 0x51, 0xC2, 0x45,
0xE4, 0x85, 0xB5, 0x76, 0x62, 0x5E, 0x7E, 0xC6, 0xF4, 0x4C, 0x42, 0xE9,
0xA6, 0x3A, 0x36, 0x21, 0x00, 0x00, 0x00, 0x00, 0x00, 0x09, 0x05, 0x63,
};
static const uint8_t dh_G[] = { 2 };
/**
***
**/
static void
ensureKeyExists (tr_crypto * crypto)
{
if (crypto->dh == NULL)
{
size_t public_key_length;
crypto->dh = tr_dh_new (dh_P, sizeof (dh_P), dh_G, sizeof (dh_G));
tr_dh_make_key (crypto->dh, DH_PRIVKEY_LEN, crypto->myPublicKey, &public_key_length);
assert (public_key_length == KEY_LEN);
}
}
void
tr_cryptoConstruct (tr_crypto * crypto, const uint8_t * torrentHash, bool isIncoming)
{
memset (crypto, 0, sizeof (tr_crypto));
crypto->isIncoming = isIncoming;
tr_cryptoSetTorrentHash (crypto, torrentHash);
}
void
tr_cryptoDestruct (tr_crypto * crypto)
{
tr_dh_secret_free (crypto->mySecret);
tr_dh_free (crypto->dh);
tr_rc4_free (crypto->enc_key);
tr_rc4_free (crypto->dec_key);
}
/**
***
**/
bool
tr_cryptoComputeSecret (tr_crypto * crypto,
const uint8_t * peerPublicKey)
{
ensureKeyExists (crypto);
crypto->mySecret = tr_dh_agree (crypto->dh, peerPublicKey, KEY_LEN);
return crypto->mySecret != NULL;
}
const uint8_t*
tr_cryptoGetMyPublicKey (const tr_crypto * crypto,
int * setme_len)
{
ensureKeyExists ((tr_crypto *) crypto);
*setme_len = KEY_LEN;
return crypto->myPublicKey;
}
/**
***
**/
static void
initRC4 (tr_crypto * crypto,
tr_rc4_ctx_t * setme,
const char * key)
{
uint8_t buf[SHA_DIGEST_LENGTH];
assert (crypto->torrentHashIsSet);
if (*setme == NULL)
*setme = tr_rc4_new ();
if (tr_cryptoSecretKeySha1 (crypto,
key, 4,
crypto->torrentHash, SHA_DIGEST_LENGTH,
buf))
tr_rc4_set_key (*setme, buf, SHA_DIGEST_LENGTH);
}
void
tr_cryptoDecryptInit (tr_crypto * crypto)
{
unsigned char discard[1024];
const char * txt = crypto->isIncoming ? "keyA" : "keyB";
initRC4 (crypto, &crypto->dec_key, txt);
tr_rc4_process (crypto->dec_key, discard, discard, sizeof (discard));
}
void
tr_cryptoDecrypt (tr_crypto * crypto,
size_t buf_len,
const void * buf_in,
void * buf_out)
{
/* FIXME: someone calls this function with uninitialized key */
if (crypto->dec_key == NULL)
{
if (buf_in != buf_out)
memmove (buf_out, buf_in, buf_len);
return;
}
tr_rc4_process (crypto->dec_key, buf_in, buf_out, buf_len);
}
void
tr_cryptoEncryptInit (tr_crypto * crypto)
{
unsigned char discard[1024];
const char * txt = crypto->isIncoming ? "keyB" : "keyA";
initRC4 (crypto, &crypto->enc_key, txt);
tr_rc4_process (crypto->enc_key, discard, discard, sizeof (discard));
}
void
tr_cryptoEncrypt (tr_crypto * crypto,
size_t buf_len,
const void * buf_in,
void * buf_out)
{
/* FIXME: someone calls this function with uninitialized key */
if (crypto->enc_key == NULL)
{
if (buf_in != buf_out)
memmove (buf_out, buf_in, buf_len);
return;
}
tr_rc4_process (crypto->enc_key, buf_in, buf_out, buf_len);
}
bool
tr_cryptoSecretKeySha1 (const tr_crypto * crypto,
const void * prepend_data,
size_t prepend_data_size,
const void * append_data,
size_t append_data_size,
uint8_t * hash)
{
assert (crypto != NULL);
assert (crypto->mySecret != NULL);
return tr_dh_secret_derive (crypto->mySecret,
prepend_data, prepend_data_size,
append_data, append_data_size,
hash);
}
/**
***
**/
void
tr_cryptoSetTorrentHash (tr_crypto * crypto,
const uint8_t * hash)
{
crypto->torrentHashIsSet = hash != NULL;
if (hash)
memcpy (crypto->torrentHash, hash, SHA_DIGEST_LENGTH);
else
memset (crypto->torrentHash, 0, SHA_DIGEST_LENGTH);
}
const uint8_t*
tr_cryptoGetTorrentHash (const tr_crypto * crypto)
{
assert (crypto);
return crypto->torrentHashIsSet ? crypto->torrentHash : NULL;
}
bool
tr_cryptoHasTorrentHash (const tr_crypto * crypto)
{
assert (crypto);
return crypto->torrentHashIsSet;
}