408 lines
9.1 KiB
C
408 lines
9.1 KiB
C
/*
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* This file Copyright (C) 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 <stdarg.h>
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#include <stdlib.h> /* abs () */
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#include <string.h> /* memcpy (), memset (), strcmp () */
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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 "log.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, const void * content1, int content1_len, ...)
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{
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va_list vl;
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SHA_CTX sha;
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const void * content;
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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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while ((content = va_arg (vl, const void*)))
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SHA1_Update (&sha, content, va_arg (vl, int));
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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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/**
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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_logLevelIsActive (TR_LOG_ERROR)) { \
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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_logAddMessage (__FILE__, __LINE__, TR_LOG_ERROR, 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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{
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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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}
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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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void
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tr_cryptoConstruct (tr_crypto * crypto, const uint8_t * torrentHash, bool isIncoming)
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{
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memset (crypto, 0, sizeof (tr_crypto));
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crypto->dh = NULL;
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crypto->isIncoming = isIncoming;
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tr_cryptoSetTorrentHash (crypto, torrentHash);
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}
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void
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tr_cryptoDestruct (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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}
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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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DH * dh;
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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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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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{
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logErrorFromSSL ();
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}
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else
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{
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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 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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unsigned 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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tr_cryptoRandBuf (salt, saltval_len);
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for (i=0; i<saltval_len; ++i)
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salt[i] = salter[ salt[i] % 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 easier */
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return tr_strdup (&buf);
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}
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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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bool result;
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const size_t sourcelen = strlen (source);
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/* extract the salt */
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if (sourcelen < 2*SHA_DIGEST_LENGTH-1)
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return false;
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saltlen = sourcelen - 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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