transmission/libtransmission/crypto-utils.cc

296 lines
6.3 KiB
C++

/*
* 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.
*
*/
#include <stdarg.h>
#include <stdlib.h> /* abs(), srand(), rand() */
#include <string.h> /* memcpy(), memmove(), memset(), strcmp(), strlen() */
#include <arc4.h>
extern "C"
{
#include <b64/cdecode.h>
#include <b64/cencode.h>
}
#include "transmission.h"
#include "crypto-utils.h"
#include "tr-assert.h"
#include "utils.h"
/***
****
***/
void tr_dh_align_key(uint8_t* key_buffer, size_t key_size, size_t buffer_size)
{
TR_ASSERT(key_size <= buffer_size);
/* DH can generate key sizes that are smaller than the size of
key buffer with exponentially decreasing probability, in which case
the msb's of key buffer need to be zeroed appropriately. */
if (key_size < buffer_size)
{
size_t const offset = buffer_size - key_size;
memmove(key_buffer + offset, key_buffer, key_size);
memset(key_buffer, 0, offset);
}
}
/***
****
***/
bool tr_sha1(uint8_t* hash, void const* data1, int data1_length, ...)
{
tr_sha1_ctx_t sha;
if ((sha = tr_sha1_init()) == nullptr)
{
return false;
}
if (tr_sha1_update(sha, data1, data1_length))
{
va_list vl;
void const* data;
va_start(vl, data1_length);
while ((data = va_arg(vl, void const*)) != nullptr)
{
int const data_length = va_arg(vl, int);
TR_ASSERT(data_length >= 0);
if (!tr_sha1_update(sha, data, data_length))
{
break;
}
}
va_end(vl);
/* did we reach the end of argument list? */
if (data == nullptr)
{
return tr_sha1_final(sha, hash);
}
}
tr_sha1_final(sha, nullptr);
return false;
}
/***
****
***/
int tr_rand_int(int upper_bound)
{
TR_ASSERT(upper_bound > 0);
unsigned int noise;
if (tr_rand_buffer(&noise, sizeof(noise)))
{
return noise % upper_bound;
}
/* fall back to a weaker implementation... */
return tr_rand_int_weak(upper_bound);
}
int tr_rand_int_weak(int upper_bound)
{
TR_ASSERT(upper_bound > 0);
static bool init = false;
if (!init)
{
srand(tr_time_msec());
init = true;
}
return rand() % upper_bound;
}
/***
****
***/
char* tr_ssha1(char const* plain_text)
{
TR_ASSERT(plain_text != nullptr);
enum
{
saltval_len = 8,
salter_len = 64
};
static char const* salter =
"0123456789"
"abcdefghijklmnopqrstuvwxyz"
"ABCDEFGHIJKLMNOPQRSTUVWXYZ"
"./";
unsigned char salt[saltval_len];
uint8_t sha[SHA_DIGEST_LENGTH];
char buf[2 * SHA_DIGEST_LENGTH + saltval_len + 2];
tr_rand_buffer(salt, saltval_len);
for (size_t i = 0; i < saltval_len; ++i)
{
salt[i] = salter[salt[i] % salter_len];
}
tr_sha1(sha, plain_text, (int)strlen(plain_text), salt, saltval_len, nullptr);
tr_sha1_to_hex(&buf[1], sha);
memcpy(&buf[1 + 2 * SHA_DIGEST_LENGTH], &salt, saltval_len);
buf[1 + 2 * SHA_DIGEST_LENGTH + saltval_len] = '\0';
buf[0] = '{'; /* signal that this is a hash. this makes saving/restoring easier */
return tr_strdup(buf);
}
bool tr_ssha1_matches(char const* ssha1, char const* plain_text)
{
TR_ASSERT(ssha1 != nullptr);
TR_ASSERT(plain_text != nullptr);
size_t const brace_len = 1;
size_t const brace_and_hash_len = brace_len + 2 * SHA_DIGEST_LENGTH;
size_t const source_len = strlen(ssha1);
if (source_len < brace_and_hash_len || ssha1[0] != '{')
{
return false;
}
/* extract the salt */
char const* const salt = ssha1 + brace_and_hash_len;
size_t const salt_len = source_len - brace_and_hash_len;
uint8_t buf[SHA_DIGEST_LENGTH * 2 + 1];
/* hash pass + salt */
tr_sha1(buf, plain_text, (int)strlen(plain_text), salt, (int)salt_len, nullptr);
tr_sha1_to_hex((char*)buf, buf);
return strncmp(ssha1 + brace_len, (char const*)buf, SHA_DIGEST_LENGTH * 2) == 0;
}
/***
****
***/
void* tr_base64_encode(void const* input, size_t input_length, size_t* output_length)
{
char* ret;
if (input != nullptr)
{
if (input_length != 0)
{
size_t ret_length = 4 * ((input_length + 2) / 3);
base64_encodestate state;
#ifdef USE_SYSTEM_B64
/* Additional space is needed for newlines if we're using unpatched libb64 */
ret_length += ret_length / 72 + 1;
#endif
ret = tr_new(char, ret_length + 8);
base64_init_encodestate(&state);
ret_length = base64_encode_block(static_cast<char const*>(input), input_length, ret, &state);
ret_length += base64_encode_blockend(ret + ret_length, &state);
if (output_length != nullptr)
{
*output_length = ret_length;
}
ret[ret_length] = '\0';
return ret;
}
else
{
ret = tr_strdup("");
}
}
else
{
ret = nullptr;
}
if (output_length != nullptr)
{
*output_length = 0;
}
return ret;
}
void* tr_base64_encode_str(char const* input, size_t* output_length)
{
return tr_base64_encode(input, input == nullptr ? 0 : strlen(input), output_length);
}
void* tr_base64_decode(void const* input, size_t input_length, size_t* output_length)
{
char* ret;
if (input != nullptr)
{
if (input_length != 0)
{
size_t ret_length = input_length / 4 * 3;
base64_decodestate state;
ret = tr_new(char, ret_length + 8);
base64_init_decodestate(&state);
ret_length = base64_decode_block(static_cast<char const*>(input), input_length, ret, &state);
if (output_length != nullptr)
{
*output_length = ret_length;
}
ret[ret_length] = '\0';
return ret;
}
else
{
ret = tr_strdup("");
}
}
else
{
ret = nullptr;
}
if (output_length != nullptr)
{
*output_length = 0;
}
return ret;
}
void* tr_base64_decode_str(char const* input, size_t* output_length)
{
return tr_base64_decode(input, input == nullptr ? 0 : strlen(input), output_length);
}