transmission/libtransmission/crypto-utils.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.
*
* $Id$
*/
#include <assert.h>
#include <stdarg.h>
#include <stdlib.h> /* abs (), srand (), rand () */
#include <string.h> /* memcpy (), memmove (), memset (), strcmp (), strlen () */
#include <b64/cdecode.h>
#include <b64/cencode.h>
#include "transmission.h"
#include "crypto-utils.h"
#include "utils.h"
/***
****
***/
void
tr_dh_align_key (uint8_t * key_buffer,
size_t key_size,
size_t buffer_size)
{
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)
{
const size_t offset = buffer_size - key_size;
memmove (key_buffer + offset, key_buffer, key_size);
memset (key_buffer, 0, offset);
}
}
/***
****
***/
bool
tr_sha1 (uint8_t * hash,
const void * data1,
int data1_length,
...)
{
tr_sha1_ctx_t sha;
if ((sha = tr_sha1_init ()) == NULL)
return false;
if (tr_sha1_update (sha, data1, data1_length))
{
va_list vl;
const void * data;
va_start (vl, data1_length);
while ((data = va_arg (vl, const void *)) != NULL)
{
const int data_length = va_arg (vl, int);
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 == NULL)
return tr_sha1_final (sha, hash);
}
tr_sha1_final (sha, NULL);
return false;
}
/***
****
***/
int
tr_rand_int (int upper_bound)
{
int noise;
assert (upper_bound > 0);
while (tr_rand_buffer (&noise, sizeof (noise)))
{
noise = abs(noise) % upper_bound;
/* abs(INT_MIN) is undefined and could return negative value */
if (noise >= 0)
return noise;
}
/* fall back to a weaker implementation... */
return tr_rand_int_weak (upper_bound);
}
int
tr_rand_int_weak (int upper_bound)
{
static bool init = false;
assert (upper_bound > 0);
if (!init)
{
srand (tr_time_msec ());
init = true;
}
return rand () % upper_bound;
}
/***
****
***/
char *
tr_ssha1 (const char * plain_text)
{
enum { saltval_len = 8,
salter_len = 64 };
static const char * salter = "0123456789"
"abcdefghijklmnopqrstuvwxyz"
"ABCDEFGHIJKLMNOPQRSTUVWXYZ"
"./";
size_t i;
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 (i = 0; i < saltval_len; ++i)
salt[i] = salter[salt[i] % salter_len];
tr_sha1 (sha, plain_text, strlen (plain_text), salt, (size_t) saltval_len, NULL);
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 (const char * ssha1,
const char * plain_text)
{
char * salt;
size_t saltlen;
char * my_ssha1;
uint8_t buf[SHA_DIGEST_LENGTH];
bool result;
const size_t sourcelen = strlen (ssha1);
/* extract the salt */
if (sourcelen < 2 * SHA_DIGEST_LENGTH - 1)
return false;
saltlen = sourcelen - 2 * SHA_DIGEST_LENGTH - 1;
salt = tr_malloc (saltlen);
memcpy (salt, ssha1 + 2 * SHA_DIGEST_LENGTH + 1, saltlen);
/* hash pass + salt */
my_ssha1 = tr_malloc (2 * SHA_DIGEST_LENGTH + saltlen + 2);
tr_sha1 (buf, plain_text, strlen (plain_text), salt, saltlen, NULL);
tr_sha1_to_hex (&my_ssha1[1], buf);
memcpy (my_ssha1 + 1 + 2 * SHA_DIGEST_LENGTH, salt, saltlen);
my_ssha1[1 + 2 * SHA_DIGEST_LENGTH + saltlen] = '\0';
my_ssha1[0] = '{';
result = strcmp (ssha1, my_ssha1) == 0;
tr_free (my_ssha1);
tr_free (salt);
return result;
}
/***
****
***/
void *
tr_base64_encode (const void * input,
size_t input_length,
size_t * output_length)
{
char * ret;
if (input != NULL)
{
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 + 1);
base64_init_encodestate (&state);
ret_length = base64_encode_block (input, input_length, ret, &state);
ret_length += base64_encode_blockend (ret + ret_length, &state);
if (output_length != NULL)
*output_length = ret_length;
ret[ret_length] = '\0';
return ret;
}
else
ret = tr_strdup ("");
}
else
{
ret = NULL;
}
if (output_length != NULL)
*output_length = 0;
return ret;
}
void *
tr_base64_encode_str (const char * input,
size_t * output_length)
{
return tr_base64_encode (input, input == NULL ? 0 : strlen (input), output_length);
}
void *
tr_base64_decode (const void * input,
size_t input_length,
size_t * output_length)
{
char * ret;
if (input != NULL)
{
if (input_length != 0)
{
size_t ret_length = input_length / 4 * 3;
base64_decodestate state;
ret = tr_new (char, ret_length + 1);
base64_init_decodestate (&state);
ret_length = base64_decode_block (input, input_length, ret, &state);
if (output_length != NULL)
*output_length = ret_length;
ret[ret_length] = '\0';
return ret;
}
else
ret = tr_strdup ("");
}
else
{
ret = NULL;
}
if (output_length != NULL)
*output_length = 0;
return ret;
}
void *
tr_base64_decode_str (const char * input,
size_t * output_length)
{
return tr_base64_decode (input, input == NULL ? 0 : strlen (input), output_length);
}