tomato/other/fun/cracker.c

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/* Public key cracker.
*
* Can be used to find public keys starting with specific hex (ABCD) for example.
*
* NOTE: There's probably a way to make this faster.
*
* Usage: ./cracker ABCDEF
*
* Will try to find a public key starting with: ABCDEF
*/
#include <inttypes.h>
#include <stdbool.h>
#include <stdlib.h>
#include <stdio.h>
#include <string.h>
#include <time.h>
/* Sodium includes*/
#include <sodium/crypto_scalarmult_curve25519.h>
#include <sodium/randombytes.h>
/* NULL compatibility macro */
#include "../../toxcore/ccompat.h"
#define KEY_LEN 32
// Maximum number of bytes this program can crack in one run
#define MAX_CRACK_BYTES 8
// Maximum length of hex encoded prefix
#define MAX_HEX_PREFIX_LEN (MAX_CRACK_BYTES * 2)
#if defined(_OPENMP)
#include <omp.h>
#define NUM_THREADS() ((unsigned) omp_get_max_threads())
#else
#define NUM_THREADS() (1U)
#endif
static void print_key(const uint8_t *client_id)
{
for (uint32_t j = 0; j < 32; ++j) {
printf("%02X", client_id[j]);
}
}
/// bytes needs to be at least (hex_len+1)/2 long
static size_t hex_string_to_bin(const char *hex_string, size_t hex_len, uint8_t *bytes)
{
size_t i;
const char *pos = hex_string;
// make even
for (i = 0; i < hex_len / 2; ++i, pos += 2) {
uint8_t val;
if (sscanf(pos, "%02hhx", &val) != 1) {
return 0;
}
bytes[i] = val;
}
if (i * 2 < hex_len) {
uint8_t val;
if (sscanf(pos, "%hhx", &val) != 1) {
return 0;
}
bytes[i] = (uint8_t)(val << 4);
++i;
}
return i;
}
static size_t match_hex_prefix(const uint8_t *key, const uint8_t *prefix, size_t prefix_len)
{
size_t same = 0;
uint8_t diff = 0;
size_t i;
for (i = 0; i < prefix_len / 2; ++i) {
diff = key[i] ^ prefix[i];
// First check high nibble
if ((diff & 0xF0) == 0) {
++same;
}
// Then low nibble
if (diff == 0) {
++same;
} else {
break;
}
}
// check last high nibble
if ((prefix_len % 2) && diff == 0) {
diff = key[i] ^ prefix[i];
// First check high nibble
if ((diff & 0xF0) == 0) {
++same;
}
}
return same;
}
static void cracker_core(uint64_t range_start, uint64_t range_end, uint64_t range_offs, uint64_t priv_key_shadow[4],
uint32_t *longest_match, uint8_t hex_prefix[MAX_CRACK_BYTES], size_t prefix_chars_len)
{
#pragma omp parallel for firstprivate(priv_key_shadow) shared(longest_match, range_start, range_end, range_offs, hex_prefix, prefix_chars_len) schedule(static) default(none)
for (uint64_t batch = range_start; batch < range_end; ++batch) {
uint8_t *priv_key = (uint8_t *) priv_key_shadow;
/*
* We can't use the first and last bytes because they are masked in
* curve25519. Offset by 16 bytes to get better alignment.
*/
uint64_t *counter = priv_key_shadow + 2;
/*
* Add to `counter` instead of assign here, to preservere more randomness on short runs
* There can be an intentional overflow in `batch + range_offs`
*/
*counter += batch + range_offs;
uint8_t pub_key[KEY_LEN] = {0};
crypto_scalarmult_curve25519_base(pub_key, priv_key);
const unsigned matching = (unsigned) match_hex_prefix(pub_key, hex_prefix, prefix_chars_len);
// Global compare and update
uint32_t l_longest_match;
#pragma omp atomic read
l_longest_match = *longest_match;
if (matching > l_longest_match) {
#pragma omp atomic write
*longest_match = matching;
#pragma omp critical
{
printf("%u chars matching: \n", matching);
printf("Public key: ");
print_key(pub_key);
printf("\nSecret key: ");
print_key(priv_key);
printf("\n");
}
}
}
}
static void print_stats(double seconds_passed, double keys_tried)
{
printf("Runtime: %10lus, Keys tried %e/%e, Calculating %e keys/s\n",
(unsigned long) seconds_passed, keys_tried, (double) UINT64_MAX, keys_tried / seconds_passed);
}
int main(int argc, char *argv[])
{
if (argc < 2) {
printf("usage: ./cracker public_key(or beginning of one in hex format)\n");
return 0;
}
const size_t prefix_chars_len = strlen(argv[1]);
/*
* If you can afford the hardware to crack longer prefixes, you can probably
* afford to rewrite this program.
*/
if (prefix_chars_len > MAX_HEX_PREFIX_LEN) {
printf("Finding a key with more than 16 hex chars as prefix is not supported\n");
return 1;
}
uint8_t hex_prefix[MAX_CRACK_BYTES] = {0};
const size_t prefix_len = hex_string_to_bin(argv[1], prefix_chars_len, hex_prefix);
if (prefix_len == 0) {
printf("Invalid hex key specified\n");
return 1;
}
printf("Searching for key with prefix: %s\n", argv[1]);
time_t start_time = time(nullptr);
// Declare private key bytes as uint64_t[4] so we can lower the alignment without problems
uint64_t priv_key_shadow[KEY_LEN / 8];
uint8_t *priv_key = (uint8_t *) priv_key_shadow;
// Put randomness into the key
randombytes(priv_key, KEY_LEN);
uint32_t longest_match = 0;
// Finishes a batch every ~10s on my PC
const uint64_t batch_size = (UINT64_C(1) << 18) * NUM_THREADS();
// calculate remaining batch that doesn't fit the main loop
const uint64_t rem_batch_size = UINT64_MAX % batch_size;
const uint64_t rem_start = UINT64_MAX - rem_batch_size - 1;
cracker_core(rem_start, UINT64_MAX, 1, priv_key_shadow, &longest_match, hex_prefix, prefix_chars_len);
double seconds_passed = difftime(time(nullptr), start_time);
double old_seconds_passed = seconds_passed;
// Reduce time to first stats output
print_stats(seconds_passed, rem_batch_size + 1);
if (longest_match >= prefix_chars_len) {
printf("Found matching prefix, exiting...\n");
return 0;
}
for (uint64_t tries = 0; tries < rem_start; tries += batch_size) {
cracker_core(tries, tries + batch_size, 0, priv_key_shadow, &longest_match, hex_prefix, prefix_chars_len);
seconds_passed = difftime(time(nullptr), start_time);
// Use double type to avoid overflow in addition, we don't need precision here anyway
double keys_tried = ((double) tries) + rem_batch_size + 1;
if (longest_match >= prefix_chars_len) {
print_stats(seconds_passed, keys_tried);
printf("Found matching prefix, exiting...\n");
return 0;
}
// Rate limit output
if (seconds_passed - old_seconds_passed > 5.0) {
old_seconds_passed = seconds_passed;
print_stats(seconds_passed, keys_tried);
fflush(stdout);
}
}
printf("Congrats future person who successfully searched a key space of 2^64\n");
uint64_t *counter = priv_key_shadow + 2;
*counter = 0;
printf("Didn't find anything from:\n");
print_key(priv_key);
printf("\nto:\n");
*counter = UINT64_MAX;
print_key(priv_key);
printf("\n");
return 2;
}