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Optimized legbrute
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Removed multithreading and bottlenecks in favor of sequentially generated keys.
Multithreading can/should be reimplemented but optimized for keyspaces
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@Antiklesys
Antiklesys committed Sep 17, 2024
1 parent 5bbffaf commit f70008b
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Showing 2 changed files with 39 additions and 71 deletions.
109 changes: 38 additions & 71 deletions client/src/cmdhficlass.c
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Original file line number Diff line number Diff line change
Expand Up @@ -3923,6 +3923,22 @@ void *generate_key_blocks(void *arg) {
return NULL;
}

void generate_key_block_inverted(const uint8_t *startingKey, uint32_t index, uint8_t *keyBlock) {
uint32_t carry = index;
memcpy(keyBlock, startingKey, PICOPASS_BLOCK_SIZE);

for (int j = PICOPASS_BLOCK_SIZE - 1; j >= 0; j--) {
uint8_t increment_value = (carry & 0x1F) << 3; // Use the first 5 bits of carry and shift left by 3 to occupy the first 5 bits
keyBlock[j] = (keyBlock[j] & 0x07) | increment_value; // Preserve last 3 bits, modify the first 5 bits

carry >>= 5; // Shift right by 5 bits for the next byte
if (carry == 0) {
// If no more carry, break early to avoid unnecessary loops
break;
}
}
}

static int CmdHFiClassLegRecLookUp(const char *Cmd) {

//Standalone Command Start
Expand All @@ -3939,6 +3955,7 @@ static int CmdHFiClassLegRecLookUp(const char *Cmd) {
arg_str1(NULL, "macs1", "<hex>", "MACs captured from the reader"),
arg_str1(NULL, "macs2", "<hex>", "MACs captured from the reader, different than the first set (with the same csn and epurse value)"),
arg_str1(NULL, "pk", "<hex>", "Partial Key from legrec or starting key of keyblock from legbrute"),
arg_int0(NULL, "index", "<dec>", "Where to start from to retrieve the key, default 0"),
arg_param_end
};
CLIExecWithReturn(ctx, Cmd, argtable, false);
Expand Down Expand Up @@ -4003,6 +4020,8 @@ static int CmdHFiClassLegRecLookUp(const char *Cmd) {
}
}

uint64_t index = arg_get_int_def(ctx, 6, 0); //has to be 64 as we're bruteforcing 40 bits

CLIParserFree(ctx);
//Standalone Command End

Expand All @@ -4029,80 +4048,31 @@ static int CmdHFiClassLegRecLookUp(const char *Cmd) {
PrintAndLogEx(SUCCESS, "TAG MAC2: %s", sprint_hex(MAC_TAG2, sizeof(MAC_TAG2)));
PrintAndLogEx(SUCCESS, "Starting Key: %s", sprint_hex(startingKey, 8));

uint32_t keycount = 1000000;
uint32_t keys_per_thread = 250000;
uint32_t num_threads = keycount / keys_per_thread;
pthread_t threads[num_threads];
ThreadData thread_data[num_threads];
iclass_prekey_t *prekey = NULL;
iclass_prekey_t lookup;
iclass_prekey_t *item = NULL;

memcpy(lookup.mac, MAC_TAG, 4);

uint32_t block_index = 0;
bool verified = false;
uint8_t div_key[PICOPASS_BLOCK_SIZE] = {0};
uint8_t generated_mac[4] = {0, 0, 0, 0};

while (!verified) {
for (uint32_t t = 0; t < num_threads; t++) {
thread_data[t].start_index = block_index * keycount + t * keys_per_thread;
thread_data[t].keycount = keys_per_thread;
thread_data[t].startingKey = startingKey;
thread_data[t].keyBlock = calloc(keys_per_thread, PICOPASS_BLOCK_SIZE);

if (thread_data[t].keyBlock == NULL) {
PrintAndLogEx(ERR, "Memory allocation failed for keyBlock in thread %d.", t);
for (uint32_t i = 0; i < t; i++) {
free(thread_data[i].keyBlock);
}
return PM3_EINVARG;
}

pthread_create(&threads[t], NULL, generate_key_blocks, (void *)&thread_data[t]);
}
//generate the key block
generate_key_block_inverted(startingKey, index, div_key);

for (uint32_t t = 0; t < num_threads; t++) {
pthread_join(threads[t], NULL);
}

if (prekey == NULL) {
prekey = calloc(keycount, sizeof(iclass_prekey_t));
} else {
prekey = realloc(prekey, (block_index + 1) * keycount * sizeof(iclass_prekey_t));
}

if (prekey == NULL) {
PrintAndLogEx(ERR, "Memory allocation failed for prekey.");
for (uint32_t t = 0; t < num_threads; t++) {
free(thread_data[t].keyBlock);
}
return PM3_EINVARG;
}
//generate the relevant macs

PrintAndLogEx(INFO, "Generating diversified keys...Index: " _YELLOW_("%d")" of ~1099511",block_index);
for (uint32_t t = 0; t < num_threads; t++) {
if(!t){
PrintAndLogEx(SUCCESS, "KeyBlock Starting Key: %s", sprint_hex(thread_data[t].keyBlock[0], 8));
doMAC(CCNR, div_key, generated_mac);
bool mac_match = true;
for (int i = 0; i < 4; i++) {
if (MAC_TAG[i] != generated_mac[i]) {
mac_match = false;
}
GenerateMacKeyFrom(csn, CCNR, true, false, (uint8_t *)thread_data[t].keyBlock, keys_per_thread, prekey + (block_index * keycount) + (t * keys_per_thread));
}

PrintAndLogEx(INFO, "Sorting...");

// Sort mac list
qsort(prekey, (block_index + 1) * keycount, sizeof(iclass_prekey_t), cmp_uint32);

PrintAndLogEx(SUCCESS, "Searching for " _YELLOW_("%s") " key...", "DEBIT");

// Binary search
item = (iclass_prekey_t *)bsearch(&lookup, prekey, (block_index + 1) * keycount, sizeof(iclass_prekey_t), cmp_uint32);

if (item != NULL) {
if (mac_match) {
//verify this against macs2
PrintAndLogEx(WARNING, _YELLOW_("Found potentially valid RAW key ") _GREEN_("%s")_YELLOW_(" verifying it..."), sprint_hex(item->key, 8));
PrintAndLogEx(WARNING, _YELLOW_("Found potentially valid RAW key ") _GREEN_("%s")_YELLOW_(" verifying it..."), sprint_hex(div_key, 8));
//generate the macs from the key and not the other way around, so we can quickly validate it
uint8_t verification_mac[4] = {0, 0, 0, 0};
doMAC(CCNR2, item->key, verification_mac);
doMAC(CCNR2, div_key, verification_mac);
PrintAndLogEx(INFO, "Usr Provided Mac2: " _GREEN_("%s"), sprint_hex(MAC_TAG2, sizeof(MAC_TAG2)));
PrintAndLogEx(INFO, "Verification Mac: " _GREEN_("%s"), sprint_hex(verification_mac, sizeof(verification_mac)));
bool check_values = true;
Expand All @@ -4112,23 +4082,20 @@ static int CmdHFiClassLegRecLookUp(const char *Cmd) {
}
}
if(check_values){
PrintAndLogEx(SUCCESS, _GREEN_("CONFIRMED VALID RAW key ") _RED_("%s"), sprint_hex(item->key, 8));
PrintAndLogEx(SUCCESS, _GREEN_("CONFIRMED VALID RAW key ") _RED_("%s"), sprint_hex(div_key, 8));
verified = true;
}else{
PrintAndLogEx(INFO, _YELLOW_("Found potentially valid RAW key ") _GREEN_("%s")_YELLOW_(" verifying it..."), sprint_hex(item->key, 8));
item = NULL;
PrintAndLogEx(INFO, _YELLOW_("Found potentially valid RAW key ") _GREEN_("%s")_YELLOW_(" verifying it..."), sprint_hex(div_key, 8));
}

}

for (uint32_t t = 0; t < num_threads; t++) {
free(thread_data[t].keyBlock);
if(index % 1000000 == 0){
PrintAndLogEx(INFO, "Tested: " _YELLOW_("%d")" keys", index);

Check failure

Code scanning / CodeQL

Wrong type of arguments to formatting function High

This format specifier for type 'int' does not match the argument type 'unsigned long'.
PrintAndLogEx(INFO, "Last Generated Key Value: " _YELLOW_("%s"), sprint_hex(div_key, 8));
}

block_index++;
index++;
}

free(prekey);
PrintAndLogEx(NORMAL, "");
return PM3_SUCCESS;
}
Expand Down
1 change: 1 addition & 0 deletions client/src/cmdhficlass.h
View file
Original file line number Diff line number Diff line change
Expand Up @@ -43,4 +43,5 @@ uint32_t picopass_elite_rng(void);
uint32_t picopass_elite_lcg(void);
uint8_t picopass_elite_nextByte(void);
void *generate_key_blocks(void *arg);
void generate_key_block_inverted(const uint8_t *startingKey, uint32_t index, uint8_t *keyBlock);
#endif

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