X-Git-Url: https://git.zerfleddert.de/cgi-bin/gitweb.cgi/proxmark3-svn/blobdiff_plain/97d582a69235c88c8f30a88193769dbddb74e9b1..refs/pull/278/head:/client/mifarehost.c?ds=inline

diff --git a/client/mifarehost.c b/client/mifarehost.c
index 72e70662..c6c6877e 100644
--- a/client/mifarehost.c
+++ b/client/mifarehost.c
@@ -8,25 +8,234 @@
 // mifare commands
 //-----------------------------------------------------------------------------
 
+#include "mifarehost.h"
+
 #include <stdio.h>
 #include <stdlib.h> 
 #include <string.h>
 #include <pthread.h>
-#include "mifarehost.h"
-#include "proxmark3.h"
 
-// MIFARE
-int compar_int(const void * a, const void * b) {
+#include "crapto1/crapto1.h"
+#include "proxmark3.h"
+#include "usb_cmd.h"
+#include "cmdmain.h"
+#include "ui.h"
+#include "util.h"
+#include "iso14443crc.h"
+
+// mifare tracer flags used in mfTraceDecode()
+#define TRACE_IDLE		 				0x00
+#define TRACE_AUTH1		 				0x01
+#define TRACE_AUTH2		 				0x02
+#define TRACE_AUTH_OK	 				0x03
+#define TRACE_READ_DATA 				0x04
+#define TRACE_WRITE_OK					0x05
+#define TRACE_WRITE_DATA				0x06
+#define TRACE_ERROR		 				0xFF
+
+
+static int compare_uint64(const void *a, const void *b) {
 	// didn't work: (the result is truncated to 32 bits)
-	//return (*(uint64_t*)b - *(uint64_t*)a);
+	//return (*(int64_t*)b - *(int64_t*)a);
 
 	// better:
 	if (*(uint64_t*)b == *(uint64_t*)a) return 0;
-	else if (*(uint64_t*)b > *(uint64_t*)a) return 1;
+	else if (*(uint64_t*)b < *(uint64_t*)a) return 1;
 	else return -1;
 }
 
 
+// create the intersection (common members) of two sorted lists. Lists are terminated by -1. Result will be in list1. Number of elements is returned.
+static uint32_t intersection(uint64_t *list1, uint64_t *list2)
+{
+	if (list1 == NULL || list2 == NULL) {
+		return 0;
+	}
+	uint64_t *p1, *p2, *p3;
+	p1 = p3 = list1; 
+	p2 = list2;
+
+	while ( *p1 != -1 && *p2 != -1 ) {
+		if (compare_uint64(p1, p2) == 0) {
+			*p3++ = *p1++;
+			p2++;
+		}
+		else {
+			while (compare_uint64(p1, p2) < 0) ++p1;
+			while (compare_uint64(p1, p2) > 0) ++p2;
+		}
+	}
+	*p3 = -1;
+	return p3 - list1;
+}
+
+
+// Darkside attack (hf mf mifare)
+static uint32_t nonce2key(uint32_t uid, uint32_t nt, uint32_t nr, uint64_t par_info, uint64_t ks_info, uint64_t **keys) {
+	struct Crypto1State *states;
+	uint32_t i, pos, rr; //nr_diff;
+	uint8_t bt, ks3x[8], par[8][8];
+	uint64_t key_recovered;
+	static uint64_t *keylist;
+	rr = 0;
+
+	// Reset the last three significant bits of the reader nonce
+	nr &= 0xffffff1f;
+
+	for (pos=0; pos<8; pos++) {
+		ks3x[7-pos] = (ks_info >> (pos*8)) & 0x0f;
+		bt = (par_info >> (pos*8)) & 0xff;
+		for (i=0; i<8; i++)	{
+				par[7-pos][i] = (bt >> i) & 0x01;
+		}
+	}
+
+	states = lfsr_common_prefix(nr, rr, ks3x, par, (par_info == 0));
+
+	if (states == NULL) {
+		*keys = NULL;
+		return 0;
+	}
+
+	keylist = (uint64_t*)states;
+	
+	for (i = 0; keylist[i]; i++) {
+		lfsr_rollback_word(states+i, uid^nt, 0);
+		crypto1_get_lfsr(states+i, &key_recovered);
+		keylist[i] = key_recovered;
+	}
+	keylist[i] = -1;
+
+	*keys = keylist;
+	return i;
+}
+
+
+int mfDarkside(uint64_t *key)
+{
+	uint32_t uid = 0;
+	uint32_t nt = 0, nr = 0;
+	uint64_t par_list = 0, ks_list = 0;
+	uint64_t *keylist = NULL, *last_keylist = NULL;
+	uint32_t keycount = 0;
+	int16_t isOK = 0;
+
+	UsbCommand c = {CMD_READER_MIFARE, {true, 0, 0}};
+
+	// message
+	printf("-------------------------------------------------------------------------\n");
+	printf("Executing command. Expected execution time: 25sec on average\n");
+	printf("Press button on the proxmark3 device to abort both proxmark3 and client.\n");
+	printf("-------------------------------------------------------------------------\n");
+
+	
+	while (true) {
+		clearCommandBuffer();
+		SendCommand(&c);
+		
+		//flush queue
+		while (ukbhit()) {
+			int c = getchar(); (void) c;
+		}
+		
+		// wait cycle
+		while (true) {
+			printf(".");
+			fflush(stdout);
+			if (ukbhit()) {
+				return -5;
+				break;
+			}
+			
+			UsbCommand resp;
+			if (WaitForResponseTimeout(CMD_ACK, &resp, 1000)) {
+				isOK  = resp.arg[0];
+				if (isOK < 0) {
+					return isOK;
+				}
+				uid = (uint32_t)bytes_to_num(resp.d.asBytes +  0, 4);
+				nt =  (uint32_t)bytes_to_num(resp.d.asBytes +  4, 4);
+				par_list = bytes_to_num(resp.d.asBytes +  8, 8);
+				ks_list = bytes_to_num(resp.d.asBytes +  16, 8);
+				nr = bytes_to_num(resp.d.asBytes + 24, 4);
+				break;
+			}
+		}	
+
+		if (par_list == 0 && c.arg[0] == true) {
+			PrintAndLog("Parity is all zero. Most likely this card sends NACK on every failed authentication.");
+			PrintAndLog("Attack will take a few seconds longer because we need two consecutive successful runs.");
+		}
+		c.arg[0] = false;
+
+		keycount = nonce2key(uid, nt, nr, par_list, ks_list, &keylist);
+
+		if (keycount == 0) {
+			PrintAndLog("Key not found (lfsr_common_prefix list is null). Nt=%08x", nt);	
+			PrintAndLog("This is expected to happen in 25%% of all cases. Trying again with a different reader nonce...");
+			continue;
+		}
+
+		qsort(keylist, keycount, sizeof(*keylist), compare_uint64);
+		keycount = intersection(last_keylist, keylist);
+		if (keycount == 0) {
+			free(last_keylist);
+			last_keylist = keylist;
+			continue;
+		}
+
+		if (keycount > 1) {
+			PrintAndLog("Found %u possible keys. Trying to authenticate with each of them ...\n", keycount);
+		} else {
+			PrintAndLog("Found a possible key. Trying to authenticate...\n");
+		}		
+
+		*key = -1;
+		uint8_t keyBlock[USB_CMD_DATA_SIZE];
+		int max_keys = USB_CMD_DATA_SIZE/6;
+		for (int i = 0; i < keycount; i += max_keys) {
+			int size = keycount - i > max_keys ? max_keys : keycount - i;
+			for (int j = 0; j < size; j++) {
+				if (last_keylist == NULL) {
+					num_to_bytes(keylist[i*max_keys + j], 6, keyBlock);
+				} else {
+					num_to_bytes(last_keylist[i*max_keys + j], 6, keyBlock);
+				}
+			}
+			if (!mfCheckKeys(0, 0, false, size, keyBlock, key)) {
+				break;
+			}
+		}	
+		
+		if (*key != -1) {
+			free(last_keylist);
+			free(keylist);
+			break;
+		} else {
+			PrintAndLog("Authentication failed. Trying again...");
+			free(last_keylist);
+			last_keylist = keylist;
+		}
+	}
+	
+	return 0;
+}
+
+
+int mfCheckKeys (uint8_t blockNo, uint8_t keyType, bool clear_trace, uint8_t keycnt, uint8_t * keyBlock, uint64_t * key){
+
+	*key = 0;
+
+	UsbCommand c = {CMD_MIFARE_CHKKEYS, {((blockNo & 0xff) | ((keyType&0xff)<<8)), clear_trace, keycnt}};
+	memcpy(c.d.asBytes, keyBlock, 6 * keycnt);
+	SendCommand(&c);
+
+	UsbCommand resp;
+	if (!WaitForResponseTimeout(CMD_ACK,&resp,3000)) return 1;
+	if ((resp.arg[0] & 0xff) != 0x01) return 2;
+	*key = bytes_to_num(resp.d.asBytes, 6);
+	return 0;
+}
 
 // Compare 16 Bits out of cryptostate
 int Compare16Bits(const void * a, const void * b) {
@@ -35,7 +244,6 @@ int Compare16Bits(const void * a, const void * b) {
 	else return -1;
 }
 
-
 typedef 
 	struct {
 		union {
@@ -70,45 +278,39 @@ void* nested_worker_thread(void *arg)
 	return statelist->head.slhead;
 }
 
-
-
-
-int mfnested(uint8_t blockNo, uint8_t keyType, uint8_t * key, uint8_t trgBlockNo, uint8_t trgKeyType, uint8_t * resultKey, bool calibrate) 
+int mfnested(uint8_t blockNo, uint8_t keyType, uint8_t *key, uint8_t trgBlockNo, uint8_t trgKeyType, uint8_t *resultKey, bool calibrate) 
 {
-	uint16_t i, len;
+	uint16_t i;
 	uint32_t uid;
 	UsbCommand resp;
 
-	
 	StateList_t statelists[2];
 	struct Crypto1State *p1, *p2, *p3, *p4;
 	
 	// flush queue
-	WaitForResponseTimeout(CMD_ACK,NULL,100);
+	WaitForResponseTimeout(CMD_ACK, NULL, 100);
 	
 	UsbCommand c = {CMD_MIFARE_NESTED, {blockNo + keyType * 0x100, trgBlockNo + trgKeyType * 0x100, calibrate}};
 	memcpy(c.d.asBytes, key, 6);
 	SendCommand(&c);
 
-	if (WaitForResponseTimeout(CMD_ACK,&resp,1500)) {
-		len = resp.arg[1];
-		if (len == 2) {	
-			memcpy(&uid, resp.d.asBytes, 4);
-			PrintAndLog("uid:%08x len=%d trgbl=%d trgkey=%x", uid, len, (uint16_t)resp.arg[2] & 0xff, (uint16_t)resp.arg[2] >> 8);
-			
-			for (i = 0; i < 2; i++) {
-				statelists[i].blockNo = resp.arg[2] & 0xff;
-				statelists[i].keyType = (resp.arg[2] >> 8) & 0xff;
-				statelists[i].uid = uid;
+	if (!WaitForResponseTimeout(CMD_ACK, &resp, 1500)) {
+		return -1;
+	}
 
-				memcpy(&statelists[i].nt,  (void *)(resp.d.asBytes + 4 + i * 8 + 0), 4);
-				memcpy(&statelists[i].ks1, (void *)(resp.d.asBytes + 4 + i * 8 + 4), 4);
-			}
-		}
-		else {
-			PrintAndLog("Got 0 keys from proxmark."); 
-			return 1;
-		}
+	if (resp.arg[0]) {
+		return resp.arg[0];  // error during nested
+	}
+		
+	memcpy(&uid, resp.d.asBytes, 4);
+	PrintAndLog("uid:%08x trgbl=%d trgkey=%x", uid, (uint16_t)resp.arg[2] & 0xff, (uint16_t)resp.arg[2] >> 8);
+	
+	for (i = 0; i < 2; i++) {
+		statelists[i].blockNo = resp.arg[2] & 0xff;
+		statelists[i].keyType = (resp.arg[2] >> 8) & 0xff;
+		statelists[i].uid = uid;
+		memcpy(&statelists[i].nt,  (void *)(resp.d.asBytes + 4 + i * 8 + 0), 4);
+		memcpy(&statelists[i].ks1, (void *)(resp.d.asBytes + 4 + i * 8 + 4), 4);
 	}
 	
 	// calc keys
@@ -154,8 +356,8 @@ int mfnested(uint8_t blockNo, uint8_t keyType, uint8_t * key, uint8_t trgBlockNo
 			while (Compare16Bits(p1, p2) == 1) p2++;
 		}
 	}
-	p3->even = 0; p3->odd = 0;
-	p4->even = 0; p4->odd = 0;
+	*(uint64_t*)p3 = -1;
+	*(uint64_t*)p4 = -1;
 	statelists[0].len = p3 - statelists[0].head.slhead;
 	statelists[1].len = p4 - statelists[1].head.slhead;
 	statelists[0].tail.sltail=--p3;
@@ -163,24 +365,9 @@ int mfnested(uint8_t blockNo, uint8_t keyType, uint8_t * key, uint8_t trgBlockNo
 
 	// the statelists now contain possible keys. The key we are searching for must be in the
 	// intersection of both lists. Create the intersection:
-	qsort(statelists[0].head.keyhead, statelists[0].len, sizeof(uint64_t), compar_int);
-	qsort(statelists[1].head.keyhead, statelists[1].len, sizeof(uint64_t), compar_int);
-
-	uint64_t *p5, *p6, *p7;
-	p5 = p7 = statelists[0].head.keyhead; 
-	p6 = statelists[1].head.keyhead;
-	while (p5 <= statelists[0].tail.keytail && p6 <= statelists[1].tail.keytail) {
-		if (compar_int(p5, p6) == 0) {
-			*p7++ = *p5++;
-			p6++;
-		}
-		else {
-			while (compar_int(p5, p6) == -1) p5++;
-			while (compar_int(p5, p6) == 1) p6++;
-		}
-	}
-	statelists[0].len = p7 - statelists[0].head.keyhead;
-	statelists[0].tail.keytail=--p7;
+	qsort(statelists[0].head.keyhead, statelists[0].len, sizeof(uint64_t), compare_uint64);
+	qsort(statelists[1].head.keyhead, statelists[1].len, sizeof(uint64_t), compare_uint64);
+	statelists[0].len = intersection(statelists[0].head.keyhead, statelists[1].head.keyhead);
 
 	memset(resultKey, 0, 6);
 	// The list may still contain several key candidates. Test each of them with mfCheckKeys
@@ -190,7 +377,7 @@ int mfnested(uint8_t blockNo, uint8_t keyType, uint8_t * key, uint8_t trgBlockNo
 		crypto1_get_lfsr(statelists[0].head.slhead + i, &key64);
 		num_to_bytes(key64, 6, keyBlock);
 		key64 = 0;
-		if (!mfCheckKeys(statelists[0].blockNo, statelists[0].keyType, 1, keyBlock, &key64)) {
+		if (!mfCheckKeys(statelists[0].blockNo, statelists[0].keyType, false, 1, keyBlock, &key64)) {
 			num_to_bytes(key64, 6, resultKey);
 			break;
 		}
@@ -202,21 +389,6 @@ int mfnested(uint8_t blockNo, uint8_t keyType, uint8_t * key, uint8_t trgBlockNo
 	return 0;
 }
 
-int mfCheckKeys (uint8_t blockNo, uint8_t keyType, uint8_t keycnt, uint8_t * keyBlock, uint64_t * key){
-
-	*key = 0;
-
-	UsbCommand c = {CMD_MIFARE_CHKKEYS, {blockNo, keyType, keycnt}};
-	memcpy(c.d.asBytes, keyBlock, 6 * keycnt);
-	SendCommand(&c);
-
-	UsbCommand resp;
-	if (!WaitForResponseTimeout(CMD_ACK,&resp,3000)) return 1;
-	if ((resp.arg[0] & 0xff) != 0x01) return 2;
-	*key = bytes_to_num(resp.d.asBytes, 6);
-	return 0;
-}
-
 // EMULATOR
 
 int mfEmlGetMem(uint8_t *data, int blockNum, int blocksCount) {
@@ -238,30 +410,16 @@ int mfEmlSetMem(uint8_t *data, int blockNum, int blocksCount) {
 
 // "MAGIC" CARD
 
-int mfCSetUID(uint8_t *uid, uint8_t *oldUID, int wantWipe) {
-	uint8_t block0[16];
-	memset(block0, 0, 16);
-	memcpy(block0, uid, 4); 
-	block0[4] = block0[0]^block0[1]^block0[2]^block0[3]; // Mifare UID BCC
-	// mifare classic SAK(byte 5) and ATQA(byte 6 and 7)
-	block0[5] = 0x88;
-	block0[6] = 0x04;
-	block0[7] = 0x00;
-	
-	return mfCSetBlock(0, block0, oldUID, wantWipe, CSETBLOCK_SINGLE_OPER);
-}
-
-int mfCSetBlock(uint8_t blockNo, uint8_t *data, uint8_t *uid, int wantWipe, uint8_t params) {
+int mfCGetBlock(uint8_t blockNo, uint8_t *data, uint8_t params) {
 	uint8_t isOK = 0;
 
-	UsbCommand c = {CMD_MIFARE_EML_CSETBLOCK, {wantWipe, params & (0xFE | (uid == NULL ? 0:1)), blockNo}};
-	memcpy(c.d.asBytes, data, 16); 
+	UsbCommand c = {CMD_MIFARE_CGETBLOCK, {params, 0, blockNo}};
 	SendCommand(&c);
 
   UsbCommand resp;
 	if (WaitForResponseTimeout(CMD_ACK,&resp,1500)) {
 		isOK  = resp.arg[0] & 0xff;
-		if (uid != NULL) memcpy(uid, resp.d.asBytes, 4);
+		memcpy(data, resp.d.asBytes, 16);
 		if (!isOK) return 2;
 	} else {
 		PrintAndLog("Command execute timeout");
@@ -270,17 +428,20 @@ int mfCSetBlock(uint8_t blockNo, uint8_t *data, uint8_t *uid, int wantWipe, uint
 	return 0;
 }
 
-int mfCGetBlock(uint8_t blockNo, uint8_t *data, uint8_t params) {
-	uint8_t isOK = 0;
+int mfCSetBlock(uint8_t blockNo, uint8_t *data, uint8_t *uid, bool wantWipe, uint8_t params) {
 
-	UsbCommand c = {CMD_MIFARE_EML_CGETBLOCK, {params, 0, blockNo}};
+	uint8_t isOK = 0;
+	UsbCommand c = {CMD_MIFARE_CSETBLOCK, {wantWipe, params & (0xFE | (uid == NULL ? 0:1)), blockNo}};
+	memcpy(c.d.asBytes, data, 16); 
 	SendCommand(&c);
 
   UsbCommand resp;
 	if (WaitForResponseTimeout(CMD_ACK,&resp,1500)) {
 		isOK  = resp.arg[0] & 0xff;
-		memcpy(data, resp.d.asBytes, 16);
-		if (!isOK) return 2;
+		if (uid != NULL) 
+			memcpy(uid, resp.d.asBytes, 4);
+		if (!isOK) 
+			return 2;
 	} else {
 		PrintAndLog("Command execute timeout");
 		return 1;
@@ -288,15 +449,43 @@ int mfCGetBlock(uint8_t blockNo, uint8_t *data, uint8_t params) {
 	return 0;
 }
 
+int mfCSetUID(uint8_t *uid, uint8_t *atqa, uint8_t *sak, uint8_t *oldUID, bool wantWipe) {
+	uint8_t oldblock0[16] = {0x00};
+	uint8_t block0[16] = {0x00};
+
+	int old = mfCGetBlock(0, oldblock0, CSETBLOCK_SINGLE_OPER);
+	if (old == 0) {
+		memcpy(block0, oldblock0, 16);
+		PrintAndLog("old block 0:  %s", sprint_hex(block0,16));
+	} else {
+		PrintAndLog("Couldn't get old data. Will write over the last bytes of Block 0.");
+	}
+
+	// fill in the new values
+	// UID
+	memcpy(block0, uid, 4); 
+	// Mifare UID BCC
+	block0[4] = block0[0]^block0[1]^block0[2]^block0[3];
+	// mifare classic SAK(byte 5) and ATQA(byte 6 and 7, reversed)
+	if (sak!=NULL)
+		block0[5]=sak[0];
+	if (atqa!=NULL) {
+		block0[6]=atqa[1];
+		block0[7]=atqa[0];
+	}
+	PrintAndLog("new block 0:  %s", sprint_hex(block0,16));
+	return mfCSetBlock(0, block0, oldUID, wantWipe, CSETBLOCK_SINGLE_OPER);
+}
+
 // SNIFFER
 
 // constants
 static uint8_t trailerAccessBytes[4] = {0x08, 0x77, 0x8F, 0x00};
 
 // variables
-char logHexFileName[200] = {0x00};
+char logHexFileName[FILE_PATH_SIZE] = {0x00};
 static uint8_t traceCard[4096] = {0x00};
-static char traceFileName[200] = {0};
+static char traceFileName[FILE_PATH_SIZE] = {0x00};
 static int traceState = TRACE_IDLE;
 static uint8_t traceCurBlock = 0;
 static uint8_t traceCurKey = 0;
@@ -310,12 +499,9 @@ uint32_t ks3;
 
 uint32_t uid;     // serial number
 uint32_t nt;      // tag challenge
-uint32_t nt_par; 
 uint32_t nr_enc;  // encrypted reader challenge
 uint32_t ar_enc;  // encrypted reader response
-uint32_t nr_ar_par; 
 uint32_t at_enc;  // encrypted tag response
-uint32_t at_par; 
 
 int isTraceCardEmpty(void) {
 	return ((traceCard[0] == 0) && (traceCard[1] == 0) && (traceCard[2] == 0) && (traceCard[3] == 0));
@@ -332,31 +518,55 @@ int isBlockTrailer(int blockN) {
  return ((blockN & 0x03) == 0x03);
 }
 
+int saveTraceCard(void) {
+	FILE * f;
+	
+	if ((!strlen(traceFileName)) || (isTraceCardEmpty())) return 0;
+	
+	f = fopen(traceFileName, "w+");
+	if ( !f ) return 1;
+	
+	for (int i = 0; i < 64; i++) {  // blocks
+		for (int j = 0; j < 16; j++)  // bytes
+			fprintf(f, "%02x", *(traceCard + i * 16 + j)); 
+		fprintf(f,"\n");
+	}
+	fclose(f);
+	return 0;
+}
+
 int loadTraceCard(uint8_t *tuid) {
 	FILE * f;
-	char buf[64];
-	uint8_t buf8[64];
+	char buf[64] = {0x00};
+	uint8_t buf8[64] = {0x00};
 	int i, blockNum;
 	
-	if (!isTraceCardEmpty()) saveTraceCard();
+	if (!isTraceCardEmpty()) 
+		saveTraceCard();
+		
 	memset(traceCard, 0x00, 4096);
 	memcpy(traceCard, tuid + 3, 4);
+
 	FillFileNameByUID(traceFileName, tuid, ".eml", 7);
 
 	f = fopen(traceFileName, "r");
 	if (!f) return 1;
 	
 	blockNum = 0;
+		
 	while(!feof(f)){
+	
 		memset(buf, 0, sizeof(buf));
 		if (fgets(buf, sizeof(buf), f) == NULL) {
-      PrintAndLog("File reading error.");
+			PrintAndLog("File reading error.");
+			fclose(f);
 			return 2;
-    }
+    	}
 
 		if (strlen(buf) < 32){
 			if (feof(f)) break;
 			PrintAndLog("File content error. Block data must include 32 HEX symbols");
+			fclose(f);
 			return 2;
 		}
 		for (i = 0; i < 32; i += 2)
@@ -371,28 +581,16 @@ int loadTraceCard(uint8_t *tuid) {
 	return 0;
 }
 
-int saveTraceCard(void) {
-	FILE * f;
-	
-	if ((!strlen(traceFileName)) || (isTraceCardEmpty())) return 0;
-	
-	f = fopen(traceFileName, "w+");
-	for (int i = 0; i < 64; i++) {  // blocks
-		for (int j = 0; j < 16; j++)  // bytes
-			fprintf(f, "%02x", *(traceCard + i * 16 + j)); 
-		fprintf(f,"\n");
-	}
-	fclose(f);
-
-	return 0;
-}
-
 int mfTraceInit(uint8_t *tuid, uint8_t *atqa, uint8_t sak, bool wantSaveToEmlFile) {
 
-	if (traceCrypto1) crypto1_destroy(traceCrypto1);
+	if (traceCrypto1) 
+		crypto1_destroy(traceCrypto1);
+
 	traceCrypto1 = NULL;
 
-	if (wantSaveToEmlFile) loadTraceCard(tuid);
+	if (wantSaveToEmlFile) 
+		loadTraceCard(tuid);
+		
 	traceCard[4] = traceCard[0] ^ traceCard[1] ^ traceCard[2] ^ traceCard[3];
 	traceCard[5] = sak;
 	memcpy(&traceCard[6], atqa, 2);
@@ -422,7 +620,7 @@ void mf_crypto1_decrypt(struct Crypto1State *pcs, uint8_t *data, int len, bool i
 }
 
 
-int mfTraceDecode(uint8_t *data_src, int len, uint32_t parity, bool wantSaveToEmlFile) {
+int mfTraceDecode(uint8_t *data_src, int len, bool wantSaveToEmlFile) {
 	uint8_t data[64];
 
 	if (traceState == TRACE_ERROR) return 1;
@@ -523,9 +721,7 @@ int mfTraceDecode(uint8_t *data_src, int len, uint32_t parity, bool wantSaveToEm
 	case TRACE_AUTH1: 
 		if (len == 4) {
 			traceState = TRACE_AUTH2;
-
 			nt = bytes_to_num(data, 4);
-			nt_par = parity;
 			return 0;
 		} else {
 			traceState = TRACE_ERROR;
@@ -539,7 +735,6 @@ int mfTraceDecode(uint8_t *data_src, int len, uint32_t parity, bool wantSaveToEm
 
 			nr_enc = bytes_to_num(data, 4);
 			ar_enc = bytes_to_num(data + 4, 4);
-			nr_ar_par = parity;
 			return 0;
 		} else {
 			traceState = TRACE_ERROR;
@@ -552,7 +747,6 @@ int mfTraceDecode(uint8_t *data_src, int len, uint32_t parity, bool wantSaveToEm
 			traceState = TRACE_IDLE;
 
 			at_enc = bytes_to_num(data, 4);
-			at_par = parity;
 			
 			//  decode key here)
 			ks2 = ar_enc ^ prng_successor(nt, 64);
@@ -562,6 +756,7 @@ int mfTraceDecode(uint8_t *data_src, int len, uint32_t parity, bool wantSaveToEm
 			lfsr_rollback_word(revstate, 0, 0);
 			lfsr_rollback_word(revstate, nr_enc, 1);
 			lfsr_rollback_word(revstate, uid ^ nt, 0);
+
 			crypto1_get_lfsr(revstate, &lfsr);
 			printf("key> %x%x\n", (unsigned int)((lfsr & 0xFFFFFFFF00000000) >> 32), (unsigned int)(lfsr & 0xFFFFFFFF));
 			AddLogUint64(logHexFileName, "key> ", lfsr); 
@@ -605,3 +800,23 @@ int mfTraceDecode(uint8_t *data_src, int len, uint32_t parity, bool wantSaveToEm
 
 	return 0;
 }
+
+int tryDecryptWord(uint32_t nt, uint32_t ar_enc, uint32_t at_enc, uint8_t *data, int len){
+	/*
+	uint32_t nt;      // tag challenge
+	uint32_t ar_enc;  // encrypted reader response
+	uint32_t at_enc;  // encrypted tag response
+	*/
+	if (traceCrypto1) {
+		crypto1_destroy(traceCrypto1);
+	}
+	ks2 = ar_enc ^ prng_successor(nt, 64);
+	ks3 = at_enc ^ prng_successor(nt, 96);
+	traceCrypto1 = lfsr_recovery64(ks2, ks3);
+
+	mf_crypto1_decrypt(traceCrypto1, data, len, 0);
+
+	PrintAndLog("Decrypted data: [%s]", sprint_hex(data,len) );
+	crypto1_destroy(traceCrypto1);
+	return 0;
+}