diff --git a/client/cmdhfmfhard.c b/client/cmdhfmfhard.c
new file mode 100644
index 00000000..093e13d5
--- /dev/null
+++ b/client/cmdhfmfhard.c
@@ -0,0 +1,843 @@
+//-----------------------------------------------------------------------------
+// Copyright (C) 2015 piwi
+//
+// 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.
+//-----------------------------------------------------------------------------
+// Implements a card only attack based on crypto text (encrypted nonces
+// received during a nested authentication) only. Unlike other card only
+// attacks this doesn't rely on implementation errors but only on the
+// inherent weaknesses of the crypto1 cypher. Described in
+//   Carlo Meijer, Roel Verdult, "Ciphertext-only Cryptanalysis on Hardened
+//   Mifare Classic Cards" in Proceedings of the 22nd ACM SIGSAC Conference on 
+//   Computer and Communications Security, 2015
+//-----------------------------------------------------------------------------
+
+#include <stdio.h>
+#include <stdlib.h> 
+#include <string.h>
+#include <pthread.h>
+#include <math.h>
+#include "proxmark3.h"
+#include "cmdmain.h"
+#include "ui.h"
+#include "util.h"
+#include "nonce2key/crapto1.h"
+
+
+typedef struct noncelistentry {
+	uint32_t nonce_enc;
+	uint8_t par_enc;
+	void *next;
+} noncelistentry_t;
+
+typedef struct noncelist {
+	uint16_t num;
+	uint16_t Sum;
+	uint16_t Sum8_guess;
+	float Sum8_prob;
+	bool updated;
+	noncelistentry_t *first;
+} noncelist_t;
+
+
+static uint32_t cuid;
+static noncelist_t nonces[256];
+static uint16_t first_byte_Sum = 0;
+static uint16_t first_byte_num = 0;
+static uint8_t best_first_byte;
+static uint16_t guessed_Sum8;
+static float guessed_Sum8_confidence;
+
+
+typedef enum {
+	EVEN_STATE = 0,
+	ODD_STATE = 1
+} odd_even_t;
+
+#define MAX_PARTIAL_ODD_STATES	248801		// we know from pre-computing. Includes 0xffffffff as End Of List marker
+#define MAX_PARTIAL_EVEN_STATES	124401		// dito
+
+typedef struct {
+	uint32_t *states;
+	uint32_t len;
+	uint32_t *index[256];
+} partial_indexed_statelist_t;
+
+typedef struct {
+	uint32_t *states[2];
+	uint32_t len[2];
+	void* next;
+} statelist_t;
+
+
+partial_indexed_statelist_t partial_statelist_odd[17];
+partial_indexed_statelist_t partial_statelist_even[17];
+
+statelist_t *candidates = NULL;
+
+
+static int add_nonce(uint32_t nonce_enc, uint8_t par_enc) 
+{
+	uint8_t first_byte = nonce_enc >> 24;
+	noncelistentry_t *p1 = nonces[first_byte].first;
+	noncelistentry_t *p2 = NULL;
+
+	if (p1 == NULL) {			// first nonce with this 1st byte
+		first_byte_num++;
+		first_byte_Sum += parity((nonce_enc & 0xff000000) | (par_enc & 0x08) | 0x01); // 1st byte sum property. Note: added XOR 1
+		// printf("Adding nonce 0x%08x, par_enc 0x%02x, parity(0x%08x) = %d\n", 
+			// nonce_enc, 
+			// par_enc, 
+			// (nonce_enc & 0xff000000) | (par_enc & 0x08) |0x01, 
+			// parity((nonce_enc & 0xff000000) | (par_enc & 0x08) | 0x01));
+	}
+
+	while (p1 != NULL && (p1->nonce_enc & 0x00ff0000) < (nonce_enc & 0x00ff0000)) {
+		p2 = p1;
+		p1 = p1->next;
+	}
+	
+	if (p1 == NULL) { 																	// need to add at the end of the list
+		if (p2 == NULL) { 			// list is empty yet. Add first entry.
+			p2 = nonces[first_byte].first = malloc(sizeof(noncelistentry_t));
+		} else {					// add new entry at end of existing list.
+			p2 = p2->next = malloc(sizeof(noncelistentry_t));
+		}
+	} else if ((p1->nonce_enc & 0x00ff0000) != (nonce_enc & 0x00ff0000)) {				// found distinct 2nd byte. Need to insert.
+		if (p2 == NULL) {			// need to insert at start of list
+			p2 = nonces[first_byte].first = malloc(sizeof(noncelistentry_t));
+		} else {
+			p2 = p2->next = malloc(sizeof(noncelistentry_t));
+		}
+	} else {											// we have seen this 2nd byte before. Nothing to add or insert. 
+		return (0);
+	}
+
+	// add or insert new data
+	p2->next = p1;
+	p2->nonce_enc = nonce_enc;
+	p2->par_enc = par_enc;
+
+	nonces[first_byte].num++;
+	nonces[first_byte].Sum += parity((nonce_enc & 0x00ff0000) | (par_enc & 0x04) | 0x01); // 2nd byte sum property. Note: added XOR 1
+	nonces[first_byte].updated = true;   // indicates that we need to recalculate the Sum(a8) probability for this first byte
+
+	return (1);				// new nonce added
+}
+
+
+static uint16_t SumPropertyOdd(uint32_t odd_state)
+{ 
+	uint16_t oddsum = 0;
+	for (uint16_t j = 0; j < 16; j++) {
+		uint32_t oddstate = odd_state;
+		uint16_t part_sum = 0;
+		for (uint16_t i = 0; i < 5; i++) {
+			part_sum ^= filter(oddstate);
+			oddstate = (oddstate << 1) | ((j >> (3-i)) & 0x01) ;
+		}
+		oddsum += part_sum;
+	}
+	return oddsum;
+}
+
+
+static uint16_t SumPropertyEven(uint32_t even_state)
+{
+	uint16_t evensum = 0;
+	for (uint16_t j = 0; j < 16; j++) {
+		uint32_t evenstate = even_state;
+		uint16_t part_sum = 0;
+		for (uint16_t i = 0; i < 4; i++) {
+			evenstate = (evenstate << 1) | ((j >> (3-i)) & 0x01) ;
+			part_sum ^= filter(evenstate);
+		}
+		evensum += part_sum;
+	}
+	return evensum;
+}
+
+
+static uint16_t SumProperty(struct Crypto1State *s)
+{
+	uint16_t sum_odd = SumPropertyOdd(s->odd);
+	uint16_t sum_even = SumPropertyEven(s->even);
+	return (sum_odd*(16-sum_even) + (16-sum_odd)*sum_even);
+}
+
+
+static double p_hypergeometric(uint16_t N, uint16_t K, uint16_t n, uint16_t k) 
+{
+	// for efficient computation we are using the recursive definition
+	//						(K-k+1) * (n-k+1)
+	// P(X=k) = P(X=k-1) * --------------------
+	//						   k * (N-K-n+k)
+	// and
+	//           (N-K)*(N-K-1)*...*(N-K-n+1)
+	// P(X=0) = -----------------------------
+	//               N*(N-1)*...*(N-n+1)
+
+	if (n-k > N-K || k > K) return 0.0;	// avoids log(x<=0) in calculation below
+	if (k == 0) {
+		// use logarithms to avoid overflow with huge factorials (double type can only hold 170!)
+		double log_result = 0.0;
+		for (int16_t i = N-K; i >= N-K-n+1; i--) {
+			log_result += log(i);
+		} 
+		for (int16_t i = N; i >= N-n+1; i--) {
+			log_result -= log(i);
+		}
+		return exp(log_result);
+	} else {
+		if (n-k == N-K) {	// special case. The published recursion below would fail with a divide by zero exception
+			double log_result = 0.0;
+			for (int16_t i = k+1; i <= n; i++) {
+				log_result += log(i);
+			}
+			for (int16_t i = K+1; i <= N; i++) {
+				log_result -= log(i);
+			}
+			return exp(log_result);
+		} else { 			// recursion
+			return (p_hypergeometric(N, K, n, k-1) * (K-k+1) * (n-k+1) / (k * (N-K-n+k)));
+		}
+	}
+}
+	
+	
+static float sum_probability(uint16_t K, uint16_t n, uint16_t k)
+{
+	const uint16_t N = 256;
+	
+	const float p[257] = {
+		0.0290, 0.0000, 0.0000, 0.0000, 0.0000, 0.0000, 0.0000, 0.0000, 
+		0.0000, 0.0000, 0.0000, 0.0000, 0.0000, 0.0000, 0.0000, 0.0000,
+		0.0000, 0.0000, 0.0000, 0.0000, 0.0000, 0.0000, 0.0000, 0.0000, 
+		0.0000, 0.0000, 0.0000, 0.0000, 0.0000, 0.0000, 0.0000, 0.0000,
+		0.0083, 0.0000, 0.0000, 0.0000, 0.0000, 0.0000, 0.0000, 0.0000, 
+		0.0000, 0.0000, 0.0000, 0.0000, 0.0000, 0.0000, 0.0000, 0.0000,
+		0.0000, 0.0000, 0.0000, 0.0000, 0.0000, 0.0000, 0.0000, 0.0000, 
+		0.0006, 0.0000, 0.0000, 0.0000, 0.0000, 0.0000, 0.0000, 0.0000,
+		0.0339, 0.0000, 0.0000, 0.0000, 0.0000, 0.0000, 0.0000, 0.0000, 
+		0.0000, 0.0000, 0.0000, 0.0000, 0.0000, 0.0000, 0.0000, 0.0000,
+		0.0048, 0.0000, 0.0000, 0.0000, 0.0000, 0.0000, 0.0000, 0.0000, 
+		0.0000, 0.0000, 0.0000, 0.0000, 0.0000, 0.0000, 0.0000, 0.0000,
+		0.0934, 0.0000, 0.0000, 0.0000, 0.0000, 0.0000, 0.0000, 0.0000, 
+		0.0119, 0.0000, 0.0000, 0.0000, 0.0000, 0.0000, 0.0000, 0.0000,
+		0.0489, 0.0000, 0.0000, 0.0000, 0.0000, 0.0000, 0.0000, 0.0000, 
+		0.0602, 0.0000, 0.0000, 0.0000, 0.0000, 0.0000, 0.0000, 0.0000,
+		0.4180, 0.0000, 0.0000, 0.0000, 0.0000, 0.0000, 0.0000, 0.0000, 
+		0.0602, 0.0000, 0.0000, 0.0000, 0.0000, 0.0000, 0.0000, 0.0000,
+		0.0489, 0.0000, 0.0000, 0.0000, 0.0000, 0.0000, 0.0000, 0.0000, 
+		0.0119, 0.0000, 0.0000, 0.0000, 0.0000, 0.0000, 0.0000, 0.0000,
+		0.0934, 0.0000, 0.0000, 0.0000, 0.0000, 0.0000, 0.0000, 0.0000, 
+		0.0000, 0.0000, 0.0000, 0.0000, 0.0000, 0.0000, 0.0000, 0.0000,
+		0.0048, 0.0000, 0.0000, 0.0000, 0.0000, 0.0000, 0.0000, 0.0000, 
+		0.0000, 0.0000, 0.0000, 0.0000, 0.0000, 0.0000, 0.0000, 0.0000,
+		0.0339, 0.0000, 0.0000, 0.0000, 0.0000, 0.0000, 0.0000, 0.0000, 
+		0.0006, 0.0000, 0.0000, 0.0000, 0.0000, 0.0000, 0.0000, 0.0000,
+		0.0000, 0.0000, 0.0000, 0.0000, 0.0000, 0.0000, 0.0000, 0.0000, 
+		0.0000, 0.0000, 0.0000, 0.0000, 0.0000, 0.0000, 0.0000, 0.0000,
+		0.0083, 0.0000, 0.0000, 0.0000, 0.0000, 0.0000, 0.0000, 0.0000, 
+		0.0000, 0.0000, 0.0000, 0.0000, 0.0000, 0.0000, 0.0000, 0.0000,
+		0.0000, 0.0000, 0.0000, 0.0000, 0.0000, 0.0000, 0.0000, 0.0000,
+		0.0000, 0.0000, 0.0000, 0.0000, 0.0000, 0.0000, 0.0000, 0.0000,
+		0.02900 };	
+
+		if (k > K || p[K] == 0.0) return 0.0;
+
+		double p_T_is_k_when_S_is_K = p_hypergeometric(N, K, n, k);
+		double p_S_is_K = p[K];
+		double p_T_is_k = 0;
+		for (uint16_t i = 0; i <= 256; i++) {
+			if (p[i] != 0.0) {
+				p_T_is_k += p[i] * p_hypergeometric(N, i, n, k);
+			}
+		}
+		return(p_T_is_k_when_S_is_K * p_S_is_K / p_T_is_k);
+}
+
+		
+static void Tests()
+{
+	printf("Tests: Partial Statelist sizes\n");
+	for (uint16_t i = 0; i <= 16; i+=2) {
+		printf("Partial State List Odd [%2d] has %8d entries\n", i, partial_statelist_odd[i].len);
+	}
+	for (uint16_t i = 0; i <= 16; i+=2) {
+		printf("Partial State List Even	[%2d] has %8d entries\n", i, partial_statelist_even[i].len);
+	}
+	// printf("Tests: State List Odd [4] content:\n");
+	// for (uint32_t i = 0; i < partial_statelist_odd[4].len; i++) {
+		// printf("State_List_Odd[4][%d] = 0x%08x\n", i, partial_statelist_odd[4].states[i]);
+	// }
+	
+ 	#define NUM_STATISTICS 100000
+	uint64_t statistics[257];
+	uint32_t statistics_odd[17];
+	uint32_t statistics_even[17];
+	struct Crypto1State cs;
+	time_t time1 = clock();
+
+	for (uint16_t i = 0; i < 257; i++) {
+		statistics[i] = 0;
+	}
+	for (uint16_t i = 0; i < 17; i++) {
+		statistics_odd[i] = 0;
+		statistics_even[i] = 0;
+	}
+	
+	for (uint64_t i = 0; i < NUM_STATISTICS; i++) {
+		cs.odd = (rand() & 0xfff) << 12 | (rand() & 0xfff);
+		cs.even = (rand() & 0xfff) << 12 | (rand() & 0xfff);
+		uint16_t sum_property = SumProperty(&cs);
+		statistics[sum_property] += 1;
+		sum_property=SumPropertyEven(cs.even);
+		statistics_even[sum_property]++;
+		sum_property=SumPropertyOdd(cs.odd);
+		statistics_odd[sum_property]++;
+		if (i%(NUM_STATISTICS/100) == 0) printf("."); 
+	}
+	
+	printf("\nTests: Calculated %d Sum properties in %0.3f seconds (%0.0f calcs/second)\n", NUM_STATISTICS, ((float)clock() - time1)/CLOCKS_PER_SEC, NUM_STATISTICS/((float)clock() - time1)*CLOCKS_PER_SEC);
+	for (uint16_t i = 0; i < 257; i++) {
+		if (statistics[i] != 0) {
+			printf("probability[%3d] = %0.5f\n", i, (float)statistics[i]/NUM_STATISTICS);
+		}
+	}
+	for (uint16_t i = 0; i <= 16; i++) {
+		if (statistics_odd[i] != 0) {
+			printf("probability odd [%2d] = %0.5f\n", i, (float)statistics_odd[i]/NUM_STATISTICS);
+		}
+	}
+	for (uint16_t i = 0; i <= 16; i++) {
+		if (statistics_odd[i] != 0) {
+			printf("probability even [%2d] = %0.5f\n", i, (float)statistics_even[i]/NUM_STATISTICS);
+		}
+	}
+
+	printf("Tests: Sum Probabilities based on Partial Sums\n");
+	for (uint16_t i = 0; i < 257; i++) {
+		statistics[i] = 0;
+	}
+	uint64_t num_states = 0;
+	for (uint16_t oddsum = 0; oddsum <= 16; oddsum += 2) {
+		for (uint16_t evensum = 0; evensum <= 16; evensum += 2) {
+			uint16_t sum = oddsum*(16-evensum) + (16-oddsum)*evensum;
+			statistics[sum] += (uint64_t)partial_statelist_odd[oddsum].len * (1<<4) * partial_statelist_even[evensum].len * (1<<5);
+			num_states += (uint64_t)partial_statelist_odd[oddsum].len * (1<<4) * partial_statelist_even[evensum].len * (1<<5);
+		}
+	}
+	printf("num_states = %lld, expected %lld\n", num_states, (1LL<<48));
+	for (uint16_t i = 0; i < 257; i++) {
+		if (statistics[i] != 0) {
+			printf("probability[%3d] = %0.5f\n", i, (float)statistics[i]/num_states);
+		}
+	}
+	
+	printf("\nTests: Hypergeometric Probability for selected parameters\n");
+	printf("p_hypergeometric(256, 206, 255, 206) = %0.8f\n", p_hypergeometric(256, 206, 255, 206));
+	printf("p_hypergeometric(256, 206, 255, 205) = %0.8f\n", p_hypergeometric(256, 206, 255, 205));
+	printf("p_hypergeometric(256, 156, 1, 1) = %0.8f\n", p_hypergeometric(256, 156, 1, 1));
+	printf("p_hypergeometric(256, 156, 1, 0) = %0.8f\n", p_hypergeometric(256, 156, 1, 0));
+	printf("p_hypergeometric(256, 1, 1, 1) = %0.8f\n", p_hypergeometric(256, 1, 1, 1));
+	printf("p_hypergeometric(256, 1, 1, 0) = %0.8f\n", p_hypergeometric(256, 1, 1, 0));
+	
+	struct Crypto1State *pcs;
+	pcs = crypto1_create(0xffffffffffff);
+	printf("\nTests: for key = 0xffffffffffff:\nSum(a0) = %d\nodd_state =  0x%06x\neven_state = 0x%06x\n", 
+		SumProperty(pcs), pcs->odd & 0x00ffffff, pcs->even & 0x00ffffff);
+	crypto1_destroy(pcs);
+	pcs = crypto1_create(0xa0a1a2a3a4a5);
+	printf("Tests: for key = 0xa0a1a2a3a4a5:\nSum(a0) = %d\nodd_state =  0x%06x\neven_state = 0x%06x\n",
+		SumProperty(pcs), pcs->odd & 0x00ffffff, pcs->even & 0x00ffffff);
+	crypto1_destroy(pcs);
+
+	}
+	
+
+static float estimate_second_byte_sum(uint8_t *best_first_byte, uint16_t *best_Sum8_guess) 
+{
+	float max_prob = 0.0;
+	for (uint16_t first_byte = 0; first_byte < 256; first_byte++) {
+		float Sum8_prob = 0.0;
+		uint16_t Sum8 = 0;
+		if (nonces[first_byte].updated) {
+			for (uint16_t sum = 0; sum <= 256; sum++) {
+				float prob = sum_probability(sum, nonces[first_byte].num, nonces[first_byte].Sum);
+				if (prob > Sum8_prob) {
+					Sum8_prob = prob;
+					Sum8 = sum;
+				}
+			}
+			nonces[first_byte].Sum8_guess = Sum8;
+			nonces[first_byte].Sum8_prob = Sum8_prob;
+			nonces[first_byte].updated = false;
+		}
+		if (nonces[first_byte].Sum8_prob > max_prob) {
+			max_prob = nonces[first_byte].Sum8_prob;
+			*best_first_byte = first_byte;
+			*best_Sum8_guess = nonces[first_byte].Sum8_guess;
+		}
+	}
+	return max_prob;
+}	
+
+
+static int read_nonce_file(void)
+{
+	FILE *fnonces = NULL;
+	uint8_t trgBlockNo;
+	uint8_t trgKeyType;
+	uint8_t read_buf[9];
+	uint32_t nt_enc1, nt_enc2;
+	uint8_t par_enc;
+	int total_num_nonces = 0;
+	
+	if ((fnonces = fopen("nonces.bin","rb")) == NULL) { 
+		PrintAndLog("Could not open file nonces.bin");
+		return 1;
+	}
+
+	PrintAndLog("Reading nonces from file nonces.bin...");
+	if (fread(read_buf, 1, 6, fnonces) == 0) {
+		PrintAndLog("File reading error.");
+		fclose(fnonces);
+		return 1;
+	}
+	cuid = bytes_to_num(read_buf, 4);
+	trgBlockNo = bytes_to_num(read_buf+4, 1);
+	trgKeyType = bytes_to_num(read_buf+5, 1);
+
+	while (fread(read_buf, 1, 9, fnonces) == 9) {
+		nt_enc1 = bytes_to_num(read_buf, 4);
+		nt_enc2 = bytes_to_num(read_buf+4, 4);
+		par_enc = bytes_to_num(read_buf+8, 1);
+		//printf("Encrypted nonce: %08x, encrypted_parity: %02x\n", nt_enc1, par_enc >> 4);
+		//printf("Encrypted nonce: %08x, encrypted_parity: %02x\n", nt_enc2, par_enc & 0x0f);
+		add_nonce(nt_enc1, par_enc >> 4);
+		add_nonce(nt_enc2, par_enc & 0x0f);
+		total_num_nonces += 2;
+	}
+	fclose(fnonces);
+	PrintAndLog("Read %d nonces from file. cuid=%08x, Block=%d, Keytype=%c", total_num_nonces, cuid, trgBlockNo, trgKeyType==0?'A':'B');
+
+	return 0;
+}
+
+
+int static acquire_nonces(uint8_t blockNo, uint8_t keyType, uint8_t *key, uint8_t trgBlockNo, uint8_t trgKeyType, bool nonce_file_write, bool slow)
+{
+	clock_t time1 = clock();
+	bool initialize = true;
+	bool field_off = false;
+	bool finished = false;
+	uint32_t flags = 0;
+	uint8_t write_buf[9];
+	uint32_t total_num_nonces = 0;
+	uint32_t next_thousand = 1000;
+	uint32_t total_added_nonces = 0;
+	FILE *fnonces = NULL;
+	UsbCommand resp;
+
+	#define CONFIDENCE_THRESHOLD	0.95		// Collect nonces until we are certain enough to have guessed Sum(a8) correctly
+
+	clearCommandBuffer();
+
+	do {
+		flags = 0;
+		flags |= initialize ? 0x0001 : 0;
+		flags |= slow ? 0x0002 : 0;
+		flags |= field_off ? 0x0004 : 0;
+		UsbCommand c = {CMD_MIFARE_ACQUIRE_ENCRYPTED_NONCES, {blockNo + keyType * 0x100, trgBlockNo + trgKeyType * 0x100, flags}};
+		memcpy(c.d.asBytes, key, 6);
+
+		SendCommand(&c);
+		
+		if (field_off) finished = true;
+		
+		if (initialize) {
+			if (!WaitForResponseTimeout(CMD_ACK, &resp, 3000)) return 1;
+			if (resp.arg[0]) return resp.arg[0];  // error during nested_hard
+
+			cuid = resp.arg[1];
+			// PrintAndLog("Acquiring nonces for CUID 0x%08x", cuid); 
+			if (nonce_file_write && fnonces == NULL) {
+				if ((fnonces = fopen("nonces.bin","wb")) == NULL) { 
+					PrintAndLog("Could not create file nonces.bin");
+					return 3;
+				}
+				PrintAndLog("Writing acquired nonces to binary file nonces.bin");
+				num_to_bytes(cuid, 4, write_buf);
+				fwrite(write_buf, 1, 4, fnonces);
+				fwrite(&trgBlockNo, 1, 1, fnonces);
+				fwrite(&trgKeyType, 1, 1, fnonces);
+			}
+		}
+
+		if (!initialize) {
+			uint32_t nt_enc1, nt_enc2;
+			uint8_t par_enc;
+			uint16_t num_acquired_nonces = resp.arg[2];
+			uint8_t *bufp = resp.d.asBytes;
+			for (uint16_t i = 0; i < num_acquired_nonces; i+=2) {
+				nt_enc1 = bytes_to_num(bufp, 4);
+				nt_enc2 = bytes_to_num(bufp+4, 4);
+				par_enc = bytes_to_num(bufp+8, 1);
+				
+				//printf("Encrypted nonce: %08x, encrypted_parity: %02x\n", nt_enc1, par_enc >> 4);
+				total_added_nonces += add_nonce(nt_enc1, par_enc >> 4);
+				//printf("Encrypted nonce: %08x, encrypted_parity: %02x\n", nt_enc2, par_enc & 0x0f);
+				total_added_nonces += add_nonce(nt_enc2, par_enc & 0x0f);
+				
+
+				if (nonce_file_write) {
+					fwrite(bufp, 1, 9, fnonces);
+				}
+				
+				bufp += 9;
+			}
+
+			total_num_nonces += num_acquired_nonces;
+		}
+		
+		if (first_byte_num == 256 ) {
+			// printf("first_byte_num = %d, first_byte_Sum = %d\n", first_byte_num, first_byte_Sum);
+			float last_confidence = guessed_Sum8_confidence;
+			uint16_t last_Sum8 = guessed_Sum8;
+			guessed_Sum8_confidence = estimate_second_byte_sum(&best_first_byte, &guessed_Sum8);
+			if (guessed_Sum8_confidence > last_confidence || guessed_Sum8 != last_Sum8 || total_num_nonces > next_thousand) {
+				next_thousand = (total_num_nonces/1000+1) * 1000;
+				PrintAndLog("Acquired %5d nonces (%5d with distinct bytes 0 and 1). Guessed Sum(a8) = %3d for first nonce byte = 0x%02x, probability for correct guess = %1.2f%%",
+					total_num_nonces, 
+					total_added_nonces,
+					guessed_Sum8, 
+					best_first_byte, 
+					guessed_Sum8_confidence*100);
+			}
+			if (guessed_Sum8_confidence >= CONFIDENCE_THRESHOLD) {
+				field_off = true;	// switch off field with next SendCommand and then finish
+			}
+		}
+
+		if (!initialize) {
+			if (!WaitForResponseTimeout(CMD_ACK, &resp, 3000)) return 1;
+			if (resp.arg[0]) return resp.arg[0];  // error during nested_hard
+		}
+
+		initialize = false;
+
+	} while (!finished);
+
+	
+	if (nonce_file_write) {
+		fclose(fnonces);
+	}
+	
+	PrintAndLog("Acquired a total of %d nonces in %1.1f seconds (%d nonces/minute)", 
+		total_num_nonces, 
+		((float)clock()-time1)/CLOCKS_PER_SEC, 
+		total_num_nonces*60*CLOCKS_PER_SEC/(clock()-time1));
+	
+	return 0;
+}
+
+
+static int init_partial_statelists(void)
+{
+	printf("Allocating memory for partial statelists...\n");
+	for (uint16_t i = 0; i <= 16; i++) {
+		partial_statelist_odd[i].len = 0;
+		if (i % 2) {	// partial Sum Properties are even.
+			partial_statelist_odd[i].states = NULL;
+		} else {	
+			// 20 Bits are relevant for odd states. Less than a half per Sum is expected
+			partial_statelist_odd[i].states = malloc(sizeof(uint32_t) << 19);  
+			if (partial_statelist_odd[i].states == NULL) {
+				PrintAndLog("Cannot allocate enough memory. Aborting");
+				return 4;
+			}
+			for (uint16_t j = 0; j < 256; j++) {
+				partial_statelist_odd[i].index[j] = NULL;
+			}
+		}
+		partial_statelist_even[i].len = 0;
+		if (i % 2) {	// partial Sum Properties are even.
+			partial_statelist_even[i].states = NULL;
+		} else {
+			// 19 Bits are relevant for even states. Less than a half per Sum is expected
+			partial_statelist_even[i].states = malloc(sizeof(uint32_t) << 18);
+			if (partial_statelist_even[i].states == NULL) {
+				PrintAndLog("Cannot allocate enough memory. Aborting");
+				return 4;
+			}
+			for (uint16_t j = 0; j < 256; j++) {
+				partial_statelist_even[i].index[j] = NULL;
+			}
+		}
+	}
+		
+	printf("Generating partial statelists odd...\n");
+	uint32_t index = -1;
+	for (uint32_t oddstate = 0; oddstate < (1 << 20); oddstate++) {
+		uint16_t odd_sum_property = SumPropertyOdd(oddstate);
+		uint32_t *p = partial_statelist_odd[odd_sum_property].states;
+		p += partial_statelist_odd[odd_sum_property].len;
+		*p = oddstate;
+		partial_statelist_odd[odd_sum_property].len++;
+		if ((oddstate & 0x000ff000) != index) {
+			index = oddstate & 0x000ff000;
+		}
+		if (partial_statelist_odd[odd_sum_property].index[index >> 12] == NULL) {
+			partial_statelist_odd[odd_sum_property].index[index >> 12] = p;
+		}
+	}
+	// add End Of List markers
+	for (uint16_t i = 0; i <= 16; i += 2) {
+		uint32_t *p = partial_statelist_odd[i].states;
+		p += partial_statelist_odd[i].len;
+		*p = 0xffffffff;
+	}
+	
+	printf("Generating partial statelists even...\n");
+	index = -1;
+	for (uint32_t evenstate = 0; evenstate < (1 << 19); evenstate++) {
+		uint16_t even_sum_property = SumPropertyEven(evenstate);
+		uint32_t *p = partial_statelist_even[even_sum_property].states;
+		p += partial_statelist_even[even_sum_property].len;
+		*p = evenstate;
+		partial_statelist_even[even_sum_property].len++;
+		if ((evenstate & 0x000ff000) != index) {
+			index = evenstate & 0x000ff000;
+		}
+		if (partial_statelist_even[even_sum_property].index[index >> 12] == NULL) {
+			partial_statelist_even[even_sum_property].index[index >> 12] = p;
+		}
+	}
+	// add End Of List markers
+	for (uint16_t i = 0; i <= 16; i += 2) {
+		uint32_t *p = partial_statelist_even[i].states;
+		p += partial_statelist_even[i].len;
+		*p = 0xffffffff;
+	}
+	
+	return 0;
+}	
+		
+		
+static void add_state(statelist_t *sl, uint32_t state, odd_even_t odd_even)
+{
+	uint32_t *p;
+
+	p = sl->states[odd_even];
+	p += sl->len[odd_even];
+	*p = state;
+	sl->len[odd_even]++;
+}
+
+
+uint32_t *find_first_state(uint32_t state, partial_indexed_statelist_t *sl)
+{
+	uint32_t *p = sl->index[state >> 12];		// first 8 Bits as index
+
+	if (p == NULL) return NULL;
+	while ((*p & 0x000ffff0) < state) p++;
+	if (*p == 0xffffffff) return NULL;			// reached end of list, no match
+	if ((*p & 0x000ffff0) == state) return p;	// found a match.
+	return NULL;								// no match
+}
+
+
+static int add_matching_states(statelist_t *candidates, uint16_t part_sum_a0, uint16_t part_sum_a8, odd_even_t odd_even)
+{
+	uint32_t worstcase_size = (odd_even==ODD_STATE) ? 1<<24 : 1<<23;
+	
+	if (odd_even == ODD_STATE) {
+		candidates->states[odd_even] = (uint32_t *)malloc(sizeof(uint32_t) * worstcase_size);
+		if (candidates->states[odd_even] == NULL) {
+			PrintAndLog("Out of memory error.\n");
+			return 4;
+		}
+		for (uint32_t *p1 = partial_statelist_odd[part_sum_a0].states; *p1 != 0xffffffff; p1++) {
+			uint32_t *p2 = find_first_state((*p1 << 4) & 0x000ffff0, &partial_statelist_odd[part_sum_a8]);
+			while (p2 != NULL && ((*p1 << 4) & 0x000ffff0) == (*p2 & 0x000ffff0) && *p2 != 0xffffffff) {
+				add_state(candidates, (*p1 << 4) | *p2, odd_even);
+				p2++;
+			}
+			p2 = candidates->states[odd_even];
+			p2 += candidates->len[odd_even];
+			*p2 = 0xffffffff;
+		}
+		candidates->states[odd_even] = realloc(candidates->states[odd_even], sizeof(uint32_t) * (candidates->len[odd_even] + 1));
+	} else {
+		candidates->states[odd_even] = (uint32_t *)malloc(sizeof(uint32_t) * worstcase_size);
+		if (candidates->states[odd_even] == NULL) {
+			PrintAndLog("Out of memory error.\n");
+			return 4;
+		}
+		for (uint32_t *p1 = partial_statelist_even[part_sum_a0].states; *p1 != 0xffffffff; p1++) {
+			uint32_t *p2 = find_first_state((*p1 << 4) & 0x0007fff0, &partial_statelist_even[part_sum_a8]);
+			while (p2 != NULL && ((*p1 << 4) & 0x0007fff0) == (*p2 & 0x0007fff0) && *p2 != 0xffffffff) {
+				add_state(candidates, (*p1 << 4) | *p2, odd_even);
+				p2++;
+			}
+			p2 = candidates->states[odd_even];
+			p2 += candidates->len[odd_even];
+			*p2 = 0xffffffff;
+		}
+		candidates->states[odd_even] = realloc(candidates->states[odd_even], sizeof(uint32_t) * (candidates->len[odd_even] + 1));
+	}
+	return 0;
+}
+
+
+static statelist_t *add_more_candidates(statelist_t *current_candidates)
+{
+	statelist_t *new_candidates = NULL;
+	if (current_candidates == NULL) {
+		if (candidates == NULL) {
+			candidates = (statelist_t *)malloc(sizeof(statelist_t));
+		}
+		new_candidates = candidates;
+	} else {
+		new_candidates = current_candidates->next = (statelist_t *)malloc(sizeof(statelist_t));
+	}
+	new_candidates->next = NULL;
+	new_candidates->len[ODD_STATE] = 0;
+	new_candidates->len[EVEN_STATE] = 0;
+	new_candidates->states[ODD_STATE] = NULL;
+	new_candidates->states[EVEN_STATE] = NULL;
+	return new_candidates;
+}
+
+
+static void TestIfKeyExists(uint64_t key)
+{
+	struct Crypto1State *pcs;
+	pcs = crypto1_create(key);
+	crypto1_byte(pcs, (cuid >> 24) ^ best_first_byte, true);
+
+	uint32_t state_odd = pcs->odd & 0x00ffffff;
+	uint32_t state_even = pcs->even & 0x00ffffff;
+	printf("searching for key %llx after first byte 0x%02x (state_odd = 0x%06x, state_even = 0x%06x) ...\n", key, best_first_byte, state_odd, state_even);
+	
+	for (statelist_t *p = candidates; p != NULL; p = p->next) {
+		uint32_t *p_odd = p->states[ODD_STATE];
+		uint32_t *p_even = p->states[EVEN_STATE];
+		while (*p_odd != 0xffffffff) {
+			if (*p_odd == state_odd) printf("o");
+			p_odd++;
+		}
+		while (*p_even != 0xffffffff) {
+			if (*p_even == (state_even & 0x007fffff)) printf("e");
+			p_even++;
+		}
+		printf("|");
+	}
+	printf("\n");
+	crypto1_destroy(pcs);
+}
+
+	
+static void generate_candidates(uint16_t sum_a0, uint16_t sum_a8)
+{
+	printf("Generating crypto1 state candidates... \n");
+	
+	statelist_t *current_candidates = NULL;
+	// estimate maximum candidate states
+	uint64_t maximum_states = 0;
+	for (uint16_t sum_odd = 0; sum_odd <= 16; sum_odd += 2) {
+		for (uint16_t sum_even = 0; sum_even <= 16; sum_even += 2) {
+			if (sum_odd*(16-sum_even) + (16-sum_odd)*sum_even == sum_a0) {
+				maximum_states += (uint64_t)partial_statelist_odd[sum_odd].len * (1<<4) * partial_statelist_even[sum_even].len * (1<<5);
+			}
+		}
+	}
+	printf("Estimated number of possible keys with S(a0) = %d: %lld (2^%1.1f)\n", sum_a0, maximum_states, log(maximum_states)/log(2.0));
+	
+	for (uint16_t p = 0; p <= 16; p += 2) {
+		for (uint16_t q = 0; q <= 16; q += 2) {
+			if (p*(16-q) + (16-p)*q == sum_a0) {
+				printf("Reducing Partial Statelists (p,q) = (%d,%d) with lengths %d, %d\n", 
+						p, q, partial_statelist_odd[p].len, partial_statelist_even[q].len);
+				for (uint16_t r = 0; r <= 16; r += 2) {
+					for (uint16_t s = 0; s <= 16; s += 2) {
+						if (r*(16-s) + (16-r)*s == sum_a8) {
+							current_candidates = add_more_candidates(current_candidates);
+							add_matching_states(current_candidates, p, r, ODD_STATE);
+							printf("Odd state candidates: %d (2^%0.1f)\n", current_candidates->len[ODD_STATE], log(current_candidates->len[ODD_STATE])/log(2)); 
+							add_matching_states(current_candidates, q, s, EVEN_STATE);
+							printf("Even state candidates: %d (2^%0.1f)\n", current_candidates->len[EVEN_STATE]*2, log(current_candidates->len[EVEN_STATE]*2)/log(2)); 
+						}
+					}
+				}
+			}
+		}
+	}					
+
+	
+	maximum_states = 0;
+	for (statelist_t *sl = candidates; sl != NULL; sl = sl->next) {
+		maximum_states += (uint64_t)sl->len[ODD_STATE] * sl->len[EVEN_STATE] * 2;
+	}
+	printf("Estimated number of possible keys with S(a0) = %d AND S(a8)=%d: %lld (2^%1.1f)\n", sum_a0, sum_a8, maximum_states, log(maximum_states)/log(2.0));
+
+	TestIfKeyExists(0xffffffffffff);
+	TestIfKeyExists(0xa0a1a2a3a4a5);
+	
+}
+
+
+int mfnestedhard(uint8_t blockNo, uint8_t keyType, uint8_t *key, uint8_t trgBlockNo, uint8_t trgKeyType, bool nonce_file_read, bool nonce_file_write, bool slow) 
+{
+	
+	// initialize the list of nonces
+	for (uint16_t i = 0; i < 256; i++) {
+		nonces[i].num = 0;
+		nonces[i].Sum = 0;
+		nonces[i].Sum8_guess = 0;
+		nonces[i].Sum8_prob = 0.0;
+		nonces[i].updated = true;
+		nonces[i].first = NULL;
+	}
+	first_byte_num = 0;
+	first_byte_Sum = 0;
+	guessed_Sum8 = 0;
+	best_first_byte = 0;
+	guessed_Sum8_confidence = 0.0;
+		
+	init_partial_statelists();
+	
+	if (nonce_file_read) {  	// use pre-acquired data from file nonces.bin
+		if (read_nonce_file() != 0) {
+			return 3;
+		}
+		guessed_Sum8_confidence = estimate_second_byte_sum(&best_first_byte, &guessed_Sum8);
+	} else {					// acquire nonces.
+		uint16_t is_OK = acquire_nonces(blockNo, keyType, key, trgBlockNo, trgKeyType, nonce_file_write, slow);
+		if (is_OK != 0) {
+			return is_OK;
+		}
+	}
+
+	Tests();
+
+	PrintAndLog("");
+	PrintAndLog("Sum(a0) = %d", first_byte_Sum);
+	PrintAndLog("Guess for Sum(a8) = %d for first nonce byte = 0x%02x, n = %d, k = %d, probability for correct guess = %1.0f%%\n", 
+		guessed_Sum8,
+		best_first_byte,
+		nonces[best_first_byte].num,
+		nonces[best_first_byte].Sum,
+		guessed_Sum8_confidence*100);		
+
+	generate_candidates(first_byte_Sum, guessed_Sum8);
+	
+	PrintAndLog("Brute force phase not yet implemented");
+	
+	return 0;
+}
+
+
diff --git a/client/cmdhfmfhard.h b/client/cmdhfmfhard.h
new file mode 100644
index 00000000..94c57717
--- /dev/null
+++ b/client/cmdhfmfhard.h
@@ -0,0 +1,11 @@
+//-----------------------------------------------------------------------------
+// Copyright (C) 2015 piwi
+//
+// 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.
+//-----------------------------------------------------------------------------
+// hf mf hardnested command
+//-----------------------------------------------------------------------------
+
+int mfnestedhard(uint8_t blockNo, uint8_t keyType, uint8_t * key, uint8_t trgBlockNo, uint8_t trgKeyType, bool nonce_file_read, bool nonce_file_write, bool slow);