From: marshmellow42 <marshmellowrf@gmail.com>
Date: Sun, 26 Mar 2017 12:09:40 +0000 (-0400)
Subject: split fdx-b demod to its own file
X-Git-Tag: v3.0.0~31^2
X-Git-Url: http://cvs.zerfleddert.de/cgi-bin/gitweb.cgi/proxmark3-svn/commitdiff_plain/refs/pull/251/head

split fdx-b demod to its own file

added @iceman1001 s read/sim/clone commands for fdx--b
check changelog.md for cli changes!
---

diff --git a/CHANGELOG.md b/CHANGELOG.md
index ef9c316c..7994c987 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -5,8 +5,11 @@ This project uses the changelog in accordance with [keepchangelog](http://keepac
 ## [unreleased][unreleased]
 
 ### Added
-- Added lf gproxii read - reads a gproxii tag from the antenna
-- Added lf indala read - reads an indala tag from the antenna
+- Added lf fdx sim (iceman)
+- Added lf fdx clone - clones an fdx-b animal tag to t55x7 or q5 (iceman)
+- Added lf fdx read - reads a fdx-b tag from the antenna (iceman)
+- Added lf gproxii read - reads a gproxii tag from the antenna (marshmellow)
+- Added lf indala read - reads an indala tag from the antenna (marshmellow)
 - Added lf visa2000 demod, read, clone, sim commands (iceman)
 - Added markers in the graph around found Sequence Terminator after askmandemod.
 - Added data mtrim <start> <stop> command to trim out samples between start and stop
@@ -47,6 +50,7 @@ This project uses the changelog in accordance with [keepchangelog](http://keepac
 - Added option c to 'hf list' (mark CRC bytes) (piwi)
 
 ### Changed
+- `data fdxdemod` has been moved to `lf fdx demod` (reads from graphbuffer)
 - `data askgproxiidemod has been moved to `lf gproxii demod` (reads from graphbuffer)
 - `lf indalaclone` has been moved to `lf indala clone`
 - `lf indalademod` has been moved to `lf indala altdemod` (reads from graphbuffer)
diff --git a/client/Makefile b/client/Makefile
index fa4690db..4bac1ac9 100644
--- a/client/Makefile
+++ b/client/Makefile
@@ -92,6 +92,7 @@ CMDSRCS = 	crapto1/crapto1.c\
 			cmdlfawid.c \
 			cmdlfcotag.c\
 			cmdlfem4x.c \
+			cmdlffdx.c \
 			cmdlfgproxii.c \
 			cmdlfhid.c \
 			cmdlfhitag.c \
diff --git a/client/cmddata.c b/client/cmddata.c
index 1acce2ed..2444fb32 100644
--- a/client/cmddata.c
+++ b/client/cmddata.c
@@ -850,98 +850,6 @@ int CmdFSKdemodParadox(const char *Cmd)
 	return 1;
 }
 
-// FDX-B ISO11784/85 demod  (aka animal tag)  BIPHASE, inverted, rf/32,  with preamble of 00000000001 (128bits)
-// 8 databits + 1 parity (1)
-// CIITT 16 chksum
-// NATIONAL CODE, ICAR database
-// COUNTRY CODE (ISO3166) or http://cms.abvma.ca/uploads/ManufacturersISOsandCountryCodes.pdf
-// FLAG (animal/non-animal)
-/*
-38 IDbits   
-10 country code 
-1 extra app bit
-14 reserved bits
-1 animal bit
-16 ccitt CRC chksum over 64bit ID CODE.
-24 appli bits.
-
--- sample: 985121004515220  [ 37FF65B88EF94 ]
-*/
-int CmdFDXBdemodBI(const char *Cmd){
-
-	int invert = 1;
-	int clk = 32;		
-	int errCnt = 0;
-	int maxErr = 0;
-	uint8_t BitStream[MAX_DEMOD_BUF_LEN];	
-	size_t size = getFromGraphBuf(BitStream);	
-	
-	errCnt = askdemod(BitStream, &size, &clk, &invert, maxErr, 0, 0);
-	if ( errCnt < 0 || errCnt > maxErr ) { 
-		if (g_debugMode) PrintAndLog("DEBUG: no data or error found %d, clock: %d", errCnt, clk);
-		return 0;
-	}
-
-	errCnt = BiphaseRawDecode(BitStream, &size, maxErr, 1);
-	if (errCnt < 0 || errCnt > maxErr ) {
-		if (g_debugMode) PrintAndLog("Error BiphaseRawDecode: %d", errCnt);
-		return 0;
-	} 
-
-	int preambleIndex = FDXBdemodBI(BitStream, &size);
-	if (preambleIndex < 0){
-		if (g_debugMode) PrintAndLog("Error FDXBDemod , no startmarker found :: %d",preambleIndex);
-		return 0;
-	}
-	if (size != 128) {
-		if (g_debugMode) PrintAndLog("Error incorrect data length found");
-		return 0;
-	}
-
-	setDemodBuf(BitStream, 128, preambleIndex);
-
-	// remove marker bits (1's every 9th digit after preamble) (pType = 2)
-	size = removeParity(BitStream, preambleIndex + 11, 9, 2, 117);
-	if ( size != 104 ) {
-		if (g_debugMode) PrintAndLog("Error removeParity:: %d", size);
-		return 0;
-	}
-	if (g_debugMode) {
-		char *bin = sprint_bin_break(BitStream,size,16);
-		PrintAndLog("DEBUG BinStream:\n%s",bin);
-	}
-	PrintAndLog("\nFDX-B / ISO 11784/5 Animal Tag ID Found:");
-	if (g_debugMode) PrintAndLog("Start marker %d;   Size %d", preambleIndex, size);
-
-	//got a good demod
-	uint64_t NationalCode = ((uint64_t)(bytebits_to_byteLSBF(BitStream+32,6)) << 32) | bytebits_to_byteLSBF(BitStream,32);
-	uint32_t countryCode = bytebits_to_byteLSBF(BitStream+38,10);
-	uint8_t dataBlockBit = BitStream[48];
-	uint32_t reservedCode = bytebits_to_byteLSBF(BitStream+49,14);
-	uint8_t animalBit = BitStream[63];
-	uint32_t crc16 = bytebits_to_byteLSBF(BitStream+64,16);
-	uint32_t extended = bytebits_to_byteLSBF(BitStream+80,24);
-
-	uint64_t rawid = ((uint64_t)bytebits_to_byte(BitStream,32)<<32) | bytebits_to_byte(BitStream+32,32);
-	uint8_t raw[8];
-	num_to_bytes(rawid, 8, raw);
-
-	if (g_debugMode) PrintAndLog("Raw ID Hex: %s", sprint_hex(raw,8));
-
-	uint16_t calcCrc = crc16_ccitt_kermit(raw, 8);
-	PrintAndLog("Animal ID:     %04u-%012" PRIu64, countryCode, NationalCode);
-	PrintAndLog("National Code: %012" PRIu64, NationalCode);
-	PrintAndLog("CountryCode:   %04u", countryCode);
-	PrintAndLog("Extended Data: %s", dataBlockBit ? "True" : "False");
-	PrintAndLog("reserved Code: %u", reservedCode);
-	PrintAndLog("Animal Tag:    %s", animalBit ? "True" : "False");
-	PrintAndLog("CRC:           0x%04X - [%04X] - %s", crc16, calcCrc, (calcCrc == crc16) ? "Passed" : "Failed");
-	PrintAndLog("Extended:      0x%X\n", extended);
-	
-	return 1;
-}
-
-
 //by marshmellow
 //attempt to psk1 demod graph buffer
 int PSKDemod(const char *Cmd, bool verbose)
@@ -1717,7 +1625,6 @@ static command_t CommandTable[] =
 	{"buffclear",       CmdBuffClear,       1, "Clear sample buffer and graph window"},
 	{"dec",             CmdDec,             1, "Decimate samples"},
 	{"detectclock",     CmdDetectClockRate, 1, "[modulation] Detect clock rate of wave in GraphBuffer (options: 'a','f','n','p' for ask, fsk, nrz, psk respectively)"},
-	{"fdxbdemod",       CmdFDXBdemodBI    , 1, "Demodulate a FDX-B ISO11784/85 Biphase tag from GraphBuffer"},
 	//{"fskfcdetect",   CmdFSKfcDetect,     1, "Try to detect the Field Clock of an FSK wave"},
 	{"fskparadoxdemod", CmdFSKdemodParadox, 1, "Demodulate a Paradox FSK tag from GraphBuffer"},
 	{"getbitstream",    CmdGetBitStream,    1, "Convert GraphBuffer's >=1 values to 1 and <1 to 0"},
diff --git a/client/cmdlf.c b/client/cmdlf.c
index 10a70d7c..9743749d 100644
--- a/client/cmdlf.c
+++ b/client/cmdlf.c
@@ -37,6 +37,7 @@
 #include "cmdlfvisa2000.h"  // for VISA2000 menu
 #include "cmdlfindala.h" // for indala menu
 #include "cmdlfgproxii.h"// for gproxii menu
+#include "cmdlffdx.h"    // for fdx-b menu
 
 bool g_lf_threshold_set = false;
 static int CmdHelp(const char *Cmd);
@@ -974,7 +975,7 @@ int CmdLFfind(const char *Cmd)
 		return CheckChipType(cmdp);
 	}
 
-	ans=CmdFDXBdemodBI("");
+	ans=CmdFdxDemod("");
 	if (ans>0) {
 		PrintAndLog("\nValid FDX-B ID Found!");
 		return CheckChipType(cmdp);
@@ -1044,6 +1045,7 @@ static command_t CommandTable[] =
 	{"awid",        CmdLFAWID,          1, "{ AWID RFIDs...    }"},
 	{"cotag",       CmdLFCOTAG,         1, "{ COTAG RFIDs...   }"},
 	{"em",          CmdLFEM4X,          1, "{ EM4X RFIDs...    }"},
+	{"fdx",         CmdLFFdx,           1, "{ FDX-B tags...    }"},
 	{"gproxii",     CmdLF_G_Prox_II,    1, "{ G Prox II tags...    }"},
 	{"hid",         CmdLFHID,           1, "{ HID RFIDs...     }"},
 	{"hitag",       CmdLFHitag,         1, "{ Hitag tags and transponders... }"},
diff --git a/client/cmdlffdx.c b/client/cmdlffdx.c
new file mode 100644
index 00000000..69c3c483
--- /dev/null
+++ b/client/cmdlffdx.c
@@ -0,0 +1,316 @@
+//-----------------------------------------------------------------------------
+//
+// 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.
+//-----------------------------------------------------------------------------
+// Low frequency fdx-b tag commands
+//-----------------------------------------------------------------------------
+
+#include "cmdlffdx.h"
+
+#include <inttypes.h>
+#include "proxmark3.h"
+#include "ui.h"         // for PrintAndLog
+#include "util.h"
+#include "cmdparser.h"
+#include "cmddata.h"
+#include "cmdmain.h"
+#include "cmdlf.h"
+#include "crc16.h"
+#include "protocols.h"
+#include "lfdemod.h"
+
+/*
+	FDX-B ISO11784/85 demod  (aka animal tag)  BIPHASE, inverted, rf/32,  with preamble of 00000000001 (128bits)
+	8 databits + 1 parity (1)
+	CIITT 16 checksum
+	NATIONAL CODE, ICAR database
+	COUNTRY CODE (ISO3166) or http://cms.abvma.ca/uploads/ManufacturersISOsandCountryCodes.pdf
+	FLAG (animal/non-animal)
+
+	38 IDbits   
+	10 country code 
+	1 extra app bit
+	14 reserved bits
+	1 animal bit
+	16 ccitt CRC chksum over 64bit ID CODE.
+	24 appli bits.
+
+	sample: 985121004515220  [ 37FF65B88EF94 ]
+*/
+
+static int CmdHelp(const char *Cmd);
+
+int usage_lf_fdx_clone(void){
+	PrintAndLog("Clone a FDX-B animal tag to a T55x7 tag.");
+	PrintAndLog("Usage: lf animal clone [h] <country id> <animal id> <Q5>");
+	PrintAndLog("Options:");
+	PrintAndLog("      h            : This help");
+	PrintAndLog("      <country id> : Country id");
+	PrintAndLog("      <animal id>  : Animal id");
+	// has extended data?
+	//reserved/rfu
+	//is animal tag
+	// extended data
+	PrintAndLog("      <Q5>        : Specify write to Q5 (t5555 instead of t55x7)");
+	PrintAndLog("");
+	PrintAndLog("Sample: lf animal clone 999 112233");
+	return 0;
+}
+
+int usage_lf_fdx_sim(void) {
+	PrintAndLog("Enables simulation of FDX-B animal tag");
+	PrintAndLog("Simulation runs until the button is pressed or another USB command is issued.");
+	PrintAndLog("");
+	PrintAndLog("Usage:  lf animal sim [h] <country id> <animal id>");
+	PrintAndLog("Options:");
+	PrintAndLog("      h            : This help");
+	PrintAndLog("      <country id> : Country ID");
+	PrintAndLog("      <animal id>  : Animal ID");
+	PrintAndLog("");
+	PrintAndLog("Sample: lf animal sim 999 112233");
+	return 0;
+}
+// clearing the topbit needed for the preambl detection. 
+static void verify_values(uint32_t countryid, uint64_t animalid){
+	if ((animalid & 0x3FFFFFFFFF) != animalid) {
+		animalid &= 0x3FFFFFFFFF;
+		PrintAndLog("Animal ID Truncated to 38bits: %"PRIx64, animalid);
+	}	
+	if ( (countryid & 0x3ff) != countryid ) {
+		countryid &= 0x3ff;
+		PrintAndLog("Country ID Truncated to 10bits: %03d", countryid);
+	}
+}
+
+int getFDXBits(uint64_t national_id, uint16_t country, uint8_t isanimal, uint8_t isextended, uint32_t extended, uint8_t *bits) {
+
+	// 128bits
+	// every 9th bit is 0x01, but we can just fill the rest with 0x01 and overwrite
+	memset(bits, 0x01, 128);
+
+	// add preamble ten 0x00 and one 0x01
+	memset(bits, 0x00, 10);
+
+	// add reserved 
+	num_to_bytebitsLSBF(0x00, 7, bits + 66);
+	num_to_bytebitsLSBF(0x00 >> 7, 7, bits + 74);
+
+	// add animal flag - OK
+	bits[65] = isanimal;
+
+	// add extended flag - OK
+	bits[81] = isextended;
+
+	// add national code 40bits - OK
+	num_to_bytebitsLSBF(national_id >> 0, 8, bits+11);
+	num_to_bytebitsLSBF(national_id >> 8, 8, bits+20);
+	num_to_bytebitsLSBF(national_id >> 16, 8, bits+29);
+	num_to_bytebitsLSBF(national_id >> 24, 8, bits+38);
+	num_to_bytebitsLSBF(national_id >> 32, 6, bits+47);
+
+	// add country code - OK
+	num_to_bytebitsLSBF(country >> 0, 2, bits+53);
+	num_to_bytebitsLSBF(country >> 2, 8, bits+56);
+
+	// add crc-16 - OK
+	uint8_t raw[8];
+	for (uint8_t i=0; i<8; ++i)
+		raw[i] = bytebits_to_byte(bits + 11 + i * 9, 8);
+
+	uint16_t crc = crc16_ccitt_kermit(raw, 8);
+	num_to_bytebitsLSBF(crc >> 0, 8, bits+83);
+	num_to_bytebitsLSBF(crc >> 8, 8, bits+92);
+
+	// extended data - OK
+	num_to_bytebitsLSBF( extended >> 0 , 8, bits+101);
+	num_to_bytebitsLSBF( extended >> 8 , 8, bits+110);
+	num_to_bytebitsLSBF( extended >> 16, 8, bits+119);
+	return 1;
+}
+
+int CmdFdxDemod(const char *Cmd){
+
+	//Differential Biphase / di-phase (inverted biphase)
+	//get binary from ask wave
+	if (!ASKbiphaseDemod("0 32 1 0", FALSE)) {
+		if (g_debugMode) PrintAndLog("DEBUG: Error - FDX-B ASKbiphaseDemod failed");
+		return 0;
+	}
+	size_t size = DemodBufferLen;
+	int preambleIndex = FDXBdemodBI(DemodBuffer, &size);
+	if (preambleIndex < 0){
+		if (g_debugMode){
+			if (preambleIndex == -1)
+				PrintAndLog("DEBUG: Error - FDX-B too few bits found");
+			else if (preambleIndex == -2)
+				PrintAndLog("DEBUG: Error - FDX-B preamble not found");
+			else if (preambleIndex == -3)
+				PrintAndLog("DEBUG: Error - FDX-B Size not correct: %d", size);
+			else
+				PrintAndLog("DEBUG: Error - FDX-B ans: %d", preambleIndex);
+		}
+		return 0;
+	}
+
+	// set and leave DemodBuffer intact
+	setDemodBuf(DemodBuffer, 128, preambleIndex);
+	uint8_t bits_no_spacer[117];
+	memcpy(bits_no_spacer, DemodBuffer + 11, 117);
+
+	// remove marker bits (1's every 9th digit after preamble) (pType = 2)
+	size = removeParity(bits_no_spacer, 0, 9, 2, 117);
+	if ( size != 104 ) {
+		if (g_debugMode) PrintAndLog("DEBUG: Error removeParity:: %d", size);
+		return 0;
+	}
+
+	//got a good demod
+	uint64_t NationalCode = ((uint64_t)(bytebits_to_byteLSBF(bits_no_spacer+32,6)) << 32) | bytebits_to_byteLSBF(bits_no_spacer,32);
+	uint32_t countryCode = bytebits_to_byteLSBF(bits_no_spacer+38,10);
+	uint8_t dataBlockBit = bits_no_spacer[48];
+	uint32_t reservedCode = bytebits_to_byteLSBF(bits_no_spacer+49,14);
+	uint8_t animalBit = bits_no_spacer[63];
+	uint32_t crc16 = bytebits_to_byteLSBF(bits_no_spacer+64,16);
+	uint32_t extended = bytebits_to_byteLSBF(bits_no_spacer+80,24);
+
+	uint64_t rawid = ((uint64_t)bytebits_to_byte(bits_no_spacer,32)<<32) | bytebits_to_byte(bits_no_spacer+32,32);
+	uint8_t raw[8];
+	num_to_bytes(rawid, 8, raw);
+
+	if (g_debugMode) {
+		PrintAndLog("DEBUG: bits_no_spacer:\n%s",sprint_bin_break(bits_no_spacer,size,16));
+		PrintAndLog("DEBUG: Start marker %d;   Size %d", preambleIndex, size);
+		PrintAndLog("DEBUG: Raw ID Hex: %s", sprint_hex(raw,8));
+	}
+
+	uint16_t calcCrc = crc16_ccitt_kermit(raw, 8);
+	PrintAndLog("\nFDX-B / ISO 11784/5 Animal Tag ID Found:");
+	PrintAndLog("Animal ID:     %04u-%012" PRIu64, countryCode, NationalCode);
+	PrintAndLog("National Code: %012" PRIu64, NationalCode);
+	PrintAndLog("CountryCode:   %04u", countryCode);
+	PrintAndLog("Reserved Code: %u", reservedCode);
+	PrintAndLog("Animal Tag:    %s", animalBit ? "True" : "False");
+	PrintAndLog("Has Extended:  %s [0x%X]", dataBlockBit ? "True" : "False", extended);
+	PrintAndLog("CRC:           0x%04X - 0x%04X - [%s]\n", crc16, calcCrc, (calcCrc == crc16) ? "Passed" : "Failed");
+	
+	// set block 0 for later
+	//g_DemodConfig = T55x7_MODULATION_DIPHASE | T55x7_BITRATE_RF_32 | 4 << T55x7_MAXBLOCK_SHIFT;
+	return 1;
+}
+
+int CmdFdxRead(const char *Cmd) {
+	CmdLFRead("s");
+	getSamples("10000", TRUE);
+	return CmdFdxDemod(Cmd);
+}
+
+int CmdFdxClone(const char *Cmd) {
+
+	uint32_t countryid = 0;
+	uint64_t animalid = 0;
+	uint32_t blocks[5] = {T55x7_MODULATION_DIPHASE | T55x7_BITRATE_RF_32 | 4 << T55x7_MAXBLOCK_SHIFT, 0, 0, 0, 0};
+	uint8_t bits[128];
+	uint8_t *bs = bits;
+	memset(bs, 0, sizeof(bits));
+	
+	char cmdp = param_getchar(Cmd, 0);
+	if (strlen(Cmd) == 0 || cmdp == 'h' || cmdp == 'H') return usage_lf_fdx_clone();
+
+	countryid = param_get32ex(Cmd, 0, 0, 10);
+	animalid = param_get64ex(Cmd, 1, 0, 10);
+	
+	//Q5
+	if (param_getchar(Cmd, 2) == 'Q' || param_getchar(Cmd, 2) == 'q') {
+		//t5555 (Q5) BITRATE = (RF-2)/2 (iceman)
+		blocks[0] = T5555_MODULATION_BIPHASE | T5555_INVERT_OUTPUT | ((32-2)>>1) << T5555_BITRATE_SHIFT | 4 << T5555_MAXBLOCK_SHIFT;
+	}
+	
+	verify_values(countryid, animalid);
+	
+	// getFDXBits(uint64_t national_id, uint16_t country, uint8_t isanimal, uint8_t isextended, uint32_t extended, uint8_t *bits) 
+	if ( !getFDXBits(animalid, countryid, 1, 0, 0, bs)) {
+		PrintAndLog("Error with tag bitstream generation.");
+		return 1;
+	}	
+	
+	// convert from bit stream to block data
+	blocks[1] = bytebits_to_byte(bs,32);
+	blocks[2] = bytebits_to_byte(bs+32,32);
+	blocks[3] = bytebits_to_byte(bs+64,32);
+	blocks[4] = bytebits_to_byte(bs+96,32);
+
+	PrintAndLog("Preparing to clone FDX-B to T55x7 with animal ID: %04u-%"PRIu64, countryid, animalid);
+	PrintAndLog("Blk | Data ");
+	PrintAndLog("----+------------");
+	PrintAndLog(" 00 | 0x%08x", blocks[0]);
+	PrintAndLog(" 01 | 0x%08x", blocks[1]);
+	PrintAndLog(" 02 | 0x%08x", blocks[2]);
+	PrintAndLog(" 03 | 0x%08x", blocks[3]);
+	PrintAndLog(" 04 | 0x%08x", blocks[4]);
+	
+	UsbCommand resp;
+	UsbCommand c = {CMD_T55XX_WRITE_BLOCK, {0,0,0}};
+
+	for (int i = 4; i >= 0; --i) {
+		c.arg[0] = blocks[i];
+		c.arg[1] = i;
+		clearCommandBuffer();
+		SendCommand(&c);
+		if (!WaitForResponseTimeout(CMD_ACK, &resp, T55XX_WRITE_TIMEOUT)){
+			PrintAndLog("Error occurred, device did not respond during write operation.");
+			return -1;
+		}
+	}
+	return 0;
+}
+
+int CmdFdxSim(const char *Cmd) {
+	uint32_t countryid = 0;
+	uint64_t animalid = 0;
+
+	char cmdp = param_getchar(Cmd, 0);
+	if (strlen(Cmd) == 0 || cmdp == 'h' || cmdp == 'H') return usage_lf_fdx_sim();
+
+	countryid = param_get32ex(Cmd, 0, 0, 10);
+	animalid = param_get64ex(Cmd, 1, 0, 10);
+	
+	verify_values(countryid, animalid);
+
+	uint8_t clk = 32, encoding = 2, separator = 0, invert = 1;
+	uint16_t arg1, arg2;
+	size_t size = 128;
+	arg1 = clk << 8 | encoding;
+	arg2 = invert << 8 | separator;
+
+	PrintAndLog("Simulating FDX-B animal ID: %04u-%"PRIu64, countryid, animalid);
+
+	UsbCommand c = {CMD_ASK_SIM_TAG, {arg1, arg2, size}};
+
+	 //getFDXBits(uint64_t national_id, uint16_t country, uint8_t isanimal, uint8_t isextended, uint32_t extended, uint8_t *bits) 
+	getFDXBits(animalid, countryid, 1, 0, 0, c.d.asBytes);
+	clearCommandBuffer();
+	SendCommand(&c);
+	return 0;
+}
+
+static command_t CommandTable[] = {
+	{"help",  CmdHelp,    1, "This help"},
+	{"demod", CmdFdxDemod,1, "Attempt to extract FDX-B ISO11784/85 data from the GraphBuffer"},
+	{"read",  CmdFdxRead, 0, "Attempt to read and extract FDX-B ISO11784/85 data"},
+	{"clone", CmdFdxClone,0, "Clone animal ID tag to T55x7 (or to q5/T5555)"},
+	{"sim",   CmdFdxSim,  0, "Animal ID tag simulator"},
+	{NULL, NULL, 0, NULL}
+};
+
+int CmdLFFdx(const char *Cmd) {
+	clearCommandBuffer();
+	CmdsParse(CommandTable, Cmd);
+	return 0;
+}
+
+int CmdHelp(const char *Cmd) {
+	CmdsHelp(CommandTable);
+	return 0;
+}
diff --git a/client/cmdlffdx.h b/client/cmdlffdx.h
new file mode 100644
index 00000000..d11daec4
--- /dev/null
+++ b/client/cmdlffdx.h
@@ -0,0 +1,17 @@
+//-----------------------------------------------------------------------------
+//
+// 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.
+//-----------------------------------------------------------------------------
+// Low frequency fdx-b tag commands
+//-----------------------------------------------------------------------------
+#ifndef CMDLFFDX_H__
+#define CMDLFFDX_H__
+
+extern int CmdLFFdx(const char *Cmd);
+extern int CmdFdxClone(const char *Cmd);
+extern int CmdFdxSim(const char *Cmd);
+extern int CmdFdxRead(const char *Cmd);
+extern int CmdFdxDemod(const char *Cmd);
+#endif
diff --git a/common/lfdemod.c b/common/lfdemod.c
index 8307a890..eb84203e 100644
--- a/common/lfdemod.c
+++ b/common/lfdemod.c
@@ -1703,6 +1703,8 @@ int FDXBdemodBI(uint8_t *dest, size_t *size) {
 
 	uint8_t errChk = preambleSearch(dest, preamble, sizeof(preamble), size, &startIdx);
 	if (errChk == 0) return -2; //preamble not found
+	if (*size != 128) return -3; //wrong size for fdxb
+	//return start position
 	return (int)startIdx;
 }