[proxmark3-svn] / client / cmdlfem4x.c

 //-----------------------------------------------------------------------------
// Copyright (C) 2010 iZsh <izsh at fail0verflow.com>
//
// 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 EM4x commands
//-----------------------------------------------------------------------------

#include <stdio.h>
#include <string.h>
#include <inttypes.h>
#include "proxmark3.h"
#include "ui.h"
#include "graph.h"
#include "cmdmain.h"
#include "cmdparser.h"
#include "cmddata.h"
#include "cmdlf.h"
#include "cmdlfem4x.h"
#include "util.h"
#include "data.h"
#define LF_TRACE_BUFF_SIZE 12000
#define LF_BITSSTREAM_LEN 1000

char *global_em410xId;

static int CmdHelp(const char *Cmd);

/* Read the ID of an EM410x tag.
 * Format:
 *   1111 1111 1           <-- standard non-repeatable header
 *   XXXX [row parity bit] <-- 10 rows of 5 bits for our 40 bit tag ID
 *   ....
 *   CCCC                  <-- each bit here is parity for the 10 bits above in corresponding column
 *   0                     <-- stop bit, end of tag
 */
int CmdEM410xRead(const char *Cmd)
{
  int i, j, clock, header, rows, bit, hithigh, hitlow, first, bit2idx, high, low;
  int parity[4];
  char id[11];
  char id2[11];
  int retested = 0;
  uint8_t BitStream[MAX_GRAPH_TRACE_LEN];
  high = low = 0;

  /* Detect high and lows and clock */
  for (i = 0; i < GraphTraceLen; i++)
  {
    if (GraphBuffer[i] > high)
      high = GraphBuffer[i];
    else if (GraphBuffer[i] < low)
      low = GraphBuffer[i];
  }

  /* get clock */
  clock = GetClock(Cmd, high, 0);
   
  /* parity for our 4 columns */
  parity[0] = parity[1] = parity[2] = parity[3] = 0;
  header = rows = 0;

  /* manchester demodulate */
  bit = bit2idx = 0;
  for (i = 0; i < (int)(GraphTraceLen / clock); i++)
  {
    hithigh = 0;
    hitlow = 0;
    first = 1;

    /* Find out if we hit both high and low peaks */
    for (j = 0; j < clock; j++)
    {
      if (GraphBuffer[(i * clock) + j] == high)
        hithigh = 1;
      else if (GraphBuffer[(i * clock) + j] == low)
        hitlow = 1;

      /* it doesn't count if it's the first part of our read
       because it's really just trailing from the last sequence */
      if (first && (hithigh || hitlow))
        hithigh = hitlow = 0;
      else
        first = 0;

      if (hithigh && hitlow)
        break;
    }

    /* If we didn't hit both high and low peaks, we had a bit transition */
    if (!hithigh || !hitlow)
      bit ^= 1;

    BitStream[bit2idx++] = bit;
  }

retest:
  /* We go till 5 before the graph ends because we'll get that far below */
  for (i = 0; i < bit2idx - 5; i++)
  {
    /* Step 2: We have our header but need our tag ID */
    if (header == 9 && rows < 10)
    {
      /* Confirm parity is correct */
      if ((BitStream[i] ^ BitStream[i+1] ^ BitStream[i+2] ^ BitStream[i+3]) == BitStream[i+4])
      {
        /* Read another byte! */
        sprintf(id+rows, "%x", (8 * BitStream[i]) + (4 * BitStream[i+1]) + (2 * BitStream[i+2]) + (1 * BitStream[i+3]));
        sprintf(id2+rows, "%x", (8 * BitStream[i+3]) + (4 * BitStream[i+2]) + (2 * BitStream[i+1]) + (1 * BitStream[i]));
        rows++;

        /* Keep parity info */
        parity[0] ^= BitStream[i];
        parity[1] ^= BitStream[i+1];
        parity[2] ^= BitStream[i+2];
        parity[3] ^= BitStream[i+3];

        /* Move 4 bits ahead */
        i += 4;
      }

      /* Damn, something wrong! reset */
      else
      {
        PrintAndLog("Thought we had a valid tag but failed at word %d (i=%d)", rows + 1, i);

        /* Start back rows * 5 + 9 header bits, -1 to not start at same place */
        i -= 9 + (5 * rows) -5;

        rows = header = 0;
      }
    }

    /* Step 3: Got our 40 bits! confirm column parity */
    else if (rows == 10)
    {
      /* We need to make sure our 4 bits of parity are correct and we have a stop bit */
      if (BitStream[i] == parity[0] && BitStream[i+1] == parity[1] &&
        BitStream[i+2] == parity[2] && BitStream[i+3] == parity[3] &&
        BitStream[i+4] == 0)
      {
        /* Sweet! */
        PrintAndLog("EM410x Tag ID: %s", id);
        PrintAndLog("Unique Tag ID: %s", id2);

                global_em410xId = id;
                
        /* Stop any loops */
        return 1;
      }

      /* Crap! Incorrect parity or no stop bit, start all over */
      else
      {
        rows = header = 0;

        /* Go back 59 bits (9 header bits + 10 rows at 4+1 parity) */
        i -= 59;
      }
    }

    /* Step 1: get our header */
    else if (header < 9)
    {
      /* Need 9 consecutive 1's */
      if (BitStream[i] == 1)
        header++;

      /* We don't have a header, not enough consecutive 1 bits */
      else
        header = 0;
    }
  }

  /* if we've already retested after flipping bits, return */
  if (retested++){
    return 0;
        }

  /* if this didn't work, try flipping bits */
  for (i = 0; i < bit2idx; i++)
    BitStream[i] ^= 1;

  goto retest;
}

/* emulate an EM410X tag
 * Format:
 *   1111 1111 1           <-- standard non-repeatable header
 *   XXXX [row parity bit] <-- 10 rows of 5 bits for our 40 bit tag ID
 *   ....
 *   CCCC                  <-- each bit here is parity for the 10 bits above in corresponding column
 *   0                     <-- stop bit, end of tag
 */
int CmdEM410xSim(const char *Cmd)
{       
        int i, n, j, binary[4], parity[4];

        char cmdp = param_getchar(Cmd, 0);
        uint8_t uid[5] = {0x00};

        if (cmdp == 'h' || cmdp == 'H') {
                PrintAndLog("Usage:  lf em4x 410xsim <UID>");
                PrintAndLog("");
                PrintAndLog("     sample: lf em4x 410xsim 0F0368568B");
                return 0;
        }

        if (param_gethex(Cmd, 0, uid, 10)) {
                PrintAndLog("UID must include 10 HEX symbols");
                return 0;
        }
        
        PrintAndLog("Starting simulating UID %02X%02X%02X%02X%02X", uid[0],uid[1],uid[2],uid[3],uid[4]);
        PrintAndLog("Press pm3-button to about simulation");
  
  /* clock is 64 in EM410x tags */
  int clock = 64;

  /* clear our graph */
  ClearGraph(0);
  
    /* write 9 start bits */
    for (i = 0; i < 9; i++)
      AppendGraph(0, clock, 1);

    /* for each hex char */
    parity[0] = parity[1] = parity[2] = parity[3] = 0;
    for (i = 0; i < 10; i++)
    {
      /* read each hex char */
      sscanf(&Cmd[i], "%1x", &n);
      for (j = 3; j >= 0; j--, n/= 2)
        binary[j] = n % 2;

      /* append each bit */
      AppendGraph(0, clock, binary[0]);
      AppendGraph(0, clock, binary[1]);
      AppendGraph(0, clock, binary[2]);
      AppendGraph(0, clock, binary[3]);

      /* append parity bit */
      AppendGraph(0, clock, binary[0] ^ binary[1] ^ binary[2] ^ binary[3]);

      /* keep track of column parity */
      parity[0] ^= binary[0];
      parity[1] ^= binary[1];
      parity[2] ^= binary[2];
      parity[3] ^= binary[3];
    }

    /* parity columns */
    AppendGraph(0, clock, parity[0]);
    AppendGraph(0, clock, parity[1]);
    AppendGraph(0, clock, parity[2]);
    AppendGraph(0, clock, parity[3]);

  /* stop bit */
  AppendGraph(1, clock, 0);
 
  CmdLFSim("240"); //240 start_gap.
  return 0;
}

/* Function is equivalent of lf read + data samples + em410xread
 * looped until an EM410x tag is detected 
 * 
 * Why is CmdSamples("16000")?
 *  TBD: Auto-grow sample size based on detected sample rate.  IE: If the
 *       rate gets lower, then grow the number of samples
 *  Changed by martin, 4000 x 4 = 16000, 
 *  see http://www.proxmark.org/forum/viewtopic.php?pid=7235#p7235

*/
int CmdEM410xWatch(const char *Cmd)
{
        int read_h = (*Cmd == 'h');
        do
        {
                if (ukbhit()) {
                        printf("\naborted via keyboard!\n");
                        break;
                }
                
                CmdLFRead(read_h ? "h" : "");
                CmdSamples("6000");
                
        } while (
                !CmdEM410xRead("") 
        );
        return 0;
}

int CmdEM410xWatchnSpoof(const char *Cmd)
{
        CmdEM410xWatch(Cmd);
    PrintAndLog("# Replaying : %s",global_em410xId);
    CmdEM410xSim(global_em410xId);
  return 0;
}

/* Read the transmitted data of an EM4x50 tag
 * Format:
 *
 *  XXXXXXXX [row parity bit (even)] <- 8 bits plus parity
 *  XXXXXXXX [row parity bit (even)] <- 8 bits plus parity
 *  XXXXXXXX [row parity bit (even)] <- 8 bits plus parity
 *  XXXXXXXX [row parity bit (even)] <- 8 bits plus parity
 *  CCCCCCCC                         <- column parity bits
 *  0                                <- stop bit
 *  LW                               <- Listen Window
 *
 * This pattern repeats for every block of data being transmitted.
 * Transmission starts with two Listen Windows (LW - a modulated
 * pattern of 320 cycles each (32/32/128/64/64)).
 *
 * Note that this data may or may not be the UID. It is whatever data
 * is stored in the blocks defined in the control word First and Last
 * Word Read values. UID is stored in block 32.
 */
int CmdEM4x50Read(const char *Cmd)
{
  int i, j, startblock, skip, block, start, end, low, high;
  bool complete= false;
  int tmpbuff[MAX_GRAPH_TRACE_LEN / 64];
  char tmp[6];

  high= low= 0;
  memset(tmpbuff, 0, MAX_GRAPH_TRACE_LEN / 64);

  /* first get high and low values */
  for (i = 0; i < GraphTraceLen; i++)
  {
    if (GraphBuffer[i] > high)
      high = GraphBuffer[i];
    else if (GraphBuffer[i] < low)
      low = GraphBuffer[i];
  }

  /* populate a buffer with pulse lengths */
  i= 0;
  j= 0;
  while (i < GraphTraceLen)
  {
    // measure from low to low
    while ((GraphBuffer[i] > low) && (i<GraphTraceLen))
      ++i;
    start= i;
    while ((GraphBuffer[i] < high) && (i<GraphTraceLen))
      ++i;
    while ((GraphBuffer[i] > low) && (i<GraphTraceLen))
      ++i;
    if (j>=(MAX_GRAPH_TRACE_LEN/64)) {
      break;
    }
    tmpbuff[j++]= i - start;
  }

  /* look for data start - should be 2 pairs of LW (pulses of 192,128) */
  start= -1;
  skip= 0;
  for (i= 0; i < j - 4 ; ++i)
  {
    skip += tmpbuff[i];
    if (tmpbuff[i] >= 190 && tmpbuff[i] <= 194)
      if (tmpbuff[i+1] >= 126 && tmpbuff[i+1] <= 130)
        if (tmpbuff[i+2] >= 190 && tmpbuff[i+2] <= 194)
          if (tmpbuff[i+3] >= 126 && tmpbuff[i+3] <= 130)
          {
            start= i + 3;
            break;
          }
  }
  startblock= i + 3;

  /* skip over the remainder of the LW */
  skip += tmpbuff[i+1]+tmpbuff[i+2];
  while (skip < MAX_GRAPH_TRACE_LEN && GraphBuffer[skip] > low)
    ++skip;
  skip += 8;

  /* now do it again to find the end */
  end= start;
  for (i += 3; i < j - 4 ; ++i)
  {
    end += tmpbuff[i];
    if (tmpbuff[i] >= 190 && tmpbuff[i] <= 194)
      if (tmpbuff[i+1] >= 126 && tmpbuff[i+1] <= 130)
        if (tmpbuff[i+2] >= 190 && tmpbuff[i+2] <= 194)
          if (tmpbuff[i+3] >= 126 && tmpbuff[i+3] <= 130)
          {
            complete= true;
            break;
          }
  }

  if (start >= 0)
    PrintAndLog("Found data at sample: %i",skip);
  else
  {
    PrintAndLog("No data found!");
    PrintAndLog("Try again with more samples.");
    return 0;
  }

  if (!complete)
  {
    PrintAndLog("*** Warning!");
    PrintAndLog("Partial data - no end found!");
    PrintAndLog("Try again with more samples.");
  }

  /* get rid of leading crap */
  sprintf(tmp,"%i",skip);
  CmdLtrim(tmp);

  /* now work through remaining buffer printing out data blocks */
  block= 0;
  i= startblock;
  while (block < 6)
  {
    PrintAndLog("Block %i:", block);
    // mandemod routine needs to be split so we can call it for data
    // just print for now for debugging
    CmdManchesterDemod("i 64");
    skip= 0;
    /* look for LW before start of next block */
    for ( ; i < j - 4 ; ++i)
    {
      skip += tmpbuff[i];
      if (tmpbuff[i] >= 190 && tmpbuff[i] <= 194)
        if (tmpbuff[i+1] >= 126 && tmpbuff[i+1] <= 130)
          break;
    }
    while (GraphBuffer[skip] > low)
      ++skip;
    skip += 8;
    sprintf(tmp,"%i",skip);
    CmdLtrim(tmp);
    start += skip;
    block++;
  }
  return 0;
}

int CmdEM410xWrite(const char *Cmd)
{
  uint64_t id = 0xFFFFFFFFFFFFFFFF; // invalid id value
  int card = 0xFF; // invalid card value
        unsigned int clock = 0; // invalid clock value

        sscanf(Cmd, "%" PRIx64 " %d %d", &id, &card, &clock);

        // Check ID
        if (id == 0xFFFFFFFFFFFFFFFF) {
                PrintAndLog("Error! ID is required.\n");
                return 0;
        }
        if (id >= 0x10000000000) {
                PrintAndLog("Error! Given EM410x ID is longer than 40 bits.\n");
                return 0;
        }

        // Check Card
        if (card == 0xFF) {
                PrintAndLog("Error! Card type required.\n");
                return 0;
        }
        if (card < 0) {
                PrintAndLog("Error! Bad card type selected.\n");
                return 0;
        }

        // Check Clock
        if (card == 1)
        {
                // Default: 64
                if (clock == 0)
                        clock = 64;

                // Allowed clock rates: 16, 32 and 64
                if ((clock != 16) && (clock != 32) && (clock != 64)) {
                        PrintAndLog("Error! Clock rate %d not valid. Supported clock rates are 16, 32 and 64.\n", clock);
                        return 0;
                }
        }
        else if (clock != 0)
        {
                PrintAndLog("Error! Clock rate is only supported on T55x7 tags.\n");
                return 0;
        }

        if (card == 1) {
                PrintAndLog("Writing %s tag with UID 0x%010" PRIx64 " (clock rate: %d)", "T55x7", id, clock);
                // NOTE: We really should pass the clock in as a separate argument, but to
                //   provide for backwards-compatibility for older firmware, and to avoid
                //   having to add another argument to CMD_EM410X_WRITE_TAG, we just store
                //   the clock rate in bits 8-15 of the card value
                card = (card & 0xFF) | (((uint64_t)clock << 8) & 0xFF00);
        }
        else if (card == 0)
                PrintAndLog("Writing %s tag with UID 0x%010" PRIx64, "T5555", id, clock);
        else {
                PrintAndLog("Error! Bad card type selected.\n");
                return 0;
        }

  UsbCommand c = {CMD_EM410X_WRITE_TAG, {card, (uint32_t)(id >> 32), (uint32_t)id}};
  SendCommand(&c);

  return 0;
}

int CmdReadWord(const char *Cmd)
{
        int Word = -1; //default to invalid word
        UsbCommand c;
  
        sscanf(Cmd, "%d", &Word);
  
        if ( (Word > 15) | (Word < 0) ) {
                PrintAndLog("Word must be between 0 and 15");
                return 1;
        }
  
        PrintAndLog("Reading word %d", Word);
  
        c.cmd = CMD_EM4X_READ_WORD;
        c.d.asBytes[0] = 0x0; //Normal mode
        c.arg[0] = 0;
        c.arg[1] = Word;
        c.arg[2] = 0;
        SendCommand(&c);
        WaitForResponse(CMD_ACK, NULL);

        uint8_t data[LF_TRACE_BUFF_SIZE] = {0x00};

        GetFromBigBuf(data,LF_TRACE_BUFF_SIZE,3560);  //3560 -- should be offset..
        WaitForResponseTimeout(CMD_ACK,NULL, 1500);

        for (int j = 0; j < LF_TRACE_BUFF_SIZE; j++) {
                GraphBuffer[j] = ((int)data[j]);
        }
        GraphTraceLen = LF_TRACE_BUFF_SIZE;
        
        uint8_t bits[LF_BITSSTREAM_LEN] = {0x00};
        uint8_t * bitstream = bits;
        manchester_decode(GraphBuffer, LF_TRACE_BUFF_SIZE, bitstream,LF_BITSSTREAM_LEN);
        RepaintGraphWindow();
  return 0;
}

int CmdReadWordPWD(const char *Cmd)
{
        int Word = -1; //default to invalid word
        int Password = 0xFFFFFFFF; //default to blank password
        UsbCommand c;

        sscanf(Cmd, "%d %x", &Word, &Password);

        if ( (Word > 15) | (Word < 0) ) {
                PrintAndLog("Word must be between 0 and 15");
                return 1;
        }
  
        PrintAndLog("Reading word %d with password %08X", Word, Password);

        c.cmd = CMD_EM4X_READ_WORD;
        c.d.asBytes[0] = 0x1; //Password mode
        c.arg[0] = 0;
        c.arg[1] = Word;
        c.arg[2] = Password;
        SendCommand(&c);
        WaitForResponse(CMD_ACK, NULL);
                
        uint8_t data[LF_TRACE_BUFF_SIZE] = {0x00};

        GetFromBigBuf(data,LF_TRACE_BUFF_SIZE,3560);  //3560 -- should be offset..
        WaitForResponseTimeout(CMD_ACK,NULL, 1500);

        for (int j = 0; j < LF_TRACE_BUFF_SIZE; j++) {
                GraphBuffer[j] = ((int)data[j]);
        }
        GraphTraceLen = LF_TRACE_BUFF_SIZE;
        
        uint8_t bits[LF_BITSSTREAM_LEN] = {0x00};
        uint8_t * bitstream = bits;     
        manchester_decode(GraphBuffer, LF_TRACE_BUFF_SIZE, bitstream, LF_BITSSTREAM_LEN);
        RepaintGraphWindow();
  return 0;
}

int CmdWriteWord(const char *Cmd)
{
  int Word = 16; //default to invalid block
  int Data = 0xFFFFFFFF; //default to blank data
  UsbCommand c;
  
  sscanf(Cmd, "%x %d", &Data, &Word);
  
  if (Word > 15) {
    PrintAndLog("Word must be between 0 and 15");
    return 1;
  }
  
  PrintAndLog("Writing word %d with data %08X", Word, Data);
  
  c.cmd = CMD_EM4X_WRITE_WORD;
  c.d.asBytes[0] = 0x0; //Normal mode
  c.arg[0] = Data;
  c.arg[1] = Word;
  c.arg[2] = 0;
  SendCommand(&c);
  return 0;
}

int CmdWriteWordPWD(const char *Cmd)
{
  int Word = 16; //default to invalid word
  int Data = 0xFFFFFFFF; //default to blank data
  int Password = 0xFFFFFFFF; //default to blank password
  UsbCommand c;
  
  sscanf(Cmd, "%x %d %x", &Data, &Word, &Password);
  
  if (Word > 15) {
    PrintAndLog("Word must be between 0 and 15");
    return 1;
  }
  
  PrintAndLog("Writing word %d with data %08X and password %08X", Word, Data, Password);
  
  c.cmd = CMD_EM4X_WRITE_WORD;
  c.d.asBytes[0] = 0x1; //Password mode
  c.arg[0] = Data;
  c.arg[1] = Word;
  c.arg[2] = Password;
  SendCommand(&c);
  return 0;
}

static command_t CommandTable[] =
{
  {"help", CmdHelp, 1, "This help"},
  
  {"410xread", CmdEM410xRead, 1, "[clock rate] -- Extract ID from EM410x tag"},
  {"410xsim", CmdEM410xSim, 0, "<UID> -- Simulate EM410x tag"},
  {"replay",  MWRem4xReplay, 0, "Watches for tag and simulates manchester encoded em4x tag"},
  {"410xwatch", CmdEM410xWatch, 0, "['h'] -- Watches for EM410x 125/134 kHz tags (option 'h' for 134)"},
  {"410xspoof", CmdEM410xWatchnSpoof, 0, "['h'] --- Watches for EM410x 125/134 kHz tags, and replays them. (option 'h' for 134)" },
  {"410xwrite", CmdEM410xWrite, 1, "<UID> <'0' T5555> <'1' T55x7> [clock rate] -- Write EM410x UID to T5555(Q5) or T55x7 tag, optionally setting clock rate"},
  {"4x50read", CmdEM4x50Read, 1, "Extract data from EM4x50 tag"},
  {"rd", CmdReadWord, 1, "<Word 1-15> -- Read EM4xxx word data"},
  {"rdpwd", CmdReadWordPWD, 1, "<Word 1-15> <Password> -- Read EM4xxx word data  in password mode "},
  {"wr", CmdWriteWord, 1, "<Data> <Word 1-15> -- Write EM4xxx word data"},
  {"wrpwd", CmdWriteWordPWD, 1, "<Data> <Word 1-15> <Password> -- Write EM4xxx word data in password mode"},
  {NULL, NULL, 0, NULL}
};


//Confirms the parity of a bitstream as well as obtaining the data (TagID) from within the appropriate memory space.
//Arguments:
// Pointer to a string containing the desired bitsream
// Pointer to a string that will receive the decoded tag ID
// Length of the bitsream pointed at in the first argument, char* _strBitStream
//Retuns:
//1 Parity confirmed
//0 Parity not confirmed
int ConfirmEm410xTagParity( char* _strBitStream, char* pID, int LengthOfBitstream )
{
        int i = 0;
        int rows = 0;
        int Parity[4] = {0x00};
        char ID[11] = {0x00};
        int k = 0;
        int BitStream[70] = {0x00};
        int counter = 0;
        //prepare variables
        for ( i = 0; i <= LengthOfBitstream; i++)
        {
                if (_strBitStream[i] == '1')
                {
                        k =1;
                        memcpy(&BitStream[i], &k,4);
                }
                else if (_strBitStream[i] == '0')
                {
                        k = 0;
                        memcpy(&BitStream[i], &k,4);
                }
        }
        while ( counter < 2 )
        {
                //set/reset variables and counters
                memset(ID,0x00,sizeof(ID));
                memset(Parity,0x00,sizeof(Parity));
                rows = 0;
                for ( i = 9; i <= LengthOfBitstream; i++)
                {
                        if ( rows < 10 )
                        {
                                if ((BitStream[i] ^ BitStream[i+1] ^ BitStream[i+2] ^ BitStream[i+3]) == BitStream[i+4])
                                {
                                        sprintf(ID+rows, "%x", (8 * BitStream[i]) + (4 * BitStream[i+1]) + (2 * BitStream[i+2]) + (1 * BitStream[i+3]));
                                        rows++;
                                        /* Keep parity info and move four bits ahead*/
                                        Parity[0] ^= BitStream[i];
                                        Parity[1] ^= BitStream[i+1];
                                        Parity[2] ^= BitStream[i+2];
                                        Parity[3] ^= BitStream[i+3];
                                        i += 4;
                                }
                        }
                        if ( rows == 10 )
                        {
                                if (    BitStream[i] == Parity[0] && BitStream[i+1] == Parity[1] &&
                                        BitStream[i+2] == Parity[2] && BitStream[i+3] == Parity[3] &&
                                        BitStream[i+4] == 0)
                                {
                                        memcpy(pID,ID,strlen(ID));
                                        return 1;
                                }
                        }
                }
                printf("[PARITY ->]Failed. Flipping Bits, and rechecking parity for bitstream:\n[PARITY ->]");  
                for (k = 0; k < LengthOfBitstream; k++)
                {
                        BitStream[k] ^= 1;
                        printf("%i", BitStream[k]);
                }
                puts(" ");
                counter++;
        }
        return 0;
}
//Reads and demodulates an em410x RFID tag. It further allows slight modification to the decoded bitstream
//Once a suitable bitstream has been identified, and if needed, modified, it is replayed. Allowing emulation of the
//"stolen" rfid tag.
//No meaningful returns or arguments.
int MWRem4xReplay(const char* Cmd)
{
        // //header traces
        // static char ArrayTraceZero[] = { '0','0','0','0','0','0','0','0','0' };
        // static char ArrayTraceOne[] =  { '1','1','1','1','1','1','1','1','1' };
        // //local string variables
        // char strClockRate[10] = {0x00};
        // char strAnswer[4] = {0x00};
        // char strTempBufferMini[2] = {0x00}; 
        // //our outbound bit-stream
        // char strSimulateBitStream[65] = {0x00};
        // //integers
        // int iClockRate = 0;
        // int needle = 0;
        // int j = 0;
        // int iFirstHeaderOffset = 0x00000000;
        // int numManchesterDemodBits=0;
        // //boolean values
        // bool bInverted = false;
        // //pointers to strings. memory will be allocated.
        // char* pstrInvertBitStream = 0x00000000;
        // char* pTempBuffer = 0x00000000;
        // char* pID = 0x00000000;
        // char* strBitStreamBuffer = 0x00000000;
                

        // puts("###################################");
        // puts("#### Em4x Replay                 ##");
        // puts("#### R.A.M.           June 2013  ##");
        // puts("###################################");
        // //initialize
        // CmdLFRead("");
        // //Collect ourselves 10,000 samples
        // CmdSamples("10000");
        // puts("[->]preforming ASK demodulation\n");
        // //demodulate ask
        // Cmdaskdemod("0");
        // iClockRate = DetectClock(0);
        // sprintf(strClockRate, "%i\n",iClockRate);
        // printf("[->]Detected ClockRate: %s\n", strClockRate);
        
        // //If detected clock rate is something completely unreasonable, dont go ahead
        // if ( iClockRate < 0xFFFE )
        // {  
            // pTempBuffer = (char*)malloc(MAX_GRAPH_TRACE_LEN);
            // if (pTempBuffer == 0x00000000)
              // return 0;
            // memset(pTempBuffer,0x00,MAX_GRAPH_TRACE_LEN);
            // //Preform manchester de-modulation and display in a single line.
            // numManchesterDemodBits = CmdManchesterDemod( strClockRate ); 
            // //note: numManchesterDemodBits is set above in CmdManchesterDemod()
            // if ( numManchesterDemodBits == 0 )
              // return 0;
            // strBitStreamBuffer = malloc(numManchesterDemodBits+1);
            // if ( strBitStreamBuffer == 0x00000000 )
                // return 0;
            // memset(strBitStreamBuffer, 0x00, (numManchesterDemodBits+1));
            // //fill strBitStreamBuffer with demodulated, string formatted bits.
            // for ( j = 0; j <= numManchesterDemodBits; j++ )
            // {
                // sprintf(strTempBufferMini, "%i",BitStream[j]);
                // strcat(strBitStreamBuffer,strTempBufferMini);
            // }
            // printf("[->]Demodulated Bitstream: \n%s\n", strBitStreamBuffer);
            // //Reset counter and select most probable bit stream
            // j = 0;
                // while ( j < numManchesterDemodBits )
                // {
                    // memset(strSimulateBitStream,0x00,64);
                    // //search for header of nine (9) 0's : 000000000 or nine (9) 1's : 1111 1111 1
                        // if ( ( strncmp(strBitStreamBuffer+j, ArrayTraceZero, sizeof(ArrayTraceZero)) == 0 ) ||
                            // ( strncmp(strBitStreamBuffer+j, ArrayTraceOne, sizeof(ArrayTraceOne)) == 0  ) )
                        // {
                                // iFirstHeaderOffset = j;
                            // memcpy(strSimulateBitStream, strBitStreamBuffer+j,64);
                            // printf("[->]Offset of Header");
                                // if ( strncmp(strBitStreamBuffer+iFirstHeaderOffset, "0", 1) == 0 )
                                        // printf("'%s'", ArrayTraceZero );
                                // else
                                        // printf("'%s'", ArrayTraceOne );
                                // printf(": %i\nHighlighted string : %s\n",iFirstHeaderOffset,strSimulateBitStream);
                            // //allow us to escape loop or choose another frame
                            // puts("[<-]Are we happy with this sample? [Y]es/[N]o");
                            // gets(strAnswer);
                            // if ( ( strncmp(strAnswer,"y",1) == 0 )  || ( strncmp(strAnswer,"Y",1) == 0 ) )
                            // {
                                    // j = numManchesterDemodBits+1;
                                    // break;
                            // }
                        // }
                        // j++;
                // }
        // }
        // else return 0;
        
        // //Do we want the buffer inverted?
        // memset(strAnswer, 0x00, sizeof(strAnswer));
        // printf("[<-]Do you wish to invert the highlighted bitstream? [Y]es/[N]o\n");
        // gets(strAnswer);
        // if ( ( strncmp("y", strAnswer,1) == 0 )  || ( strncmp("Y", strAnswer, 1 ) == 0 ) )
        // {
                // //allocate heap memory
                // pstrInvertBitStream = (char*)malloc(numManchesterDemodBits);
                // if ( pstrInvertBitStream != 0x00000000 )
                // {
                        // memset(pstrInvertBitStream,0x00,numManchesterDemodBits);
                        // bInverted = true;
                        // //Invert Bitstream
                        // for ( needle = 0; needle <= numManchesterDemodBits; needle++ )
                        // {
                                // if (strSimulateBitStream[needle] == '0')
                                        // strcat(pstrInvertBitStream,"1");
                                // else if (strSimulateBitStream[needle] == '1')
                                        // strcat(pstrInvertBitStream,"0");
                        // }
                        // printf("[->]Inverted bitstream: %s\n", pstrInvertBitStream);
                // }
        // }    
    // //Confirm parity of selected string
        // pID = (char*)malloc(11);
        // if (pID != 0x00000000)
        // {
                // memset(pID, 0x00, 11);
                // if (ConfirmEm410xTagParity(strSimulateBitStream,pID, 64) == 1)
                // {
                        // printf("[->]Parity confirmed for selected bitstream!\n");
                        // printf("[->]Tag ID was detected as: [hex]:%s\n",pID );
                // }
                // else
                        // printf("[->]Parity check failed for the selected bitstream!\n");     
        // }
        
        // //Spoof
        // memset(strAnswer, 0x00, sizeof(strAnswer));  
        // printf("[<-]Do you wish to continue with the EM4x simulation? [Y]es/[N]o\n");
        // gets(strAnswer);
        // if ( ( strncmp(strAnswer,"y",1) == 0 )  || ( strncmp(strAnswer,"Y",1) == 0 ) )
        // {
                // strcat(pTempBuffer, strClockRate);
                // strcat(pTempBuffer, " ");
                // if (bInverted == true)
                        // strcat(pTempBuffer,pstrInvertBitStream);
                // if (bInverted == false)
                        // strcat(pTempBuffer,strSimulateBitStream);
                // //inform the user
                // puts("[->]Starting simulation now: \n");
                // //Simulate tag with prepared buffer.
                // CmdLFSimManchester(pTempBuffer);
        // }
        // else if ( ( strcmp("n", strAnswer) == 0 )  || ( strcmp("N", strAnswer ) == 0 ) )
                // printf("[->]Exiting procedure now...\n");
        // else
                // printf("[->]Erroneous selection\nExiting procedure now....\n");
        
        // //Clean up -- Exit function
        // //clear memory, then release pointer.
        // if ( pstrInvertBitStream != 0x00000000 )
        // {
            // memset(pstrInvertBitStream,0x00,numManchesterDemodBits);
            // free(pstrInvertBitStream);
        // }
        // if ( pTempBuffer != 0x00000000 )
        // {
            // memset(pTempBuffer,0x00,MAX_GRAPH_TRACE_LEN);
            // free(pTempBuffer);
        // }
        // if ( pID != 0x00000000 )
        // {
            // memset(pID,0x00,11);
            // free(pID);
        // }
        // if ( strBitStreamBuffer != 0x00000000 )
        // {
            // memset(strBitStreamBuffer,0x00,numManchesterDemodBits);
            // free(strBitStreamBuffer);
        // }
        return 0;
}

int CmdLFEM4X(const char *Cmd)
{
  CmdsParse(CommandTable, Cmd);
  return 0;
}

int CmdHelp(const char *Cmd)
{
  CmdsHelp(CommandTable);
  return 0;
}