]> git.zerfleddert.de Git - proxmark3-svn/blobdiff - armsrc/iso14443a.c
Fixed the write raw 14a, now finally functional... at least let's hope so
[proxmark3-svn] / armsrc / iso14443a.c
index 54fbb246458f36ec1695a0841de26556659ddba9..bd7e758d0b0796ac62883060a8923d876ed0b42c 100644 (file)
@@ -1,5 +1,5 @@
 //-----------------------------------------------------------------------------
-// Merlok - June 2011
+// Merlok - June 2011, 2012
 // Gerhard de Koning Gans - May 2008
 // Hagen Fritsch - June 2010
 //
 #include "apps.h"
 #include "util.h"
 #include "string.h"
+#include "cmd.h"
 
 #include "iso14443crc.h"
 #include "iso14443a.h"
 #include "crapto1.h"
 #include "mifareutil.h"
 
-static uint8_t *trace = (uint8_t *) BigBuf;
-static int traceLen = 0;
-static int rsamples = 0;
-static int tracing = TRUE;
 static uint32_t iso14a_timeout;
+uint8_t *trace = (uint8_t *) BigBuf+TRACE_OFFSET;
+int traceLen = 0;
+int rsamples = 0;
+int tracing = TRUE;
+uint8_t trigger = 0;
+// the block number for the ISO14443-4 PCB
+static uint8_t iso14_pcb_blocknum = 0;
 
 // CARD TO READER - manchester
 // Sequence D: 11110000 modulation with subcarrier during first half
@@ -41,7 +45,7 @@ static uint32_t iso14a_timeout;
 #define        SEC_Y 0x00
 #define        SEC_Z 0xc0
 
-static const uint8_t OddByteParity[256] = {
+const uint8_t OddByteParity[256] = {
   1, 0, 0, 1, 0, 1, 1, 0, 0, 1, 1, 0, 1, 0, 0, 1,
   0, 1, 1, 0, 1, 0, 0, 1, 1, 0, 0, 1, 0, 1, 1, 0,
   0, 1, 1, 0, 1, 0, 0, 1, 1, 0, 0, 1, 0, 1, 1, 0,
@@ -60,18 +64,24 @@ static const uint8_t OddByteParity[256] = {
   1, 0, 0, 1, 0, 1, 1, 0, 0, 1, 1, 0, 1, 0, 0, 1
 };
 
-uint8_t trigger = 0;
-void iso14a_set_trigger(int enable) {
+
+void iso14a_set_trigger(bool enable) {
        trigger = enable;
 }
 
-void iso14a_clear_tracelen(void) {
+void iso14a_clear_trace() {
+  memset(trace, 0x44, TRACE_SIZE);
        traceLen = 0;
 }
-void iso14a_set_tracing(int enable) {
+
+void iso14a_set_tracing(bool enable) {
        tracing = enable;
 }
 
+void iso14a_set_timeout(uint32_t timeout) {
+       iso14a_timeout = timeout;
+}
+
 //-----------------------------------------------------------------------------
 // Generate the parity value for a byte sequence
 //
@@ -99,10 +109,11 @@ void AppendCrc14443a(uint8_t* data, int len)
   ComputeCrc14443(CRC_14443_A,data,len,data+len,data+len+1);
 }
 
-int LogTrace(const uint8_t * btBytes, int iLen, int iSamples, uint32_t dwParity, int bReader)
+// The function LogTrace() is also used by the iClass implementation in iClass.c
+int RAMFUNC LogTrace(const uint8_t * btBytes, int iLen, int iSamples, uint32_t dwParity, int bReader)
 {
   // Return when trace is full
-  if (traceLen >= TRACE_LENGTH) return FALSE;
+  if (traceLen >= TRACE_SIZE) return FALSE;
 
   // Trace the random, i'm curious
   rsamples += iSamples;
@@ -127,32 +138,7 @@ int LogTrace(const uint8_t * btBytes, int iLen, int iSamples, uint32_t dwParity,
 // The software UART that receives commands from the reader, and its state
 // variables.
 //-----------------------------------------------------------------------------
-static struct {
-    enum {
-        STATE_UNSYNCD,
-        STATE_START_OF_COMMUNICATION,
-               STATE_MILLER_X,
-               STATE_MILLER_Y,
-               STATE_MILLER_Z,
-        STATE_ERROR_WAIT
-    }       state;
-    uint16_t    shiftReg;
-    int     bitCnt;
-    int     byteCnt;
-    int     byteCntMax;
-    int     posCnt;
-    int     syncBit;
-       int     parityBits;
-       int     samples;
-    int     highCnt;
-    int     bitBuffer;
-       enum {
-               DROP_NONE,
-               DROP_FIRST_HALF,
-               DROP_SECOND_HALF
-       }               drop;
-    uint8_t   *output;
-} Uart;
+static tUart Uart;
 
 static RAMFUNC int MillerDecoding(int bit)
 {
@@ -391,32 +377,7 @@ static RAMFUNC int MillerDecoding(int bit)
 //=============================================================================
 // ISO 14443 Type A - Manchester
 //=============================================================================
-
-static struct {
-    enum {
-        DEMOD_UNSYNCD,
-               DEMOD_START_OF_COMMUNICATION,
-               DEMOD_MANCHESTER_D,
-               DEMOD_MANCHESTER_E,
-               DEMOD_MANCHESTER_F,
-        DEMOD_ERROR_WAIT
-    }       state;
-    int     bitCount;
-    int     posCount;
-       int     syncBit;
-       int     parityBits;
-    uint16_t    shiftReg;
-       int     buffer;
-       int     buff;
-       int     samples;
-    int     len;
-       enum {
-               SUB_NONE,
-               SUB_FIRST_HALF,
-               SUB_SECOND_HALF
-       }               sub;
-    uint8_t   *output;
-} Demod;
+static tDemod Demod;
 
 static RAMFUNC int ManchesterDecoding(int v)
 {
@@ -616,166 +577,147 @@ static RAMFUNC int ManchesterDecoding(int v)
 // triggering so that we start recording at the point that the tag is moved
 // near the reader.
 //-----------------------------------------------------------------------------
-void RAMFUNC SnoopIso14443a(void)
-{
-//     #define RECV_CMD_OFFSET         2032    // original (working as of 21/2/09) values
-//     #define RECV_RES_OFFSET         2096    // original (working as of 21/2/09) values
-//     #define DMA_BUFFER_OFFSET       2160    // original (working as of 21/2/09) values
-//     #define DMA_BUFFER_SIZE         4096    // original (working as of 21/2/09) values
-//     #define TRACE_LENGTH            2000    // original (working as of 21/2/09) values
-
-    // We won't start recording the frames that we acquire until we trigger;
-    // a good trigger condition to get started is probably when we see a
-    // response from the tag.
-    int triggered = FALSE; // FALSE to wait first for card
-
-    // The command (reader -> tag) that we're receiving.
+void RAMFUNC SnoopIso14443a(uint8_t param) {
+       // param:
+       // bit 0 - trigger from first card answer
+       // bit 1 - trigger from first reader 7-bit request
+       
+       LEDsoff();
+       // init trace buffer
+    iso14a_clear_trace();
+
+       // We won't start recording the frames that we acquire until we trigger;
+       // a good trigger condition to get started is probably when we see a
+       // response from the tag.
+       // triggered == FALSE -- to wait first for card
+       int triggered = !(param & 0x03); 
+
+       // The command (reader -> tag) that we're receiving.
        // The length of a received command will in most cases be no more than 18 bytes.
        // So 32 should be enough!
-    uint8_t *receivedCmd = (((uint8_t *)BigBuf) + RECV_CMD_OFFSET);
-    // The response (tag -> reader) that we're receiving.
-    uint8_t *receivedResponse = (((uint8_t *)BigBuf) + RECV_RES_OFFSET);
+       uint8_t *receivedCmd = (((uint8_t *)BigBuf) + RECV_CMD_OFFSET);
+       // The response (tag -> reader) that we're receiving.
+       uint8_t *receivedResponse = (((uint8_t *)BigBuf) + RECV_RES_OFFSET);
 
-    // As we receive stuff, we copy it from receivedCmd or receivedResponse
-    // into trace, along with its length and other annotations.
-    //uint8_t *trace = (uint8_t *)BigBuf;
-    
-    traceLen = 0; // uncommented to fix ISSUE 15 - gerhard - jan2011
-
-    // The DMA buffer, used to stream samples from the FPGA
-    int8_t *dmaBuf = ((int8_t *)BigBuf) + DMA_BUFFER_OFFSET;
-    int lastRxCounter;
-    int8_t *upTo;
-    int smpl;
-    int maxBehindBy = 0;
-
-    // Count of samples received so far, so that we can include timing
-    // information in the trace buffer.
-    int samples = 0;
-    int rsamples = 0;
-
-    memset(trace, 0x44, RECV_CMD_OFFSET);
-
-    // Set up the demodulator for tag -> reader responses.
-    Demod.output = receivedResponse;
-    Demod.len = 0;
-    Demod.state = DEMOD_UNSYNCD;
-
-    // Setup for the DMA.
-    FpgaSetupSsc();
-    upTo = dmaBuf;
-    lastRxCounter = DMA_BUFFER_SIZE;
-    FpgaSetupSscDma((uint8_t *)dmaBuf, DMA_BUFFER_SIZE);
-
-    // And the reader -> tag commands
-    memset(&Uart, 0, sizeof(Uart));
-    Uart.output = receivedCmd;
-    Uart.byteCntMax = 32; // was 100 (greg)////////////////////////////////////////////////////////////////////////
-    Uart.state = STATE_UNSYNCD;
+       // As we receive stuff, we copy it from receivedCmd or receivedResponse
+       // into trace, along with its length and other annotations.
+       //uint8_t *trace = (uint8_t *)BigBuf;
+       
+       // The DMA buffer, used to stream samples from the FPGA
+       int8_t *dmaBuf = ((int8_t *)BigBuf) + DMA_BUFFER_OFFSET;
+       int8_t *data = dmaBuf;
+       int maxDataLen = 0;
+       int dataLen = 0;
 
-    // And put the FPGA in the appropriate mode
-    // Signal field is off with the appropriate LED
-    LED_D_OFF();
-    FpgaWriteConfWord(FPGA_MAJOR_MODE_HF_ISO14443A | FPGA_HF_ISO14443A_SNIFFER);
-    SetAdcMuxFor(GPIO_MUXSEL_HIPKD);
+       // Set up the demodulator for tag -> reader responses.
+       Demod.output = receivedResponse;
+       Demod.len = 0;
+       Demod.state = DEMOD_UNSYNCD;
 
+       // Set up the demodulator for the reader -> tag commands
+       memset(&Uart, 0, sizeof(Uart));
+       Uart.output = receivedCmd;
+       Uart.byteCntMax = 32;                        // was 100 (greg)//////////////////
+       Uart.state = STATE_UNSYNCD;
 
-    // And now we loop, receiving samples.
-    for(;;) {
-        LED_A_ON();
-        WDT_HIT();
-        int behindBy = (lastRxCounter - AT91C_BASE_PDC_SSC->PDC_RCR) &
-                                (DMA_BUFFER_SIZE-1);
-        if(behindBy > maxBehindBy) {
-            maxBehindBy = behindBy;
-            if(behindBy > 400) {
-                Dbprintf("blew circular buffer! behindBy=0x%x", behindBy);
-                goto done;
-            }
-        }
-        if(behindBy < 1) continue;
+       // Setup for the DMA.
+       FpgaSetupSsc();
+       FpgaSetupSscDma((uint8_t *)dmaBuf, DMA_BUFFER_SIZE);
 
-       LED_A_OFF();
-        smpl = upTo[0];
-        upTo++;
-        lastRxCounter -= 1;
-        if(upTo - dmaBuf > DMA_BUFFER_SIZE) {
-            upTo -= DMA_BUFFER_SIZE;
-            lastRxCounter += DMA_BUFFER_SIZE;
-            AT91C_BASE_PDC_SSC->PDC_RNPR = (uint32_t) upTo;
-            AT91C_BASE_PDC_SSC->PDC_RNCR = DMA_BUFFER_SIZE;
-        }
+       // And put the FPGA in the appropriate mode
+       // Signal field is off with the appropriate LED
+       LED_D_OFF();
+       FpgaWriteConfWord(FPGA_MAJOR_MODE_HF_ISO14443A | FPGA_HF_ISO14443A_SNIFFER);
+       SetAdcMuxFor(GPIO_MUXSEL_HIPKD);
 
-        samples += 4;
-        if(MillerDecoding((smpl & 0xF0) >> 4)) {
-            rsamples = samples - Uart.samples;
-            LED_C_ON();
-            if(triggered) {
-                trace[traceLen++] = ((rsamples >>  0) & 0xff);
-                trace[traceLen++] = ((rsamples >>  8) & 0xff);
-                trace[traceLen++] = ((rsamples >> 16) & 0xff);
-                trace[traceLen++] = ((rsamples >> 24) & 0xff);
-                trace[traceLen++] = ((Uart.parityBits >>  0) & 0xff);
-                trace[traceLen++] = ((Uart.parityBits >>  8) & 0xff);
-                trace[traceLen++] = ((Uart.parityBits >> 16) & 0xff);
-                trace[traceLen++] = ((Uart.parityBits >> 24) & 0xff);
-                trace[traceLen++] = Uart.byteCnt;
-                memcpy(trace+traceLen, receivedCmd, Uart.byteCnt);
-                traceLen += Uart.byteCnt;
-                if(traceLen > TRACE_LENGTH) break;
-            }
-            /* And ready to receive another command. */
-            Uart.state = STATE_UNSYNCD;
-            /* And also reset the demod code, which might have been */
-            /* false-triggered by the commands from the reader. */
-            Demod.state = DEMOD_UNSYNCD;
-            LED_B_OFF();
-        }
+       // Count of samples received so far, so that we can include timing
+       // information in the trace buffer.
+       rsamples = 0;
+       // And now we loop, receiving samples.
+       while(true) {
+               if(BUTTON_PRESS()) {
+                       DbpString("cancelled by button");
+                       goto done;
+               }
 
-        if(ManchesterDecoding(smpl & 0x0F)) {
-            rsamples = samples - Demod.samples;
-            LED_B_ON();
-
-            // timestamp, as a count of samples
-            trace[traceLen++] = ((rsamples >>  0) & 0xff);
-            trace[traceLen++] = ((rsamples >>  8) & 0xff);
-            trace[traceLen++] = ((rsamples >> 16) & 0xff);
-            trace[traceLen++] = 0x80 | ((rsamples >> 24) & 0xff);
-            trace[traceLen++] = ((Demod.parityBits >>  0) & 0xff);
-            trace[traceLen++] = ((Demod.parityBits >>  8) & 0xff);
-            trace[traceLen++] = ((Demod.parityBits >> 16) & 0xff);
-            trace[traceLen++] = ((Demod.parityBits >> 24) & 0xff);
-            // length
-            trace[traceLen++] = Demod.len;
-            memcpy(trace+traceLen, receivedResponse, Demod.len);
-            traceLen += Demod.len;
-            if(traceLen > TRACE_LENGTH) break;
-
-            triggered = TRUE;
-
-            // And ready to receive another response.
-            memset(&Demod, 0, sizeof(Demod));
-            Demod.output = receivedResponse;
-            Demod.state = DEMOD_UNSYNCD;
-            LED_C_OFF();
-        }
+               LED_A_ON();
+               WDT_HIT();
 
-        if(BUTTON_PRESS()) {
-            DbpString("cancelled_a");
-            goto done;
-        }
-    }
+               int register readBufDataP = data - dmaBuf;
+               int register dmaBufDataP = DMA_BUFFER_SIZE - AT91C_BASE_PDC_SSC->PDC_RCR;
+               if (readBufDataP <= dmaBufDataP){
+                       dataLen = dmaBufDataP - readBufDataP;
+               } else {
+                       dataLen = DMA_BUFFER_SIZE - readBufDataP + dmaBufDataP + 1;
+               }
+               // test for length of buffer
+               if(dataLen > maxDataLen) {
+                       maxDataLen = dataLen;
+                       if(dataLen > 400) {
+                               Dbprintf("blew circular buffer! dataLen=0x%x", dataLen);
+                               goto done;
+                       }
+               }
+               if(dataLen < 1) continue;
+
+               // primary buffer was stopped( <-- we lost data!
+               if (!AT91C_BASE_PDC_SSC->PDC_RCR) {
+                       AT91C_BASE_PDC_SSC->PDC_RPR = (uint32_t) dmaBuf;
+                       AT91C_BASE_PDC_SSC->PDC_RCR = DMA_BUFFER_SIZE;
+               }
+               // secondary buffer sets as primary, secondary buffer was stopped
+               if (!AT91C_BASE_PDC_SSC->PDC_RNCR) {
+                       AT91C_BASE_PDC_SSC->PDC_RNPR = (uint32_t) dmaBuf;
+                       AT91C_BASE_PDC_SSC->PDC_RNCR = DMA_BUFFER_SIZE;
+               }
+
+               LED_A_OFF();
+               
+               rsamples += 4;
+               if(MillerDecoding((data[0] & 0xF0) >> 4)) {
+                       LED_C_ON();
+
+                       // check - if there is a short 7bit request from reader
+                       if ((!triggered) && (param & 0x02) && (Uart.byteCnt == 1) && (Uart.bitCnt = 9)) triggered = TRUE;
 
-    DbpString("COMMAND FINISHED");
+                       if(triggered) {
+                               if (!LogTrace(receivedCmd, Uart.byteCnt, 0 - Uart.samples, Uart.parityBits, TRUE)) break;
+                       }
+                       /* And ready to receive another command. */
+                       Uart.state = STATE_UNSYNCD;
+                       /* And also reset the demod code, which might have been */
+                       /* false-triggered by the commands from the reader. */
+                       Demod.state = DEMOD_UNSYNCD;
+                       LED_B_OFF();
+               }
+
+               if(ManchesterDecoding(data[0] & 0x0F)) {
+                       LED_B_ON();
+
+                       if (!LogTrace(receivedResponse, Demod.len, 0 - Demod.samples, Demod.parityBits, FALSE)) break;
+
+                       if ((!triggered) && (param & 0x01)) triggered = TRUE;
+
+                       // And ready to receive another response.
+                       memset(&Demod, 0, sizeof(Demod));
+                       Demod.output = receivedResponse;
+                       Demod.state = DEMOD_UNSYNCD;
+                       LED_C_OFF();
+               }
+
+               data++;
+               if(data > dmaBuf + DMA_BUFFER_SIZE) {
+                       data = dmaBuf;
+               }
+       } // main cycle
+
+       DbpString("COMMAND FINISHED");
 
 done:
-    AT91C_BASE_PDC_SSC->PDC_PTCR = AT91C_PDC_RXTDIS;
-    Dbprintf("maxBehindBy=%x, Uart.state=%x, Uart.byteCnt=%x", maxBehindBy, Uart.state, Uart.byteCnt);
-    Dbprintf("Uart.byteCntMax=%x, traceLen=%x, Uart.output[0]=%x", Uart.byteCntMax, traceLen, (int)Uart.output[0]);
-    LED_A_OFF();
-    LED_B_OFF();
-       LED_C_OFF();
-       LED_D_OFF();
+       AT91C_BASE_PDC_SSC->PDC_PTCR = AT91C_PDC_RXTDIS;
+       Dbprintf("maxDataLen=%x, Uart.state=%x, Uart.byteCnt=%x", maxDataLen, Uart.state, Uart.byteCnt);
+       Dbprintf("Uart.byteCntMax=%x, traceLen=%x, Uart.output[0]=%08x", Uart.byteCntMax, traceLen, (int)Uart.output[0]);
+       LEDsoff();
 }
 
 //-----------------------------------------------------------------------------
@@ -956,51 +898,105 @@ static int GetIso14443aCommandFromReader(uint8_t *received, int *len, int maxLen
         }
     }
 }
+
 static int EmSendCmd14443aRaw(uint8_t *resp, int respLen, int correctionNeeded);
+int EmSend4bitEx(uint8_t resp, int correctionNeeded);
+int EmSend4bit(uint8_t resp);
+int EmSendCmdExPar(uint8_t *resp, int respLen, int correctionNeeded, uint32_t par);
+int EmSendCmdExPar(uint8_t *resp, int respLen, int correctionNeeded, uint32_t par);
+int EmSendCmdEx(uint8_t *resp, int respLen, int correctionNeeded);
+int EmSendCmd(uint8_t *resp, int respLen);
+int EmSendCmdPar(uint8_t *resp, int respLen, uint32_t par);
 
 //-----------------------------------------------------------------------------
 // Main loop of simulated tag: receive commands from reader, decide what
 // response to send, and send it.
 //-----------------------------------------------------------------------------
-void SimulateIso14443aTag(int tagType, int TagUid)
+void SimulateIso14443aTag(int tagType, int uid_1st, int uid_2nd, byte_t* data)
 {
-       // This function contains the tag emulation
-
-       // Prepare protocol messages
-    // static const uint8_t cmd1[] = { 0x26 };
-//     static const uint8_t response1[] = { 0x02, 0x00 }; // Says: I am Mifare 4k - original line - greg
-//
-       static const uint8_t response1[] = { 0x44, 0x03 }; // Says: I am a DESFire Tag, ph33r me
-//     static const uint8_t response1[] = { 0x44, 0x00 }; // Says: I am a ULTRALITE Tag, 0wn me
-
-       // UID response
-    // static const uint8_t cmd2[] = { 0x93, 0x20 };
-    //static const uint8_t response2[] = { 0x9a, 0xe5, 0xe4, 0x43, 0xd8 }; // original value - greg
+  // Enable and clear the trace
+       tracing = TRUE;
+  iso14a_clear_trace();
 
-// my desfire
-    static const uint8_t response2[] = { 0x88, 0x04, 0x21, 0x3f, 0x4d }; // known uid - note cascade (0x88), 2nd byte (0x04) = NXP/Phillips
+       // This function contains the tag emulation
+       uint8_t sak;
 
+       // The first response contains the ATQA (note: bytes are transmitted in reverse order).
+       uint8_t response1[2];
+       
+       switch (tagType) {
+               case 1: { // MIFARE Classic
+                       // Says: I am Mifare 1k - original line
+                       response1[0] = 0x04;
+                       response1[1] = 0x00;
+                       sak = 0x08;
+               } break;
+               case 2: { // MIFARE Ultralight
+                       // Says: I am a stupid memory tag, no crypto
+                       response1[0] = 0x04;
+                       response1[1] = 0x00;
+                       sak = 0x00;
+               } break;
+               case 3: { // MIFARE DESFire
+                       // Says: I am a DESFire tag, ph33r me
+                       response1[0] = 0x04;
+                       response1[1] = 0x03;
+                       sak = 0x20;
+               } break;
+               case 4: { // ISO/IEC 14443-4
+                       // Says: I am a javacard (JCOP)
+                       response1[0] = 0x04;
+                       response1[1] = 0x00;
+                       sak = 0x28;
+               } break;
+               default: {
+                       Dbprintf("Error: unkown tagtype (%d)",tagType);
+                       return;
+               } break;
+       }
+       
+       // The second response contains the (mandatory) first 24 bits of the UID
+       uint8_t response2[5];
+
+       // Check if the uid uses the (optional) part
+       uint8_t response2a[5];
+       if (uid_2nd) {
+               response2[0] = 0x88;
+               num_to_bytes(uid_1st,3,response2+1);
+               num_to_bytes(uid_2nd,4,response2a);
+               response2a[4] = response2a[0] ^ response2a[1] ^ response2a[2] ^ response2a[3];
+
+               // Configure the ATQA and SAK accordingly
+               response1[0] |= 0x40;
+               sak |= 0x04;
+       } else {
+               num_to_bytes(uid_1st,4,response2);
+               // Configure the ATQA and SAK accordingly
+               response1[0] &= 0xBF;
+               sak &= 0xFB;
+       }
 
-// When reader selects us during cascade1 it will send cmd3
-//uint8_t response3[] = { 0x04, 0x00, 0x00 }; // SAK Select (cascade1) successful response (ULTRALITE)
-uint8_t response3[] = { 0x24, 0x00, 0x00 }; // SAK Select (cascade1) successful response (DESFire)
-ComputeCrc14443(CRC_14443_A, response3, 1, &response3[1], &response3[2]);
+       // Calculate the BitCountCheck (BCC) for the first 4 bytes of the UID.
+       response2[4] = response2[0] ^ response2[1] ^ response2[2] ^ response2[3];
 
-// send cascade2 2nd half of UID
-static const uint8_t response2a[] = { 0x51, 0x48, 0x1d, 0x80, 0x84 }; //  uid - cascade2 - 2nd half (4 bytes) of UID+ BCCheck
-// NOTE : THE CRC on the above may be wrong as I have obfuscated the actual UID
+       // Prepare the mandatory SAK (for 4 and 7 byte UID)
+       uint8_t response3[3];
+       response3[0] = sak;
+       ComputeCrc14443(CRC_14443_A, response3, 1, &response3[1], &response3[2]);
 
-// When reader selects us during cascade2 it will send cmd3a
-//uint8_t response3a[] = { 0x00, 0x00, 0x00 }; // SAK Select (cascade2) successful response (ULTRALITE)
-uint8_t response3a[] = { 0x20, 0x00, 0x00 }; // SAK Select (cascade2) successful response (DESFire)
-ComputeCrc14443(CRC_14443_A, response3a, 1, &response3a[1], &response3a[2]);
+       // Prepare the optional second SAK (for 7 byte UID), drop the cascade bit
+       uint8_t response3a[3];
+       response3a[0] = sak & 0xFB;
+       ComputeCrc14443(CRC_14443_A, response3a, 1, &response3a[1], &response3a[2]);
 
-    static const uint8_t response5[] = { 0x00, 0x00, 0x00, 0x00 }; // Very random tag nonce
+       uint8_t response5[] = { 0x00, 0x00, 0x00, 0x00 }; // Very random tag nonce
+       uint8_t response6[] = { 0x03, 0x3B, 0x00, 0x00, 0x00 }; // dummy ATS (pseudo-ATR), answer to RATS
+       ComputeCrc14443(CRC_14443_A, response6, 3, &response6[3], &response6[4]);
 
-    uint8_t *resp;
-    int respLen;
+       uint8_t *resp = NULL;
+       int respLen;
 
-    // Longest possible response will be 16 bytes + 2 CRC = 18 bytes
+  // Longest possible response will be 16 bytes + 2 CRC = 18 bytes
        // This will need
        //    144        data bits (18 * 8)
        //     18        parity bits
@@ -1013,41 +1009,41 @@ ComputeCrc14443(CRC_14443_A, response3a, 1, &response3a[1], &response3a[2]);
        // 166 bytes, since every bit that needs to be send costs us a byte
        //
 
-    // Respond with card type
-    uint8_t *resp1 = (((uint8_t *)BigBuf) + 800);
-    int resp1Len;
+       // Respond with card type
+       uint8_t *resp1 = (((uint8_t *)BigBuf) + FREE_BUFFER_OFFSET);
+       int resp1Len;
 
-    // Anticollision cascade1 - respond with uid
-    uint8_t *resp2 = (((uint8_t *)BigBuf) + 970);
-    int resp2Len;
+       // Anticollision cascade1 - respond with uid
+       uint8_t *resp2 = (((uint8_t *)BigBuf) + FREE_BUFFER_OFFSET + 166);
+       int resp2Len;
 
-    // Anticollision cascade2 - respond with 2nd half of uid if asked
-    // we're only going to be asked if we set the 1st byte of the UID (during cascade1) to 0x88
-    uint8_t *resp2a = (((uint8_t *)BigBuf) + 1140);
-    int resp2aLen;
+       // Anticollision cascade2 - respond with 2nd half of uid if asked
+       // we're only going to be asked if we set the 1st byte of the UID (during cascade1) to 0x88
+       uint8_t *resp2a = (((uint8_t *)BigBuf) + 1140);
+       int resp2aLen;
 
-    // Acknowledge select - cascade 1
-    uint8_t *resp3 = (((uint8_t *)BigBuf) + 1310);
-    int resp3Len;
+       // Acknowledge select - cascade 1
+       uint8_t *resp3 = (((uint8_t *)BigBuf) + FREE_BUFFER_OFFSET + (166*2));
+       int resp3Len;
 
-    // Acknowledge select - cascade 2
-    uint8_t *resp3a = (((uint8_t *)BigBuf) + 1480);
-    int resp3aLen;
+       // Acknowledge select - cascade 2
+       uint8_t *resp3a = (((uint8_t *)BigBuf) + FREE_BUFFER_OFFSET + (166*3));
+       int resp3aLen;
 
-    // Response to a read request - not implemented atm
-    uint8_t *resp4 = (((uint8_t *)BigBuf) + 1550);
-    int resp4Len;
+       // Response to a read request - not implemented atm
+       uint8_t *resp4 = (((uint8_t *)BigBuf) + FREE_BUFFER_OFFSET + (166*4));
+//     int resp4Len;
 
-    // Authenticate response - nonce
-    uint8_t *resp5 = (((uint8_t *)BigBuf) + 1720);
-    int resp5Len;
+       // Authenticate response - nonce
+       uint8_t *resp5 = (((uint8_t *)BigBuf) + FREE_BUFFER_OFFSET + (166*5));
+       int resp5Len;
 
-    uint8_t *receivedCmd = (uint8_t *)BigBuf;
-    int len;
+       // Authenticate response - nonce
+       uint8_t *resp6 = (((uint8_t *)BigBuf) + FREE_BUFFER_OFFSET + (166*6));
+       int resp6Len;
 
-    //int i;
-       //int u;
-       //uint8_t b;
+       uint8_t *receivedCmd = (((uint8_t *)BigBuf) + RECV_CMD_OFFSET);
+       int len;
 
        // To control where we are in the protocol
        int order = 0;
@@ -1057,130 +1053,130 @@ ComputeCrc14443(CRC_14443_A, response3a, 1, &response3a[1], &response3a[2]);
        int happened = 0;
        int happened2 = 0;
 
-    int cmdsRecvd = 0;
-
-       //int fdt_indicator;
+       int cmdsRecvd = 0;
+       uint8_t* respdata = NULL;
+       int respsize = 0;
+//     uint8_t nack = 0x04;
 
-    memset(receivedCmd, 0x44, 400);
+       memset(receivedCmd, 0x44, RECV_CMD_SIZE);
 
        // Prepare the responses of the anticollision phase
        // there will be not enough time to do this at the moment the reader sends it REQA
 
        // Answer to request
        CodeIso14443aAsTag(response1, sizeof(response1));
-    memcpy(resp1, ToSend, ToSendMax); resp1Len = ToSendMax;
+       memcpy(resp1, ToSend, ToSendMax); resp1Len = ToSendMax;
 
        // Send our UID (cascade 1)
        CodeIso14443aAsTag(response2, sizeof(response2));
-    memcpy(resp2, ToSend, ToSendMax); resp2Len = ToSendMax;
+       memcpy(resp2, ToSend, ToSendMax); resp2Len = ToSendMax;
 
        // Answer to select (cascade1)
        CodeIso14443aAsTag(response3, sizeof(response3));
-    memcpy(resp3, ToSend, ToSendMax); resp3Len = ToSendMax;
+       memcpy(resp3, ToSend, ToSendMax); resp3Len = ToSendMax;
 
        // Send the cascade 2 2nd part of the uid
        CodeIso14443aAsTag(response2a, sizeof(response2a));
-    memcpy(resp2a, ToSend, ToSendMax); resp2aLen = ToSendMax;
+       memcpy(resp2a, ToSend, ToSendMax); resp2aLen = ToSendMax;
 
        // Answer to select (cascade 2)
        CodeIso14443aAsTag(response3a, sizeof(response3a));
-    memcpy(resp3a, ToSend, ToSendMax); resp3aLen = ToSendMax;
+       memcpy(resp3a, ToSend, ToSendMax); resp3aLen = ToSendMax;
 
        // Strange answer is an example of rare message size (3 bits)
        CodeStrangeAnswerAsTag();
-       memcpy(resp4, ToSend, ToSendMax); resp4Len = ToSendMax;
+       memcpy(resp4, ToSend, ToSendMax);// resp4Len = ToSendMax;
 
        // Authentication answer (random nonce)
        CodeIso14443aAsTag(response5, sizeof(response5));
-    memcpy(resp5, ToSend, ToSendMax); resp5Len = ToSendMax;
+       memcpy(resp5, ToSend, ToSendMax); resp5Len = ToSendMax;
 
-    // We need to listen to the high-frequency, peak-detected path.
-    SetAdcMuxFor(GPIO_MUXSEL_HIPKD);
-    FpgaSetupSsc();
+       // dummy ATS (pseudo-ATR), answer to RATS
+       CodeIso14443aAsTag(response6, sizeof(response6));
+       memcpy(resp6, ToSend, ToSendMax); resp6Len = ToSendMax;
 
-    cmdsRecvd = 0;
+       // We need to listen to the high-frequency, peak-detected path.
+       SetAdcMuxFor(GPIO_MUXSEL_HIPKD);
+       FpgaSetupSsc();
 
-    LED_A_ON();
-       for(;;) {
+       cmdsRecvd = 0;
 
-               if(!GetIso14443aCommandFromReader(receivedCmd, &len, 100)) {
-            DbpString("button press");
-            break;
-        }
-       // doob - added loads of debug strings so we can see what the reader is saying to us during the sim as hi14alist is not populated
-        // Okay, look at the command now.
-        lastorder = order;
-               //i = 1; // first byte transmitted
-        if(receivedCmd[0] == 0x26) {
-                       // Received a REQUEST
+       LED_A_ON();
+       for(;;) {
+       
+               if(!GetIso14443aCommandFromReader(receivedCmd, &len, RECV_CMD_SIZE)) {
+                       DbpString("button press");
+                       break;
+               }
+    
+    if (tracing) {
+                       LogTrace(receivedCmd,len, 0, Uart.parityBits, TRUE);
+    }
+    
+               // doob - added loads of debug strings so we can see what the reader is saying to us during the sim as hi14alist is not populated
+               // Okay, look at the command now.
+               lastorder = order;
+               if(receivedCmd[0] == 0x26) { // Received a REQUEST
                        resp = resp1; respLen = resp1Len; order = 1;
-                       //DbpString("Hello request from reader:");
-               } else if(receivedCmd[0] == 0x52) {
-                       // Received a WAKEUP
+                       respdata = response1;
+                       respsize = sizeof(response1);
+               } else if(receivedCmd[0] == 0x52) { // Received a WAKEUP
                        resp = resp1; respLen = resp1Len; order = 6;
-//                     //DbpString("Wakeup request from reader:");
-
-               } else if(receivedCmd[1] == 0x20 && receivedCmd[0] == 0x93) {   // greg - cascade 1 anti-collision
-                       // Received request for UID (cascade 1)
+                       respdata = response1;
+                       respsize = sizeof(response1);
+               } else if(receivedCmd[1] == 0x20 && receivedCmd[0] == 0x93) {   // Received request for UID (cascade 1)
                        resp = resp2; respLen = resp2Len; order = 2;
-//                     DbpString("UID (cascade 1) request from reader:");
-//                     DbpIntegers(receivedCmd[0], receivedCmd[1], receivedCmd[2]);
-
-
-               } else if(receivedCmd[1] == 0x20 && receivedCmd[0] ==0x95) {    // greg - cascade 2 anti-collision
-                       // Received request for UID (cascade 2)
+                       respdata = response2;
+                       respsize = sizeof(response2);
+               } else if(receivedCmd[1] == 0x20 && receivedCmd[0] == 0x95) { // Received request for UID (cascade 2)
                        resp = resp2a; respLen = resp2aLen; order = 20;
-//                     DbpString("UID (cascade 2) request from reader:");
-//                     DbpIntegers(receivedCmd[0], receivedCmd[1], receivedCmd[2]);
-
-
-               } else if(receivedCmd[1] == 0x70 && receivedCmd[0] ==0x93) {    // greg - cascade 1 select
-                       // Received a SELECT
+                       respdata = response2a;
+                       respsize = sizeof(response2a);
+               } else if(receivedCmd[1] == 0x70 && receivedCmd[0] == 0x93) {   // Received a SELECT (cascade 1)
                        resp = resp3; respLen = resp3Len; order = 3;
-//                     DbpString("Select (cascade 1) request from reader:");
-//                     DbpIntegers(receivedCmd[0], receivedCmd[1], receivedCmd[2]);
-
-
-               } else if(receivedCmd[1] == 0x70 && receivedCmd[0] ==0x95) {    // greg - cascade 2 select
-                       // Received a SELECT
+                       respdata = response3;
+                       respsize = sizeof(response3);
+               } else if(receivedCmd[1] == 0x70 && receivedCmd[0] == 0x95) {   // Received a SELECT (cascade 2)
                        resp = resp3a; respLen = resp3aLen; order = 30;
-//                     DbpString("Select (cascade 2) request from reader:");
-//                     DbpIntegers(receivedCmd[0], receivedCmd[1], receivedCmd[2]);
-
-
-               } else if(receivedCmd[0] == 0x30) {
-                       // Received a READ
-                       resp = resp4; respLen = resp4Len; order = 4; // Do nothing
-                       Dbprintf("Read request from reader: %x %x %x",
-                               receivedCmd[0], receivedCmd[1], receivedCmd[2]);
-
-
-               } else if(receivedCmd[0] == 0x50) {
-                       // Received a HALT
-                       resp = resp1; respLen = 0; order = 5; // Do nothing
-                       DbpString("Reader requested we HALT!:");
-
-               } else if(receivedCmd[0] == 0x60) {
-                       // Received an authentication request
-                       resp = resp5; respLen = resp5Len; order = 7;
-                       Dbprintf("Authenticate request from reader: %x %x %x",
-                               receivedCmd[0], receivedCmd[1], receivedCmd[2]);
-
-               } else if(receivedCmd[0] == 0xE0) {
-                       // Received a RATS request
-                       resp = resp1; respLen = 0;order = 70;
-                       Dbprintf("RATS request from reader: %x %x %x",
-                               receivedCmd[0], receivedCmd[1], receivedCmd[2]);
-        } else {
-            // Never seen this command before
-               Dbprintf("Unknown command received from reader (len=%d): %x %x %x %x %x %x %x %x %x",
-                       len,
-                       receivedCmd[0], receivedCmd[1], receivedCmd[2],
-                       receivedCmd[3], receivedCmd[4], receivedCmd[5],
-                       receivedCmd[6], receivedCmd[7], receivedCmd[8]);
+                       respdata = response3a;
+                       respsize = sizeof(response3a);
+               } else if(receivedCmd[0] == 0x30) {     // Received a (plain) READ
+//                     resp = resp4; respLen = resp4Len; order = 4; // Do nothing
+//                     respdata = &nack;
+//                     respsize = sizeof(nack); // 4-bit answer
+      EmSendCmdEx(data+(4*receivedCmd[0]),16,false);
+                       Dbprintf("Read request from reader: %x %x",receivedCmd[0],receivedCmd[1]);
+      // We already responded, do not send anything with the EmSendCmd14443aRaw() that is called below
+      respLen = 0;
+               } else if(receivedCmd[0] == 0x50) {     // Received a HALT
+//                     DbpString("Reader requested we HALT!:");
                        // Do not respond
                        resp = resp1; respLen = 0; order = 0;
-        }
+                       respdata = NULL;
+                       respsize = 0;
+               } else if(receivedCmd[0] == 0x60 || receivedCmd[0] == 0x61) {   // Received an authentication request
+                       resp = resp5; respLen = resp5Len; order = 7;
+                       respdata = response5;
+                       respsize = sizeof(response5);
+               } else if(receivedCmd[0] == 0xE0) {     // Received a RATS request
+                       resp = resp6; respLen = resp6Len; order = 70;
+                       respdata = response6;
+                       respsize = sizeof(response6);
+               } else {
+      if (order == 7 && len ==8) {
+        uint32_t nr = bytes_to_num(receivedCmd,4);
+        uint32_t ar = bytes_to_num(receivedCmd+4,4);
+        Dbprintf("Auth attempt {nr}{ar}: %08x %08x",nr,ar);
+      } else {
+        // Never seen this command before
+        Dbprintf("Received unknown command (len=%d):",len);
+        Dbhexdump(len,receivedCmd,false);
+      }
+      // Do not respond
+      resp = resp1; respLen = 0; order = 0;
+      respdata = NULL;
+      respsize = 0;
+               }
 
                // Count number of wakeups received after a halt
                if(order == 6 && lastorder == 5) { happened++; }
@@ -1194,168 +1190,109 @@ ComputeCrc14443(CRC_14443_A, response3a, 1, &response3a[1], &response3a[2]);
                        //i = 0;
                }
 
-        memset(receivedCmd, 0x44, 32);
-
                if(cmdsRecvd > 999) {
                        DbpString("1000 commands later...");
-            break;
-        }
-               else {
+                       break;
+               } else {
                        cmdsRecvd++;
                }
 
-        if(respLen <= 0) continue;
-               //----------------------------
-               //u = 0;
-               //b = 0x00;
-               //fdt_indicator = FALSE;
-
-               EmSendCmd14443aRaw(resp, respLen, receivedCmd[0] == 0x52);
-/*        // Modulate Manchester
-               FpgaWriteConfWord(FPGA_MAJOR_MODE_HF_ISO14443A | FPGA_HF_ISO14443A_TAGSIM_MOD);
-        AT91C_BASE_SSC->SSC_THR = 0x00;
-        FpgaSetupSsc();
-
-               // ### Transmit the response ###
-               u = 0;
-               b = 0x00;
-               fdt_indicator = FALSE;
-        for(;;) {
-            if(AT91C_BASE_SSC->SSC_SR & (AT91C_SSC_RXRDY)) {
-                               volatile uint8_t b = (uint8_t)AT91C_BASE_SSC->SSC_RHR;
-                (void)b;
-            }
-            if(AT91C_BASE_SSC->SSC_SR & (AT91C_SSC_TXRDY)) {
-                               if(i > respLen) {
-                                       b = 0x00;
-                                       u++;
-                               } else {
-                                       b = resp[i];
-                                       i++;
-                               }
-                               AT91C_BASE_SSC->SSC_THR = b;
-
-                if(u > 4) {
-                    break;
-                }
-            }
-                       if(BUTTON_PRESS()) {
-                           break;
+               if(respLen > 0) {
+                       EmSendCmd14443aRaw(resp, respLen, receivedCmd[0] == 0x52);
+               }
+               
+               if (tracing) {
+                       if (respdata != NULL) {
+                               LogTrace(respdata,respsize, 0, SwapBits(GetParity(respdata,respsize),respsize), FALSE);
                        }
-        }
-*/
-    }
+                       if(traceLen > TRACE_SIZE) {
+                               DbpString("Trace full");
+                               break;
+                       }
+               }
+
+               memset(receivedCmd, 0x44, RECV_CMD_SIZE);
+  }
 
        Dbprintf("%x %x %x", happened, happened2, cmdsRecvd);
        LED_A_OFF();
 }
 
-//-----------------------------------------------------------------------------
-// Transmit the command (to the tag) that was placed in ToSend[].
-//-----------------------------------------------------------------------------
-static void TransmitFor14443a(const uint8_t *cmd, int len, int *samples, int *wait)
-{
-  int c;
 
-  FpgaWriteConfWord(FPGA_MAJOR_MODE_HF_ISO14443A | FPGA_HF_ISO14443A_READER_MOD);
+// prepare a delayed transfer. This simply shifts ToSend[] by a number
+// of bits specified in the delay parameter.
+void PrepareDelayedTransfer(uint16_t delay)
+{
+       uint8_t bitmask = 0;
+       uint8_t bits_to_shift = 0;
+       uint8_t bits_shifted = 0;
+       
+       delay &= 0x07;
+       if (delay) {
+               for (uint16_t i = 0; i < delay; i++) {
+                       bitmask |= (0x01 << i);
+               }
+               ToSend[++ToSendMax] = 0x00;
+               for (uint16_t i = 0; i < ToSendMax; i++) {
+                       bits_to_shift = ToSend[i] & bitmask;
+                       ToSend[i] = ToSend[i] >> delay;
+                       ToSend[i] = ToSend[i] | (bits_shifted << (8 - delay));
+                       bits_shifted = bits_to_shift;
+               }
+       }
+}
 
-       if (wait)
-    if(*wait < 10)
-      *wait = 10;
 
-  for(c = 0; c < *wait;) {
-    if(AT91C_BASE_SSC->SSC_SR & (AT91C_SSC_TXRDY)) {
-      AT91C_BASE_SSC->SSC_THR = 0x00;          // For exact timing!
-      c++;
-    }
-    if(AT91C_BASE_SSC->SSC_SR & (AT91C_SSC_RXRDY)) {
-      volatile uint32_t r = AT91C_BASE_SSC->SSC_RHR;
-      (void)r;
-    }
-    WDT_HIT();
-  }
 
-  c = 0;
-  for(;;) {
-    if(AT91C_BASE_SSC->SSC_SR & (AT91C_SSC_TXRDY)) {
-      AT91C_BASE_SSC->SSC_THR = cmd[c];
-      c++;
-      if(c >= len) {
-        break;
-      }
-    }
-    if(AT91C_BASE_SSC->SSC_SR & (AT91C_SSC_RXRDY)) {
-      volatile uint32_t r = AT91C_BASE_SSC->SSC_RHR;
-      (void)r;
-    }
-    WDT_HIT();
-  }
-       if (samples) *samples = (c + *wait) << 3;
-}
 
 //-----------------------------------------------------------------------------
-// Code a 7-bit command without parity bit
-// This is especially for 0x26 and 0x52 (REQA and WUPA)
+// Transmit the command (to the tag) that was placed in ToSend[].
+// Parameter timing:
+// if NULL: ignored
+// if == 0:    return time of transfer
+// if != 0: delay transfer until time specified
 //-----------------------------------------------------------------------------
-void ShortFrameFromReader(const uint8_t bt)
+static void TransmitFor14443a(const uint8_t *cmd, int len, uint32_t *timing)
 {
-       int j;
-       int last;
-  uint8_t b;
+       int c;
 
-       ToSendReset();
+       FpgaWriteConfWord(FPGA_MAJOR_MODE_HF_ISO14443A | FPGA_HF_ISO14443A_READER_MOD);
 
-       // Start of Communication (Seq. Z)
-       ToSend[++ToSendMax] = SEC_Z;
-       last = 0;
 
-       b = bt;
-       for(j = 0; j < 7; j++) {
-               if(b & 1) {
-                       // Sequence X
-                       ToSend[++ToSendMax] = SEC_X;
-                       last = 1;
+       if (timing) {
+               if(*timing == 0) {                                                                              // Measure time
+                       *timing = (GetCountMifare() + 8) & 0xfffffff8;
                } else {
-                       if(last == 0) {
-                               // Sequence Z
-                               ToSend[++ToSendMax] = SEC_Z;
-                       }
-                       else {
-                               // Sequence Y
-                               ToSend[++ToSendMax] = SEC_Y;
-                               last = 0;
-                       }
+                       PrepareDelayedTransfer(*timing & 0x00000007);           // Delay transfer (fine tuning - up to 7 MF clock ticks)
                }
-               b >>= 1;
+               if(MF_DBGLEVEL >= 4 && GetCountMifare() >= (*timing & 0xfffffff8)) Dbprintf("TransmitFor14443a: Missed timing");
+               while(GetCountMifare() < (*timing & 0xfffffff8));               // Delay transfer (multiple of 8 MF clock ticks)
        }
 
-       // End of Communication
-       if(last == 0) {
-               // Sequence Z
-               ToSend[++ToSendMax] = SEC_Z;
+       for(c = 0; c < 10;) {   // standard delay for each transfer (allow tag to be ready after last transmission)
+               if(AT91C_BASE_SSC->SSC_SR & (AT91C_SSC_TXRDY)) {
+                       AT91C_BASE_SSC->SSC_THR = 0x00; 
+                       c++;
+               }
        }
-       else {
-               // Sequence Y
-               ToSend[++ToSendMax] = SEC_Y;
-               last = 0;
+       
+       c = 0;
+       for(;;) {
+               if(AT91C_BASE_SSC->SSC_SR & (AT91C_SSC_TXRDY)) {
+                       AT91C_BASE_SSC->SSC_THR = cmd[c];
+                       c++;
+                       if(c >= len) {
+                               break;
+                       }
+               }
        }
-       // Sequence Y
-       ToSend[++ToSendMax] = SEC_Y;
-
-       // Just to be sure!
-       ToSend[++ToSendMax] = SEC_Y;
-       ToSend[++ToSendMax] = SEC_Y;
-       ToSend[++ToSendMax] = SEC_Y;
 
-    // Convert from last character reference to length
-    ToSendMax++;
 }
 
 //-----------------------------------------------------------------------------
-// Prepare reader command to send to FPGA
-//
+// Prepare reader command (in bits, support short frames) to send to FPGA
 //-----------------------------------------------------------------------------
-void CodeIso14443aAsReaderPar(const uint8_t * cmd, int len, uint32_t dwParity)
+void CodeIso14443aBitsAsReaderPar(const uint8_t * cmd, int bits, uint32_t dwParity)
 {
   int i, j;
   int last;
@@ -1367,12 +1304,14 @@ void CodeIso14443aAsReaderPar(const uint8_t * cmd, int len, uint32_t dwParity)
   ToSend[++ToSendMax] = SEC_Z;
   last = 0;
 
+  size_t bytecount = nbytes(bits);
   // Generate send structure for the data bits
-  for (i = 0; i < len; i++) {
+  for (i = 0; i < bytecount; i++) {
     // Get the current byte to send
     b = cmd[i];
+    size_t bitsleft = MIN((bits-(i*8)),8);
 
-    for (j = 0; j < 8; j++) {
+    for (j = 0; j < bitsleft; j++) {
       if (b & 1) {
         // Sequence X
          ToSend[++ToSendMax] = SEC_X;
@@ -1390,19 +1329,22 @@ void CodeIso14443aAsReaderPar(const uint8_t * cmd, int len, uint32_t dwParity)
       b >>= 1;
     }
 
-    // Get the parity bit
-    if ((dwParity >> i) & 0x01) {
-      // Sequence X
-       ToSend[++ToSendMax] = SEC_X;
-      last = 1;
-    } else {
-      if (last == 0) {
-        // Sequence Z
-         ToSend[++ToSendMax] = SEC_Z;
+    // Only transmit (last) parity bit if we transmitted a complete byte
+    if (j == 8) {
+      // Get the parity bit
+      if ((dwParity >> i) & 0x01) {
+        // Sequence X
+        ToSend[++ToSendMax] = SEC_X;
+        last = 1;
       } else {
-        // Sequence Y
-         ToSend[++ToSendMax] = SEC_Y;
-        last = 0;
+        if (last == 0) {
+          // Sequence Z
+          ToSend[++ToSendMax] = SEC_Z;
+        } else {
+          // Sequence Y
+          ToSend[++ToSendMax] = SEC_Y;
+          last = 0;
+        }
       }
     }
   }
@@ -1428,6 +1370,14 @@ void CodeIso14443aAsReaderPar(const uint8_t * cmd, int len, uint32_t dwParity)
   ToSendMax++;
 }
 
+//-----------------------------------------------------------------------------
+// Prepare reader command to send to FPGA
+//-----------------------------------------------------------------------------
+void CodeIso14443aAsReaderPar(const uint8_t * cmd, int len, uint32_t dwParity)
+{
+  CodeIso14443aBitsAsReaderPar(cmd,len*8,dwParity);
+}
+
 //-----------------------------------------------------------------------------
 // Wait for commands from reader
 // Stop when button is pressed (return 1) or field was gone (return 2)
@@ -1593,7 +1543,7 @@ static int GetIso14443aAnswerFromTag(uint8_t *receivedResponse, int maxLen, int
        // Signal field is on with the appropriate LED
        LED_D_ON();
        FpgaWriteConfWord(FPGA_MAJOR_MODE_HF_ISO14443A | FPGA_HF_ISO14443A_READER_LISTEN);
-
+       
        // Now get the answer from the card
        Demod.output = receivedResponse;
        Demod.len = 0;
@@ -1606,10 +1556,10 @@ static int GetIso14443aAnswerFromTag(uint8_t *receivedResponse, int maxLen, int
        for(;;) {
                WDT_HIT();
 
-               if(AT91C_BASE_SSC->SSC_SR & (AT91C_SSC_TXRDY)) {
-                       AT91C_BASE_SSC->SSC_THR = 0x00;  // To make use of exact timing of next command from reader!!
-                       if (elapsed) (*elapsed)++;
-               }
+               // if(AT91C_BASE_SSC->SSC_SR & (AT91C_SSC_TXRDY)) {
+                       // AT91C_BASE_SSC->SSC_THR = 0x00;  // To make use of exact timing of next command from reader!!
+                       // if (elapsed) (*elapsed)++;
+               // }
                if(AT91C_BASE_SSC->SSC_SR & (AT91C_SSC_RXRDY)) {
                        if(c < iso14a_timeout) { c++; } else { return FALSE; }
                        b = (uint8_t)AT91C_BASE_SSC->SSC_RHR;
@@ -1625,43 +1575,29 @@ static int GetIso14443aAnswerFromTag(uint8_t *receivedResponse, int maxLen, int
        }
 }
 
-void ReaderTransmitShort(const uint8_t* bt)
+void ReaderTransmitBitsPar(uint8_t* frame, int bits, uint32_t par, uint32_t *timing)
 {
-  int wait = 0;
-  int samples = 0;
-
-  ShortFrameFromReader(*bt);
-
-  // Select the card
-  TransmitFor14443a(ToSend, ToSendMax, &samples, &wait);
-
-  // Store reader command in buffer
-  if (tracing) LogTrace(bt,1,0,GetParity(bt,1),TRUE);
-}
-
-void ReaderTransmitPar(uint8_t* frame, int len, uint32_t par)
-{
-  int wait = 0;
-  int samples = 0;
-
-  // This is tied to other size changes
-  //   uint8_t* frame_addr = ((uint8_t*)BigBuf) + 2024;
-  CodeIso14443aAsReaderPar(frame,len,par);
-
+  CodeIso14443aBitsAsReaderPar(frame,bits,par);
+  
   // Select the card
-  TransmitFor14443a(ToSend, ToSendMax, &samples, &wait);
+  TransmitFor14443a(ToSend, ToSendMax, timing);
   if(trigger)
        LED_A_ON();
-
+  
   // Store reader command in buffer
-  if (tracing) LogTrace(frame,len,0,par,TRUE);
+  if (tracing) LogTrace(frame,nbytes(bits),0,par,TRUE);
 }
 
+void ReaderTransmitPar(uint8_t* frame, int len, uint32_t par, uint32_t *timing)
+{
+  ReaderTransmitBitsPar(frame,len*8,par, timing);
+}
 
-void ReaderTransmit(uint8_t* frame, int len)
+void ReaderTransmit(uint8_t* frame, int len, uint32_t *timing)
 {
   // Generate parity and redirect
-  ReaderTransmitPar(frame,len,GetParity(frame,len));
+  ReaderTransmitBitsPar(frame,len*8,GetParity(frame,len), timing);
 }
 
 int ReaderReceive(uint8_t* receivedAnswer)
@@ -1686,90 +1622,117 @@ int ReaderReceivePar(uint8_t* receivedAnswer, uint32_t * parptr)
 /* performs iso14443a anticolision procedure
  * fills the uid pointer unless NULL
  * fills resp_data unless NULL */
-int iso14443a_select_card(uint8_t * uid_ptr, iso14a_card_select_t * resp_data, uint32_t * cuid_ptr) {
-       uint8_t wupa[]       = { 0x52 };  // 0x26 - REQA  0x52 - WAKE-UP
-       uint8_t sel_all[]    = { 0x93,0x20 };
-       uint8_t sel_uid[]    = { 0x93,0x70,0x00,0x00,0x00,0x00,0x00,0x00,0x00 };
-       uint8_t rats[]       = { 0xE0,0x80,0x00,0x00 }; // FSD=256, FSDI=8, CID=0
-
-       uint8_t* resp = (((uint8_t *)BigBuf) + 3560);   // was 3560 - tied to other size changes
-
-       uint8_t sak = 0x04; // cascade uid
-       int cascade_level = 0;
-
-       int len;
+int iso14443a_select_card(byte_t* uid_ptr, iso14a_card_select_t* p_hi14a_card, uint32_t* cuid_ptr) {
+  uint8_t wupa[]       = { 0x52 };  // 0x26 - REQA  0x52 - WAKE-UP
+  uint8_t sel_all[]    = { 0x93,0x20 };
+  uint8_t sel_uid[]    = { 0x93,0x70,0x00,0x00,0x00,0x00,0x00,0x00,0x00 };
+  uint8_t rats[]       = { 0xE0,0x80,0x00,0x00 }; // FSD=256, FSDI=8, CID=0
+  uint8_t* resp = (((uint8_t *)BigBuf) + FREE_BUFFER_OFFSET);  // was 3560 - tied to other size changes
+  byte_t uid_resp[4];
+  size_t uid_resp_len;
+
+  uint8_t sak = 0x04; // cascade uid
+  int cascade_level = 0;
+  int len;
+        
+  // Broadcast for a card, WUPA (0x52) will force response from all cards in the field
+    ReaderTransmitBitsPar(wupa,7,0, NULL);
+  // Receive the ATQA
+  if(!ReaderReceive(resp)) return 0;
+//  Dbprintf("atqa: %02x %02x",resp[0],resp[1]);
+
+  if(p_hi14a_card) {
+    memcpy(p_hi14a_card->atqa, resp, 2);
+    p_hi14a_card->uidlen = 0;
+    memset(p_hi14a_card->uid,0,10);
+  }
        
-       // clear uid
-       memset(uid_ptr, 0, 8);
-
-       // Broadcast for a card, WUPA (0x52) will force response from all cards in the field
-       ReaderTransmitShort(wupa);
-       // Receive the ATQA
-       if(!ReaderReceive(resp)) return 0;
+  // clear uid
+  if (uid_ptr) {
+    memset(uid_ptr,0,10);
+  }
 
-       if(resp_data)
-               memcpy(resp_data->atqa, resp, 2);
-       
-       // OK we will select at least at cascade 1, lets see if first byte of UID was 0x88 in
-       // which case we need to make a cascade 2 request and select - this is a long UID
-       // While the UID is not complete, the 3nd bit (from the right) is set in the SAK.
-       for(; sak & 0x04; cascade_level++)
-       {
-               // SELECT_* (L1: 0x93, L2: 0x95, L3: 0x97)
-               sel_uid[0] = sel_all[0] = 0x93 + cascade_level * 2;
+  // OK we will select at least at cascade 1, lets see if first byte of UID was 0x88 in
+  // which case we need to make a cascade 2 request and select - this is a long UID
+  // While the UID is not complete, the 3nd bit (from the right) is set in the SAK.
+  for(; sak & 0x04; cascade_level++) {
+    // SELECT_* (L1: 0x93, L2: 0x95, L3: 0x97)
+    sel_uid[0] = sel_all[0] = 0x93 + cascade_level * 2;
 
-               // SELECT_ALL
-               ReaderTransmit(sel_all,sizeof(sel_all));
-               if (!ReaderReceive(resp)) return 0;
-               if(uid_ptr) memcpy(uid_ptr + cascade_level*4, resp, 4);
-               
-               // calculate crypto UID
-               if(cuid_ptr) *cuid_ptr = bytes_to_num(resp, 4);
+    // SELECT_ALL
+    ReaderTransmit(sel_all,sizeof(sel_all), NULL);
+    if (!ReaderReceive(resp)) return 0;
+    
+    // First backup the current uid
+    memcpy(uid_resp,resp,4);
+    uid_resp_len = 4;
+    //    Dbprintf("uid: %02x %02x %02x %02x",uid_resp[0],uid_resp[1],uid_resp[2],uid_resp[3]);
+    
+       // calculate crypto UID. Always use last 4 Bytes.
+       if(cuid_ptr) {
+               *cuid_ptr = bytes_to_num(uid_resp, 4);
+    }
 
-               // Construct SELECT UID command
+    // Construct SELECT UID command
                memcpy(sel_uid+2,resp,5);
-               AppendCrc14443a(sel_uid,7);
-               ReaderTransmit(sel_uid,sizeof(sel_uid));
+    AppendCrc14443a(sel_uid,7);
+    ReaderTransmit(sel_uid,sizeof(sel_uid), NULL);
+
+    // Receive the SAK
+    if (!ReaderReceive(resp)) return 0;
+    sak = resp[0];
+
+    // Test if more parts of the uid are comming
+    if ((sak & 0x04) && uid_resp[0] == 0x88) {
+      // Remove first byte, 0x88 is not an UID byte, it CT, see page 3 of:
+      // http://www.nxp.com/documents/application_note/AN10927.pdf
+      memcpy(uid_resp, uid_resp + 1, 3);
+      uid_resp_len = 3;
+    }
+    
+    if(uid_ptr) {
+      memcpy(uid_ptr + (cascade_level*3), uid_resp, uid_resp_len);
+    }
+    
+    if(p_hi14a_card) {
+      memcpy(p_hi14a_card->uid + (cascade_level*3), uid_resp, uid_resp_len);
+      p_hi14a_card->uidlen += uid_resp_len;
+    }
+  }
 
-               // Receive the SAK
-               if (!ReaderReceive(resp)) return 0;
-               sak = resp[0];
-       }
-       if(resp_data) {
-               resp_data->sak = sak;
-               resp_data->ats_len = 0;
-       }
-       //--  this byte not UID, it CT.  http://www.nxp.com/documents/application_note/AN10927.pdf  page 3
-       if (uid_ptr[0] == 0x88) {  
-               memcpy(uid_ptr, uid_ptr + 1, 7);
-               uid_ptr[7] = 0;
-       }
+  if(p_hi14a_card) {
+    p_hi14a_card->sak = sak;
+    p_hi14a_card->ats_len = 0;
+  }
 
-       if( (sak & 0x20) == 0)
-               return 2; // non iso14443a compliant tag
+  if( (sak & 0x20) == 0) {
+    return 2; // non iso14443a compliant tag
+  }
 
-       // Request for answer to select
-       if(resp_data) {  // JCOP cards - if reader sent RATS then there is no MIFARE session at all!!!
-               AppendCrc14443a(rats, 2);
-               ReaderTransmit(rats, sizeof(rats));
-               
-               if (!(len = ReaderReceive(resp))) return 0;
-               
-               memcpy(resp_data->ats, resp, sizeof(resp_data->ats));
-               resp_data->ats_len = len;
-       }
+  // Request for answer to select
+  AppendCrc14443a(rats, 2);
+  ReaderTransmit(rats, sizeof(rats), NULL);
+
+  if (!(len = ReaderReceive(resp))) return 0;
+
+  if(p_hi14a_card) {
+    memcpy(p_hi14a_card->ats, resp, sizeof(p_hi14a_card->ats));
+    p_hi14a_card->ats_len = len;
+  }
        
-       return 1;
+  // reset the PCB block number
+  iso14_pcb_blocknum = 0;
+  return 1;
 }
 
 void iso14443a_setup() {
-       // Setup SSC
+       // Set up the synchronous serial port
        FpgaSetupSsc();
        // Start from off (no field generated)
        // Signal field is off with the appropriate LED
-       LED_D_OFF();
-       FpgaWriteConfWord(FPGA_MAJOR_MODE_OFF);
-       SpinDelay(200);
+//     LED_D_OFF();
+//     FpgaWriteConfWord(FPGA_MAJOR_MODE_OFF);
+       // SpinDelay(50);
 
        SetAdcMuxFor(GPIO_MUXSEL_HIPKD);
 
@@ -1777,7 +1740,7 @@ void iso14443a_setup() {
        // Signal field is on with the appropriate LED
        LED_D_ON();
        FpgaWriteConfWord(FPGA_MAJOR_MODE_HF_ISO14443A | FPGA_HF_ISO14443A_READER_MOD);
-       SpinDelay(200);
+       SpinDelay(7); // iso14443-3 specifies 5ms max.
 
        iso14a_timeout = 2048; //default
 }
@@ -1785,35 +1748,53 @@ void iso14443a_setup() {
 int iso14_apdu(uint8_t * cmd, size_t cmd_len, void * data) {
        uint8_t real_cmd[cmd_len+4];
        real_cmd[0] = 0x0a; //I-Block
+       // put block number into the PCB
+       real_cmd[0] |= iso14_pcb_blocknum;
        real_cmd[1] = 0x00; //CID: 0 //FIXME: allow multiple selected cards
        memcpy(real_cmd+2, cmd, cmd_len);
        AppendCrc14443a(real_cmd,cmd_len+2);
  
-       ReaderTransmit(real_cmd, cmd_len+4);
+       ReaderTransmit(real_cmd, cmd_len+4, NULL);
        size_t len = ReaderReceive(data);
-       if(!len)
-               return -1; //DATA LINK ERROR
-       
+       uint8_t * data_bytes = (uint8_t *) data;
+       if (!len)
+               return 0; //DATA LINK ERROR
+       // if we received an I- or R(ACK)-Block with a block number equal to the
+       // current block number, toggle the current block number
+       else if (len >= 4 // PCB+CID+CRC = 4 bytes
+                && ((data_bytes[0] & 0xC0) == 0 // I-Block
+                    || (data_bytes[0] & 0xD0) == 0x80) // R-Block with ACK bit set to 0
+                && (data_bytes[0] & 0x01) == iso14_pcb_blocknum) // equal block numbers
+       {
+               iso14_pcb_blocknum ^= 1;
+       }
+
        return len;
 }
 
-
 //-----------------------------------------------------------------------------
 // Read an ISO 14443a tag. Send out commands and store answers.
 //
 //-----------------------------------------------------------------------------
-void ReaderIso14443a(UsbCommand * c, UsbCommand * ack)
+void ReaderIso14443a(UsbCommand * c)
 {
        iso14a_command_t param = c->arg[0];
        uint8_t * cmd = c->d.asBytes;
        size_t len = c->arg[1];
-
-       if(param & ISO14A_REQUEST_TRIGGER) iso14a_set_trigger(1);
+       uint32_t arg0 = 0;
+       byte_t buf[USB_CMD_DATA_SIZE];
+  
+       iso14a_clear_trace();
+       iso14a_set_tracing(true);
+
+       if(param & ISO14A_REQUEST_TRIGGER) {
+               iso14a_set_trigger(1);
+       }
 
        if(param & ISO14A_CONNECT) {
                iso14443a_setup();
-               ack->arg[0] = iso14443a_select_card(ack->d.asBytes, (iso14a_card_select_t *) (ack->d.asBytes+12), NULL);
-               UsbSendPacket((void *)ack, sizeof(UsbCommand));
+               arg0 = iso14443a_select_card(NULL, (iso14a_card_select_t*)buf, NULL);
+               cmd_send(CMD_ACK,arg0,0,0,buf,sizeof(iso14a_card_select_t));
        }
 
        if(param & ISO14A_SET_TIMEOUT) {
@@ -1825,8 +1806,8 @@ void ReaderIso14443a(UsbCommand * c, UsbCommand * ack)
        }
 
        if(param & ISO14A_APDU) {
-               ack->arg[0] = iso14_apdu(cmd, len, ack->d.asBytes);
-               UsbSendPacket((void *)ack, sizeof(UsbCommand));
+               arg0 = iso14_apdu(cmd, len, buf);
+               cmd_send(CMD_ACK,arg0,0,0,buf,sizeof(buf));
        }
 
        if(param & ISO14A_RAW) {
@@ -1834,99 +1815,208 @@ void ReaderIso14443a(UsbCommand * c, UsbCommand * ack)
                        AppendCrc14443a(cmd,len);
                        len += 2;
                }
-               ReaderTransmit(cmd,len);
-               ack->arg[0] = ReaderReceive(ack->d.asBytes);
-               UsbSendPacket((void *)ack, sizeof(UsbCommand));
+               ReaderTransmit(cmd,len, NULL);
+               arg0 = ReaderReceive(buf);
+               cmd_send(CMD_ACK,arg0,0,0,buf,sizeof(buf));
        }
 
-       if(param & ISO14A_REQUEST_TRIGGER) iso14a_set_trigger(0);
+       if(param & ISO14A_REQUEST_TRIGGER) {
+               iso14a_set_trigger(0);
+       }
 
-       if(param & ISO14A_NO_DISCONNECT)
+       if(param & ISO14A_NO_DISCONNECT) {
                return;
+       }
 
        FpgaWriteConfWord(FPGA_MAJOR_MODE_OFF);
        LEDsoff();
 }
+
+
+// Determine the distance between two nonces.
+// Assume that the difference is small, but we don't know which is first.
+// Therefore try in alternating directions.
+int32_t dist_nt(uint32_t nt1, uint32_t nt2) {
+
+       uint16_t i;
+       uint32_t nttmp1, nttmp2;
+
+       if (nt1 == nt2) return 0;
+
+       nttmp1 = nt1;
+       nttmp2 = nt2;
+       
+       for (i = 1; i < 32768; i++) {
+               nttmp1 = prng_successor(nttmp1, 1);
+               if (nttmp1 == nt2) return i;
+               nttmp2 = prng_successor(nttmp2, 1);
+                       if (nttmp2 == nt1) return -i;
+               }
+       
+       return(-99999); // either nt1 or nt2 are invalid nonces
+}
+
+
 //-----------------------------------------------------------------------------
-// Read an ISO 14443a tag. Send out commands and store answers.
-//
+// Recover several bits of the cypher stream. This implements (first stages of)
+// the algorithm described in "The Dark Side of Security by Obscurity and
+// Cloning MiFare Classic Rail and Building Passes, Anywhere, Anytime"
+// (article by Nicolas T. Courtois, 2009)
 //-----------------------------------------------------------------------------
-void ReaderMifare(uint32_t parameter)
+void ReaderMifare(bool first_try)
 {
        // Mifare AUTH
        uint8_t mf_auth[]    = { 0x60,0x00,0xf5,0x7b };
        uint8_t mf_nr_ar[]   = { 0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00 };
+       static uint8_t mf_nr_ar3;
 
-       uint8_t* receivedAnswer = (((uint8_t *)BigBuf) + 3560); // was 3560 - tied to other size changes
+       uint8_t* receivedAnswer = (((uint8_t *)BigBuf) + FREE_BUFFER_OFFSET);
        traceLen = 0;
        tracing = false;
 
-       iso14443a_setup();
-
-       LED_A_ON();
-       LED_B_OFF();
-       LED_C_OFF();
-
        byte_t nt_diff = 0;
-       LED_A_OFF();
        byte_t par = 0;
        //byte_t par_mask = 0xff;
-       byte_t par_low = 0;
-       int led_on = TRUE;
-       uint8_t uid[8];
+       static byte_t par_low = 0;
+       bool led_on = TRUE;
+       uint8_t uid[10];
        uint32_t cuid;
 
-       tracing = FALSE;
-       byte_t nt[4] = {0,0,0,0};
-       byte_t nt_attacked[4], nt_noattack[4];
+       uint32_t nt, previous_nt;
+       static uint32_t nt_attacked = 0;
        byte_t par_list[8] = {0,0,0,0,0,0,0,0};
        byte_t ks_list[8] = {0,0,0,0,0,0,0,0};
-       num_to_bytes(parameter, 4, nt_noattack);
-       int isOK = 0, isNULL = 0;
 
-       while(TRUE)
-       {
-               LED_C_ON();
-               FpgaWriteConfWord(FPGA_MAJOR_MODE_OFF);
-               SpinDelay(200);
-               FpgaWriteConfWord(FPGA_MAJOR_MODE_HF_ISO14443A | FPGA_HF_ISO14443A_READER_MOD);
-               LED_C_OFF();
+       static uint32_t sync_time;
+       static uint32_t sync_cycles;
+       int catch_up_cycles = 0;
+       int last_catch_up = 0;
+       uint16_t consecutive_resyncs = 0;
+       int isOK = 0;
+
+
+
+       if (first_try) { 
+               StartCountMifare();
+               mf_nr_ar3 = 0;
+               iso14443a_setup();
+               while((GetCountMifare() & 0xffff0000) != 0x10000);              // wait for counter to reset and "warm up" 
+               sync_time = GetCountMifare() & 0xfffffff8;
+               sync_cycles = 65536;                                                                    // theory: Mifare Classic's random generator repeats every 2^16 cycles (and so do the nonces).
+               nt_attacked = 0;
+               nt = 0;
+               par = 0;
+       }
+       else {
+               // we were unsuccessful on a previous call. Try another READER nonce (first 3 parity bits remain the same)
+               // nt_attacked = prng_successor(nt_attacked, 1);
+               mf_nr_ar3++;
+               mf_nr_ar[3] = mf_nr_ar3;
+               par = par_low;
+       }
+
+       LED_A_ON();
+       LED_B_OFF();
+       LED_C_OFF();
+       
+  
+       for(uint16_t i = 0; TRUE; i++) {
+               
+               WDT_HIT();
 
                // Test if the action was cancelled
                if(BUTTON_PRESS()) {
                        break;
                }
+               
+               LED_C_ON();
 
-               if(!iso14443a_select_card(uid, NULL, &cuid)) continue;
+               if(!iso14443a_select_card(uid, NULL, &cuid)) {
+                       if (MF_DBGLEVEL >= 1)   Dbprintf("Mifare: Can't select card");
+                       continue;
+               }
 
-               // Transmit MIFARE_CLASSIC_AUTH
-               ReaderTransmit(mf_auth, sizeof(mf_auth));
+               //keep the card active
+               FpgaWriteConfWord(FPGA_MAJOR_MODE_HF_ISO14443A | FPGA_HF_ISO14443A_READER_MOD);
 
-               // Receive the (16 bit) "random" nonce
-               if (!ReaderReceive(receivedAnswer)) continue;
-               memcpy(nt, receivedAnswer, 4);
+               // CodeIso14443aBitsAsReaderPar(mf_auth, sizeof(mf_auth)*8, GetParity(mf_auth, sizeof(mf_auth)*8));
 
-               // Transmit reader nonce and reader answer
-               ReaderTransmitPar(mf_nr_ar, sizeof(mf_nr_ar),par);
+               sync_time = (sync_time & 0xfffffff8) + sync_cycles + catch_up_cycles;
+               catch_up_cycles = 0;
 
-               // Receive 4 bit answer
-               if (ReaderReceive(receivedAnswer))
-               {
-                       if ( (parameter != 0) && (memcmp(nt, nt_noattack, 4) == 0) ) continue;
+               // if we missed the sync time already, advance to the next nonce repeat
+               while(GetCountMifare() > sync_time) {
+                       sync_time = (sync_time & 0xfffffff8) + sync_cycles;
+               }
+
+               // Transmit MIFARE_CLASSIC_AUTH at synctime. Should result in returning the same tag nonce (== nt_attacked) 
+               ReaderTransmit(mf_auth, sizeof(mf_auth), &sync_time);
+
+               // Receive the (4 Byte) "random" nonce
+               if (!ReaderReceive(receivedAnswer)) {
+                       if (MF_DBGLEVEL >= 1)   Dbprintf("Mifare: Couldn't receive tag nonce");
+                       continue;
+                 }
 
-                       isNULL = (nt_attacked[0] == 0) && (nt_attacked[1] == 0) && (nt_attacked[2] == 0) && (nt_attacked[3] == 0);
-                       if ( (isNULL != 0 ) && (memcmp(nt, nt_attacked, 4) != 0) ) continue;
+               previous_nt = nt;
+               nt = bytes_to_num(receivedAnswer, 4);
+
+               // Transmit reader nonce with fake par
+               ReaderTransmitPar(mf_nr_ar, sizeof(mf_nr_ar), par, NULL);
+
+               if (first_try && previous_nt && !nt_attacked) { // we didn't calibrate our clock yet
+                       int nt_distance = dist_nt(previous_nt, nt);
+                       if (nt_distance == 0) {
+                               nt_attacked = nt;
+                       }
+                       else {
+                               if (nt_distance == -99999) { // invalid nonce received, try again
+                                       continue;
+                               }
+                               sync_cycles = (sync_cycles - nt_distance);
+                               if (MF_DBGLEVEL >= 3) Dbprintf("calibrating in cycle %d. nt_distance=%d, Sync_cycles: %d\n", i, nt_distance, sync_cycles);
+                               continue;
+                       }
+               }
 
+               if ((nt != nt_attacked) && nt_attacked) {       // we somehow lost sync. Try to catch up again...
+                       catch_up_cycles = -dist_nt(nt_attacked, nt);
+                       if (catch_up_cycles == 99999) {                 // invalid nonce received. Don't resync on that one.
+                               catch_up_cycles = 0;
+                               continue;
+                       }
+                       if (catch_up_cycles == last_catch_up) {
+                               consecutive_resyncs++;
+                       }
+                       else {
+                               last_catch_up = catch_up_cycles;
+                           consecutive_resyncs = 0;
+                       }
+                       if (consecutive_resyncs < 3) {
+                               if (MF_DBGLEVEL >= 3) Dbprintf("Lost sync in cycle %d. nt_distance=%d. Consecutive Resyncs = %d. Trying one time catch up...\n", i, -catch_up_cycles, consecutive_resyncs);
+                       }
+                       else {  
+                               sync_cycles = sync_cycles + catch_up_cycles;
+                               if (MF_DBGLEVEL >= 3) Dbprintf("Lost sync in cycle %d for the fourth time consecutively (nt_distance = %d). Adjusting sync_cycles to %d.\n", i, -catch_up_cycles, sync_cycles);
+                       }
+                       continue;
+               }
+               consecutive_resyncs = 0;
+               
+               // Receive answer. This will be a 4 Bit NACK when the 8 parity bits are OK after decoding
+               if (ReaderReceive(receivedAnswer))
+               {
+                       catch_up_cycles = 8;    // the PRNG is delayed by 8 cycles due to the NAC (4Bits = 0x05 encrypted) transfer
+       
                        if (nt_diff == 0)
                        {
-                               LED_A_ON();
-                               memcpy(nt_attacked, nt, 4);
-                               //par_mask = 0xf8;
-                               par_low = par & 0x07;
+                               par_low = par & 0x07; // there is no need to check all parities for other nt_diff. Parity Bits for mf_nr_ar[0..2] won't change
                        }
 
                        led_on = !led_on;
                        if(led_on) LED_B_ON(); else LED_B_OFF();
+
                        par_list[nt_diff] = par;
                        ks_list[nt_diff] = receivedAnswer[0] ^ 0x05;
 
@@ -1937,10 +2027,10 @@ void ReaderMifare(uint32_t parameter)
                        }
 
                        nt_diff = (nt_diff + 1) & 0x07;
-                       mf_nr_ar[3] = nt_diff << 5;
+                       mf_nr_ar[3] = (mf_nr_ar[3] & 0x1F) | (nt_diff << 5);
                        par = par_low;
                } else {
-                       if (nt_diff == 0)
+                       if (nt_diff == 0 && first_try)
                        {
                                par++;
                        } else {
@@ -1949,29 +2039,27 @@ void ReaderMifare(uint32_t parameter)
                }
        }
 
-       LogTrace(nt, 4, 0, GetParity(nt, 4), TRUE);
+       LogTrace((const uint8_t *)&nt, 4, 0, GetParity((const uint8_t *)&nt, 4), TRUE);
        LogTrace(par_list, 8, 0, GetParity(par_list, 8), TRUE);
        LogTrace(ks_list, 8, 0, GetParity(ks_list, 8), TRUE);
 
-       UsbCommand ack = {CMD_ACK, {isOK, 0, 0}};
-       memcpy(ack.d.asBytes + 0,  uid, 4);
-       memcpy(ack.d.asBytes + 4,  nt, 4);
-       memcpy(ack.d.asBytes + 8,  par_list, 8);
-       memcpy(ack.d.asBytes + 16, ks_list, 8);
+       mf_nr_ar[3] &= 0x1F;
+       
+       byte_t buf[28];
+       memcpy(buf + 0,  uid, 4);
+       num_to_bytes(nt, 4, buf + 4);
+       memcpy(buf + 8,  par_list, 8);
+       memcpy(buf + 16, ks_list, 8);
+       memcpy(buf + 24, mf_nr_ar, 4);
                
-       LED_B_ON();
-       UsbSendPacket((uint8_t *)&ack, sizeof(UsbCommand));
-       LED_B_OFF();    
+       cmd_send(CMD_ACK,isOK,0,0,buf,28);
 
        // Thats it...
        FpgaWriteConfWord(FPGA_MAJOR_MODE_OFF);
        LEDsoff();
        tracing = TRUE;
-       
-       if (MF_DBGLEVEL >= 1)   DbpString("COMMAND mifare FINISHED");
 }
 
-
 //-----------------------------------------------------------------------------
 // MIFARE 1K simulate. 
 // 
@@ -2077,7 +2165,7 @@ void Mifare1ksim(uint8_t arg0, uint8_t arg1, uint8_t arg2, uint8_t *datain)
                } 
 
                if (cardSTATE != MFEMUL_NOFIELD) {
-                       res = EmGetCmd(receivedCmd, &len, 100); // (+ nextCycleTimeout)
+                       res = EmGetCmd(receivedCmd, &len, RECV_CMD_SIZE); // (+ nextCycleTimeout)
                        if (res == 2) {
                                cardSTATE = MFEMUL_NOFIELD;
                                LEDsoff();
@@ -2391,9 +2479,7 @@ lbWORK:   if (len == 0) break;
                                cardSTATE = MFEMUL_WORK;
                                break;
                        }
-               
                }
-       
        }
 
        FpgaWriteConfWord(FPGA_MAJOR_MODE_OFF);
@@ -2405,3 +2491,149 @@ lbWORK: if (len == 0) break;
 
        if (MF_DBGLEVEL >= 1)   Dbprintf("Emulator stopped. Tracing: %d  trace length: %d ",    tracing, traceLen);
 }
+
+//-----------------------------------------------------------------------------
+// MIFARE sniffer. 
+// 
+//-----------------------------------------------------------------------------
+void RAMFUNC SniffMifare(uint8_t param) {
+       // param:
+       // bit 0 - trigger from first card answer
+       // bit 1 - trigger from first reader 7-bit request
+
+       // C(red) A(yellow) B(green)
+       LEDsoff();
+       // init trace buffer
+    iso14a_clear_trace();
+
+       // The command (reader -> tag) that we're receiving.
+       // The length of a received command will in most cases be no more than 18 bytes.
+       // So 32 should be enough!
+       uint8_t *receivedCmd = (((uint8_t *)BigBuf) + RECV_CMD_OFFSET);
+       // The response (tag -> reader) that we're receiving.
+       uint8_t *receivedResponse = (((uint8_t *)BigBuf) + RECV_RES_OFFSET);
+
+       // As we receive stuff, we copy it from receivedCmd or receivedResponse
+       // into trace, along with its length and other annotations.
+       //uint8_t *trace = (uint8_t *)BigBuf;
+       
+       // The DMA buffer, used to stream samples from the FPGA
+       int8_t *dmaBuf = ((int8_t *)BigBuf) + DMA_BUFFER_OFFSET;
+       int8_t *data = dmaBuf;
+       int maxDataLen = 0;
+       int dataLen = 0;
+
+       // Set up the demodulator for tag -> reader responses.
+       Demod.output = receivedResponse;
+       Demod.len = 0;
+       Demod.state = DEMOD_UNSYNCD;
+
+       // Set up the demodulator for the reader -> tag commands
+       memset(&Uart, 0, sizeof(Uart));
+       Uart.output = receivedCmd;
+       Uart.byteCntMax = 32; // was 100 (greg)//////////////////
+       Uart.state = STATE_UNSYNCD;
+
+       // Setup for the DMA.
+       FpgaSetupSsc();
+       FpgaSetupSscDma((uint8_t *)dmaBuf, DMA_BUFFER_SIZE);
+
+       // And put the FPGA in the appropriate mode
+       // Signal field is off with the appropriate LED
+       LED_D_OFF();
+       FpgaWriteConfWord(FPGA_MAJOR_MODE_HF_ISO14443A | FPGA_HF_ISO14443A_SNIFFER);
+       SetAdcMuxFor(GPIO_MUXSEL_HIPKD);
+       
+       // init sniffer
+       MfSniffInit();
+       int sniffCounter = 0;
+
+       // And now we loop, receiving samples.
+       while(true) {
+               if(BUTTON_PRESS()) {
+                       DbpString("cancelled by button");
+                       goto done;
+               }
+
+               LED_A_ON();
+               WDT_HIT();
+               
+               if (++sniffCounter > 65) {
+                       if (MfSniffSend(2000)) {
+                               FpgaEnableSscDma();
+                       }
+                       sniffCounter = 0;
+               }
+
+               int register readBufDataP = data - dmaBuf;
+               int register dmaBufDataP = DMA_BUFFER_SIZE - AT91C_BASE_PDC_SSC->PDC_RCR;
+               if (readBufDataP <= dmaBufDataP){
+                       dataLen = dmaBufDataP - readBufDataP;
+               } else {
+                       dataLen = DMA_BUFFER_SIZE - readBufDataP + dmaBufDataP + 1;
+               }
+               // test for length of buffer
+               if(dataLen > maxDataLen) {
+                       maxDataLen = dataLen;
+                       if(dataLen > 400) {
+                               Dbprintf("blew circular buffer! dataLen=0x%x", dataLen);
+                               goto done;
+                       }
+               }
+               if(dataLen < 1) continue;
+
+               // primary buffer was stopped( <-- we lost data!
+               if (!AT91C_BASE_PDC_SSC->PDC_RCR) {
+                       AT91C_BASE_PDC_SSC->PDC_RPR = (uint32_t) dmaBuf;
+                       AT91C_BASE_PDC_SSC->PDC_RCR = DMA_BUFFER_SIZE;
+                       Dbprintf("RxEmpty ERROR!!! data length:%d", dataLen); // temporary
+               }
+               // secondary buffer sets as primary, secondary buffer was stopped
+               if (!AT91C_BASE_PDC_SSC->PDC_RNCR) {
+                       AT91C_BASE_PDC_SSC->PDC_RNPR = (uint32_t) dmaBuf;
+                       AT91C_BASE_PDC_SSC->PDC_RNCR = DMA_BUFFER_SIZE;
+               }
+
+               LED_A_OFF();
+               
+               if(MillerDecoding((data[0] & 0xF0) >> 4)) {
+                       LED_C_INV();
+                       // check - if there is a short 7bit request from reader
+                       if (MfSniffLogic(receivedCmd, Uart.byteCnt, Uart.parityBits, Uart.bitCnt, TRUE)) break;
+
+                       /* And ready to receive another command. */
+                       Uart.state = STATE_UNSYNCD;
+                       
+                       /* And also reset the demod code */
+                       Demod.state = DEMOD_UNSYNCD;
+               }
+
+               if(ManchesterDecoding(data[0] & 0x0F)) {
+                       LED_C_INV();
+
+                       if (MfSniffLogic(receivedResponse, Demod.len, Demod.parityBits, Demod.bitCount, FALSE)) break;
+
+                       // And ready to receive another response.
+                       memset(&Demod, 0, sizeof(Demod));
+                       Demod.output = receivedResponse;
+                       Demod.state = DEMOD_UNSYNCD;
+
+                       /* And also reset the uart code */
+                       Uart.state = STATE_UNSYNCD;
+               }
+
+               data++;
+               if(data > dmaBuf + DMA_BUFFER_SIZE) {
+                       data = dmaBuf;
+               }
+       } // main cycle
+
+       DbpString("COMMAND FINISHED");
+
+done:
+       FpgaDisableSscDma();
+       MfSniffEnd();
+       
+       Dbprintf("maxDataLen=%x, Uart.state=%x, Uart.byteCnt=%x Uart.byteCntMax=%x", maxDataLen, Uart.state, Uart.byteCnt, Uart.byteCntMax);
+       LEDsoff();
+}
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