Changelog modified

[proxmark3-svn] / armsrc / iso14443a.c

diff --git a/armsrc/iso14443a.c b/armsrc/iso14443a.c
index 06a134f6b56f519d076295ef15885461ed2c96bc..27574dad2601cceda2f59b785445a1915a958892 100644 (file)
--- a/armsrc/iso14443a.c
+++ b/armsrc/iso14443a.c
@@ -213,6 +213,12 @@ void AppendCrc14443a(uint8_t* data, int len)
        ComputeCrc14443(CRC_14443_A,data,len,data+len,data+len+1);
 }
 
        ComputeCrc14443(CRC_14443_A,data,len,data+len,data+len+1);
 }
 

+void AppendCrc14443b(uint8_t* data, int len)
+{
+       ComputeCrc14443(CRC_14443_B,data,len,data+len,data+len+1);
+}
+
+

 //=============================================================================
 // ISO 14443 Type A - Miller decoder
 //=============================================================================
 //=============================================================================
 // ISO 14443 Type A - Miller decoder
 //=============================================================================


@@ -232,13 +238,17 @@ void AppendCrc14443a(uint8_t* data, int len)
 static tUart Uart;
 
 // Lookup-Table to decide if 4 raw bits are a modulation.
 static tUart Uart;
 
 // Lookup-Table to decide if 4 raw bits are a modulation.

-// We accept two or three consecutive "0" in any position with the rest "1"
+// We accept the following:
+// 0001  -   a 3 tick wide pause
+// 0011  -   a 2 tick wide pause, or a three tick wide pause shifted left
+// 0111  -   a 2 tick wide pause shifted left
+// 1001  -   a 2 tick wide pause shifted right

 const bool Mod_Miller_LUT[] = {
 const bool Mod_Miller_LUT[] = {

-       TRUE,  TRUE,  FALSE, TRUE,  FALSE, FALSE, FALSE, FALSE,
-       TRUE,  TRUE,  FALSE, FALSE, TRUE,  FALSE, FALSE, FALSE
+       FALSE,  TRUE, FALSE, TRUE,  FALSE, FALSE, FALSE, TRUE,
+       FALSE,  TRUE, FALSE, FALSE, FALSE, FALSE, FALSE, FALSE

 };
 };

-#define IsMillerModulationNibble1(b) (Mod_Miller_LUT[(b & 0x00F0) >> 4])
-#define IsMillerModulationNibble2(b) (Mod_Miller_LUT[(b & 0x000F)])
+#define IsMillerModulationNibble1(b) (Mod_Miller_LUT[(b & 0x000000F0) >> 4])
+#define IsMillerModulationNibble2(b) (Mod_Miller_LUT[(b & 0x0000000F)])

 
 void UartReset()
 {
 
 void UartReset()
 {


@@ -248,7 +258,6 @@ void UartReset()
        Uart.parityLen = 0;                                     // number of decoded parity bytes
        Uart.shiftReg = 0;                                      // shiftreg to hold decoded data bits
        Uart.parityBits = 0;                            // holds 8 parity bits
        Uart.parityLen = 0;                                     // number of decoded parity bytes
        Uart.shiftReg = 0;                                      // shiftreg to hold decoded data bits
        Uart.parityBits = 0;                            // holds 8 parity bits

-       Uart.fourBits = 0x00000000;                     // buffer for 4 Bits

        Uart.startTime = 0;
        Uart.endTime = 0;
 }
        Uart.startTime = 0;
        Uart.endTime = 0;
 }


@@ -257,6 +266,7 @@ void UartInit(uint8_t *data, uint8_t *parity)
 {
        Uart.output = data;
        Uart.parity = parity;
 {
        Uart.output = data;
        Uart.parity = parity;

+       Uart.fourBits = 0x00000000;                     // clear the buffer for 4 Bits

        UartReset();
 }
 
        UartReset();
 }
 


@@ -269,18 +279,21 @@ static RAMFUNC bool MillerDecoding(uint8_t bit, uint32_t non_real_time)
        if (Uart.state == STATE_UNSYNCD) {                                                                                      // not yet synced
        
                Uart.syncBit = 9999;                                                                                                    // not set
        if (Uart.state == STATE_UNSYNCD) {                                                                                      // not yet synced
        
                Uart.syncBit = 9999;                                                                                                    // not set

-               // we look for a ...xxxx1111111100x11111xxxxxx pattern 
-               // (unmodulated, followed by the start bit = 8 '1's followed by 2 '0's, eventually followed by another '0', followed by 5 '1's)
-#define ISO14443A_STARTBIT_MASK                0x007FEF80                                                                      // mask is    00000000 01111111 11101111 10000000
-#define ISO14443A_STARTBIT_PATTERN     0x007F8F80                                                                      // pattern is 00000000 01111111 10001111 10000000
-               if              ((Uart.fourBits & ISO14443A_STARTBIT_MASK) >> 0 == ISO14443A_STARTBIT_PATTERN >> 0) Uart.syncBit = 7;
-               else if ((Uart.fourBits & ISO14443A_STARTBIT_MASK) >> 1 == ISO14443A_STARTBIT_PATTERN >> 1) Uart.syncBit = 6;
-               else if ((Uart.fourBits & ISO14443A_STARTBIT_MASK) >> 2 == ISO14443A_STARTBIT_PATTERN >> 2) Uart.syncBit = 5;
-               else if ((Uart.fourBits & ISO14443A_STARTBIT_MASK) >> 3 == ISO14443A_STARTBIT_PATTERN >> 3) Uart.syncBit = 4;
-               else if ((Uart.fourBits & ISO14443A_STARTBIT_MASK) >> 4 == ISO14443A_STARTBIT_PATTERN >> 4) Uart.syncBit = 3;
-               else if ((Uart.fourBits & ISO14443A_STARTBIT_MASK) >> 5 == ISO14443A_STARTBIT_PATTERN >> 5) Uart.syncBit = 2;
-               else if ((Uart.fourBits & ISO14443A_STARTBIT_MASK) >> 6 == ISO14443A_STARTBIT_PATTERN >> 6) Uart.syncBit = 1;
-               else if ((Uart.fourBits & ISO14443A_STARTBIT_MASK) >> 7 == ISO14443A_STARTBIT_PATTERN >> 7) Uart.syncBit = 0;
+               // The start bit is one ore more Sequence Y followed by a Sequence Z (... 11111111 00x11111). We need to distinguish from
+               // Sequence X followed by Sequence Y followed by Sequence Z (111100x1 11111111 00x11111)
+               // we therefore look for a ...xx11111111111100x11111xxxxxx... pattern 
+               // (12 '1's followed by 2 '0's, eventually followed by another '0', followed by 5 '1's)
+               #define ISO14443A_STARTBIT_MASK         0x07FFEF80                                                      // mask is    00000111 11111111 11101111 10000000
+               #define ISO14443A_STARTBIT_PATTERN      0x07FF8F80                                                      // pattern is 00000111 11111111 10001111 10000000
+               if              ((Uart.fourBits & (ISO14443A_STARTBIT_MASK >> 0)) == ISO14443A_STARTBIT_PATTERN >> 0) Uart.syncBit = 7;
+               else if ((Uart.fourBits & (ISO14443A_STARTBIT_MASK >> 1)) == ISO14443A_STARTBIT_PATTERN >> 1) Uart.syncBit = 6;
+               else if ((Uart.fourBits & (ISO14443A_STARTBIT_MASK >> 2)) == ISO14443A_STARTBIT_PATTERN >> 2) Uart.syncBit = 5;
+               else if ((Uart.fourBits & (ISO14443A_STARTBIT_MASK >> 3)) == ISO14443A_STARTBIT_PATTERN >> 3) Uart.syncBit = 4;
+               else if ((Uart.fourBits & (ISO14443A_STARTBIT_MASK >> 4)) == ISO14443A_STARTBIT_PATTERN >> 4) Uart.syncBit = 3;
+               else if ((Uart.fourBits & (ISO14443A_STARTBIT_MASK >> 5)) == ISO14443A_STARTBIT_PATTERN >> 5) Uart.syncBit = 2;
+               else if ((Uart.fourBits & (ISO14443A_STARTBIT_MASK >> 6)) == ISO14443A_STARTBIT_PATTERN >> 6) Uart.syncBit = 1;
+               else if ((Uart.fourBits & (ISO14443A_STARTBIT_MASK >> 7)) == ISO14443A_STARTBIT_PATTERN >> 7) Uart.syncBit = 0;
+

                if (Uart.syncBit != 9999) {                                                                                             // found a sync bit
                        Uart.startTime = non_real_time?non_real_time:(GetCountSspClk() & 0xfffffff8);
                        Uart.startTime -= Uart.syncBit;
                if (Uart.syncBit != 9999) {                                                                                             // found a sync bit
                        Uart.startTime = non_real_time?non_real_time:(GetCountSspClk() & 0xfffffff8);
                        Uart.startTime -= Uart.syncBit;


@@ -542,12 +555,8 @@ void RAMFUNC SnoopIso14443a(uint8_t param) {
        
        LEDsoff();
 
        
        LEDsoff();
 

-       // 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
-       bool triggered = !(param & 0x03); 
-       
+       iso14443a_setup(FPGA_HF_ISO14443A_SNIFFER);
+

        // Allocate memory from BigBuf for some buffers
        // free all previous allocations first
        BigBuf_free();
        // Allocate memory from BigBuf for some buffers
        // free all previous allocations first
        BigBuf_free();


@@ -574,8 +583,6 @@ void RAMFUNC SnoopIso14443a(uint8_t param) {
        bool TagIsActive = FALSE;
        bool ReaderIsActive = FALSE;
        
        bool TagIsActive = FALSE;
        bool ReaderIsActive = FALSE;
        

-       iso14443a_setup(FPGA_HF_ISO14443A_SNIFFER);
-

        // Set up the demodulator for tag -> reader responses.
        DemodInit(receivedResponse, receivedResponsePar);
        
        // Set up the demodulator for tag -> reader responses.
        DemodInit(receivedResponse, receivedResponsePar);
        


@@ -585,6 +592,12 @@ void RAMFUNC SnoopIso14443a(uint8_t param) {
        // Setup and start DMA.
        FpgaSetupSscDma((uint8_t *)dmaBuf, DMA_BUFFER_SIZE);
        
        // Setup and start DMA.
        FpgaSetupSscDma((uint8_t *)dmaBuf, DMA_BUFFER_SIZE);
        

+       // 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
+       bool triggered = !(param & 0x03); 
+       

        // And now we loop, receiving samples.
        for(uint32_t rsamples = 0; TRUE; ) {
 
        // And now we loop, receiving samples.
        for(uint32_t rsamples = 0; TRUE; ) {
 


@@ -671,6 +684,9 @@ void RAMFUNC SnoopIso14443a(uint8_t param) {
 
                                        // And ready to receive another response.
                                        DemodReset();
 
                                        // And ready to receive another response.
                                        DemodReset();

+                                       // And reset the Miller decoder including itS (now outdated) input buffer
+                                       UartInit(receivedCmd, receivedCmdPar);
+

                                        LED_C_OFF();
                                } 
                                TagIsActive = (Demod.state != DEMOD_UNSYNCD);
                                        LED_C_OFF();
                                } 
                                TagIsActive = (Demod.state != DEMOD_UNSYNCD);


@@ -1017,6 +1033,9 @@ void SimulateIso14443aTag(int tagType, int uid_1st, int uid_2nd, byte_t* data)
                .modulation_n = 0
        };
   
                .modulation_n = 0
        };
   

+       // We need to listen to the high-frequency, peak-detected path.
+       iso14443a_setup(FPGA_HF_ISO14443A_TAGSIM_LISTEN);
+

        BigBuf_free_keep_EM();
 
        // allocate buffers:
        BigBuf_free_keep_EM();
 
        // allocate buffers:


@@ -1045,16 +1064,12 @@ void SimulateIso14443aTag(int tagType, int uid_1st, int uid_2nd, byte_t* data)
        int happened2 = 0;
        int cmdsRecvd = 0;
 
        int happened2 = 0;
        int cmdsRecvd = 0;
 

-       // We need to listen to the high-frequency, peak-detected path.
-       iso14443a_setup(FPGA_HF_ISO14443A_TAGSIM_LISTEN);
-

        cmdsRecvd = 0;
        tag_response_info_t* p_response;
 
        LED_A_ON();
        for(;;) {
                // Clean receive command buffer
        cmdsRecvd = 0;
        tag_response_info_t* p_response;
 
        LED_A_ON();
        for(;;) {
                // Clean receive command buffer

-               

                if(!GetIso14443aCommandFromReader(receivedCmd, receivedCmdPar, &len)) {
                        DbpString("Button press");
                        break;
                if(!GetIso14443aCommandFromReader(receivedCmd, receivedCmdPar, &len)) {
                        DbpString("Button press");
                        break;


@@ -1328,7 +1343,7 @@ void CodeIso14443aBitsAsReaderPar(const uint8_t *cmd, uint16_t bits, const uint8
                }
 
                // Only transmit parity bit if we transmitted a complete byte
                }
 
                // Only transmit parity bit if we transmitted a complete byte

-               if (j == 8) {
+               if (j == 8 && parity != NULL) {

                        // Get the parity bit
                        if (parity[i>>3] & (0x80 >> (i&0x0007))) {
                                // Sequence X
                        // Get the parity bit
                        if (parity[i>>3] & (0x80 >> (i&0x0007))) {
                                // Sequence X


@@ -1622,6 +1637,7 @@ static int GetIso14443aAnswerFromTag(uint8_t *receivedResponse, uint8_t *receive
        }
 }
 
        }
 }
 

+

 void ReaderTransmitBitsPar(uint8_t* frame, uint16_t bits, uint8_t *par, uint32_t *timing)
 {
        CodeIso14443aBitsAsReaderPar(frame, bits, par);
 void ReaderTransmitBitsPar(uint8_t* frame, uint16_t bits, uint8_t *par, uint32_t *timing)
 {
        CodeIso14443aBitsAsReaderPar(frame, bits, par);


@@ -1637,11 +1653,13 @@ void ReaderTransmitBitsPar(uint8_t* frame, uint16_t bits, uint8_t *par, uint32_t
        }
 }
 
        }
 }
 

+

 void ReaderTransmitPar(uint8_t* frame, uint16_t len, uint8_t *par, uint32_t *timing)
 {
   ReaderTransmitBitsPar(frame, len*8, par, timing);
 }
 
 void ReaderTransmitPar(uint8_t* frame, uint16_t len, uint8_t *par, uint32_t *timing)
 {
   ReaderTransmitBitsPar(frame, len*8, par, timing);
 }
 

+

 void ReaderTransmitBits(uint8_t* frame, uint16_t len, uint32_t *timing)
 {
   // Generate parity and redirect
 void ReaderTransmitBits(uint8_t* frame, uint16_t len, uint32_t *timing)
 {
   // Generate parity and redirect


@@ -1650,6 +1668,7 @@ void ReaderTransmitBits(uint8_t* frame, uint16_t len, uint32_t *timing)
   ReaderTransmitBitsPar(frame, len, par, timing);
 }
 
   ReaderTransmitBitsPar(frame, len, par, timing);
 }
 

+

 void ReaderTransmit(uint8_t* frame, uint16_t len, uint32_t *timing)
 {
   // Generate parity and redirect
 void ReaderTransmit(uint8_t* frame, uint16_t len, uint32_t *timing)
 {
   // Generate parity and redirect


@@ -1923,15 +1942,38 @@ void ReaderIso14443a(UsbCommand *c)
 
        if(param & ISO14A_RAW) {
                if(param & ISO14A_APPEND_CRC) {
 
        if(param & ISO14A_RAW) {
                if(param & ISO14A_APPEND_CRC) {

-                       AppendCrc14443a(cmd,len);
+                       if(param & ISO14A_TOPAZMODE) {
+                               AppendCrc14443b(cmd,len);
+                       } else {
+                               AppendCrc14443a(cmd,len);
+                       }

                        len += 2;
                        if (lenbits) lenbits += 16;
                }
                        len += 2;
                        if (lenbits) lenbits += 16;
                }

-               if(lenbits>0) {
-                       GetParity(cmd, lenbits/8, par);
-                       ReaderTransmitBitsPar(cmd, lenbits, par, NULL);
-               } else {
-                       ReaderTransmit(cmd,len, NULL);
+               if(lenbits>0) {                         // want to send a specific number of bits (e.g. short commands)
+                       if(param & ISO14A_TOPAZMODE) {
+                               int bits_to_send = lenbits;
+                               uint16_t i = 0;
+                               ReaderTransmitBitsPar(&cmd[i++], MIN(bits_to_send, 7), NULL, NULL);             // first byte is always short (7bits) and no parity
+                               bits_to_send -= 7;
+                               while (bits_to_send > 0) {
+                                       ReaderTransmitBitsPar(&cmd[i++], MIN(bits_to_send, 8), NULL, NULL);     // following bytes are 8 bit and no parity
+                                       bits_to_send -= 8;
+                               }
+                       } else {
+                               GetParity(cmd, lenbits/8, par);
+                               ReaderTransmitBitsPar(cmd, lenbits, par, NULL);                                                 // bytes are 8 bit with odd parity
+                       }
+               } else {                                        // want to send complete bytes only
+                       if(param & ISO14A_TOPAZMODE) {
+                               uint16_t i = 0;
+                               ReaderTransmitBitsPar(&cmd[i++], 7, NULL, NULL);                                                // first byte: 7 bits, no paritiy
+                               while (i < len) {
+                                       ReaderTransmitBitsPar(&cmd[i++], 8, NULL, NULL);                                        // following bytes: 8 bits, no paritiy
+                               }
+                       } else {
+                               ReaderTransmit(cmd,len, NULL);                                                                                  // 8 bits, odd parity
+                       }

                }
                arg0 = ReaderReceive(buf, par);
                cmd_send(CMD_ACK,arg0,0,0,buf,sizeof(buf));
                }
                arg0 = ReaderReceive(buf, par);
                cmd_send(CMD_ACK,arg0,0,0,buf,sizeof(buf));


@@ -1967,7 +2009,7 @@ int32_t dist_nt(uint32_t nt1, uint32_t nt2) {
                nttmp1 = prng_successor(nttmp1, 1);
                if (nttmp1 == nt2) return i;
                nttmp2 = prng_successor(nttmp2, 1);
                nttmp1 = prng_successor(nttmp1, 1);
                if (nttmp1 == nt2) return i;
                nttmp2 = prng_successor(nttmp2, 1);

-                       if (nttmp2 == nt1) return -i;
+               if (nttmp2 == nt1) return -i;

                }
        
        return(-99999); // either nt1 or nt2 are invalid nonces
                }
        
        return(-99999); // either nt1 or nt2 are invalid nonces


@@ -1990,6 +2032,10 @@ void ReaderMifare(bool first_try)
        uint8_t receivedAnswer[MAX_MIFARE_FRAME_SIZE];
        uint8_t receivedAnswerPar[MAX_MIFARE_PARITY_SIZE];
 
        uint8_t receivedAnswer[MAX_MIFARE_FRAME_SIZE];
        uint8_t receivedAnswerPar[MAX_MIFARE_PARITY_SIZE];
 

+       if (first_try) { 
+               iso14443a_setup(FPGA_HF_ISO14443A_READER_MOD);
+       }
+       

        // free eventually allocated BigBuf memory. We want all for tracing.
        BigBuf_free();
        
        // free eventually allocated BigBuf memory. We want all for tracing.
        BigBuf_free();
        


@@ -2009,20 +2055,20 @@ void ReaderMifare(bool first_try)
        byte_t par_list[8] = {0x00};
        byte_t ks_list[8] = {0x00};
 
        byte_t par_list[8] = {0x00};
        byte_t ks_list[8] = {0x00};
 

+       #define PRNG_SEQUENCE_LENGTH  (1 << 16);

        static uint32_t sync_time;
        static uint32_t sync_time;

-       static uint32_t sync_cycles;
+       static int32_t sync_cycles;

        int catch_up_cycles = 0;
        int last_catch_up = 0;
        int catch_up_cycles = 0;
        int last_catch_up = 0;

+       uint16_t elapsed_prng_sequences;

        uint16_t consecutive_resyncs = 0;
        int isOK = 0;
 
        if (first_try) { 
                mf_nr_ar3 = 0;
        uint16_t consecutive_resyncs = 0;
        int isOK = 0;
 
        if (first_try) { 
                mf_nr_ar3 = 0;

-               iso14443a_setup(FPGA_HF_ISO14443A_READER_MOD);

                sync_time = GetCountSspClk() & 0xfffffff8;
                sync_time = GetCountSspClk() & 0xfffffff8;

-               sync_cycles = 65536;                                                                    // theory: Mifare Classic's random generator repeats every 2^16 cycles (and so do the nonces).
+               sync_cycles = PRNG_SEQUENCE_LENGTH;                                                     // theory: Mifare Classic's random generator repeats every 2^16 cycles (and so do the tag nonces).

                nt_attacked = 0;
                nt_attacked = 0;

-               nt = 0;

                par[0] = 0;
        }
        else {
                par[0] = 0;
        }
        else {


@@ -2036,33 +2082,84 @@ void ReaderMifare(bool first_try)
        LED_B_OFF();
        LED_C_OFF();
        
        LED_B_OFF();
        LED_C_OFF();
        

-  
+
+       #define MAX_UNEXPECTED_RANDOM   4               // maximum number of unexpected (i.e. real) random numbers when trying to sync. Then give up.
+       #define MAX_SYNC_TRIES                  32
+       #define NUM_DEBUG_INFOS                 8               // per strategy
+       #define MAX_STRATEGY                    3
+       uint16_t unexpected_random = 0;
+       uint16_t sync_tries = 0;
+       int16_t debug_info_nr = -1;
+       uint16_t strategy = 0;
+       int32_t debug_info[MAX_STRATEGY][NUM_DEBUG_INFOS];
+       uint32_t select_time;
+       uint32_t halt_time;
+       

        for(uint16_t i = 0; TRUE; i++) {
                
        for(uint16_t i = 0; TRUE; i++) {
                

+               LED_C_ON();

                WDT_HIT();
 
                // Test if the action was cancelled
                if(BUTTON_PRESS()) {
                WDT_HIT();
 
                // Test if the action was cancelled
                if(BUTTON_PRESS()) {

+                       isOK = -1;

                        break;
                }
                
                        break;
                }
                

-               LED_C_ON();
+               if (strategy == 2) {
+                       // test with additional hlt command
+                       halt_time = 0;
+                       int len = mifare_sendcmd_short(NULL, false, 0x50, 0x00, receivedAnswer, receivedAnswerPar, &halt_time);
+                       if (len && MF_DBGLEVEL >= 3) {
+                               Dbprintf("Unexpected response of %d bytes to hlt command (additional debugging).", len);
+                       }
+               }

 
 

+               if (strategy == 3) {
+                       // test with FPGA power off/on
+                       FpgaWriteConfWord(FPGA_MAJOR_MODE_OFF);
+                       SpinDelay(200);
+                       iso14443a_setup(FPGA_HF_ISO14443A_READER_MOD);
+                       SpinDelay(100);
+               }
+               

                if(!iso14443a_select_card(uid, NULL, &cuid)) {
                        if (MF_DBGLEVEL >= 1)   Dbprintf("Mifare: Can't select card");
                        continue;
                }
                if(!iso14443a_select_card(uid, NULL, &cuid)) {
                        if (MF_DBGLEVEL >= 1)   Dbprintf("Mifare: Can't select card");
                        continue;
                }

+               select_time = GetCountSspClk();

 
 

-               sync_time = (sync_time & 0xfffffff8) + sync_cycles + catch_up_cycles;
-               catch_up_cycles = 0;
+               elapsed_prng_sequences = 1;
+               if (debug_info_nr == -1) {
+                       sync_time = (sync_time & 0xfffffff8) + sync_cycles + catch_up_cycles;
+                       catch_up_cycles = 0;

 
 

-               // if we missed the sync time already, advance to the next nonce repeat
-               while(GetCountSspClk() > sync_time) {
-                       sync_time = (sync_time & 0xfffffff8) + sync_cycles;
-               }
+                       // if we missed the sync time already, advance to the next nonce repeat
+                       while(GetCountSspClk() > sync_time) {
+                               elapsed_prng_sequences++;
+                               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);
+                       // Transmit MIFARE_CLASSIC_AUTH at synctime. Should result in returning the same tag nonce (== nt_attacked) 
+                       ReaderTransmit(mf_auth, sizeof(mf_auth), &sync_time);
+               } else {
+                       // collect some information on tag nonces for debugging:
+                       #define DEBUG_FIXED_SYNC_CYCLES PRNG_SEQUENCE_LENGTH
+                       if (strategy == 0) {
+                               // nonce distances at fixed time after card select:
+                               sync_time = select_time + DEBUG_FIXED_SYNC_CYCLES;
+                       } else if (strategy == 1) {
+                               // nonce distances at fixed time between authentications:
+                               sync_time = sync_time + DEBUG_FIXED_SYNC_CYCLES;
+                       } else if (strategy == 2) {
+                               // nonce distances at fixed time after halt:
+                               sync_time = halt_time + DEBUG_FIXED_SYNC_CYCLES;
+                       } else {
+                               // nonce_distances at fixed time after power on
+                               sync_time = DEBUG_FIXED_SYNC_CYCLES;
+                       }
+                       ReaderTransmit(mf_auth, sizeof(mf_auth), &sync_time);
+               }                       

 
                // Receive the (4 Byte) "random" nonce
                if (!ReaderReceive(receivedAnswer, receivedAnswerPar)) {
 
                // Receive the (4 Byte) "random" nonce
                if (!ReaderReceive(receivedAnswer, receivedAnswerPar)) {


@@ -2080,13 +2177,37 @@ void ReaderMifare(bool first_try)
                        int nt_distance = dist_nt(previous_nt, nt);
                        if (nt_distance == 0) {
                                nt_attacked = nt;
                        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;
+                       } else {
+                               if (nt_distance == -99999) { // invalid nonce received
+                                       unexpected_random++;
+                                       if (unexpected_random > MAX_UNEXPECTED_RANDOM) {
+                                               isOK = -3;              // Card has an unpredictable PRNG. Give up      
+                                               break;
+                                       } else {
+                                               continue;               // continue trying...
+                                       }
+                               }
+                               if (++sync_tries > MAX_SYNC_TRIES) {
+                                       if (strategy > MAX_STRATEGY || MF_DBGLEVEL < 3) {
+                                               isOK = -4;                      // Card's PRNG runs at an unexpected frequency or resets unexpectedly
+                                               break;
+                                       } else {                                // continue for a while, just to collect some debug info
+                                               debug_info[strategy][debug_info_nr] = nt_distance;
+                                               debug_info_nr++;
+                                               if (debug_info_nr == NUM_DEBUG_INFOS) {
+                                                       strategy++;
+                                                       debug_info_nr = 0;
+                                               }
+                                               continue;
+                                       }
+                               }
+                               sync_cycles = (sync_cycles - nt_distance/elapsed_prng_sequences);
+                               if (sync_cycles <= 0) {
+                                       sync_cycles += PRNG_SEQUENCE_LENGTH;
+                               }
+                               if (MF_DBGLEVEL >= 3) {
+                                       Dbprintf("calibrating in cycle %d. nt_distance=%d, elapsed_prng_sequences=%d, new sync_cycles: %d\n", i, nt_distance, elapsed_prng_sequences, sync_cycles);

                                }
                                }

-                               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;
                        }
                }
                                continue;
                        }
                }


@@ -2097,6 +2218,7 @@ void ReaderMifare(bool first_try)
                                catch_up_cycles = 0;
                                continue;
                        }
                                catch_up_cycles = 0;
                                continue;
                        }

+                       catch_up_cycles /= elapsed_prng_sequences;

                        if (catch_up_cycles == last_catch_up) {
                                consecutive_resyncs++;
                        }
                        if (catch_up_cycles == last_catch_up) {
                                consecutive_resyncs++;
                        }


@@ -2110,6 +2232,9 @@ void ReaderMifare(bool first_try)
                        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);
                        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);

+                               last_catch_up = 0;
+                               catch_up_cycles = 0;
+                               consecutive_resyncs = 0;

                        }
                        continue;
                }
                        }
                        continue;
                }


@@ -2117,12 +2242,10 @@ void ReaderMifare(bool first_try)
                consecutive_resyncs = 0;
                
                // Receive answer. This will be a 4 Bit NACK when the 8 parity bits are OK after decoding
                consecutive_resyncs = 0;
                
                // Receive answer. This will be a 4 Bit NACK when the 8 parity bits are OK after decoding

-               if (ReaderReceive(receivedAnswer, receivedAnswerPar))
-               {
+               if (ReaderReceive(receivedAnswer, receivedAnswerPar)) {

                        catch_up_cycles = 8;    // the PRNG is delayed by 8 cycles due to the NAC (4Bits = 0x05 encrypted) transfer
        
                        catch_up_cycles = 8;    // the PRNG is delayed by 8 cycles due to the NAC (4Bits = 0x05 encrypted) transfer
        

-                       if (nt_diff == 0)
-                       {
+                       if (nt_diff == 0) {

                                par_low = par[0] & 0xE0; // there is no need to check all parities for other nt_diff. Parity Bits for mf_nr_ar[0..2] won't change
                        }
 
                                par_low = par[0] & 0xE0; // there is no need to check all parities for other nt_diff. Parity Bits for mf_nr_ar[0..2] won't change
                        }
 


@@ -2145,6 +2268,10 @@ void ReaderMifare(bool first_try)
                        if (nt_diff == 0 && first_try)
                        {
                                par[0]++;
                        if (nt_diff == 0 && first_try)
                        {
                                par[0]++;

+                               if (par[0] == 0x00) {           // tried all 256 possible parities without success. Card doesn't send NACK.
+                                       isOK = -2;
+                                       break;
+                               }

                        } else {
                                par[0] = ((par[0] & 0x1F) + 1) | par_low;
                        }
                        } else {
                                par[0] = ((par[0] & 0x1F) + 1) | par_low;
                        }


@@ -2153,6 +2280,16 @@ void ReaderMifare(bool first_try)
 
 
        mf_nr_ar[3] &= 0x1F;
 
 
        mf_nr_ar[3] &= 0x1F;

+
+       if (isOK == -4) {
+               if (MF_DBGLEVEL >= 3) {
+                       for (uint16_t i = 0; i <= MAX_STRATEGY; i++) {
+                               for(uint16_t j = 0; j < NUM_DEBUG_INFOS; j++) {
+                                       Dbprintf("collected debug info[%d][%d] = %d", i, j, debug_info[i][j]);
+                               }
+                       }
+               }
+       }

        
        byte_t buf[28];
        memcpy(buf + 0,  uid, 4);
        
        byte_t buf[28];
        memcpy(buf + 0,  uid, 4);


@@ -2161,7 +2298,7 @@ void ReaderMifare(bool first_try)
        memcpy(buf + 16, ks_list, 8);
        memcpy(buf + 24, mf_nr_ar, 4);
                
        memcpy(buf + 16, ks_list, 8);
        memcpy(buf + 24, mf_nr_ar, 4);
                

-       cmd_send(CMD_ACK,isOK,0,0,buf,28);
+       cmd_send(CMD_ACK, isOK, 0, 0, buf, 28);

 
        // Thats it...
        FpgaWriteConfWord(FPGA_MAJOR_MODE_OFF);
 
        // Thats it...
        FpgaWriteConfWord(FPGA_MAJOR_MODE_OFF);


@@ -2222,13 +2359,6 @@ void Mifare1ksim(uint8_t flags, uint8_t exitAfterNReads, uint8_t arg2, uint8_t *
        uint32_t ar_nr_responses[] = {0,0,0,0,0,0,0,0};
        uint8_t ar_nr_collected = 0;
 
        uint32_t ar_nr_responses[] = {0,0,0,0,0,0,0,0};
        uint8_t ar_nr_collected = 0;
 

-       // free eventually allocated BigBuf memory but keep Emulator Memory
-       BigBuf_free_keep_EM();
-
-       // clear trace
-       clear_trace();
-       set_tracing(TRUE);
-

        // Authenticate response - nonce
        uint32_t nonce = bytes_to_num(rAUTH_NT, 4);
        
        // Authenticate response - nonce
        uint32_t nonce = bytes_to_num(rAUTH_NT, 4);
        


@@ -2266,13 +2396,10 @@ void Mifare1ksim(uint8_t flags, uint8_t exitAfterNReads, uint8_t arg2, uint8_t *
        if (_7BUID) {
                rATQA[0] = 0x44;
                rUIDBCC1[0] = 0x88;
        if (_7BUID) {
                rATQA[0] = 0x44;
                rUIDBCC1[0] = 0x88;

+               rUIDBCC1[4] = rUIDBCC1[0] ^ rUIDBCC1[1] ^ rUIDBCC1[2] ^ rUIDBCC1[3];

                rUIDBCC2[4] = rUIDBCC2[0] ^ rUIDBCC2[1] ^ rUIDBCC2[2] ^ rUIDBCC2[3];
        }
 
                rUIDBCC2[4] = rUIDBCC2[0] ^ rUIDBCC2[1] ^ rUIDBCC2[2] ^ rUIDBCC2[3];
        }
 

-       // We need to listen to the high-frequency, peak-detected path.
-       iso14443a_setup(FPGA_HF_ISO14443A_TAGSIM_LISTEN);
-
-

        if (MF_DBGLEVEL >= 1)   {
                if (!_7BUID) {
                        Dbprintf("4B UID: %02x%02x%02x%02x", 
        if (MF_DBGLEVEL >= 1)   {
                if (!_7BUID) {
                        Dbprintf("4B UID: %02x%02x%02x%02x", 


@@ -2284,6 +2411,17 @@ void Mifare1ksim(uint8_t flags, uint8_t exitAfterNReads, uint8_t arg2, uint8_t *
                }
        }
 
                }
        }
 

+       // We need to listen to the high-frequency, peak-detected path.
+       iso14443a_setup(FPGA_HF_ISO14443A_TAGSIM_LISTEN);
+
+       // free eventually allocated BigBuf memory but keep Emulator Memory
+       BigBuf_free_keep_EM();
+
+       // clear trace
+       clear_trace();
+       set_tracing(TRUE);
+
+

        bool finished = FALSE;
        while (!BUTTON_PRESS() && !finished) {
                WDT_HIT();
        bool finished = FALSE;
        while (!BUTTON_PRESS() && !finished) {
                WDT_HIT();


@@ -2505,13 +2643,13 @@ void Mifare1ksim(uint8_t flags, uint8_t exitAfterNReads, uint8_t arg2, uint8_t *
                                                || receivedCmd[0] == 0xB0) { // transfer
                                        if (receivedCmd[1] >= 16 * 4) {
                                                EmSend4bit(mf_crypto1_encrypt4bit(pcs, CARD_NACK_NA));
                                                || receivedCmd[0] == 0xB0) { // transfer
                                        if (receivedCmd[1] >= 16 * 4) {
                                                EmSend4bit(mf_crypto1_encrypt4bit(pcs, CARD_NACK_NA));

-                                               if (MF_DBGLEVEL >= 2) Dbprintf("Reader tried to operate (0x%02) on out of range block: %d (0x%02x), nacking",receivedCmd[0],receivedCmd[1],receivedCmd[1]);
+                                               if (MF_DBGLEVEL >= 2) Dbprintf("Reader tried to operate (0x%02x) on out of range block: %d (0x%02x), nacking",receivedCmd[0],receivedCmd[1],receivedCmd[1]);

                                                break;
                                        }
 
                                        if (receivedCmd[1] / 4 != cardAUTHSC) {
                                                EmSend4bit(mf_crypto1_encrypt4bit(pcs, CARD_NACK_NA));
                                                break;
                                        }
 
                                        if (receivedCmd[1] / 4 != cardAUTHSC) {
                                                EmSend4bit(mf_crypto1_encrypt4bit(pcs, CARD_NACK_NA));

-                                               if (MF_DBGLEVEL >= 2) Dbprintf("Reader tried to operate (0x%02) on block (0x%02x) not authenticated for (0x%02x), nacking",receivedCmd[0],receivedCmd[1],cardAUTHSC);
+                                               if (MF_DBGLEVEL >= 2) Dbprintf("Reader tried to operate (0x%02x) on block (0x%02x) not authenticated for (0x%02x), nacking",receivedCmd[0],receivedCmd[1],cardAUTHSC);

                                                break;
                                        }
                                }
                                                break;
                                        }
                                }


@@ -2702,10 +2840,8 @@ void RAMFUNC SniffMifare(uint8_t param) {
        uint8_t receivedResponse[MAX_MIFARE_FRAME_SIZE];
        uint8_t receivedResponsePar[MAX_MIFARE_PARITY_SIZE];
 
        uint8_t receivedResponse[MAX_MIFARE_FRAME_SIZE];
        uint8_t receivedResponsePar[MAX_MIFARE_PARITY_SIZE];
 

-       // 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;
-       
+       iso14443a_setup(FPGA_HF_ISO14443A_SNIFFER);
+

        // free eventually allocated BigBuf memory
        BigBuf_free();
        // allocate the DMA buffer, used to stream samples from the FPGA
        // free eventually allocated BigBuf memory
        BigBuf_free();
        // allocate the DMA buffer, used to stream samples from the FPGA


@@ -2717,8 +2853,6 @@ void RAMFUNC SniffMifare(uint8_t param) {
        bool ReaderIsActive = FALSE;
        bool TagIsActive = FALSE;
 
        bool ReaderIsActive = FALSE;
        bool TagIsActive = FALSE;
 

-       iso14443a_setup(FPGA_HF_ISO14443A_SNIFFER);
-

        // Set up the demodulator for tag -> reader responses.
        DemodInit(receivedResponse, receivedResponsePar);
 
        // Set up the demodulator for tag -> reader responses.
        DemodInit(receivedResponse, receivedResponsePar);
 


@@ -2798,7 +2932,7 @@ void RAMFUNC SniffMifare(uint8_t param) {
                                        if (MfSniffLogic(receivedCmd, Uart.len, Uart.parity, Uart.bitCount, TRUE)) break;
 
                                        /* And ready to receive another command. */
                                        if (MfSniffLogic(receivedCmd, Uart.len, Uart.parity, Uart.bitCount, TRUE)) break;
 
                                        /* And ready to receive another command. */

-                                       UartReset();
+                                       UartInit(receivedCmd, receivedCmdPar);

                                        
                                        /* And also reset the demod code */
                                        DemodReset();
                                        
                                        /* And also reset the demod code */
                                        DemodReset();


@@ -2815,6 +2949,8 @@ void RAMFUNC SniffMifare(uint8_t param) {
 
                                        // And ready to receive another response.
                                        DemodReset();
 
                                        // And ready to receive another response.
                                        DemodReset();

+                                       // And reset the Miller decoder including its (now outdated) input buffer
+                                       UartInit(receivedCmd, receivedCmdPar);

                                }
                                TagIsActive = (Demod.state != DEMOD_UNSYNCD);
                        }
                                }
                                TagIsActive = (Demod.state != DEMOD_UNSYNCD);
                        }