]> git.zerfleddert.de Git - proxmark3-svn/blobdiff - armsrc/iso14443a.c
Only superficial changes, to get rid of compiler warnings
[proxmark3-svn] / armsrc / iso14443a.c
index 56afaeb84931dd3d1ee350576de0436c536eca4b..bd7e758d0b0796ac62883060a8923d876ed0b42c 100644 (file)
@@ -1218,47 +1218,75 @@ void SimulateIso14443aTag(int tagType, int uid_1st, int uid_2nd, byte_t* data)
        LED_A_OFF();
 }
 
        LED_A_OFF();
 }
 
+
+// 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;
+               }
+       }
+}
+
+
+
+
 //-----------------------------------------------------------------------------
 // Transmit the command (to the tag) that was placed in ToSend[].
 //-----------------------------------------------------------------------------
 // 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
 //-----------------------------------------------------------------------------
 //-----------------------------------------------------------------------------
-static void TransmitFor14443a(const uint8_t *cmd, int len, int *samples, int *wait)
+static void TransmitFor14443a(const uint8_t *cmd, int len, uint32_t *timing)
 {
 {
-  int c;
+       int c;
 
 
-  FpgaWriteConfWord(FPGA_MAJOR_MODE_HF_ISO14443A | FPGA_HF_ISO14443A_READER_MOD);
+       FpgaWriteConfWord(FPGA_MAJOR_MODE_HF_ISO14443A | FPGA_HF_ISO14443A_READER_MOD);
 
 
-       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();
-  }
+       if (timing) {
+               if(*timing == 0) {                                                                              // Measure time
+                       *timing = (GetCountMifare() + 8) & 0xfffffff8;
+               } else {
+                       PrepareDelayedTransfer(*timing & 0x00000007);           // Delay transfer (fine tuning - up to 7 MF clock ticks)
+               }
+               if(MF_DBGLEVEL >= 4 && GetCountMifare() >= (*timing & 0xfffffff8)) Dbprintf("TransmitFor14443a: Missed timing");
+               while(GetCountMifare() < (*timing & 0xfffffff8));               // Delay transfer (multiple of 8 MF clock ticks)
+       }
+
+       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++;
+               }
+       }
+       
+       c = 0;
+       for(;;) {
+               if(AT91C_BASE_SSC->SSC_SR & (AT91C_SSC_TXRDY)) {
+                       AT91C_BASE_SSC->SSC_THR = cmd[c];
+                       c++;
+                       if(c >= len) {
+                               break;
+                       }
+               }
+       }
 
 
-  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;
 }
 
 //-----------------------------------------------------------------------------
 }
 
 //-----------------------------------------------------------------------------
@@ -1528,10 +1556,10 @@ static int GetIso14443aAnswerFromTag(uint8_t *receivedResponse, int maxLen, int
        for(;;) {
                WDT_HIT();
 
        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;
                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;
@@ -1547,17 +1575,13 @@ static int GetIso14443aAnswerFromTag(uint8_t *receivedResponse, int maxLen, int
        }
 }
 
        }
 }
 
-void ReaderTransmitBitsPar(uint8_t* frame, int bits, uint32_t par)
+void ReaderTransmitBitsPar(uint8_t* frame, int bits, uint32_t par, uint32_t *timing)
 {
 {
-  int wait = 0;
-  int samples = 0;
-  
-  // This is tied to other size changes
-  //   uint8_t* frame_addr = ((uint8_t*)BigBuf) + 2024;
   CodeIso14443aBitsAsReaderPar(frame,bits,par);
   
   // Select the card
   CodeIso14443aBitsAsReaderPar(frame,bits,par);
   
   // Select the card
-  TransmitFor14443a(ToSend, ToSendMax, &samples, &wait);
+  TransmitFor14443a(ToSend, ToSendMax, timing);
   if(trigger)
        LED_A_ON();
   
   if(trigger)
        LED_A_ON();
   
@@ -1565,15 +1589,15 @@ void ReaderTransmitBitsPar(uint8_t* frame, int bits, uint32_t par)
   if (tracing) LogTrace(frame,nbytes(bits),0,par,TRUE);
 }
 
   if (tracing) LogTrace(frame,nbytes(bits),0,par,TRUE);
 }
 
-void ReaderTransmitPar(uint8_t* frame, int len, uint32_t par)
+void ReaderTransmitPar(uint8_t* frame, int len, uint32_t par, uint32_t *timing)
 {
 {
-  ReaderTransmitBitsPar(frame,len*8,par);
+  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
 {
   // Generate parity and redirect
-  ReaderTransmitBitsPar(frame,len*8,GetParity(frame,len));
+  ReaderTransmitBitsPar(frame,len*8,GetParity(frame,len), timing);
 }
 
 int ReaderReceive(uint8_t* receivedAnswer)
 }
 
 int ReaderReceive(uint8_t* receivedAnswer)
@@ -1612,7 +1636,7 @@ int iso14443a_select_card(byte_t* uid_ptr, iso14a_card_select_t* p_hi14a_card, u
   int len;
         
   // Broadcast for a card, WUPA (0x52) will force response from all cards in the field
   int len;
         
   // Broadcast for a card, WUPA (0x52) will force response from all cards in the field
-    ReaderTransmitBitsPar(wupa,7,0);
+    ReaderTransmitBitsPar(wupa,7,0, NULL);
   // Receive the ATQA
   if(!ReaderReceive(resp)) return 0;
 //  Dbprintf("atqa: %02x %02x",resp[0],resp[1]);
   // Receive the ATQA
   if(!ReaderReceive(resp)) return 0;
 //  Dbprintf("atqa: %02x %02x",resp[0],resp[1]);
@@ -1636,7 +1660,7 @@ int iso14443a_select_card(byte_t* uid_ptr, iso14a_card_select_t* p_hi14a_card, u
     sel_uid[0] = sel_all[0] = 0x93 + cascade_level * 2;
 
     // SELECT_ALL
     sel_uid[0] = sel_all[0] = 0x93 + cascade_level * 2;
 
     // SELECT_ALL
-    ReaderTransmit(sel_all,sizeof(sel_all));
+    ReaderTransmit(sel_all,sizeof(sel_all), NULL);
     if (!ReaderReceive(resp)) return 0;
     
     // First backup the current uid
     if (!ReaderReceive(resp)) return 0;
     
     // First backup the current uid
@@ -1644,15 +1668,15 @@ int iso14443a_select_card(byte_t* uid_ptr, iso14a_card_select_t* p_hi14a_card, u
     uid_resp_len = 4;
     //    Dbprintf("uid: %02x %02x %02x %02x",uid_resp[0],uid_resp[1],uid_resp[2],uid_resp[3]);
     
     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
-               if(cuid_ptr) {
-      *cuid_ptr = bytes_to_num(uid_resp, 4);
+       // calculate crypto UID. Always use last 4 Bytes.
+       if(cuid_ptr) {
+               *cuid_ptr = bytes_to_num(uid_resp, 4);
     }
 
     // Construct SELECT UID command
                memcpy(sel_uid+2,resp,5);
     AppendCrc14443a(sel_uid,7);
     }
 
     // Construct SELECT UID command
                memcpy(sel_uid+2,resp,5);
     AppendCrc14443a(sel_uid,7);
-    ReaderTransmit(sel_uid,sizeof(sel_uid));
+    ReaderTransmit(sel_uid,sizeof(sel_uid), NULL);
 
     // Receive the SAK
     if (!ReaderReceive(resp)) return 0;
 
     // Receive the SAK
     if (!ReaderReceive(resp)) return 0;
@@ -1687,7 +1711,7 @@ int iso14443a_select_card(byte_t* uid_ptr, iso14a_card_select_t* p_hi14a_card, u
 
   // Request for answer to select
   AppendCrc14443a(rats, 2);
 
   // Request for answer to select
   AppendCrc14443a(rats, 2);
-  ReaderTransmit(rats, sizeof(rats));
+  ReaderTransmit(rats, sizeof(rats), NULL);
 
   if (!(len = ReaderReceive(resp))) return 0;
 
 
   if (!(len = ReaderReceive(resp))) return 0;
 
@@ -1702,13 +1726,13 @@ int iso14443a_select_card(byte_t* uid_ptr, iso14a_card_select_t* p_hi14a_card, u
 }
 
 void iso14443a_setup() {
 }
 
 void iso14443a_setup() {
-  // Set up the synchronous serial port
-  FpgaSetupSsc();
+       // Set up the synchronous serial port
+       FpgaSetupSsc();
        // Start from off (no field generated)
        // Signal field is off with the appropriate LED
        // Start from off (no field generated)
        // Signal field is off with the appropriate LED
-       LED_D_OFF();
-       FpgaWriteConfWord(FPGA_MAJOR_MODE_OFF);
-       SpinDelay(50);
+//     LED_D_OFF();
+//     FpgaWriteConfWord(FPGA_MAJOR_MODE_OFF);
+       // SpinDelay(50);
 
        SetAdcMuxFor(GPIO_MUXSEL_HIPKD);
 
 
        SetAdcMuxFor(GPIO_MUXSEL_HIPKD);
 
@@ -1716,7 +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);
        // Signal field is on with the appropriate LED
        LED_D_ON();
        FpgaWriteConfWord(FPGA_MAJOR_MODE_HF_ISO14443A | FPGA_HF_ISO14443A_READER_MOD);
-       SpinDelay(50);
+       SpinDelay(7); // iso14443-3 specifies 5ms max.
 
        iso14a_timeout = 2048; //default
 }
 
        iso14a_timeout = 2048; //default
 }
@@ -1730,7 +1754,7 @@ int iso14_apdu(uint8_t * cmd, size_t cmd_len, void * data) {
        memcpy(real_cmd+2, cmd, cmd_len);
        AppendCrc14443a(real_cmd,cmd_len+2);
  
        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);
        uint8_t * data_bytes = (uint8_t *) data;
        if (!len)
        size_t len = ReaderReceive(data);
        uint8_t * data_bytes = (uint8_t *) data;
        if (!len)
@@ -1757,21 +1781,20 @@ void ReaderIso14443a(UsbCommand * c)
        iso14a_command_t param = c->arg[0];
        uint8_t * cmd = c->d.asBytes;
        size_t len = c->arg[1];
        iso14a_command_t param = c->arg[0];
        uint8_t * cmd = c->d.asBytes;
        size_t len = c->arg[1];
-  uint32_t arg0 = 0;
-  byte_t buf[USB_CMD_DATA_SIZE];
+       uint32_t arg0 = 0;
+       byte_t buf[USB_CMD_DATA_SIZE];
   
   
-  iso14a_clear_trace();
-  iso14a_set_tracing(true);
+       iso14a_clear_trace();
+       iso14a_set_tracing(true);
 
        if(param & ISO14A_REQUEST_TRIGGER) {
 
        if(param & ISO14A_REQUEST_TRIGGER) {
-    iso14a_set_trigger(1);
-  }
+               iso14a_set_trigger(1);
+       }
 
        if(param & ISO14A_CONNECT) {
                iso14443a_setup();
 
        if(param & ISO14A_CONNECT) {
                iso14443a_setup();
-               arg0 = iso14443a_select_card(NULL,(iso14a_card_select_t*)buf,NULL);
+               arg0 = iso14443a_select_card(NULL, (iso14a_card_select_t*)buf, NULL);
                cmd_send(CMD_ACK,arg0,0,0,buf,sizeof(iso14a_card_select_t));
                cmd_send(CMD_ACK,arg0,0,0,buf,sizeof(iso14a_card_select_t));
-//    UsbSendPacket((void *)ack, sizeof(UsbCommand));
        }
 
        if(param & ISO14A_SET_TIMEOUT) {
        }
 
        if(param & ISO14A_SET_TIMEOUT) {
@@ -1785,7 +1808,6 @@ void ReaderIso14443a(UsbCommand * c)
        if(param & ISO14A_APDU) {
                arg0 = iso14_apdu(cmd, len, buf);
                cmd_send(CMD_ACK,arg0,0,0,buf,sizeof(buf));
        if(param & ISO14A_APDU) {
                arg0 = iso14_apdu(cmd, len, buf);
                cmd_send(CMD_ACK,arg0,0,0,buf,sizeof(buf));
-//             UsbSendPacket((void *)ack, sizeof(UsbCommand));
        }
 
        if(param & ISO14A_RAW) {
        }
 
        if(param & ISO14A_RAW) {
@@ -1793,50 +1815,24 @@ void ReaderIso14443a(UsbCommand * c)
                        AppendCrc14443a(cmd,len);
                        len += 2;
                }
                        AppendCrc14443a(cmd,len);
                        len += 2;
                }
-               ReaderTransmit(cmd,len);
+               ReaderTransmit(cmd,len, NULL);
                arg0 = ReaderReceive(buf);
                arg0 = ReaderReceive(buf);
-//             UsbSendPacket((void *)ack, sizeof(UsbCommand));
-    cmd_send(CMD_ACK,arg0,0,0,buf,sizeof(buf));
+               cmd_send(CMD_ACK,arg0,0,0,buf,sizeof(buf));
        }
 
        if(param & ISO14A_REQUEST_TRIGGER) {
        }
 
        if(param & ISO14A_REQUEST_TRIGGER) {
-    iso14a_set_trigger(0);
-  }
+               iso14a_set_trigger(0);
+       }
 
        if(param & ISO14A_NO_DISCONNECT) {
                return;
 
        if(param & ISO14A_NO_DISCONNECT) {
                return;
-  }
+       }
 
        FpgaWriteConfWord(FPGA_MAJOR_MODE_OFF);
        LEDsoff();
 }
 
 
 
        FpgaWriteConfWord(FPGA_MAJOR_MODE_OFF);
        LEDsoff();
 }
 
 
-// prepare the Mifare AUTH transfer with an added necessary delay.
-void PrepareDelayedAuthTransfer(uint8_t* frame, int len, uint16_t delay)
-{
-       CodeIso14443aBitsAsReaderPar(frame, len*8, GetParity(frame,len));
-
-       uint8_t bitmask = 0;
-       uint8_t bits_to_shift = 0;
-       uint8_t bits_shifted = 0;
-       
-       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;
-               }
-       }
-}
-
-
-
 // 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.
 // 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.
@@ -1904,11 +1900,8 @@ void ReaderMifare(bool first_try)
                StartCountMifare();
                mf_nr_ar3 = 0;
                iso14443a_setup();
                StartCountMifare();
                mf_nr_ar3 = 0;
                iso14443a_setup();
-               FpgaWriteConfWord(FPGA_MAJOR_MODE_HF_ISO14443A | FPGA_HF_ISO14443A_TAGSIM_LISTEN); // resets some FPGA internal registers
                while((GetCountMifare() & 0xffff0000) != 0x10000);              // wait for counter to reset and "warm up" 
                while((GetCountMifare() & 0xffff0000) != 0x10000);              // wait for counter to reset and "warm up" 
-               while(AT91C_BASE_PIOA->PIO_PDSR & GPIO_SSC_FRAME);              // wait for ssp_frame to be low
-               while(!(AT91C_BASE_PIOA->PIO_PDSR & GPIO_SSC_FRAME));   // sync on rising edge of ssp_frame
-               sync_time = GetCountMifare();
+               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;
                sync_cycles = 65536;                                                                    // theory: Mifare Classic's random generator repeats every 2^16 cycles (and so do the nonces).
                nt_attacked = 0;
                nt = 0;
@@ -1939,41 +1932,37 @@ void ReaderMifare(bool first_try)
                LED_C_ON();
 
                if(!iso14443a_select_card(uid, NULL, &cuid)) {
                LED_C_ON();
 
                if(!iso14443a_select_card(uid, NULL, &cuid)) {
+                       if (MF_DBGLEVEL >= 1)   Dbprintf("Mifare: Can't select card");
                        continue;
                }
 
                //keep the card active
                FpgaWriteConfWord(FPGA_MAJOR_MODE_HF_ISO14443A | FPGA_HF_ISO14443A_READER_MOD);
 
                        continue;
                }
 
                //keep the card active
                FpgaWriteConfWord(FPGA_MAJOR_MODE_HF_ISO14443A | FPGA_HF_ISO14443A_READER_MOD);
 
-               PrepareDelayedAuthTransfer(mf_auth, sizeof(mf_auth), (sync_cycles + catch_up_cycles) & 0x00000007);
+               // CodeIso14443aBitsAsReaderPar(mf_auth, sizeof(mf_auth)*8, GetParity(mf_auth, sizeof(mf_auth)*8));
 
 
-               sync_time = sync_time + ((sync_cycles + catch_up_cycles) & 0xfffffff8);
+               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(GetCountMifare() > sync_time) {
                catch_up_cycles = 0;
 
                // if we missed the sync time already, advance to the next nonce repeat
                while(GetCountMifare() > sync_time) {
-                       sync_time = sync_time + (sync_cycles & 0xfffffff8);
+                       sync_time = (sync_time & 0xfffffff8) + sync_cycles;
                }
 
                }
 
-               // now sync. After syncing, the following Classic Auth will return the same tag nonce (mostly)
-               while(GetCountMifare() < sync_time);
-               
-               // Transmit MIFARE_CLASSIC_AUTH
-               int samples = 0;
-               int wait = 0;
-               TransmitFor14443a(ToSend, ToSendMax, &samples, &wait);
+               // 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)) {
 
                // Receive the (4 Byte) "random" nonce
                if (!ReaderReceive(receivedAnswer)) {
+                       if (MF_DBGLEVEL >= 1)   Dbprintf("Mifare: Couldn't receive tag nonce");
                        continue;
                  }
 
                        continue;
                  }
 
                previous_nt = nt;
                nt = bytes_to_num(receivedAnswer, 4);
 
                // Transmit reader nonce with fake par
                previous_nt = nt;
                nt = bytes_to_num(receivedAnswer, 4);
 
                // Transmit reader nonce with fake par
-               ReaderTransmitPar(mf_nr_ar, sizeof(mf_nr_ar), 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 (first_try && previous_nt && !nt_attacked) { // we didn't calibrate our clock yet
                        int nt_distance = dist_nt(previous_nt, nt);
@@ -1985,7 +1974,7 @@ void ReaderMifare(bool first_try)
                                        continue;
                                }
                                sync_cycles = (sync_cycles - nt_distance);
                                        continue;
                                }
                                sync_cycles = (sync_cycles - nt_distance);
-//                             Dbprintf("calibrating in cycle %d. nt_distance=%d, Sync_cycles: %d\n", i, nt_distance, sync_cycles);
+                               if (MF_DBGLEVEL >= 3) Dbprintf("calibrating in cycle %d. nt_distance=%d, Sync_cycles: %d\n", i, nt_distance, sync_cycles);
                                continue;
                        }
                }
                                continue;
                        }
                }
@@ -2004,11 +1993,11 @@ void ReaderMifare(bool first_try)
                            consecutive_resyncs = 0;
                        }
                        if (consecutive_resyncs < 3) {
                            consecutive_resyncs = 0;
                        }
                        if (consecutive_resyncs < 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);
+                               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;
                        }
                        else {  
                                sync_cycles = sync_cycles + catch_up_cycles;
-                               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);
+                               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;
                }
                        }
                        continue;
                }
@@ -2018,7 +2007,7 @@ void ReaderMifare(bool first_try)
                // Receive answer. This will be a 4 Bit NACK when the 8 parity bits are OK after decoding
                if (ReaderReceive(receivedAnswer))
                {
                // 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 doesn't run during data transfers. 4 Bit = 8 cycles
+                       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)
                        {
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