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[proxmark3-svn] / armsrc / iclass.c

//-----------------------------------------------------------------------------
// Gerhard de Koning Gans - May 2008
// Hagen Fritsch - June 2010
// Gerhard de Koning Gans - May 2011
// Gerhard de Koning Gans - June 2012 - Added iClass card and reader emulation
//
// This code is licensed to you under the terms of the GNU GPL, version 2 or,
// at your option, any later version. See the LICENSE.txt file for the text of
// the license.
//-----------------------------------------------------------------------------
// Routines to support iClass.
//-----------------------------------------------------------------------------
// Based on ISO14443a implementation. Still in experimental phase.
// Contribution made during a security research at Radboud University Nijmegen
//
// Please feel free to contribute and extend iClass support!!
//-----------------------------------------------------------------------------
//
// FIX:
// ====
// We still have sometimes a demodulation error when snooping iClass communication.
// The resulting trace of a read-block-03 command may look something like this:
//
//  +  22279:    :     0c  03  e8  01
//
//    ...with an incorrect answer...
//
//  +     85:   0: TAG ff! ff! ff! ff! ff! ff! ff! ff! bb  33  bb  00  01! 0e! 04! bb     !crc
//
// We still left the error signalling bytes in the traces like 0xbb
//
// A correct trace should look like this:
//
// +  21112:    :     0c  03  e8  01
// +     85:   0: TAG ff  ff  ff  ff  ff  ff  ff  ff  ea  f5
//
//-----------------------------------------------------------------------------

#include "iclass.h"

#include "proxmark3.h"
#include "apps.h"
#include "util.h"
#include "string.h"
#include "common.h"
#include "cmd.h"
#include "iso14443a.h"
// Needed for CRC in emulation mode;
// same construction as in ISO 14443;
// different initial value (CRC_ICLASS)
#include "iso14443crc.h"
#include "iso15693tools.h"
#include "protocols.h"
#include "optimized_cipher.h"
#include "usb_cdc.h" // for usb_poll_validate_length
#include "fpgaloader.h"

static int timeout = 4096;

//-----------------------------------------------------------------------------
// The software UART that receives commands from the reader, and its state
// variables.
//-----------------------------------------------------------------------------
static struct {
	enum {
		STATE_UNSYNCD,
		STATE_START_OF_COMMUNICATION,
		STATE_RECEIVING
	}        state;
	uint16_t shiftReg;
	int      bitCnt;
	int      byteCnt;
	int      byteCntMax;
	int      posCnt;
	int      nOutOfCnt;
	int      OutOfCnt;
	int      syncBit;
	int      samples;
	int      highCnt;
	int      swapper;
	int      counter;
	int      bitBuffer;
	int      dropPosition;
	uint8_t  *output;
} Uart;

static RAMFUNC int OutOfNDecoding(int bit) {
	//int error = 0;
	int bitright;

	if (!Uart.bitBuffer) {
		Uart.bitBuffer = bit ^ 0xFF0;
		return false;
	} else {
		Uart.bitBuffer <<= 4;
		Uart.bitBuffer ^= bit;
	}

	/*if (Uart.swapper) {
		Uart.output[Uart.byteCnt] = Uart.bitBuffer & 0xFF;
		Uart.byteCnt++;
		Uart.swapper = 0;
		if (Uart.byteCnt > 15) { return true; }
	}
	else {
		Uart.swapper = 1;
	}*/

	if (Uart.state != STATE_UNSYNCD) {
		Uart.posCnt++;

		if ((Uart.bitBuffer & Uart.syncBit) ^ Uart.syncBit) {
			bit = 0x00;
		} else {
			bit = 0x01;
		}
		if (((Uart.bitBuffer << 1) & Uart.syncBit) ^ Uart.syncBit) {
			bitright = 0x00;
		} else {
			bitright = 0x01;
		}
		if (bit != bitright) {
			bit = bitright;
		}


		// So, now we only have to deal with *bit*, lets see...
		if (Uart.posCnt == 1) {
			// measurement first half bitperiod
			if (!bit) {
				// Drop in first half means that we are either seeing
				// an SOF or an EOF.

				if (Uart.nOutOfCnt == 1) {
					// End of Communication
					Uart.state = STATE_UNSYNCD;
					Uart.highCnt = 0;
					if (Uart.byteCnt == 0) {
						// Its not straightforward to show single EOFs
						// So just leave it and do not return true
						Uart.output[0] = 0xf0;
						Uart.byteCnt++;
					} else {
						return true;
					}
				} else if (Uart.state != STATE_START_OF_COMMUNICATION) {
					// When not part of SOF or EOF, it is an error
					Uart.state = STATE_UNSYNCD;
					Uart.highCnt = 0;
					//error = 4;
				}
			}
		} else {
			// measurement second half bitperiod
			// Count the bitslot we are in... (ISO 15693)
			Uart.nOutOfCnt++;

			if (!bit) {
				if (Uart.dropPosition) {
					if (Uart.state == STATE_START_OF_COMMUNICATION) {
						//error = 1;
					} else {
						//error = 7;
					}
					// It is an error if we already have seen a drop in current frame
					Uart.state = STATE_UNSYNCD;
					Uart.highCnt = 0;
				} else {
					Uart.dropPosition = Uart.nOutOfCnt;
				}
			}

			Uart.posCnt = 0;


			if (Uart.nOutOfCnt == Uart.OutOfCnt && Uart.OutOfCnt == 4) {
				Uart.nOutOfCnt = 0;

				if (Uart.state == STATE_START_OF_COMMUNICATION) {
					if (Uart.dropPosition == 4) {
						Uart.state = STATE_RECEIVING;
						Uart.OutOfCnt = 256;
					} else if (Uart.dropPosition == 3) {
						Uart.state = STATE_RECEIVING;
						Uart.OutOfCnt = 4;
						//Uart.output[Uart.byteCnt] = 0xdd;
						//Uart.byteCnt++;
					} else {
						Uart.state = STATE_UNSYNCD;
						Uart.highCnt = 0;
					}
					Uart.dropPosition = 0;
				} else {
					// RECEIVING DATA
					// 1 out of 4
					if (!Uart.dropPosition) {
						Uart.state = STATE_UNSYNCD;
						Uart.highCnt = 0;
						//error = 9;
					} else {
						Uart.shiftReg >>= 2;

						// Swap bit order
						Uart.dropPosition--;
						//if (Uart.dropPosition == 1) { Uart.dropPosition = 2; }
						//else if (Uart.dropPosition == 2) { Uart.dropPosition = 1; }

						Uart.shiftReg ^= ((Uart.dropPosition & 0x03) << 6);
						Uart.bitCnt += 2;
						Uart.dropPosition = 0;

						if (Uart.bitCnt == 8) {
							Uart.output[Uart.byteCnt] = (Uart.shiftReg & 0xff);
							Uart.byteCnt++;
							Uart.bitCnt = 0;
							Uart.shiftReg = 0;
						}
					}
				}
			} else if (Uart.nOutOfCnt == Uart.OutOfCnt) {
				// RECEIVING DATA
				// 1 out of 256
				if (!Uart.dropPosition) {
					Uart.state = STATE_UNSYNCD;
					Uart.highCnt = 0;
					//error = 3;
				} else {
					Uart.dropPosition--;
					Uart.output[Uart.byteCnt] = (Uart.dropPosition & 0xff);
					Uart.byteCnt++;
					Uart.bitCnt = 0;
					Uart.shiftReg = 0;
					Uart.nOutOfCnt = 0;
					Uart.dropPosition = 0;
				}
			}

			/*if (error) {
				Uart.output[Uart.byteCnt] = 0xAA;
				Uart.byteCnt++;
				Uart.output[Uart.byteCnt] = error & 0xFF;
				Uart.byteCnt++;
				Uart.output[Uart.byteCnt] = 0xAA;
				Uart.byteCnt++;
				Uart.output[Uart.byteCnt] = (Uart.bitBuffer >> 8) & 0xFF;
				Uart.byteCnt++;
				Uart.output[Uart.byteCnt] = Uart.bitBuffer & 0xFF;
				Uart.byteCnt++;
				Uart.output[Uart.byteCnt] = (Uart.syncBit >> 3) & 0xFF;
				Uart.byteCnt++;
				Uart.output[Uart.byteCnt] = 0xAA;
				Uart.byteCnt++;
				return true;
			}*/
		}

	} else {
		bit = Uart.bitBuffer & 0xf0;
		bit >>= 4;
		bit ^= 0x0F; // drops become 1s ;-)
		if (bit) {
			// should have been high or at least (4 * 128) / fc
			// according to ISO this should be at least (9 * 128 + 20) / fc
			if (Uart.highCnt == 8) {
				// we went low, so this could be start of communication
				// it turns out to be safer to choose a less significant
				// syncbit... so we check whether the neighbour also represents the drop
				Uart.posCnt = 1;   // apparently we are busy with our first half bit period
				Uart.syncBit = bit & 8;
				Uart.samples = 3;
				if (!Uart.syncBit)  { Uart.syncBit = bit & 4; Uart.samples = 2; }
				else if (bit & 4)   { Uart.syncBit = bit & 4; Uart.samples = 2; bit <<= 2; }
				if (!Uart.syncBit)  { Uart.syncBit = bit & 2; Uart.samples = 1; }
				else if (bit & 2)   { Uart.syncBit = bit & 2; Uart.samples = 1; bit <<= 1; }
				if (!Uart.syncBit)  { Uart.syncBit = bit & 1; Uart.samples = 0;
					if (Uart.syncBit && (Uart.bitBuffer & 8)) {
						Uart.syncBit = 8;

						// the first half bit period is expected in next sample
						Uart.posCnt = 0;
						Uart.samples = 3;
					}
				} else if (bit & 1) { Uart.syncBit = bit & 1; Uart.samples = 0; }

				Uart.syncBit <<= 4;
				Uart.state = STATE_START_OF_COMMUNICATION;
				Uart.bitCnt = 0;
				Uart.byteCnt = 0;
				Uart.nOutOfCnt = 0;
				Uart.OutOfCnt = 4; // Start at 1/4, could switch to 1/256
				Uart.dropPosition = 0;
				Uart.shiftReg = 0;
				//error = 0;
			} else {
				Uart.highCnt = 0;
			}
		} else if (Uart.highCnt < 8) {
			Uart.highCnt++;
		}
	}

	return false;
}


//=============================================================================
// Manchester
//=============================================================================

static struct {
	enum {
		DEMOD_UNSYNCD,
		DEMOD_START_OF_COMMUNICATION,
		DEMOD_START_OF_COMMUNICATION2,
		DEMOD_START_OF_COMMUNICATION3,
		DEMOD_SOF_COMPLETE,
		DEMOD_MANCHESTER_D,
		DEMOD_MANCHESTER_E,
		DEMOD_END_OF_COMMUNICATION,
		DEMOD_END_OF_COMMUNICATION2,
		DEMOD_MANCHESTER_F,
		DEMOD_ERROR_WAIT
	}        state;
	int      bitCount;
	int      posCount;
	int      syncBit;
	uint16_t shiftReg;
	int      buffer;
	int      buffer2;
	int      buffer3;
	int      buff;
	int      samples;
	int      len;
	enum {
		SUB_NONE,
		SUB_FIRST_HALF,
		SUB_SECOND_HALF,
		SUB_BOTH
	}        sub;
	uint8_t  *output;
} Demod;

static RAMFUNC int ManchesterDecoding(int v) {
	int bit;
	int modulation;
	int error = 0;

	bit = Demod.buffer;
	Demod.buffer = Demod.buffer2;
	Demod.buffer2 = Demod.buffer3;
	Demod.buffer3 = v;

	if (Demod.buff < 3) {
		Demod.buff++;
		return false;
	}

	if (Demod.state==DEMOD_UNSYNCD) {
		Demod.output[Demod.len] = 0xfa;
		Demod.syncBit = 0;
		//Demod.samples = 0;
		Demod.posCount = 1;     // This is the first half bit period, so after syncing handle the second part

		if (bit & 0x08) {
			Demod.syncBit = 0x08;
		}

		if (bit & 0x04) {
			if (Demod.syncBit) {
				bit <<= 4;
			}
			Demod.syncBit = 0x04;
		}

		if (bit & 0x02) {
			if (Demod.syncBit) {
				bit <<= 2;
			}
			Demod.syncBit = 0x02;
		}

		if (bit & 0x01 && Demod.syncBit) {
			Demod.syncBit = 0x01;
		}

		if (Demod.syncBit) {
			Demod.len = 0;
			Demod.state = DEMOD_START_OF_COMMUNICATION;
			Demod.sub = SUB_FIRST_HALF;
			Demod.bitCount = 0;
			Demod.shiftReg = 0;
			Demod.samples = 0;
			if (Demod.posCount) {
				//if (trigger) LED_A_OFF();  // Not useful in this case...
				switch(Demod.syncBit) {
					case 0x08: Demod.samples = 3; break;
					case 0x04: Demod.samples = 2; break;
					case 0x02: Demod.samples = 1; break;
					case 0x01: Demod.samples = 0; break;
				}
				// SOF must be long burst... otherwise stay unsynced!!!
				if (!(Demod.buffer & Demod.syncBit) || !(Demod.buffer2 & Demod.syncBit)) {
					Demod.state = DEMOD_UNSYNCD;
				}
			} else {
				// SOF must be long burst... otherwise stay unsynced!!!
				if (!(Demod.buffer2 & Demod.syncBit) || !(Demod.buffer3 & Demod.syncBit)) {
					Demod.state = DEMOD_UNSYNCD;
					error = 0x88;
				}

			}
			error = 0;

		}
	} else {
		modulation = bit & Demod.syncBit;
		modulation |= ((bit << 1) ^ ((Demod.buffer & 0x08) >> 3)) & Demod.syncBit;

		Demod.samples += 4;

		if (Demod.posCount==0) {
			Demod.posCount = 1;
			if (modulation) {
				Demod.sub = SUB_FIRST_HALF;
			} else {
				Demod.sub = SUB_NONE;
			}
		} else {
			Demod.posCount = 0;
			/*(modulation && (Demod.sub == SUB_FIRST_HALF)) {
				if (Demod.state!=DEMOD_ERROR_WAIT) {
					Demod.state = DEMOD_ERROR_WAIT;
					Demod.output[Demod.len] = 0xaa;
					error = 0x01;
				}
			}*/
			//else if (modulation) {
			if (modulation) {
				if (Demod.sub == SUB_FIRST_HALF) {
					Demod.sub = SUB_BOTH;
				} else {
					Demod.sub = SUB_SECOND_HALF;
				}
			} else if (Demod.sub == SUB_NONE) {
				if (Demod.state == DEMOD_SOF_COMPLETE) {
					Demod.output[Demod.len] = 0x0f;
					Demod.len++;
					Demod.state = DEMOD_UNSYNCD;
//                  error = 0x0f;
					return true;
				} else {
					Demod.state = DEMOD_ERROR_WAIT;
					error = 0x33;
				}
				/*if (Demod.state!=DEMOD_ERROR_WAIT) {
					Demod.state = DEMOD_ERROR_WAIT;
					Demod.output[Demod.len] = 0xaa;
					error = 0x01;
				}*/
			}

			switch(Demod.state) {
				case DEMOD_START_OF_COMMUNICATION:
					if (Demod.sub == SUB_BOTH) {
						//Demod.state = DEMOD_MANCHESTER_D;
						Demod.state = DEMOD_START_OF_COMMUNICATION2;
						Demod.posCount = 1;
						Demod.sub = SUB_NONE;
					} else {
						Demod.output[Demod.len] = 0xab;
						Demod.state = DEMOD_ERROR_WAIT;
						error = 0xd2;
					}
					break;
				case DEMOD_START_OF_COMMUNICATION2:
					if (Demod.sub == SUB_SECOND_HALF) {
						Demod.state = DEMOD_START_OF_COMMUNICATION3;
					} else {
						Demod.output[Demod.len] = 0xab;
						Demod.state = DEMOD_ERROR_WAIT;
						error = 0xd3;
					}
					break;
				case DEMOD_START_OF_COMMUNICATION3:
					if (Demod.sub == SUB_SECOND_HALF) {
//                      Demod.state = DEMOD_MANCHESTER_D;
						Demod.state = DEMOD_SOF_COMPLETE;
						//Demod.output[Demod.len] = Demod.syncBit & 0xFF;
						//Demod.len++;
					} else {
						Demod.output[Demod.len] = 0xab;
						Demod.state = DEMOD_ERROR_WAIT;
						error = 0xd4;
					}
					break;
				case DEMOD_SOF_COMPLETE:
				case DEMOD_MANCHESTER_D:
				case DEMOD_MANCHESTER_E:
					// OPPOSITE FROM ISO14443 - 11110000 = 0 (1 in 14443)
					//                          00001111 = 1 (0 in 14443)
					if (Demod.sub == SUB_SECOND_HALF) { // SUB_FIRST_HALF
						Demod.bitCount++;
						Demod.shiftReg = (Demod.shiftReg >> 1) ^ 0x100;
						Demod.state = DEMOD_MANCHESTER_D;
					} else if (Demod.sub == SUB_FIRST_HALF) { // SUB_SECOND_HALF
						Demod.bitCount++;
						Demod.shiftReg >>= 1;
						Demod.state = DEMOD_MANCHESTER_E;
					} else if (Demod.sub == SUB_BOTH) {
						Demod.state = DEMOD_MANCHESTER_F;
					} else {
						Demod.state = DEMOD_ERROR_WAIT;
						error = 0x55;
					}
					break;

				case DEMOD_MANCHESTER_F:
					// Tag response does not need to be a complete byte!
					if (Demod.len > 0 || Demod.bitCount > 0) {
						if (Demod.bitCount > 1) {  // was > 0, do not interpret last closing bit, is part of EOF
							Demod.shiftReg >>= (9 - Demod.bitCount);    // right align data
							Demod.output[Demod.len] = Demod.shiftReg & 0xff;
							Demod.len++;
						}

						Demod.state = DEMOD_UNSYNCD;
						return true;
					} else {
						Demod.output[Demod.len] = 0xad;
						Demod.state = DEMOD_ERROR_WAIT;
						error = 0x03;
					}
					break;

				case DEMOD_ERROR_WAIT:
					Demod.state = DEMOD_UNSYNCD;
					break;

				default:
					Demod.output[Demod.len] = 0xdd;
					Demod.state = DEMOD_UNSYNCD;
					break;
			}

			/*if (Demod.bitCount>=9) {
				Demod.output[Demod.len] = Demod.shiftReg & 0xff;
				Demod.len++;

				Demod.parityBits <<= 1;
				Demod.parityBits ^= ((Demod.shiftReg >> 8) & 0x01);

				Demod.bitCount = 0;
				Demod.shiftReg = 0;
			}*/
			if (Demod.bitCount >= 8) {
				Demod.shiftReg >>= 1;
				Demod.output[Demod.len] = (Demod.shiftReg & 0xff);
				Demod.len++;
				Demod.bitCount = 0;
				Demod.shiftReg = 0;
			}

			if (error) {
				Demod.output[Demod.len] = 0xBB;
				Demod.len++;
				Demod.output[Demod.len] = error & 0xFF;
				Demod.len++;
				Demod.output[Demod.len] = 0xBB;
				Demod.len++;
				Demod.output[Demod.len] = bit & 0xFF;
				Demod.len++;
				Demod.output[Demod.len] = Demod.buffer & 0xFF;
				Demod.len++;
				// Look harder ;-)
				Demod.output[Demod.len] = Demod.buffer2 & 0xFF;
				Demod.len++;
				Demod.output[Demod.len] = Demod.syncBit & 0xFF;
				Demod.len++;
				Demod.output[Demod.len] = 0xBB;
				Demod.len++;
				return true;
			}

		}

	} // end (state != UNSYNCED)

	return false;
}

//=============================================================================
// Finally, a `sniffer' for iClass communication
// Both sides of communication!
//=============================================================================

//-----------------------------------------------------------------------------
// Record the sequence of commands sent by the reader to the tag, with
// triggering so that we start recording at the point that the tag is moved
// near the reader.
//-----------------------------------------------------------------------------
void RAMFUNC SnoopIClass(void) {

	// 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.
	// The length of a received command will in most cases be no more than 18 bytes.
	// So 32 should be enough!
	#define ICLASS_BUFFER_SIZE 32
	uint8_t readerToTagCmd[ICLASS_BUFFER_SIZE];
	// The response (tag -> reader) that we're receiving.
	uint8_t tagToReaderResponse[ICLASS_BUFFER_SIZE];

	FpgaDownloadAndGo(FPGA_BITSTREAM_HF);

	// free all BigBuf memory
	BigBuf_free();
	// The DMA buffer, used to stream samples from the FPGA
	uint8_t *dmaBuf = BigBuf_malloc(DMA_BUFFER_SIZE);

	set_tracing(true);
	clear_trace();
	iso14a_set_trigger(false);

	int lastRxCounter;
	uint8_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;
	rsamples = 0;

	// Set up the demodulator for tag -> reader responses.
	Demod.output = tagToReaderResponse;
	Demod.len = 0;
	Demod.state = DEMOD_UNSYNCD;

	// Setup for the DMA.
	FpgaSetupSsc(FPGA_MAJOR_MODE_HF_ISO14443A);
	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 = readerToTagCmd;
	Uart.byteCntMax = 32; // was 100 (greg)////////////////////////////////////////////////////////////////////////
	Uart.state = STATE_UNSYNCD;

	// 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);

	uint32_t time_0 = GetCountSspClk();
	uint32_t time_start = 0;
	uint32_t time_stop  = 0;

	int div = 0;
	//int div2 = 0;
	int decbyte = 0;
	int decbyter = 0;

	// 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 > (9 * DMA_BUFFER_SIZE / 10)) {
				Dbprintf("blew circular buffer! behindBy=0x%x", behindBy);
				goto done;
			}
		}
		if (behindBy < 1) continue;

		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;
		}

		//samples += 4;
		samples += 1;

		if (smpl & 0xF) {
			decbyte ^= (1 << (3 - div));
		}

		// FOR READER SIDE COMMUMICATION...

		decbyter <<= 2;
		decbyter ^= (smpl & 0x30);

		div++;

		if ((div + 1) % 2 == 0) {
			smpl = decbyter;
			if (OutOfNDecoding((smpl & 0xF0) >> 4)) {
				rsamples = samples - Uart.samples;
				time_stop = (GetCountSspClk()-time_0) << 4;
				LED_C_ON();

				//if (!LogTrace(Uart.output, Uart.byteCnt, rsamples, Uart.parityBits,true)) break;
				//if (!LogTrace(NULL, 0, Uart.endTime*16 - DELAY_READER_AIR2ARM_AS_SNIFFER, 0, true)) break;
				uint8_t parity[MAX_PARITY_SIZE];
				GetParity(Uart.output, Uart.byteCnt, parity);
				LogTrace(Uart.output, Uart.byteCnt, time_start, time_stop, parity, true);

				/* 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();
				Uart.byteCnt = 0;
			} else {
				time_start = (GetCountSspClk()-time_0) << 4;
			}
			decbyter = 0;
		}

		if (div > 3) {
			smpl = decbyte;
			if (ManchesterDecoding(smpl & 0x0F)) {
				time_stop = (GetCountSspClk()-time_0) << 4;

				rsamples = samples - Demod.samples;
				LED_B_ON();

				uint8_t parity[MAX_PARITY_SIZE];
				GetParity(Demod.output, Demod.len, parity);
				LogTrace(Demod.output, Demod.len, time_start, time_stop, parity, false);

				// And ready to receive another response.
				memset(&Demod, 0, sizeof(Demod));
				Demod.output = tagToReaderResponse;
				Demod.state = DEMOD_UNSYNCD;
				LED_C_OFF();
			} else {
				time_start = (GetCountSspClk()-time_0) << 4;
			}

			div = 0;
			decbyte = 0x00;
		}

		if (BUTTON_PRESS()) {
			DbpString("cancelled_a");
			goto done;
		}
	}

	DbpString("COMMAND FINISHED");

	Dbprintf("%x %x %x", maxBehindBy, Uart.state, Uart.byteCnt);
	Dbprintf("%x %x %x", Uart.byteCntMax, BigBuf_get_traceLen(), (int)Uart.output[0]);

done:
	AT91C_BASE_PDC_SSC->PDC_PTCR = AT91C_PDC_RXTDIS;
	Dbprintf("%x %x %x", maxBehindBy, Uart.state, Uart.byteCnt);
	Dbprintf("%x %x %x", Uart.byteCntMax, BigBuf_get_traceLen(), (int)Uart.output[0]);
	LEDsoff();
}

void rotateCSN(uint8_t* originalCSN, uint8_t* rotatedCSN) {
	int i;
	for (i = 0; i < 8; i++) {
		rotatedCSN[i] = (originalCSN[i] >> 3) | (originalCSN[(i+1)%8] << 5);
	}
}

//-----------------------------------------------------------------------------
// Wait for commands from reader
// Stop when button is pressed
// Or return true when command is captured
//-----------------------------------------------------------------------------
static int GetIClassCommandFromReader(uint8_t *received, int *len, int maxLen)
{
	// Set FPGA mode to "simulated ISO 14443 tag", no modulation (listen
	// only, since we are receiving, not transmitting).
	// Signal field is off with the appropriate LED
	LED_D_OFF();
	FpgaWriteConfWord(FPGA_MAJOR_MODE_HF_ISO14443A | FPGA_HF_ISO14443A_TAGSIM_LISTEN);

	// Now run a `software UART' on the stream of incoming samples.
	Uart.output = received;
	Uart.byteCntMax = maxLen;
	Uart.state = STATE_UNSYNCD;

	for (;;) {
		WDT_HIT();

		if (BUTTON_PRESS()) return false;

		if (AT91C_BASE_SSC->SSC_SR & (AT91C_SSC_TXRDY)) {
			AT91C_BASE_SSC->SSC_THR = 0x00;
		}
		if (AT91C_BASE_SSC->SSC_SR & (AT91C_SSC_RXRDY)) {
			uint8_t b = (uint8_t)AT91C_BASE_SSC->SSC_RHR;

			if (OutOfNDecoding(b & 0x0f)) {
				*len = Uart.byteCnt;
				return true;
			}
		}
	}
}

static uint8_t encode4Bits(const uint8_t b) {
	uint8_t c = b & 0xF;
	// OTA, the least significant bits first
	//         The columns are
	//               1 - Bit value to send
	//               2 - Reversed (big-endian)
	//               3 - Encoded
	//               4 - Hex values

	switch(c){
	//                          1       2         3         4
	  case 15: return 0x55; // 1111 -> 1111 -> 01010101 -> 0x55
	  case 14: return 0x95; // 1110 -> 0111 -> 10010101 -> 0x95
	  case 13: return 0x65; // 1101 -> 1011 -> 01100101 -> 0x65
	  case 12: return 0xa5; // 1100 -> 0011 -> 10100101 -> 0xa5
	  case 11: return 0x59; // 1011 -> 1101 -> 01011001 -> 0x59
	  case 10: return 0x99; // 1010 -> 0101 -> 10011001 -> 0x99
	  case 9:  return 0x69; // 1001 -> 1001 -> 01101001 -> 0x69
	  case 8:  return 0xa9; // 1000 -> 0001 -> 10101001 -> 0xa9
	  case 7:  return 0x56; // 0111 -> 1110 -> 01010110 -> 0x56
	  case 6:  return 0x96; // 0110 -> 0110 -> 10010110 -> 0x96
	  case 5:  return 0x66; // 0101 -> 1010 -> 01100110 -> 0x66
	  case 4:  return 0xa6; // 0100 -> 0010 -> 10100110 -> 0xa6
	  case 3:  return 0x5a; // 0011 -> 1100 -> 01011010 -> 0x5a
	  case 2:  return 0x9a; // 0010 -> 0100 -> 10011010 -> 0x9a
	  case 1:  return 0x6a; // 0001 -> 1000 -> 01101010 -> 0x6a
	  default: return 0xaa; // 0000 -> 0000 -> 10101010 -> 0xaa

	}
}

//-----------------------------------------------------------------------------
// Prepare tag messages
//-----------------------------------------------------------------------------
static void CodeIClassTagAnswer(const uint8_t *cmd, int len) {

	/*
	 * SOF comprises 3 parts;
	 * * An unmodulated time of 56.64 us
	 * * 24 pulses of 423.75 kHz (fc/32)
	 * * A logic 1, which starts with an unmodulated time of 18.88us
	 *   followed by 8 pulses of 423.75kHz (fc/32)
	 *
	 *
	 * EOF comprises 3 parts:
	 * - A logic 0 (which starts with 8 pulses of fc/32 followed by an unmodulated
	 *   time of 18.88us.
	 * - 24 pulses of fc/32
	 * - An unmodulated time of 56.64 us
	 *
	 *
	 * A logic 0 starts with 8 pulses of fc/32
	 * followed by an unmodulated time of 256/fc (~18,88us).
	 *
	 * A logic 0 starts with unmodulated time of 256/fc (~18,88us) followed by
	 * 8 pulses of fc/32 (also 18.88us)
	 *
	 * The mode FPGA_HF_SIMULATOR_MODULATE_424K_8BIT which we use to simulate tag,
	 * works like this.
	 * - A 1-bit input to the FPGA becomes 8 pulses on 423.5kHz (fc/32) (18.88us).
	 * - A 0-bit input to the FPGA becomes an unmodulated time of 18.88us
	 *
	 * In this mode the SOF can be written as 00011101 = 0x1D
	 * The EOF can be written as 10111000 = 0xb8
	 * A logic 1 is 01
	 * A logic 0 is 10
	 *
	 * */

	int i;

	ToSendReset();

	// Send SOF
	ToSend[++ToSendMax] = 0x1D;

	for (i = 0; i < len; i++) {
		uint8_t b = cmd[i];
		ToSend[++ToSendMax] = encode4Bits(b & 0xF);       // Least significant half
		ToSend[++ToSendMax] = encode4Bits((b >>4) & 0xF); // Most significant half
	}

	// Send EOF
	ToSend[++ToSendMax] = 0xB8;
	//lastProxToAirDuration  = 8*ToSendMax - 3*8 - 3*8;//Not counting zeroes in the beginning or end
	// Convert from last byte pos to length
	ToSendMax++;
}

// Only SOF
static void CodeIClassTagSOF() {
	//So far a dummy implementation, not used
	//int lastProxToAirDuration =0;

	ToSendReset();
	// Send SOF
	ToSend[++ToSendMax] = 0x1D;
//  lastProxToAirDuration  = 8*ToSendMax - 3*8;//Not counting zeroes in the beginning

	// Convert from last byte pos to length
	ToSendMax++;
}

static void AppendCrc(uint8_t *data, int len) {
	ComputeCrc14443(CRC_ICLASS, data, len, data+len, data+len+1);
}

static int SendIClassAnswer(uint8_t *resp, int respLen, int delay) {
	int i = 0, d = 0;//, u = 0, d = 0;
	uint8_t b = 0;

	//FpgaWriteConfWord(FPGA_MAJOR_MODE_HF_SIMULATOR|FPGA_HF_SIMULATOR_MODULATE_424K);
	FpgaWriteConfWord(FPGA_MAJOR_MODE_HF_SIMULATOR | FPGA_HF_SIMULATOR_MODULATE_424K_8BIT);

	AT91C_BASE_SSC->SSC_THR = 0x00;
	FpgaSetupSsc(FPGA_MAJOR_MODE_HF_SIMULATOR);
	while (!BUTTON_PRESS()) {
		if ((AT91C_BASE_SSC->SSC_SR & AT91C_SSC_RXRDY)){
			b = AT91C_BASE_SSC->SSC_RHR; (void) b;
		}
		if (AT91C_BASE_SSC->SSC_SR & (AT91C_SSC_TXRDY)){
			b = 0x00;
			if (d < delay) {
				d++;
			}
			else {
				if (i < respLen) {
					b = resp[i];
					//Hack
					//b = 0xAC;
				}
				i++;
			}
			AT91C_BASE_SSC->SSC_THR = b;
		}

//      if (i > respLen +4) break;
		if (i > respLen + 1) break;
	}

	return 0;
}


#define MODE_SIM_CSN        0
#define MODE_EXIT_AFTER_MAC 1
#define MODE_FULLSIM        2

/**
 * @brief Does the actual simulation
 * @param csn - csn to use
 * @param breakAfterMacReceived if true, returns after reader MAC has been received.
 */
int doIClassSimulation(int simulationMode, uint8_t *reader_mac_buf) {
	// free eventually allocated BigBuf memory
	BigBuf_free_keep_EM();

	State cipher_state;
//  State cipher_state_reserve;
	uint8_t *csn = BigBuf_get_EM_addr();
	uint8_t *emulator = csn;
	uint8_t sof_data[] = { 0x0F} ;
	// CSN followed by two CRC bytes
	uint8_t anticoll_data[10] = { 0 };
	uint8_t csn_data[10] = { 0 };
	memcpy(csn_data, csn, sizeof(csn_data));
	Dbprintf("Simulating CSN %02x%02x%02x%02x%02x%02x%02x%02x", csn[0], csn[1], csn[2], csn[3], csn[4], csn[5], csn[6], csn[7]);

	// Construct anticollision-CSN
	rotateCSN(csn_data, anticoll_data);

	// Compute CRC on both CSNs
	ComputeCrc14443(CRC_ICLASS, anticoll_data, 8, &anticoll_data[8], &anticoll_data[9]);
	ComputeCrc14443(CRC_ICLASS, csn_data, 8, &csn_data[8], &csn_data[9]);

	uint8_t diversified_key[8] = { 0 };
	// e-Purse
	uint8_t card_challenge_data[8] = { 0x00 };
	if (simulationMode == MODE_FULLSIM) {
		//The diversified key should be stored on block 3
		//Get the diversified key from emulator memory
		memcpy(diversified_key, emulator + (8*3), 8);
		//Card challenge, a.k.a e-purse is on block 2
		memcpy(card_challenge_data, emulator + (8 * 2), 8);
		//Precalculate the cipher state, feeding it the CC
		cipher_state = opt_doTagMAC_1(card_challenge_data, diversified_key);
	}

	int exitLoop = 0;
	// Reader 0a
	// Tag    0f
	// Reader 0c
	// Tag    anticoll. CSN
	// Reader 81 anticoll. CSN
	// Tag    CSN

	uint8_t *modulated_response;
	int modulated_response_size = 0;
	uint8_t *trace_data = NULL;
	int trace_data_size = 0;

	// Respond SOF -- takes 1 bytes
	uint8_t *resp_sof = BigBuf_malloc(2);
	int resp_sof_Len;

	// Anticollision CSN (rotated CSN)
	// 22: Takes 2 bytes for SOF/EOF and 10 * 2 = 20 bytes (2 bytes/byte)
	uint8_t *resp_anticoll = BigBuf_malloc(28);
	int resp_anticoll_len;

	// CSN
	// 22: Takes 2 bytes for SOF/EOF and 10 * 2 = 20 bytes (2 bytes/byte)
	uint8_t *resp_csn = BigBuf_malloc(30);
	int resp_csn_len;

	// e-Purse
	// 18: Takes 2 bytes for SOF/EOF and 8 * 2 = 16 bytes (2 bytes/bit)
	uint8_t *resp_cc = BigBuf_malloc(20);
	int resp_cc_len;

	uint8_t *receivedCmd = BigBuf_malloc(MAX_FRAME_SIZE);
	int len;

	// Prepare card messages
	ToSendMax = 0;

	// First card answer: SOF
	CodeIClassTagSOF();
	memcpy(resp_sof, ToSend, ToSendMax);
	resp_sof_Len = ToSendMax;

	// Anticollision CSN
	CodeIClassTagAnswer(anticoll_data, sizeof(anticoll_data));
	memcpy(resp_anticoll, ToSend, ToSendMax);
	resp_anticoll_len = ToSendMax;

	// CSN
	CodeIClassTagAnswer(csn_data, sizeof(csn_data));
	memcpy(resp_csn, ToSend, ToSendMax);
	resp_csn_len = ToSendMax;

	// e-Purse
	CodeIClassTagAnswer(card_challenge_data, sizeof(card_challenge_data));
	memcpy(resp_cc, ToSend, ToSendMax); resp_cc_len = ToSendMax;

	//This is used for responding to READ-block commands or other data which is dynamically generated
	//First the 'trace'-data, not encoded for FPGA
	uint8_t *data_generic_trace = BigBuf_malloc(8 + 2);//8 bytes data + 2byte CRC is max tag answer
	//Then storage for the modulated data
	//Each bit is doubled when modulated for FPGA, and we also have SOF and EOF (2 bytes)
	uint8_t *data_response = BigBuf_malloc( (8+2) * 2 + 2);

	// Start from off (no field generated)
	//FpgaWriteConfWord(FPGA_MAJOR_MODE_OFF);
	//SpinDelay(200);
	FpgaWriteConfWord(FPGA_MAJOR_MODE_HF_ISO14443A | FPGA_HF_ISO14443A_TAGSIM_LISTEN);
	SpinDelay(100);
	StartCountSspClk();
	// We need to listen to the high-frequency, peak-detected path.
	SetAdcMuxFor(GPIO_MUXSEL_HIPKD);
	FpgaSetupSsc(FPGA_MAJOR_MODE_HF_ISO14443A);

	// To control where we are in the protocol
	int cmdsRecvd = 0;
	uint32_t time_0 = GetCountSspClk();
	uint32_t t2r_time =0;
	uint32_t r2t_time =0;

	LED_A_ON();
	bool buttonPressed = false;
	uint8_t response_delay = 1;
	while (!exitLoop) {
		response_delay = 1;
		LED_B_OFF();
		//Signal tracer
		// Can be used to get a trigger for an oscilloscope..
		LED_C_OFF();

		if (!GetIClassCommandFromReader(receivedCmd, &len, 100)) {
			buttonPressed = true;
			break;
		}
		r2t_time = GetCountSspClk();
		//Signal tracer
		LED_C_ON();

		// Okay, look at the command now.
		if (receivedCmd[0] == ICLASS_CMD_ACTALL) {
			// Reader in anticollission phase
			modulated_response = resp_sof;
			modulated_response_size = resp_sof_Len; //order = 1;
			trace_data = sof_data;
			trace_data_size = sizeof(sof_data);
		} else if (receivedCmd[0] == ICLASS_CMD_READ_OR_IDENTIFY && len == 1) {
			// Reader asks for anticollission CSN
			modulated_response = resp_anticoll;
			modulated_response_size = resp_anticoll_len; //order = 2;
			trace_data = anticoll_data;
			trace_data_size = sizeof(anticoll_data);
			//DbpString("Reader requests anticollission CSN:");
		} else if (receivedCmd[0] == ICLASS_CMD_SELECT) {
			// Reader selects anticollission CSN.
			// Tag sends the corresponding real CSN
			modulated_response = resp_csn;
			modulated_response_size = resp_csn_len; //order = 3;
			trace_data = csn_data;
			trace_data_size = sizeof(csn_data);
			//DbpString("Reader selects anticollission CSN:");
		} else if (receivedCmd[0] == ICLASS_CMD_READCHECK_KD) {
			// Read e-purse (88 02)
			modulated_response = resp_cc;
			modulated_response_size = resp_cc_len; //order = 4;
			trace_data = card_challenge_data;
			trace_data_size = sizeof(card_challenge_data);
			LED_B_ON();
		} else if (receivedCmd[0] == ICLASS_CMD_CHECK) {
			// Reader random and reader MAC!!!
			if (simulationMode == MODE_FULLSIM) {
				//NR, from reader, is in receivedCmd +1
				opt_doTagMAC_2(cipher_state, receivedCmd+1, data_generic_trace, diversified_key);

				trace_data = data_generic_trace;
				trace_data_size = 4;
				CodeIClassTagAnswer(trace_data, trace_data_size);
				memcpy(data_response, ToSend, ToSendMax);
				modulated_response = data_response;
				modulated_response_size = ToSendMax;
				response_delay = 0; //We need to hurry here... (but maybe not too much... ??)
				//exitLoop = true;
			} else {    //Not fullsim, we don't respond
				// We do not know what to answer, so lets keep quiet
				modulated_response = resp_sof;
				modulated_response_size = 0;
				trace_data = NULL;
				trace_data_size = 0;
				if (simulationMode == MODE_EXIT_AFTER_MAC) {
					// dbprintf:ing ...
					Dbprintf("CSN: %02x %02x %02x %02x %02x %02x %02x %02x"
							   ,csn[0],csn[1],csn[2],csn[3],csn[4],csn[5],csn[6],csn[7]);
					Dbprintf("RDR:  (len=%02d): %02x %02x %02x %02x %02x %02x %02x %02x %02x",len,
							receivedCmd[0], receivedCmd[1], receivedCmd[2],
							receivedCmd[3], receivedCmd[4], receivedCmd[5],
							receivedCmd[6], receivedCmd[7], receivedCmd[8]);
					if (reader_mac_buf != NULL) {
						memcpy(reader_mac_buf, receivedCmd+1, 8);
					}
					exitLoop = true;
				}
			}

		} else if (receivedCmd[0] == ICLASS_CMD_HALT && len == 1) {
			// Reader ends the session
			modulated_response = resp_sof;
			modulated_response_size = 0; //order = 0;
			trace_data = NULL;
			trace_data_size = 0;
		} else if (simulationMode == MODE_FULLSIM && receivedCmd[0] == ICLASS_CMD_READ_OR_IDENTIFY && len == 4) {
			//Read block
			uint16_t blk = receivedCmd[1];
			//Take the data...
			memcpy(data_generic_trace, emulator + (blk << 3), 8);
			//Add crc
			AppendCrc(data_generic_trace, 8);
			trace_data = data_generic_trace;
			trace_data_size = 10;
			CodeIClassTagAnswer(trace_data, trace_data_size);
			memcpy(data_response, ToSend, ToSendMax);
			modulated_response = data_response;
			modulated_response_size = ToSendMax;
		} else if (receivedCmd[0] == ICLASS_CMD_UPDATE && simulationMode == MODE_FULLSIM) {
			//Probably the reader wants to update the nonce. Let's just ignore that for now.
			// OBS! If this is implemented, don't forget to regenerate the cipher_state
			//We're expected to respond with the data+crc, exactly what's already in the receivedcmd
			//receivedcmd is now UPDATE 1b | ADDRESS 1b| DATA 8b| Signature 4b or CRC 2b|

			//Take the data...
			memcpy(data_generic_trace, receivedCmd+2, 8);
			//Add crc
			AppendCrc(data_generic_trace, 8);
			trace_data = data_generic_trace;
			trace_data_size = 10;
			CodeIClassTagAnswer(trace_data, trace_data_size);
			memcpy(data_response, ToSend, ToSendMax);
			modulated_response = data_response;
			modulated_response_size = ToSendMax;
		} else if (receivedCmd[0] == ICLASS_CMD_PAGESEL) {
			//Pagesel
			//Pagesel enables to select a page in the selected chip memory and return its configuration block
			//Chips with a single page will not answer to this command
			// It appears we're fine ignoring this.
			//Otherwise, we should answer 8bytes (block) + 2bytes CRC
		} else {
			//#db# Unknown command received from reader (len=5): 26 1 0 f6 a 44 44 44 44
			// 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]);
			// Do not respond
			modulated_response = resp_sof;
			modulated_response_size = 0; //order = 0;
			trace_data = NULL;
			trace_data_size = 0;
		}

		if (cmdsRecvd >  100) {
			//DbpString("100 commands later...");
			//break;
		} else {
			cmdsRecvd++;
		}
		/**
		A legit tag has about 380us delay between reader EOT and tag SOF.
		**/
		if (modulated_response_size > 0) {
			SendIClassAnswer(modulated_response, modulated_response_size, response_delay);
			t2r_time = GetCountSspClk();
		}

		uint8_t parity[MAX_PARITY_SIZE];
		GetParity(receivedCmd, len, parity);
		LogTrace(receivedCmd, len, (r2t_time-time_0) << 4, (r2t_time-time_0) << 4, parity, true);

		if (trace_data != NULL) {
			GetParity(trace_data, trace_data_size, parity);
			LogTrace(trace_data, trace_data_size, (t2r_time-time_0) << 4, (t2r_time-time_0) << 4, parity, false);
		}
		if (!get_tracing()) {
			DbpString("Trace full");
			//break;
		}
	}

	//Dbprintf("%x", cmdsRecvd);
	LED_A_OFF();
	LED_B_OFF();
	LED_C_OFF();

	if (buttonPressed)
	{
		DbpString("Button pressed");
	}
	return buttonPressed;
}

/**
 * @brief SimulateIClass simulates an iClass card.
 * @param arg0 type of simulation
 *          - 0 uses the first 8 bytes in usb data as CSN
 *          - 2 "dismantling iclass"-attack. This mode iterates through all CSN's specified
 *          in the usb data. This mode collects MAC from the reader, in order to do an offline
 *          attack on the keys. For more info, see "dismantling iclass" and proxclone.com.
 *          - Other : Uses the default CSN (031fec8af7ff12e0)
 * @param arg1 - number of CSN's contained in datain (applicable for mode 2 only)
 * @param arg2
 * @param datain
 */
void SimulateIClass(uint32_t arg0, uint32_t arg1, uint32_t arg2, uint8_t *datain) {
	uint32_t simType = arg0;
	uint32_t numberOfCSNS = arg1;
	FpgaDownloadAndGo(FPGA_BITSTREAM_HF);

	// Enable and clear the trace
	set_tracing(true);
	clear_trace();
	//Use the emulator memory for SIM
	uint8_t *emulator = BigBuf_get_EM_addr();

	if (simType == 0) {
		// Use the CSN from commandline
		memcpy(emulator, datain, 8);
		doIClassSimulation(MODE_SIM_CSN,NULL);
	} else if (simType == 1) {
		//Default CSN
		uint8_t csn_crc[] = { 0x03, 0x1f, 0xec, 0x8a, 0xf7, 0xff, 0x12, 0xe0, 0x00, 0x00 };
		// Use the CSN from commandline
		memcpy(emulator, csn_crc, 8);
		doIClassSimulation(MODE_SIM_CSN,NULL);
	} else if (simType == 2) {
		uint8_t mac_responses[USB_CMD_DATA_SIZE] = { 0 };
		Dbprintf("Going into attack mode, %d CSNS sent", numberOfCSNS);
		// In this mode, a number of csns are within datain. We'll simulate each one, one at a time
		// in order to collect MAC's from the reader. This can later be used in an offlne-attack
		// in order to obtain the keys, as in the "dismantling iclass"-paper.
		int i = 0;
		for ( ; i < numberOfCSNS && i*8+8 < USB_CMD_DATA_SIZE; i++) {
			// The usb data is 512 bytes, fitting 65 8-byte CSNs in there.
			memcpy(emulator, datain+(i*8), 8);
			if (doIClassSimulation(MODE_EXIT_AFTER_MAC,mac_responses+i*8)) {
				cmd_send(CMD_ACK, CMD_SIMULATE_TAG_ICLASS, i, 0, mac_responses, i*8);
				return; // Button pressed
			}
		}
		cmd_send(CMD_ACK, CMD_SIMULATE_TAG_ICLASS, i, 0, mac_responses, i*8);
	} else if (simType == 3) {
		//This is 'full sim' mode, where we use the emulator storage for data.
		doIClassSimulation(MODE_FULLSIM, NULL);
	} else {
		// We may want a mode here where we hardcode the csns to use (from proxclone).
		// That will speed things up a little, but not required just yet.
		Dbprintf("The mode is not implemented, reserved for future use");
	}
	Dbprintf("Done...");

}


/// THE READER CODE

//-----------------------------------------------------------------------------
// Transmit the command (to the tag) that was placed in ToSend[].
//-----------------------------------------------------------------------------
static void TransmitIClassCommand(const uint8_t *cmd, int len, int *samples, int *wait) {
	int c;
	FpgaWriteConfWord(FPGA_MAJOR_MODE_HF_ISO14443A | FPGA_HF_ISO14443A_READER_MOD);
	AT91C_BASE_SSC->SSC_THR = 0x00;
	FpgaSetupSsc(FPGA_MAJOR_MODE_HF_ISO14443A);

	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();
		}
	}

	uint8_t sendbyte;
	bool firstpart = true;
	c = 0;
	for (;;) {
		if (AT91C_BASE_SSC->SSC_SR & (AT91C_SSC_TXRDY)) {

			// DOUBLE THE SAMPLES!
			if (firstpart) {
				sendbyte = (cmd[c] & 0xf0) | (cmd[c] >> 4);
			} else {
				sendbyte = (cmd[c] & 0x0f) | (cmd[c] << 4);
				c++;
			}
			if (sendbyte == 0xff) {
				sendbyte = 0xfe;
			}
			AT91C_BASE_SSC->SSC_THR = sendbyte;
			firstpart = !firstpart;

			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 && wait) *samples = (c + *wait) << 3;
}


//-----------------------------------------------------------------------------
// Prepare iClass reader command to send to FPGA
//-----------------------------------------------------------------------------
void CodeIClassCommand(const uint8_t *cmd, int len) {
	int i, j, k;

	ToSendReset();

	// Start of Communication: 1 out of 4
	ToSend[++ToSendMax] = 0xf0;
	ToSend[++ToSendMax] = 0x00;
	ToSend[++ToSendMax] = 0x0f;
	ToSend[++ToSendMax] = 0x00;

	// Modulate the bytes
	for (i = 0; i < len; i++) {
		uint8_t b = cmd[i];
		for (j = 0; j < 4; j++) {
			for (k = 0; k < 4; k++) {
				if (k == (b & 3)) {
					ToSend[++ToSendMax] = 0x0f;
				} else {
					ToSend[++ToSendMax] = 0x00;
				}
			}
			b >>= 2;
		}
	}

	// End of Communication
	ToSend[++ToSendMax] = 0x00;
	ToSend[++ToSendMax] = 0x00;
	ToSend[++ToSendMax] = 0xf0;
	ToSend[++ToSendMax] = 0x00;

	// Convert from last character reference to length
	ToSendMax++;
}

static void ReaderTransmitIClass(uint8_t *frame, int len) {
	int wait = 0;
	int samples = 0;

	// This is tied to other size changes
	CodeIClassCommand(frame, len);

	// Select the card
	TransmitIClassCommand(ToSend, ToSendMax, &samples, &wait);
	if (trigger)
		LED_A_ON();

	// Store reader command in buffer
	uint8_t par[MAX_PARITY_SIZE];
	GetParity(frame, len, par);
	LogTrace(frame, len, rsamples, rsamples, par, true);
}

//-----------------------------------------------------------------------------
// Wait a certain time for tag response
//  If a response is captured return true
//  If it takes too long return false
//-----------------------------------------------------------------------------
static int GetIClassAnswer(uint8_t *receivedResponse, int maxLen, int *samples, int *elapsed) {
	//uint8_t *buffer
	// buffer needs to be 512 bytes
	int c;

	// Set FPGA mode to "reader listen mode", no modulation (listen
	// only, since we are receiving, not transmitting).
	FpgaWriteConfWord(FPGA_MAJOR_MODE_HF_ISO14443A | FPGA_HF_ISO14443A_READER_LISTEN);

	// Now get the answer from the card
	Demod.output = receivedResponse;
	Demod.len = 0;
	Demod.state = DEMOD_UNSYNCD;

	uint8_t b;
	if (elapsed) *elapsed = 0;

	bool skip = false;

	c = 0;
	for (;;) {
		WDT_HIT();

		if (BUTTON_PRESS()) return false;

		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 < timeout) { 
				c++; 
			} else { 
				return false; 
			}
			b = (uint8_t)AT91C_BASE_SSC->SSC_RHR;
			skip = !skip;
			if (skip) continue;

			if (ManchesterDecoding(b & 0x0f)) {
				*samples = c << 3;
				return  true;
			}
		}
	}
}

static int ReaderReceiveIClass(uint8_t *receivedAnswer) {
	int samples = 0;
	if (!GetIClassAnswer(receivedAnswer, 160, &samples, 0)) {
		return false;
	}
	rsamples += samples;
	uint8_t parity[MAX_PARITY_SIZE];
	GetParity(receivedAnswer, Demod.len, parity);
	LogTrace(receivedAnswer, Demod.len, rsamples, rsamples, parity, false);
	if (samples == 0) return false;
	return Demod.len;
}

static void setupIclassReader() {
	FpgaDownloadAndGo(FPGA_BITSTREAM_HF);
	// Reset trace buffer
	set_tracing(true);
	clear_trace();

	// Setup SSC
	FpgaSetupSsc(FPGA_MAJOR_MODE_HF_ISO14443A);
	// Start from off (no field generated)
	// Signal field is off with the appropriate LED
	LED_D_OFF();
	FpgaWriteConfWord(FPGA_MAJOR_MODE_OFF);
	SpinDelay(200);

	SetAdcMuxFor(GPIO_MUXSEL_HIPKD);

	// Now give it time to spin up.
	// Signal field is on with the appropriate LED
	FpgaWriteConfWord(FPGA_MAJOR_MODE_HF_ISO14443A | FPGA_HF_ISO14443A_READER_MOD);
	SpinDelay(200);
	LED_A_ON();

}

static bool sendCmdGetResponseWithRetries(uint8_t* command, size_t cmdsize, uint8_t* resp, uint8_t expected_size, uint8_t retries) {
	while (retries-- > 0) {
		ReaderTransmitIClass(command, cmdsize);
		if (expected_size == ReaderReceiveIClass(resp)) {
			return true;
		}
	}
	return false;//Error
}

/**
 * @brief Talks to an iclass tag, sends the commands to get CSN and CC.
 * @param card_data where the CSN and CC are stored for return
 * @return 0 = fail
 *         1 = Got CSN
 *         2 = Got CSN and CC
 */
static uint8_t handshakeIclassTag_ext(uint8_t *card_data, bool use_credit_key) {
	static uint8_t act_all[]     = { 0x0a };
	//static uint8_t identify[]    = { 0x0c };
	static uint8_t identify[]    = { 0x0c, 0x00, 0x73, 0x33 };
	static uint8_t select[]      = { 0x81, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00 };
	static uint8_t readcheck_cc[]= { 0x88, 0x02 };
	if (use_credit_key)
		readcheck_cc[0] = 0x18;
	else
		readcheck_cc[0] = 0x88;

	uint8_t resp[ICLASS_BUFFER_SIZE];

	uint8_t read_status = 0;

	// Send act_all
	ReaderTransmitIClass(act_all, 1);
	// Card present?
	if (!ReaderReceiveIClass(resp)) return read_status;//Fail
	//Send Identify
	ReaderTransmitIClass(identify, 1);
	//We expect a 10-byte response here, 8 byte anticollision-CSN and 2 byte CRC
	uint8_t len = ReaderReceiveIClass(resp);
	if (len != 10) return read_status;//Fail

	//Copy the Anti-collision CSN to our select-packet
	memcpy(&select[1], resp, 8);
	//Select the card
	ReaderTransmitIClass(select, sizeof(select));
	//We expect a 10-byte response here, 8 byte CSN and 2 byte CRC
	len = ReaderReceiveIClass(resp);
	if (len != 10) return read_status;//Fail

	//Success - level 1, we got CSN
	//Save CSN in response data
	memcpy(card_data, resp, 8);

	//Flag that we got to at least stage 1, read CSN
	read_status = 1;

	// Card selected, now read e-purse (cc) (only 8 bytes no CRC)
	ReaderTransmitIClass(readcheck_cc, sizeof(readcheck_cc));
	if (ReaderReceiveIClass(resp) == 8) {
		//Save CC (e-purse) in response data
		memcpy(card_data+8, resp, 8);
		read_status++;
	}

	return read_status;
}

static uint8_t handshakeIclassTag(uint8_t *card_data) {
	return handshakeIclassTag_ext(card_data, false);
}


// Reader iClass Anticollission
void ReaderIClass(uint8_t arg0) {

	uint8_t card_data[6 * 8] = {0};
	memset(card_data, 0xFF, sizeof(card_data));
	uint8_t last_csn[8] = {0,0,0,0,0,0,0,0};
	uint8_t resp[ICLASS_BUFFER_SIZE];
	memset(resp, 0xFF, sizeof(resp));
	//Read conf block CRC(0x01) => 0xfa 0x22
	uint8_t readConf[] = { ICLASS_CMD_READ_OR_IDENTIFY, 0x01, 0xfa, 0x22};
	//Read App Issuer Area block CRC(0x05) => 0xde  0x64
	uint8_t readAA[] = { ICLASS_CMD_READ_OR_IDENTIFY, 0x05, 0xde, 0x64};

	int read_status= 0;
	uint8_t result_status = 0;
	// flag to read until one tag is found successfully
	bool abort_after_read = arg0 & FLAG_ICLASS_READER_ONLY_ONCE;
	// flag to only try 5 times to find one tag then return
	bool try_once = arg0 & FLAG_ICLASS_READER_ONE_TRY;
	// if neither abort_after_read nor try_once then continue reading until button pressed.

	bool use_credit_key = arg0 & FLAG_ICLASS_READER_CEDITKEY;
	// test flags for what blocks to be sure to read
	uint8_t flagReadConfig = arg0 & FLAG_ICLASS_READER_CONF;
	uint8_t flagReadCC = arg0 & FLAG_ICLASS_READER_CC;
	uint8_t flagReadAA = arg0 & FLAG_ICLASS_READER_AA;

	set_tracing(true);
	setupIclassReader();

	uint16_t tryCnt = 0;
	bool userCancelled = BUTTON_PRESS() || usb_poll_validate_length();
	while (!userCancelled) {
		// if only looking for one card try 2 times if we missed it the first time
		if (try_once && tryCnt > 2) {
			break;
		}
		tryCnt++;
		if (!get_tracing()) {
			DbpString("Trace full");
			break;
		}
		WDT_HIT();

		read_status = handshakeIclassTag_ext(card_data, use_credit_key);

		if (read_status == 0) continue;
		if (read_status == 1) result_status = FLAG_ICLASS_READER_CSN;
		if (read_status == 2) result_status = FLAG_ICLASS_READER_CSN | FLAG_ICLASS_READER_CC;

		// handshakeIclass returns CSN|CC, but the actual block
		// layout is CSN|CONFIG|CC, so here we reorder the data,
		// moving CC forward 8 bytes
		memcpy(card_data+16, card_data+8, 8);
		//Read block 1, config
		if (flagReadConfig) {
			if (sendCmdGetResponseWithRetries(readConf, sizeof(readConf), resp, 10, 10)) {
				result_status |= FLAG_ICLASS_READER_CONF;
				memcpy(card_data+8, resp, 8);
			} else {
				Dbprintf("Failed to dump config block");
			}
		}

		//Read block 5, AA
		if (flagReadAA) {
			if (sendCmdGetResponseWithRetries(readAA, sizeof(readAA), resp, 10, 10)) {
				result_status |= FLAG_ICLASS_READER_AA;
				memcpy(card_data + (8*5), resp, 8);
			} else {
				//Dbprintf("Failed to dump AA block");
			}
		}

		// 0 : CSN
		// 1 : Configuration
		// 2 : e-purse
		// (3,4 write-only, kc and kd)
		// 5 Application issuer area
		//
		//Then we can 'ship' back the 8 * 6 bytes of data,
		// with 0xFF:s in block 3 and 4.

		LED_B_ON();
		//Send back to client, but don't bother if we already sent this -
		//  only useful if looping in arm (not try_once && not abort_after_read)
		if (memcmp(last_csn, card_data, 8) != 0) {
			// If caller requires that we get Conf, CC, AA, continue until we got it
			if ( (result_status ^ FLAG_ICLASS_READER_CSN ^ flagReadConfig ^ flagReadCC ^ flagReadAA) == 0) {
				cmd_send(CMD_ACK, result_status, 0, 0, card_data, sizeof(card_data));
				if (abort_after_read) {
					FpgaWriteConfWord(FPGA_MAJOR_MODE_OFF);
					LED_A_OFF();
					LED_B_OFF();
					return;
				}
				//Save that we already sent this....
				memcpy(last_csn, card_data, 8);
			}

		}
		LED_B_OFF();
		userCancelled = BUTTON_PRESS() || usb_poll_validate_length();
	}
	if (userCancelled) {
		cmd_send(CMD_ACK, 0xFF, 0, 0, card_data, 0);
	} else {
		cmd_send(CMD_ACK, 0, 0, 0, card_data, 0);
	}
	LED_A_OFF();
}

void ReaderIClass_Replay(uint8_t arg0, uint8_t *MAC) {

	uint8_t card_data[USB_CMD_DATA_SIZE]={0};
	uint16_t block_crc_LUT[255] = {0};

	//Generate a lookup table for block crc
	for (int block = 0; block < 255; block++){
		char bl = block;
		block_crc_LUT[block] = iclass_crc16(&bl ,1);
	}
	//Dbprintf("Lookup table: %02x %02x %02x" ,block_crc_LUT[0],block_crc_LUT[1],block_crc_LUT[2]);

	uint8_t check[]       = { 0x05, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00 };
	uint8_t read[]        = { 0x0c, 0x00, 0x00, 0x00 };

	uint16_t crc = 0;
	uint8_t cardsize = 0;
	uint8_t mem = 0;

	static struct memory_t {
		int k16;
		int book;
		int k2;
		int lockauth;
		int keyaccess;
	} memory;

	uint8_t resp[ICLASS_BUFFER_SIZE];

	setupIclassReader();
	set_tracing(true);

	while (!BUTTON_PRESS()) {

		WDT_HIT();

		if (!get_tracing()) {
			DbpString("Trace full");
			break;
		}

		uint8_t read_status = handshakeIclassTag(card_data);
		if (read_status < 2) continue;

		//for now replay captured auth (as cc not updated)
		memcpy(check+5, MAC, 4);

		if (!sendCmdGetResponseWithRetries(check, sizeof(check), resp, 4, 5)) {
			Dbprintf("Error: Authentication Fail!");
			continue;
		}

		//first get configuration block (block 1)
		crc = block_crc_LUT[1];
		read[1] = 1;
		read[2] = crc >> 8;
		read[3] = crc & 0xff;

		if (!sendCmdGetResponseWithRetries(read, sizeof(read),resp, 10, 10)) {
			Dbprintf("Dump config (block 1) failed");
			continue;
		}

		mem = resp[5];
		memory.k16 = (mem & 0x80);
		memory.book = (mem & 0x20);
		memory.k2 = (mem & 0x8);
		memory.lockauth = (mem & 0x2);
		memory.keyaccess = (mem & 0x1);

		cardsize = memory.k16 ? 255 : 32;
		WDT_HIT();
		//Set card_data to all zeroes, we'll fill it with data
		memset(card_data, 0x0, USB_CMD_DATA_SIZE);
		uint8_t failedRead = 0;
		uint32_t stored_data_length = 0;
		//then loop around remaining blocks
		for (int block = 0; block < cardsize; block++) {
			read[1] = block;
			crc = block_crc_LUT[block];
			read[2] = crc >> 8;
			read[3] = crc & 0xff;

			if (sendCmdGetResponseWithRetries(read, sizeof(read), resp, 10, 10)) {
				Dbprintf("     %02x: %02x %02x %02x %02x %02x %02x %02x %02x",
						block, resp[0], resp[1], resp[2],
						resp[3], resp[4], resp[5],
						resp[6], resp[7]);

				//Fill up the buffer
				memcpy(card_data+stored_data_length, resp, 8);
				stored_data_length += 8;
				if (stored_data_length +8 > USB_CMD_DATA_SIZE) {
					//Time to send this off and start afresh
					cmd_send(CMD_ACK,
							 stored_data_length,//data length
							 failedRead,//Failed blocks?
							 0,//Not used ATM
							 card_data, stored_data_length);
					//reset
					stored_data_length = 0;
					failedRead = 0;
				}

			} else {
				failedRead = 1;
				stored_data_length += 8;//Otherwise, data becomes misaligned
				Dbprintf("Failed to dump block %d", block);
			}
		}

		//Send off any remaining data
		if (stored_data_length > 0) {
			cmd_send(CMD_ACK,
					 stored_data_length,//data length
					 failedRead,//Failed blocks?
					 0,//Not used ATM
					 card_data,
					 stored_data_length);
		}
		//If we got here, let's break
		break;
	}
	//Signal end of transmission
	cmd_send(CMD_ACK,
			 0,//data length
			 0,//Failed blocks?
			 0,//Not used ATM
			 card_data,
			 0);

	FpgaWriteConfWord(FPGA_MAJOR_MODE_OFF);
	LED_A_OFF();
}

void iClass_Authentication(uint8_t *MAC) {
	uint8_t check[] = { ICLASS_CMD_CHECK, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00 };
	uint8_t resp[ICLASS_BUFFER_SIZE];
	memcpy(check+5, MAC, 4);
	bool isOK;
	isOK = sendCmdGetResponseWithRetries(check, sizeof(check), resp, 4, 6);
	cmd_send(CMD_ACK,isOK, 0, 0, 0, 0);
}

static bool iClass_ReadBlock(uint8_t blockNo, uint8_t *readdata) {
	uint8_t readcmd[] = {ICLASS_CMD_READ_OR_IDENTIFY, blockNo, 0x00, 0x00}; //0x88, 0x00 // can i use 0C?
	char bl = blockNo;
	uint16_t rdCrc = iclass_crc16(&bl, 1);
	readcmd[2] = rdCrc >> 8;
	readcmd[3] = rdCrc & 0xff;
	uint8_t resp[] = {0,0,0,0,0,0,0,0,0,0};
	bool isOK = false;

	//readcmd[1] = blockNo;
	isOK = sendCmdGetResponseWithRetries(readcmd, sizeof(readcmd), resp, 10, 10);
	memcpy(readdata, resp, sizeof(resp));

	return isOK;
}

void iClass_ReadBlk(uint8_t blockno) {
	uint8_t readblockdata[] = {0,0,0,0,0,0,0,0,0,0};
	bool isOK = false;
	isOK = iClass_ReadBlock(blockno, readblockdata);
	cmd_send(CMD_ACK, isOK, 0, 0, readblockdata, 8);
	FpgaWriteConfWord(FPGA_MAJOR_MODE_OFF);
}

void iClass_Dump(uint8_t blockno, uint8_t numblks) {
	uint8_t readblockdata[] = {0,0,0,0,0,0,0,0,0,0};
	bool isOK = false;
	uint8_t blkCnt = 0;

	BigBuf_free();
	uint8_t *dataout = BigBuf_malloc(255*8);
	if (dataout == NULL) {
		Dbprintf("out of memory");
		FpgaWriteConfWord(FPGA_MAJOR_MODE_OFF);
		LED_D_OFF();
		cmd_send(CMD_ACK, 0, 1, 0, 0, 0);
		LED_A_OFF();
		return;
	}
	memset(dataout, 0xFF, 255*8);

	for ( ; blkCnt < numblks; blkCnt++) {
		isOK = iClass_ReadBlock(blockno+blkCnt, readblockdata);
		if (!isOK || (readblockdata[0] == 0xBB || readblockdata[7] == 0xBB || readblockdata[2] == 0xBB)) { //try again
			isOK = iClass_ReadBlock(blockno+blkCnt, readblockdata);
			if (!isOK) {
				Dbprintf("Block %02X failed to read", blkCnt+blockno);
				break;
			}
		}
		memcpy(dataout + (blkCnt*8), readblockdata, 8);
	}
	//return pointer to dump memory in arg3
	cmd_send(CMD_ACK, isOK, blkCnt, BigBuf_max_traceLen(), 0, 0);
	FpgaWriteConfWord(FPGA_MAJOR_MODE_OFF);
	LEDsoff();
	BigBuf_free();
}

static bool iClass_WriteBlock_ext(uint8_t blockNo, uint8_t *data) {
	uint8_t write[] = { ICLASS_CMD_UPDATE, blockNo, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00 };
	//uint8_t readblockdata[10];
	//write[1] = blockNo;
	memcpy(write+2, data, 12); // data + mac
	char *wrCmd = (char *)(write+1);
	uint16_t wrCrc = iclass_crc16(wrCmd, 13);
	write[14] = wrCrc >> 8;
	write[15] = wrCrc & 0xff;
	uint8_t resp[] = {0,0,0,0,0,0,0,0,0,0};
	bool isOK = false;

	isOK = sendCmdGetResponseWithRetries(write, sizeof(write), resp, sizeof(resp), 10);
	if (isOK) { //if reader responded correctly
		//Dbprintf("WriteResp: %02X%02X%02X%02X%02X%02X%02X%02X%02X%02X",resp[0],resp[1],resp[2],resp[3],resp[4],resp[5],resp[6],resp[7],resp[8],resp[9]);
		if (memcmp(write+2, resp, 8)) {  //if response is not equal to write values
			if (blockNo != 3 && blockNo != 4) { //if not programming key areas (note key blocks don't get programmed with actual key data it is xor data)
				//error try again
				isOK = sendCmdGetResponseWithRetries(write, sizeof(write), resp, sizeof(resp), 10);
			}
		}
	}
	return isOK;
}

void iClass_WriteBlock(uint8_t blockNo, uint8_t *data) {
	bool isOK = iClass_WriteBlock_ext(blockNo, data);
	if (isOK){
		Dbprintf("Write block [%02x] successful", blockNo);
	} else {
		Dbprintf("Write block [%02x] failed", blockNo);
	}
	cmd_send(CMD_ACK, isOK, 0, 0, 0, 0);
	FpgaWriteConfWord(FPGA_MAJOR_MODE_OFF);
}

void iClass_Clone(uint8_t startblock, uint8_t endblock, uint8_t *data) {
	int i;
	int written = 0;
	int total_block = (endblock - startblock) + 1;
	for (i = 0; i < total_block; i++) {
		// block number
		if (iClass_WriteBlock_ext(i+startblock, data + (i*12))){
			Dbprintf("Write block [%02x] successful", i + startblock);
			written++;
		} else {
			if (iClass_WriteBlock_ext(i+startblock, data + (i*12))){
				Dbprintf("Write block [%02x] successful", i + startblock);
				written++;
			} else {
				Dbprintf("Write block [%02x] failed", i + startblock);
			}
		}
	}
	if (written == total_block)
		Dbprintf("Clone complete");
	else
		Dbprintf("Clone incomplete");

	cmd_send(CMD_ACK, 1, 0, 0, 0, 0);
	FpgaWriteConfWord(FPGA_MAJOR_MODE_OFF);
	LEDsoff();
}