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iso14443a.c
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iso14443a.c
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//-----------------------------------------------------------------------------
// Merlok - June 2011, 2012
// Gerhard de Koning Gans - May 2008
// Hagen Fritsch - June 2010
//
// 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 ISO 14443 type A.
//-----------------------------------------------------------------------------
#include "iso14443a.h"
#include <stdio.h>
#include <string.h>
#include "proxmark3.h"
#include "apps.h"
#include "util.h"
#include "usb_cdc.h"
#include "iso14443crc.h"
#include "crapto1/crapto1.h"
#include "mifareutil.h"
#include "mifaresniff.h"
#include "BigBuf.h"
#include "protocols.h"
#include "parity.h"
#include "fpgaloader.h"
typedef struct {
enum {
DEMOD_UNSYNCD,
// DEMOD_HALF_SYNCD,
// DEMOD_MOD_FIRST_HALF,
// DEMOD_NOMOD_FIRST_HALF,
DEMOD_MANCHESTER_DATA
} state;
uint16_t twoBits;
uint16_t highCnt;
uint16_t bitCount;
uint16_t collisionPos;
uint16_t syncBit;
uint8_t parityBits;
uint8_t parityLen;
uint16_t shiftReg;
uint16_t samples;
uint16_t len;
uint32_t startTime, endTime;
uint8_t *output;
uint8_t *parity;
} tDemod;
typedef enum {
MOD_NOMOD = 0,
MOD_SECOND_HALF,
MOD_FIRST_HALF,
MOD_BOTH_HALVES
} Modulation_t;
typedef struct {
enum {
STATE_UNSYNCD,
STATE_START_OF_COMMUNICATION,
STATE_MILLER_X,
STATE_MILLER_Y,
STATE_MILLER_Z,
// DROP_NONE,
// DROP_FIRST_HALF,
} state;
uint16_t shiftReg;
int16_t bitCount;
uint16_t len;
uint16_t byteCntMax;
uint16_t posCnt;
uint16_t syncBit;
uint8_t parityBits;
uint8_t parityLen;
uint32_t fourBits;
uint32_t startTime, endTime;
uint8_t *output;
uint8_t *parity;
} tUart;
static uint32_t iso14a_timeout;
#define MAX_ISO14A_TIMEOUT 524288
int rsamples = 0;
uint8_t trigger = 0;
// the block number for the ISO14443-4 PCB
static uint8_t iso14_pcb_blocknum = 0;
//
// ISO14443 timing:
//
// minimum time between the start bits of consecutive transfers from reader to tag: 7000 carrier (13.56Mhz) cycles
#define REQUEST_GUARD_TIME (7000/16 + 1)
// minimum time between last modulation of tag and next start bit from reader to tag: 1172 carrier cycles
#define FRAME_DELAY_TIME_PICC_TO_PCD (1172/16 + 1)
// bool LastCommandWasRequest = false;
//
// Total delays including SSC-Transfers between ARM and FPGA. These are in carrier clock cycles (1/13,56MHz)
//
// When the PM acts as reader and is receiving tag data, it takes
// 3 ticks delay in the AD converter
// 16 ticks until the modulation detector completes and sets curbit
// 8 ticks until bit_to_arm is assigned from curbit
// 8*16 ticks for the transfer from FPGA to ARM
// 4*16 ticks until we measure the time
// - 8*16 ticks because we measure the time of the previous transfer
#define DELAY_AIR2ARM_AS_READER (3 + 16 + 8 + 8*16 + 4*16 - 8*16)
// When the PM acts as a reader and is sending, it takes
// 4*16 ticks until we can write data to the sending hold register
// 8*16 ticks until the SHR is transferred to the Sending Shift Register
// 8 ticks until the first transfer starts
// 8 ticks later the FPGA samples the data
// 1 tick to assign mod_sig_coil
#define DELAY_ARM2AIR_AS_READER (4*16 + 8*16 + 8 + 8 + 1)
// When the PM acts as tag and is receiving it takes
// 2 ticks delay in the RF part (for the first falling edge),
// 3 ticks for the A/D conversion,
// 8 ticks on average until the start of the SSC transfer,
// 8 ticks until the SSC samples the first data
// 7*16 ticks to complete the transfer from FPGA to ARM
// 8 ticks until the next ssp_clk rising edge
// 4*16 ticks until we measure the time
// - 8*16 ticks because we measure the time of the previous transfer
#define DELAY_AIR2ARM_AS_TAG (2 + 3 + 8 + 8 + 7*16 + 8 + 4*16 - 8*16)
// The FPGA will report its internal sending delay in
uint16_t FpgaSendQueueDelay;
// the 5 first bits are the number of bits buffered in mod_sig_buf
// the last three bits are the remaining ticks/2 after the mod_sig_buf shift
#define DELAY_FPGA_QUEUE (FpgaSendQueueDelay<<1)
// When the PM acts as tag and is sending, it takes
// 4*16 + 8 ticks until we can write data to the sending hold register
// 8*16 ticks until the SHR is transferred to the Sending Shift Register
// 8 ticks later the FPGA samples the first data
// + 16 ticks until assigned to mod_sig
// + 1 tick to assign mod_sig_coil
// + a varying number of ticks in the FPGA Delay Queue (mod_sig_buf)
#define DELAY_ARM2AIR_AS_TAG (4*16 + 8 + 8*16 + 8 + 16 + 1 + DELAY_FPGA_QUEUE)
// When the PM acts as sniffer and is receiving tag data, it takes
// 3 ticks A/D conversion
// 14 ticks to complete the modulation detection
// 8 ticks (on average) until the result is stored in to_arm
// + the delays in transferring data - which is the same for
// sniffing reader and tag data and therefore not relevant
#define DELAY_TAG_AIR2ARM_AS_SNIFFER (3 + 14 + 8)
// When the PM acts as sniffer and is receiving reader data, it takes
// 2 ticks delay in analogue RF receiver (for the falling edge of the
// start bit, which marks the start of the communication)
// 3 ticks A/D conversion
// 8 ticks on average until the data is stored in to_arm.
// + the delays in transferring data - which is the same for
// sniffing reader and tag data and therefore not relevant
#define DELAY_READER_AIR2ARM_AS_SNIFFER (2 + 3 + 8)
//variables used for timing purposes:
//these are in ssp_clk cycles:
static uint32_t NextTransferTime;
static uint32_t LastTimeProxToAirStart;
static uint32_t LastProxToAirDuration;
// CARD TO READER - manchester
// Sequence D: 11110000 modulation with subcarrier during first half
// Sequence E: 00001111 modulation with subcarrier during second half
// Sequence F: 00000000 no modulation with subcarrier
// READER TO CARD - miller
// Sequence X: 00001100 drop after half a period
// Sequence Y: 00000000 no drop
// Sequence Z: 11000000 drop at start
#define SEC_D 0xf0
#define SEC_E 0x0f
#define SEC_F 0x00
#define SEC_X 0x0c
#define SEC_Y 0x00
#define SEC_Z 0xc0
void iso14a_set_trigger(bool enable) {
trigger = enable;
}
void iso14a_set_timeout(uint32_t timeout) {
// adjust timeout by FPGA delays and 2 additional ssp_frames to detect SOF
iso14a_timeout = timeout + (DELAY_AIR2ARM_AS_READER + DELAY_ARM2AIR_AS_READER)/(16*8) + 2;
if(MF_DBGLEVEL >= 3) Dbprintf("ISO14443A Timeout set to %ld (%dms)", timeout, timeout / 106);
}
uint32_t iso14a_get_timeout(void) {
return iso14a_timeout - (DELAY_AIR2ARM_AS_READER + DELAY_ARM2AIR_AS_READER)/(16*8) - 2;
}
//-----------------------------------------------------------------------------
// Generate the parity value for a byte sequence
//
//-----------------------------------------------------------------------------
void GetParity(const uint8_t *pbtCmd, uint16_t iLen, uint8_t *par)
{
uint16_t paritybit_cnt = 0;
uint16_t paritybyte_cnt = 0;
uint8_t parityBits = 0;
for (uint16_t i = 0; i < iLen; i++) {
// Generate the parity bits
parityBits |= ((oddparity8(pbtCmd[i])) << (7-paritybit_cnt));
if (paritybit_cnt == 7) {
par[paritybyte_cnt] = parityBits; // save 8 Bits parity
parityBits = 0; // and advance to next Parity Byte
paritybyte_cnt++;
paritybit_cnt = 0;
} else {
paritybit_cnt++;
}
}
// save remaining parity bits
par[paritybyte_cnt] = parityBits;
}
void AppendCrc14443a(uint8_t* data, int len)
{
ComputeCrc14443(CRC_14443_A,data,len,data+len,data+len+1);
}
static void AppendCrc14443b(uint8_t* data, int len)
{
ComputeCrc14443(CRC_14443_B,data,len,data+len,data+len+1);
}
//=============================================================================
// ISO 14443 Type A - Miller decoder
//=============================================================================
// Basics:
// This decoder is used when the PM3 acts as a tag.
// The reader will generate "pauses" by temporarily switching of the field.
// At the PM3 antenna we will therefore measure a modulated antenna voltage.
// The FPGA does a comparison with a threshold and would deliver e.g.:
// ........ 1 1 1 1 1 1 0 0 1 1 1 1 1 1 1 1 1 1 0 0 1 1 1 1 1 1 1 1 1 1 .......
// The Miller decoder needs to identify the following sequences:
// 2 (or 3) ticks pause followed by 6 (or 5) ticks unmodulated: pause at beginning - Sequence Z ("start of communication" or a "0")
// 8 ticks without a modulation: no pause - Sequence Y (a "0" or "end of communication" or "no information")
// 4 ticks unmodulated followed by 2 (or 3) ticks pause: pause in second half - Sequence X (a "1")
// Note 1: the bitstream may start at any time. We therefore need to sync.
// Note 2: the interpretation of Sequence Y and Z depends on the preceding sequence.
//-----------------------------------------------------------------------------
static tUart Uart;
// Lookup-Table to decide if 4 raw bits are a modulation.
// 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[] = {
false, true, false, true, false, false, false, true,
false, true, false, false, false, false, false, false
};
#define IsMillerModulationNibble1(b) (Mod_Miller_LUT[(b & 0x000000F0) >> 4])
#define IsMillerModulationNibble2(b) (Mod_Miller_LUT[(b & 0x0000000F)])
static void UartReset() {
Uart.state = STATE_UNSYNCD;
Uart.bitCount = 0;
Uart.len = 0; // number of decoded data bytes
Uart.parityLen = 0; // number of decoded parity bytes
Uart.shiftReg = 0; // shiftreg to hold decoded data bits
Uart.parityBits = 0; // holds 8 parity bits
}
static void UartInit(uint8_t *data, uint8_t *parity) {
Uart.output = data;
Uart.parity = parity;
Uart.fourBits = 0x00000000; // clear the buffer for 4 Bits
Uart.startTime = 0;
Uart.endTime = 0;
UartReset();
}
// use parameter non_real_time to provide a timestamp. Set to 0 if the decoder should measure real time
static RAMFUNC bool MillerDecoding(uint8_t bit, uint32_t non_real_time) {
Uart.fourBits = (Uart.fourBits << 8) | bit;
if (Uart.state == STATE_UNSYNCD) { // not yet synced
Uart.syncBit = 9999; // not set
// 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;
Uart.endTime = Uart.startTime;
Uart.state = STATE_START_OF_COMMUNICATION;
LED_B_ON();
}
} else {
if (IsMillerModulationNibble1(Uart.fourBits >> Uart.syncBit)) {
if (IsMillerModulationNibble2(Uart.fourBits >> Uart.syncBit)) { // Modulation in both halves - error
LED_B_OFF();
UartReset();
} else { // Modulation in first half = Sequence Z = logic "0"
if (Uart.state == STATE_MILLER_X) { // error - must not follow after X
LED_B_OFF();
UartReset();
} else {
Uart.bitCount++;
Uart.shiftReg = (Uart.shiftReg >> 1); // add a 0 to the shiftreg
Uart.state = STATE_MILLER_Z;
Uart.endTime = Uart.startTime + 8*(9*Uart.len + Uart.bitCount + 1) - 6;
if(Uart.bitCount >= 9) { // if we decoded a full byte (including parity)
Uart.output[Uart.len++] = (Uart.shiftReg & 0xff);
Uart.parityBits <<= 1; // make room for the parity bit
Uart.parityBits |= ((Uart.shiftReg >> 8) & 0x01); // store parity bit
Uart.bitCount = 0;
Uart.shiftReg = 0;
if((Uart.len&0x0007) == 0) { // every 8 data bytes
Uart.parity[Uart.parityLen++] = Uart.parityBits; // store 8 parity bits
Uart.parityBits = 0;
}
}
}
}
} else {
if (IsMillerModulationNibble2(Uart.fourBits >> Uart.syncBit)) { // Modulation second half = Sequence X = logic "1"
Uart.bitCount++;
Uart.shiftReg = (Uart.shiftReg >> 1) | 0x100; // add a 1 to the shiftreg
Uart.state = STATE_MILLER_X;
Uart.endTime = Uart.startTime + 8*(9*Uart.len + Uart.bitCount + 1) - 2;
if(Uart.bitCount >= 9) { // if we decoded a full byte (including parity)
Uart.output[Uart.len++] = (Uart.shiftReg & 0xff);
Uart.parityBits <<= 1; // make room for the new parity bit
Uart.parityBits |= ((Uart.shiftReg >> 8) & 0x01); // store parity bit
Uart.bitCount = 0;
Uart.shiftReg = 0;
if ((Uart.len&0x0007) == 0) { // every 8 data bytes
Uart.parity[Uart.parityLen++] = Uart.parityBits; // store 8 parity bits
Uart.parityBits = 0;
}
}
} else { // no modulation in both halves - Sequence Y
if (Uart.state == STATE_MILLER_Z || Uart.state == STATE_MILLER_Y) { // Y after logic "0" - End of Communication
LED_B_OFF();
Uart.state = STATE_UNSYNCD;
Uart.bitCount--; // last "0" was part of EOC sequence
Uart.shiftReg <<= 1; // drop it
if(Uart.bitCount > 0) { // if we decoded some bits
Uart.shiftReg >>= (9 - Uart.bitCount); // right align them
Uart.output[Uart.len++] = (Uart.shiftReg & 0xff); // add last byte to the output
Uart.parityBits <<= 1; // add a (void) parity bit
Uart.parityBits <<= (8 - (Uart.len&0x0007)); // left align parity bits
Uart.parity[Uart.parityLen++] = Uart.parityBits; // and store it
return true;
} else if (Uart.len & 0x0007) { // there are some parity bits to store
Uart.parityBits <<= (8 - (Uart.len&0x0007)); // left align remaining parity bits
Uart.parity[Uart.parityLen++] = Uart.parityBits; // and store them
}
if (Uart.len) {
return true; // we are finished with decoding the raw data sequence
} else {
UartReset(); // Nothing received - start over
}
}
if (Uart.state == STATE_START_OF_COMMUNICATION) { // error - must not follow directly after SOC
LED_B_OFF();
UartReset();
} else { // a logic "0"
Uart.bitCount++;
Uart.shiftReg = (Uart.shiftReg >> 1); // add a 0 to the shiftreg
Uart.state = STATE_MILLER_Y;
if(Uart.bitCount >= 9) { // if we decoded a full byte (including parity)
Uart.output[Uart.len++] = (Uart.shiftReg & 0xff);
Uart.parityBits <<= 1; // make room for the parity bit
Uart.parityBits |= ((Uart.shiftReg >> 8) & 0x01); // store parity bit
Uart.bitCount = 0;
Uart.shiftReg = 0;
if ((Uart.len&0x0007) == 0) { // every 8 data bytes
Uart.parity[Uart.parityLen++] = Uart.parityBits; // store 8 parity bits
Uart.parityBits = 0;
}
}
}
}
}
}
return false; // not finished yet, need more data
}
//=============================================================================
// ISO 14443 Type A - Manchester decoder
//=============================================================================
// Basics:
// This decoder is used when the PM3 acts as a reader.
// The tag will modulate the reader field by asserting different loads to it. As a consequence, the voltage
// at the reader antenna will be modulated as well. The FPGA detects the modulation for us and would deliver e.g. the following:
// ........ 0 0 1 1 1 1 0 0 0 0 0 0 0 0 1 1 1 1 1 1 1 1 0 0 0 0 0 0 0 0 0 0 0 0 0 0 .......
// The Manchester decoder needs to identify the following sequences:
// 4 ticks modulated followed by 4 ticks unmodulated: Sequence D = 1 (also used as "start of communication")
// 4 ticks unmodulated followed by 4 ticks modulated: Sequence E = 0
// 8 ticks unmodulated: Sequence F = end of communication
// 8 ticks modulated: A collision. Save the collision position and treat as Sequence D
// Note 1: the bitstream may start at any time. We therefore need to sync.
// Note 2: parameter offset is used to determine the position of the parity bits (required for the anticollision command only)
static tDemod Demod;
// Lookup-Table to decide if 4 raw bits are a modulation.
// We accept three or four "1" in any position
const bool Mod_Manchester_LUT[] = {
false, false, false, false, false, false, false, true,
false, false, false, true, false, true, true, true
};
#define IsManchesterModulationNibble1(b) (Mod_Manchester_LUT[(b & 0x00F0) >> 4])
#define IsManchesterModulationNibble2(b) (Mod_Manchester_LUT[(b & 0x000F)])
static void DemodReset() {
Demod.state = DEMOD_UNSYNCD;
Demod.len = 0; // number of decoded data bytes
Demod.parityLen = 0;
Demod.shiftReg = 0; // shiftreg to hold decoded data bits
Demod.parityBits = 0; //
Demod.collisionPos = 0; // Position of collision bit
Demod.twoBits = 0xffff; // buffer for 2 Bits
Demod.highCnt = 0;
Demod.startTime = 0;
Demod.endTime = 0;
}
static void DemodInit(uint8_t *data, uint8_t *parity) {
Demod.output = data;
Demod.parity = parity;
DemodReset();
}
// use parameter non_real_time to provide a timestamp. Set to 0 if the decoder should measure real time
static RAMFUNC int ManchesterDecoding(uint8_t bit, uint16_t offset, uint32_t non_real_time) {
Demod.twoBits = (Demod.twoBits << 8) | bit;
if (Demod.state == DEMOD_UNSYNCD) {
if (Demod.highCnt < 2) { // wait for a stable unmodulated signal
if (Demod.twoBits == 0x0000) {
Demod.highCnt++;
} else {
Demod.highCnt = 0;
}
} else {
Demod.syncBit = 0xFFFF; // not set
if ((Demod.twoBits & 0x7700) == 0x7000) Demod.syncBit = 7;
else if ((Demod.twoBits & 0x3B80) == 0x3800) Demod.syncBit = 6;
else if ((Demod.twoBits & 0x1DC0) == 0x1C00) Demod.syncBit = 5;
else if ((Demod.twoBits & 0x0EE0) == 0x0E00) Demod.syncBit = 4;
else if ((Demod.twoBits & 0x0770) == 0x0700) Demod.syncBit = 3;
else if ((Demod.twoBits & 0x03B8) == 0x0380) Demod.syncBit = 2;
else if ((Demod.twoBits & 0x01DC) == 0x01C0) Demod.syncBit = 1;
else if ((Demod.twoBits & 0x00EE) == 0x00E0) Demod.syncBit = 0;
if (Demod.syncBit != 0xFFFF) {
Demod.startTime = non_real_time?non_real_time:(GetCountSspClk() & 0xfffffff8);
Demod.startTime -= Demod.syncBit;
Demod.bitCount = offset; // number of decoded data bits
Demod.state = DEMOD_MANCHESTER_DATA;
LED_C_ON();
}
}
} else {
if (IsManchesterModulationNibble1(Demod.twoBits >> Demod.syncBit)) { // modulation in first half
if (IsManchesterModulationNibble2(Demod.twoBits >> Demod.syncBit)) { // ... and in second half = collision
if (!Demod.collisionPos) {
Demod.collisionPos = (Demod.len << 3) + Demod.bitCount;
}
} // modulation in first half only - Sequence D = 1
Demod.bitCount++;
Demod.shiftReg = (Demod.shiftReg >> 1) | 0x100; // in both cases, add a 1 to the shiftreg
if(Demod.bitCount == 9) { // if we decoded a full byte (including parity)
Demod.output[Demod.len++] = (Demod.shiftReg & 0xff);
Demod.parityBits <<= 1; // make room for the parity bit
Demod.parityBits |= ((Demod.shiftReg >> 8) & 0x01); // store parity bit
Demod.bitCount = 0;
Demod.shiftReg = 0;
if((Demod.len&0x0007) == 0) { // every 8 data bytes
Demod.parity[Demod.parityLen++] = Demod.parityBits; // store 8 parity bits
Demod.parityBits = 0;
}
}
Demod.endTime = Demod.startTime + 8*(9*Demod.len + Demod.bitCount + 1) - 4;
} else { // no modulation in first half
if (IsManchesterModulationNibble2(Demod.twoBits >> Demod.syncBit)) { // and modulation in second half = Sequence E = 0
Demod.bitCount++;
Demod.shiftReg = (Demod.shiftReg >> 1); // add a 0 to the shiftreg
if(Demod.bitCount >= 9) { // if we decoded a full byte (including parity)
Demod.output[Demod.len++] = (Demod.shiftReg & 0xff);
Demod.parityBits <<= 1; // make room for the new parity bit
Demod.parityBits |= ((Demod.shiftReg >> 8) & 0x01); // store parity bit
Demod.bitCount = 0;
Demod.shiftReg = 0;
if ((Demod.len&0x0007) == 0) { // every 8 data bytes
Demod.parity[Demod.parityLen++] = Demod.parityBits; // store 8 parity bits1
Demod.parityBits = 0;
}
}
Demod.endTime = Demod.startTime + 8*(9*Demod.len + Demod.bitCount + 1);
} else { // no modulation in both halves - End of communication
LED_C_OFF();
if(Demod.bitCount > 0) { // there are some remaining data bits
Demod.shiftReg >>= (9 - Demod.bitCount); // right align the decoded bits
Demod.output[Demod.len++] = Demod.shiftReg & 0xff; // and add them to the output
Demod.parityBits <<= 1; // add a (void) parity bit
Demod.parityBits <<= (8 - (Demod.len&0x0007)); // left align remaining parity bits
Demod.parity[Demod.parityLen++] = Demod.parityBits; // and store them
return true;
} else if (Demod.len & 0x0007) { // there are some parity bits to store
Demod.parityBits <<= (8 - (Demod.len&0x0007)); // left align remaining parity bits
Demod.parity[Demod.parityLen++] = Demod.parityBits; // and store them
}
if (Demod.len) {
return true; // we are finished with decoding the raw data sequence
} else { // nothing received. Start over
DemodReset();
}
}
}
}
return false; // not finished yet, need more data
}
//=============================================================================
// Finally, a `sniffer' for ISO 14443 Type A
// 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 SnoopIso14443a(uint8_t param) {
// param:
// bit 0 - trigger from first card answer
// bit 1 - trigger from first reader 7-bit request
LEDsoff();
LED_A_ON();
iso14443a_setup(FPGA_HF_ISO14443A_SNIFFER);
// Allocate memory from BigBuf for some buffers
// free all previous allocations first
BigBuf_free();
// The command (reader -> tag) that we're receiving.
uint8_t *receivedCmd = BigBuf_malloc(MAX_FRAME_SIZE);
uint8_t *receivedCmdPar = BigBuf_malloc(MAX_PARITY_SIZE);
// The response (tag -> reader) that we're receiving.
uint8_t *receivedResponse = BigBuf_malloc(MAX_FRAME_SIZE);
uint8_t *receivedResponsePar = BigBuf_malloc(MAX_PARITY_SIZE);
// The DMA buffer, used to stream samples from the FPGA
uint8_t *dmaBuf = BigBuf_malloc(DMA_BUFFER_SIZE);
// init trace buffer
clear_trace();
set_tracing(true);
uint8_t *data = dmaBuf;
uint8_t previous_data = 0;
int maxDataLen = 0;
int dataLen = 0;
bool TagIsActive = false;
bool ReaderIsActive = false;
// Set up the demodulator for tag -> reader responses.
DemodInit(receivedResponse, receivedResponsePar);
// Set up the demodulator for the reader -> tag commands
UartInit(receivedCmd, receivedCmdPar);
// 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; ) {
if (BUTTON_PRESS()) {
DbpString("cancelled by button");
break;
}
WDT_HIT();
int register readBufDataP = data - dmaBuf;
int register dmaBufDataP = DMA_BUFFER_SIZE - AT91C_BASE_PDC_SSC->PDC_RCR;
if (readBufDataP <= dmaBufDataP){
dataLen = dmaBufDataP - readBufDataP;
} else {
dataLen = DMA_BUFFER_SIZE - readBufDataP + dmaBufDataP;
}
// test for length of buffer
if(dataLen > maxDataLen) {
maxDataLen = dataLen;
if(dataLen > (9 * DMA_BUFFER_SIZE / 10)) {
Dbprintf("blew circular buffer! dataLen=%d", dataLen);
break;
}
}
if(dataLen < 1) continue;
// primary buffer was stopped( <-- we lost data!
if (!AT91C_BASE_PDC_SSC->PDC_RCR) {
AT91C_BASE_PDC_SSC->PDC_RPR = (uint32_t) dmaBuf;
AT91C_BASE_PDC_SSC->PDC_RCR = DMA_BUFFER_SIZE;
Dbprintf("RxEmpty ERROR!!! data length:%d", dataLen); // temporary
}
// secondary buffer sets as primary, secondary buffer was stopped
if (!AT91C_BASE_PDC_SSC->PDC_RNCR) {
AT91C_BASE_PDC_SSC->PDC_RNPR = (uint32_t) dmaBuf;
AT91C_BASE_PDC_SSC->PDC_RNCR = DMA_BUFFER_SIZE;
}
if (rsamples & 0x01) { // Need two samples to feed Miller and Manchester-Decoder
if(!TagIsActive) { // no need to try decoding reader data if the tag is sending
uint8_t readerdata = (previous_data & 0xF0) | (*data >> 4);
if (MillerDecoding(readerdata, (rsamples-1)*4)) {
// check - if there is a short 7bit request from reader
if ((!triggered) && (param & 0x02) && (Uart.len == 1) && (Uart.bitCount == 7)) {
triggered = true;
}
if(triggered) {
if (!LogTrace(receivedCmd,
Uart.len,
Uart.startTime*16 - DELAY_READER_AIR2ARM_AS_SNIFFER,
Uart.endTime*16 - DELAY_READER_AIR2ARM_AS_SNIFFER,
Uart.parity,
true)) break;
}
/* And ready to receive another command. */
UartReset();
/* And also reset the demod code, which might have been */
/* false-triggered by the commands from the reader. */
DemodReset();
}
ReaderIsActive = (Uart.state != STATE_UNSYNCD);
}
if (!ReaderIsActive) { // no need to try decoding tag data if the reader is sending - and we cannot afford the time
uint8_t tagdata = (previous_data << 4) | (*data & 0x0F);
if (ManchesterDecoding(tagdata, 0, (rsamples-1)*4)) {
if (!LogTrace(receivedResponse,
Demod.len,
Demod.startTime*16 - DELAY_TAG_AIR2ARM_AS_SNIFFER,
Demod.endTime*16 - DELAY_TAG_AIR2ARM_AS_SNIFFER,
Demod.parity,
false)) break;
if ((!triggered) && (param & 0x01)) triggered = true;
// 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);
}
}
previous_data = *data;
rsamples++;
data++;
if(data == dmaBuf + DMA_BUFFER_SIZE) {
data = dmaBuf;
}
} // main cycle
FpgaDisableSscDma();
LEDsoff();
DbpString("COMMAND FINISHED");
Dbprintf("maxDataLen=%d, Uart.state=%x, Uart.len=%d", maxDataLen, Uart.state, Uart.len);
Dbprintf("traceLen=%d, Uart.output[0]=%08x", BigBuf_get_traceLen(), (uint32_t)Uart.output[0]);
}
//-----------------------------------------------------------------------------
// Prepare tag messages
//-----------------------------------------------------------------------------
static void CodeIso14443aAsTagPar(const uint8_t *cmd, uint16_t len, uint8_t *parity) {
ToSendReset();
// Correction bit, might be removed when not needed
ToSendStuffBit(0);
ToSendStuffBit(0);
ToSendStuffBit(0);
ToSendStuffBit(0);
ToSendStuffBit(1); // 1
ToSendStuffBit(0);
ToSendStuffBit(0);
ToSendStuffBit(0);
// Send startbit
ToSend[++ToSendMax] = SEC_D;
LastProxToAirDuration = 8 * ToSendMax - 4;
for (uint16_t i = 0; i < len; i++) {
uint8_t b = cmd[i];
// Data bits
for (uint16_t j = 0; j < 8; j++) {
if(b & 1) {
ToSend[++ToSendMax] = SEC_D;
} else {
ToSend[++ToSendMax] = SEC_E;
}
b >>= 1;
}
// Get the parity bit
if (parity[i>>3] & (0x80>>(i&0x0007))) {
ToSend[++ToSendMax] = SEC_D;
LastProxToAirDuration = 8 * ToSendMax - 4;
} else {
ToSend[++ToSendMax] = SEC_E;
LastProxToAirDuration = 8 * ToSendMax;
}
}
// Send stopbit
ToSend[++ToSendMax] = SEC_F;
// Convert from last byte pos to length
ToSendMax++;
}
static void Code4bitAnswerAsTag(uint8_t cmd) {
int i;
ToSendReset();
// Correction bit, might be removed when not needed
ToSendStuffBit(0);
ToSendStuffBit(0);
ToSendStuffBit(0);
ToSendStuffBit(0);
ToSendStuffBit(1); // 1
ToSendStuffBit(0);
ToSendStuffBit(0);
ToSendStuffBit(0);
// Send startbit
ToSend[++ToSendMax] = SEC_D;
uint8_t b = cmd;
for (i = 0; i < 4; i++) {
if(b & 1) {
ToSend[++ToSendMax] = SEC_D;
LastProxToAirDuration = 8 * ToSendMax - 4;
} else {
ToSend[++ToSendMax] = SEC_E;
LastProxToAirDuration = 8 * ToSendMax;
}
b >>= 1;
}
// Send stopbit
ToSend[++ToSendMax] = SEC_F;
// Convert from last byte pos to length
ToSendMax++;
}
static uint8_t *LastReaderTraceTime = NULL;
static void EmLogTraceReader(void) {
// remember last reader trace start to fix timing info later
LastReaderTraceTime = BigBuf_get_addr() + BigBuf_get_traceLen();
LogTrace(Uart.output, Uart.len, Uart.startTime*16 - DELAY_AIR2ARM_AS_TAG, Uart.endTime*16 - DELAY_AIR2ARM_AS_TAG, Uart.parity, true);
}
static void FixLastReaderTraceTime(uint32_t tag_StartTime) {
uint32_t reader_EndTime = Uart.endTime*16 - DELAY_AIR2ARM_AS_TAG;
uint32_t reader_StartTime = Uart.startTime*16 - DELAY_AIR2ARM_AS_TAG;
uint16_t reader_modlen = reader_EndTime - reader_StartTime;
uint16_t approx_fdt = tag_StartTime - reader_EndTime;
uint16_t exact_fdt = (approx_fdt - 20 + 32)/64 * 64 + 20;
reader_StartTime = tag_StartTime - exact_fdt - reader_modlen;
LastReaderTraceTime[0] = (reader_StartTime >> 0) & 0xff;
LastReaderTraceTime[1] = (reader_StartTime >> 8) & 0xff;
LastReaderTraceTime[2] = (reader_StartTime >> 16) & 0xff;
LastReaderTraceTime[3] = (reader_StartTime >> 24) & 0xff;
}
static void EmLogTraceTag(uint8_t *tag_data, uint16_t tag_len, uint8_t *tag_Parity, uint32_t ProxToAirDuration) {
uint32_t tag_StartTime = LastTimeProxToAirStart*16 + DELAY_ARM2AIR_AS_TAG;
uint32_t tag_EndTime = (LastTimeProxToAirStart + ProxToAirDuration)*16 + DELAY_ARM2AIR_AS_TAG;
LogTrace(tag_data, tag_len, tag_StartTime, tag_EndTime, tag_Parity, false);
FixLastReaderTraceTime(tag_StartTime);
}
//-----------------------------------------------------------------------------
// Wait for commands from reader
// Stop when button is pressed
// Or return true when command is captured
//-----------------------------------------------------------------------------
static int GetIso14443aCommandFromReader(uint8_t *received, uint8_t *parity, int *len) {
// 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.
UartInit(received, parity);
// clear RXRDY:
uint8_t b = (uint8_t)AT91C_BASE_SSC->SSC_RHR;
for (;;) {
WDT_HIT();
if(BUTTON_PRESS()) return false;
if(AT91C_BASE_SSC->SSC_SR & (AT91C_SSC_RXRDY)) {
b = (uint8_t)AT91C_BASE_SSC->SSC_RHR;
if(MillerDecoding(b, 0)) {
*len = Uart.len;
EmLogTraceReader();
return true;
}
}
}
}
int EmSend4bit(uint8_t resp);
static int EmSendCmdExPar(uint8_t *resp, uint16_t respLen, uint8_t *par);
int EmSendCmd(uint8_t *resp, uint16_t respLen);
int EmSendPrecompiledCmd(tag_response_info_t *response_info);
static bool prepare_tag_modulation(tag_response_info_t* response_info, size_t max_buffer_size) {
// Example response, answer to MIFARE Classic read block will be 16 bytes + 2 CRC = 18 bytes
// This will need the following byte array for a modulation sequence
// 144 data bits (18 * 8)
// 18 parity bits
// 2 Start and stop
// 1 Correction bit (Answer in 1172 or 1236 periods, see FPGA)
// 1 just for the case
// ----------- +
// 166 bytes, since every bit that needs to be send costs us a byte
//
// Prepare the tag modulation bits from the message
GetParity(response_info->response, response_info->response_n, &(response_info->par));
CodeIso14443aAsTagPar(response_info->response,response_info->response_n, &(response_info->par));
// Make sure we do not exceed the free buffer space
if (ToSendMax > max_buffer_size) {
Dbprintf("Out of memory, when modulating bits for tag answer:");
Dbhexdump(response_info->response_n, response_info->response, false);
return false;
}
// Copy the byte array, used for this modulation to the buffer position
memcpy(response_info->modulation, ToSend, ToSendMax);
// Store the number of bytes that were used for encoding/modulation and the time needed to transfer them
response_info->modulation_n = ToSendMax;
response_info->ProxToAirDuration = LastProxToAirDuration;
return true;
}
// "precompile" responses. There are 7 predefined responses with a total of 28 bytes data to transmit.
// Coded responses need one byte per bit to transfer (data, parity, start, stop, correction)
// 28 * 8 data bits, 28 * 1 parity bits, 7 start bits, 7 stop bits, 7 correction bits for the modulation
// -> need 273 bytes buffer
#define ALLOCATED_TAG_MODULATION_BUFFER_SIZE 273
bool prepare_allocated_tag_modulation(tag_response_info_t* response_info, uint8_t **buffer, size_t *max_buffer_size) {
// Retrieve and store the current buffer index
response_info->modulation = *buffer;
// Forward the prepare tag modulation function to the inner function
if (prepare_tag_modulation(response_info, *max_buffer_size)) {
// Update the free buffer offset and the remaining buffer size
*buffer += ToSendMax;
*max_buffer_size -= ToSendMax;
return true;
} else {
return false;
}
}
//-----------------------------------------------------------------------------
// Main loop of simulated tag: receive commands from reader, decide what
// response to send, and send it.
//-----------------------------------------------------------------------------
void SimulateIso14443aTag(int tagType, int uid_1st, int uid_2nd, uint8_t* data) {
uint8_t sak;
// The first response contains the ATQA (note: bytes are transmitted in reverse order).
uint8_t response1[2];
switch (tagType) {
case 1: { // MIFARE Classic
// Says: I am Mifare 1k - original line
response1[0] = 0x04;
response1[1] = 0x00;
sak = 0x08;
} break;
case 2: { // MIFARE Ultralight
// Says: I am a stupid memory tag, no crypto
response1[0] = 0x04;
response1[1] = 0x00;
sak = 0x00;
} break;
case 3: { // MIFARE DESFire
// Says: I am a DESFire tag, ph33r me
response1[0] = 0x04;
response1[1] = 0x03;
sak = 0x20;
} break;
case 4: { // ISO/IEC 14443-4
// Says: I am a javacard (JCOP)
response1[0] = 0x04;
response1[1] = 0x00;
sak = 0x28;
} break;
case 5: { // MIFARE TNP3XXX
// Says: I am a toy
response1[0] = 0x01;
response1[1] = 0x0f;
sak = 0x01;
} break;
default: {
Dbprintf("Error: unkown tagtype (%d)",tagType);
return;
} break;
}
// The second response contains the (mandatory) first 24 bits of the UID
uint8_t response2[5] = {0x00};
// Check if the uid uses the (optional) part
uint8_t response2a[5] = {0x00};
if (uid_2nd) {
response2[0] = 0x88;
num_to_bytes(uid_1st,3,response2+1);
num_to_bytes(uid_2nd,4,response2a);
response2a[4] = response2a[0] ^ response2a[1] ^ response2a[2] ^ response2a[3];