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proxmark3/armsrc/iso14443b.c
iceman1001 17ad0e0948 ADD: @marshmellow42 's 14b fixes. 
FIX: 14b sim changes in  iso14443b.c ,  *experimental*   I took some timing loops from "14a sim" armsrc/iso14443a.c  and merged it into the "14b sim".   Now using two pm3's I can have one simulating and the other reading and it works.  Ask @pwpiwi if you want to know more of what those timing loops does.  Something about waiting for the fpga delay queue...
2015-06-25 12:25:44 +02:00

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//-----------------------------------------------------------------------------
// Jonathan Westhues, split Nov 2006
//
// 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 14443B. This includes both the reader software and
// the `fake tag' modes.
//-----------------------------------------------------------------------------
#include "proxmark3.h"
#include "apps.h"
#include "util.h"
#include "string.h"
#include "iso14443crc.h"
#define RECEIVE_SAMPLES_TIMEOUT 2000
#define ISO14443B_DMA_BUFFER_SIZE 256
//=============================================================================
// An ISO 14443 Type B tag. We listen for commands from the reader, using
// a UART kind of thing that's implemented in software. When we get a
// frame (i.e., a group of bytes between SOF and EOF), we check the CRC.
// If it's good, then we can do something appropriate with it, and send
// a response.
//=============================================================================
//-----------------------------------------------------------------------------
// Code up a string of octets at layer 2 (including CRC, we don't generate
// that here) so that they can be transmitted to the reader. Doesn't transmit
// them yet, just leaves them ready to send in ToSend[].
//-----------------------------------------------------------------------------
static void CodeIso14443bAsTag(const uint8_t *cmd, int len)
{
int i;
ToSendReset();
// Transmit a burst of ones, as the initial thing that lets the
// reader get phase sync. This (TR1) must be > 80/fs, per spec,
// but tag that I've tried (a Paypass) exceeds that by a fair bit,
// so I will too.
for(i = 0; i < 20; i++) {
ToSendStuffBit(1);
ToSendStuffBit(1);
ToSendStuffBit(1);
ToSendStuffBit(1);
}
// Send SOF.
for(i = 0; i < 10; i++) {
ToSendStuffBit(0);
ToSendStuffBit(0);
ToSendStuffBit(0);
ToSendStuffBit(0);
}
for(i = 0; i < 2; i++) {
ToSendStuffBit(1);
ToSendStuffBit(1);
ToSendStuffBit(1);
ToSendStuffBit(1);
}
for(i = 0; i < len; i++) {
int j;
uint8_t b = cmd[i];
// Start bit
ToSendStuffBit(0);
ToSendStuffBit(0);
ToSendStuffBit(0);
ToSendStuffBit(0);
// Data bits
for(j = 0; j < 8; j++) {
if(b & 1) {
ToSendStuffBit(1);
ToSendStuffBit(1);
ToSendStuffBit(1);
ToSendStuffBit(1);
} else {
ToSendStuffBit(0);
ToSendStuffBit(0);
ToSendStuffBit(0);
ToSendStuffBit(0);
}
b >>= 1;
}
// Stop bit
ToSendStuffBit(1);
ToSendStuffBit(1);
ToSendStuffBit(1);
ToSendStuffBit(1);
}
// Send EOF.
for(i = 0; i < 10; i++) {
ToSendStuffBit(0);
ToSendStuffBit(0);
ToSendStuffBit(0);
ToSendStuffBit(0);
}
for(i = 0; i < 2; i++) {
ToSendStuffBit(1);
ToSendStuffBit(1);
ToSendStuffBit(1);
ToSendStuffBit(1);
}
// Convert from last byte pos to length
ToSendMax++;
}
//-----------------------------------------------------------------------------
// The software UART that receives commands from the reader, and its state
// variables.
//-----------------------------------------------------------------------------
static struct {
enum {
STATE_UNSYNCD,
STATE_GOT_FALLING_EDGE_OF_SOF,
STATE_AWAITING_START_BIT,
STATE_RECEIVING_DATA
} state;
uint16_t shiftReg;
int bitCnt;
int byteCnt;
int byteCntMax;
int posCnt;
uint8_t *output;
} Uart;
/* Receive & handle a bit coming from the reader.
*
* This function is called 4 times per bit (every 2 subcarrier cycles).
* Subcarrier frequency fs is 848kHz, 1/fs = 1,18us, i.e. function is called every 2,36us
*
* LED handling:
* LED A -> ON once we have received the SOF and are expecting the rest.
* LED A -> OFF once we have received EOF or are in error state or unsynced
*
* Returns: true if we received a EOF
* false if we are still waiting for some more
*/
static RAMFUNC int Handle14443bUartBit(uint8_t bit)
{
switch(Uart.state) {
case STATE_UNSYNCD:
if(!bit) {
// we went low, so this could be the beginning
// of an SOF
Uart.state = STATE_GOT_FALLING_EDGE_OF_SOF;
Uart.posCnt = 0;
Uart.bitCnt = 0;
}
break;
case STATE_GOT_FALLING_EDGE_OF_SOF:
Uart.posCnt++;
if(Uart.posCnt == 2) { // sample every 4 1/fs in the middle of a bit
if(bit) {
if(Uart.bitCnt > 9) {
// we've seen enough consecutive
// zeros that it's a valid SOF
Uart.posCnt = 0;
Uart.byteCnt = 0;
Uart.state = STATE_AWAITING_START_BIT;
LED_A_ON(); // Indicate we got a valid SOF
} else {
// didn't stay down long enough
// before going high, error
Uart.state = STATE_UNSYNCD;
}
} else {
// do nothing, keep waiting
}
Uart.bitCnt++;
}
if(Uart.posCnt >= 4) Uart.posCnt = 0;
if(Uart.bitCnt > 12) {
// Give up if we see too many zeros without
// a one, too.
LED_A_OFF();
Uart.state = STATE_UNSYNCD;
}
break;
case STATE_AWAITING_START_BIT:
Uart.posCnt++;
if(bit) {
if(Uart.posCnt > 50/2) { // max 57us between characters = 49 1/fs, max 3 etus after low phase of SOF = 24 1/fs
// stayed high for too long between
// characters, error
Uart.state = STATE_UNSYNCD;
}
} else {
// falling edge, this starts the data byte
Uart.posCnt = 0;
Uart.bitCnt = 0;
Uart.shiftReg = 0;
Uart.state = STATE_RECEIVING_DATA;
}
break;
case STATE_RECEIVING_DATA:
Uart.posCnt++;
if(Uart.posCnt == 2) {
// time to sample a bit
Uart.shiftReg >>= 1;
if(bit) {
Uart.shiftReg |= 0x200;
}
Uart.bitCnt++;
}
if(Uart.posCnt >= 4) {
Uart.posCnt = 0;
}
if(Uart.bitCnt == 10) {
if((Uart.shiftReg & 0x200) && !(Uart.shiftReg & 0x001))
{
// this is a data byte, with correct
// start and stop bits
Uart.output[Uart.byteCnt] = (Uart.shiftReg >> 1) & 0xff;
Uart.byteCnt++;
if(Uart.byteCnt >= Uart.byteCntMax) {
// Buffer overflowed, give up
LED_A_OFF();
Uart.state = STATE_UNSYNCD;
} else {
// so get the next byte now
Uart.posCnt = 0;
Uart.state = STATE_AWAITING_START_BIT;
}
} else if (Uart.shiftReg == 0x000) {
// this is an EOF byte
LED_A_OFF(); // Finished receiving
Uart.state = STATE_UNSYNCD;
if (Uart.byteCnt != 0) {
return TRUE;
}
} else {
// this is an error
LED_A_OFF();
Uart.state = STATE_UNSYNCD;
}
}
break;
default:
LED_A_OFF();
Uart.state = STATE_UNSYNCD;
break;
}
return FALSE;
}
static void UartReset()
{
Uart.byteCntMax = MAX_FRAME_SIZE;
Uart.state = STATE_UNSYNCD;
Uart.byteCnt = 0;
Uart.bitCnt = 0;
}
static void UartInit(uint8_t *data)
{
Uart.output = data;
UartReset();
}
//-----------------------------------------------------------------------------
// Receive a command (from the reader to us, where we are the simulated tag),
// and store it in the given buffer, up to the given maximum length. Keeps
// spinning, waiting for a well-framed command, until either we get one
// (returns TRUE) or someone presses the pushbutton on the board (FALSE).
//
// Assume that we're called with the SSC (to the FPGA) and ADC path set
// correctly.
//-----------------------------------------------------------------------------
static int GetIso14443bCommandFromReader(uint8_t *received, uint16_t *len)
{
// Set FPGA mode to "simulated ISO 14443B 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_SIMULATOR | FPGA_HF_SIMULATOR_NO_MODULATION);
// Now run a `software UART' on the stream of incoming samples.
UartInit(received);
for(;;) {
WDT_HIT();
if(BUTTON_PRESS()) return FALSE;
if(AT91C_BASE_SSC->SSC_SR & (AT91C_SSC_RXRDY)) {
uint8_t b = (uint8_t)AT91C_BASE_SSC->SSC_RHR;
for(uint8_t mask = 0x80; mask != 0x00; mask >>= 1) {
if(Handle14443bUartBit(b & mask)) {
*len = Uart.byteCnt;
return TRUE;
}
}
}
}
return FALSE;
}
//-----------------------------------------------------------------------------
// Main loop of simulated tag: receive commands from reader, decide what
// response to send, and send it.
//-----------------------------------------------------------------------------
void SimulateIso14443bTag(void)
{
FpgaDownloadAndGo(FPGA_BITSTREAM_HF);
BigBuf_free();
// the only commands we understand is REQB, AFI=0, Select All, N=0:
static const uint8_t cmd1[] = { 0x05, 0x00, 0x08, 0x39, 0x73 };
// ... and REQB, AFI=0, Normal Request, N=0:
static const uint8_t cmd2[] = { 0x05, 0x00, 0x00, 0x71, 0xFF };
// ... and we always respond with ATQB, PUPI = 820de174, Application Data = 0x20381922,
// supports only 106kBit/s in both directions, max frame size = 32Bytes,
// supports ISO14443-4, FWI=8 (77ms), NAD supported, CID not supported:
static const uint8_t response1[] = {
0x50, 0x82, 0x0d, 0xe1, 0x74, 0x20, 0x38, 0x19, 0x22,
0x00, 0x21, 0x85, 0x5e, 0xd7
};
clear_trace();
set_tracing(TRUE);
const uint8_t *resp;
uint8_t *respCode;
uint16_t respLen, respCodeLen;
uint16_t len;
uint16_t cmdsRecvd = 0;
// allocate command receive buffer
uint8_t *receivedCmd = BigBuf_malloc(MAX_FRAME_SIZE);
// prepare the (only one) tag answer:
CodeIso14443bAsTag(response1, sizeof(response1));
uint8_t *resp1Code = BigBuf_malloc(ToSendMax);
memcpy(resp1Code, ToSend, ToSendMax);
uint16_t resp1CodeLen = ToSendMax;
// We need to listen to the high-frequency, peak-detected path.
SetAdcMuxFor(GPIO_MUXSEL_HIPKD);
FpgaSetupSsc();
cmdsRecvd = 0;
for(;;) {
if(!GetIso14443bCommandFromReader(receivedCmd, &len)) {
Dbprintf("button pressed, received %d commands", cmdsRecvd);
break;
}
if (tracing) {
uint8_t parity[MAX_PARITY_SIZE];
LogTrace(receivedCmd, len, 0, 0, parity, TRUE);
}
// Good, look at the command now.
if ( (len == sizeof(cmd1) && memcmp(receivedCmd, cmd1, len) == 0)
|| (len == sizeof(cmd2) && memcmp(receivedCmd, cmd2, len) == 0) ) {
resp = response1;
respLen = sizeof(response1);
respCode = resp1Code;
respCodeLen = resp1CodeLen;
} else {
Dbprintf("new cmd from reader: len=%d, cmdsRecvd=%d", len, cmdsRecvd);
// And print whether the CRC fails, just for good measure
uint8_t b1, b2;
ComputeCrc14443(CRC_14443_B, receivedCmd, len-2, &b1, &b2);
if(b1 != receivedCmd[len-2] || b2 != receivedCmd[len-1]) {
// Not so good, try again.
DbpString("+++CRC fail");
} else {
DbpString("CRC passes");
}
break;
}
cmdsRecvd++;
if(cmdsRecvd > 0x30) {
DbpString("many commands later...");
break;
}
if(respCodeLen <= 0) continue;
// Modulate BPSK
// Signal field is off with the appropriate LED
LED_D_OFF();
FpgaWriteConfWord(FPGA_MAJOR_MODE_HF_SIMULATOR | FPGA_HF_SIMULATOR_MODULATE_BPSK);
AT91C_BASE_SSC->SSC_THR = 0xff;
FpgaSetupSsc();
uint8_t c;
// clear receiving shift register and holding register
while(!(AT91C_BASE_SSC->SSC_SR & AT91C_SSC_RXRDY));
c = AT91C_BASE_SSC->SSC_RHR; (void) c;
while(!(AT91C_BASE_SSC->SSC_SR & AT91C_SSC_RXRDY));
c = AT91C_BASE_SSC->SSC_RHR; (void) c;
// Clear TXRDY:
AT91C_BASE_SSC->SSC_THR = 0x00;
// Transmit the response.
uint16_t FpgaSendQueueDelay = 0;
uint16_t i = 0;
for(;i < respCodeLen; ) {
if(AT91C_BASE_SSC->SSC_SR & (AT91C_SSC_TXRDY)) {
AT91C_BASE_SSC->SSC_THR = respCode[i++];
FpgaSendQueueDelay = (uint8_t)AT91C_BASE_SSC->SSC_RHR;
}
if(BUTTON_PRESS()) break;
}
// Ensure that the FPGA Delay Queue is empty before we switch to TAGSIM_LISTEN again:
uint8_t fpga_queued_bits = FpgaSendQueueDelay >> 3;
for (i = 0; i <= fpga_queued_bits/8 + 1; ) {
if(AT91C_BASE_SSC->SSC_SR & (AT91C_SSC_TXRDY)) {
AT91C_BASE_SSC->SSC_THR = 0x00;
FpgaSendQueueDelay = (uint8_t)AT91C_BASE_SSC->SSC_RHR;
i++;
}
}
// trace the response:
if (tracing) {
uint8_t parity[MAX_PARITY_SIZE];
LogTrace(resp, respLen, 0, 0, parity, FALSE);
}
}
}
//=============================================================================
// An ISO 14443 Type B reader. We take layer two commands, code them
// appropriately, and then send them to the tag. We then listen for the
// tag's response, which we leave in the buffer to be demodulated on the
// PC side.
//=============================================================================
static struct {
enum {
DEMOD_UNSYNCD,
DEMOD_PHASE_REF_TRAINING,
DEMOD_AWAITING_FALLING_EDGE_OF_SOF,
DEMOD_GOT_FALLING_EDGE_OF_SOF,
DEMOD_AWAITING_START_BIT,
DEMOD_RECEIVING_DATA
} state;
int bitCount;
int posCount;
int thisBit;
/* this had been used to add RSSI (Received Signal Strength Indication) to traces. Currently not implemented.
int metric;
int metricN;
*/
uint16_t shiftReg;
uint8_t *output;
int len;
int sumI;
int sumQ;
} Demod;
/*
* Handles reception of a bit from the tag
*
* This function is called 2 times per bit (every 4 subcarrier cycles).
* Subcarrier frequency fs is 848kHz, 1/fs = 1,18us, i.e. function is called every 4,72us
*
* LED handling:
* LED C -> ON once we have received the SOF and are expecting the rest.
* LED C -> OFF once we have received EOF or are unsynced
*
* Returns: true if we received a EOF
* false if we are still waiting for some more
*
*/
static RAMFUNC int Handle14443bSamplesDemod(int ci, int cq)
{
int v;
// The soft decision on the bit uses an estimate of just the
// quadrant of the reference angle, not the exact angle.
#define MAKE_SOFT_DECISION() { \
if(Demod.sumI > 0) { \
v = ci; \
} else { \
v = -ci; \
} \
if(Demod.sumQ > 0) { \
v += cq; \
} else { \
v -= cq; \
} \
}
#define SUBCARRIER_DETECT_THRESHOLD 8
// Subcarrier amplitude v = sqrt(ci^2 + cq^2), approximated here by abs(ci) + abs(cq)
/* #define CHECK_FOR_SUBCARRIER() { \
v = ci; \
if(v < 0) v = -v; \
if(cq > 0) { \
v += cq; \
} else { \
v -= cq; \
} \
}
*/
// Subcarrier amplitude v = sqrt(ci^2 + cq^2), approximated here by max(abs(ci),abs(cq)) + 1/2*min(abs(ci),abs(cq)))
#define CHECK_FOR_SUBCARRIER() { \
if(ci < 0) { \
if(cq < 0) { /* ci < 0, cq < 0 */ \
if (cq < ci) { \
v = -cq - (ci >> 1); \
} else { \
v = -ci - (cq >> 1); \
} \
} else { /* ci < 0, cq >= 0 */ \
if (cq < -ci) { \
v = -ci + (cq >> 1); \
} else { \
v = cq - (ci >> 1); \
} \
} \
} else { \
if(cq < 0) { /* ci >= 0, cq < 0 */ \
if (-cq < ci) { \
v = ci - (cq >> 1); \
} else { \
v = -cq + (ci >> 1); \
} \
} else { /* ci >= 0, cq >= 0 */ \
if (cq < ci) { \
v = ci + (cq >> 1); \
} else { \
v = cq + (ci >> 1); \
} \
} \
} \
}
switch(Demod.state) {
case DEMOD_UNSYNCD:
CHECK_FOR_SUBCARRIER();
if(v > SUBCARRIER_DETECT_THRESHOLD) { // subcarrier detected
Demod.state = DEMOD_PHASE_REF_TRAINING;
Demod.sumI = ci;
Demod.sumQ = cq;
Demod.posCount = 1;
}
break;
case DEMOD_PHASE_REF_TRAINING:
if(Demod.posCount < 8) {
CHECK_FOR_SUBCARRIER();
if (v > SUBCARRIER_DETECT_THRESHOLD) {
// set the reference phase (will code a logic '1') by averaging over 32 1/fs.
// note: synchronization time > 80 1/fs
Demod.sumI += ci;
Demod.sumQ += cq;
Demod.posCount++;
} else { // subcarrier lost
Demod.state = DEMOD_UNSYNCD;
}
} else {
Demod.state = DEMOD_AWAITING_FALLING_EDGE_OF_SOF;
}
break;
case DEMOD_AWAITING_FALLING_EDGE_OF_SOF:
MAKE_SOFT_DECISION();
if(v < 0) { // logic '0' detected
Demod.state = DEMOD_GOT_FALLING_EDGE_OF_SOF;
Demod.posCount = 0; // start of SOF sequence
} else {
if(Demod.posCount > 200/4) { // maximum length of TR1 = 200 1/fs
Demod.state = DEMOD_UNSYNCD;
}
}
Demod.posCount++;
break;
case DEMOD_GOT_FALLING_EDGE_OF_SOF:
Demod.posCount++;
MAKE_SOFT_DECISION();
if(v > 0) {
if(Demod.posCount < 9*2) { // low phase of SOF too short (< 9 etu). Note: spec is >= 10, but FPGA tends to "smear" edges
Demod.state = DEMOD_UNSYNCD;
} else {
LED_C_ON(); // Got SOF
Demod.state = DEMOD_AWAITING_START_BIT;
Demod.posCount = 0;
Demod.len = 0;
/* this had been used to add RSSI (Received Signal Strength Indication) to traces. Currently not implemented.
Demod.metricN = 0;
Demod.metric = 0;
*/
}
} else {
if(Demod.posCount > 12*2) { // low phase of SOF too long (> 12 etu)
Demod.state = DEMOD_UNSYNCD;
LED_C_OFF();
}
}
break;
case DEMOD_AWAITING_START_BIT:
Demod.posCount++;
MAKE_SOFT_DECISION();
if(v > 0) {
if(Demod.posCount > 3*2) { // max 19us between characters = 16 1/fs, max 3 etu after low phase of SOF = 24 1/fs
Demod.state = DEMOD_UNSYNCD;
LED_C_OFF();
}
} else { // start bit detected
Demod.bitCount = 0;
Demod.posCount = 1; // this was the first half
Demod.thisBit = v;
Demod.shiftReg = 0;
Demod.state = DEMOD_RECEIVING_DATA;
}
break;
case DEMOD_RECEIVING_DATA:
MAKE_SOFT_DECISION();
if(Demod.posCount == 0) { // first half of bit
Demod.thisBit = v;
Demod.posCount = 1;
} else { // second half of bit
Demod.thisBit += v;
/* this had been used to add RSSI (Received Signal Strength Indication) to traces. Currently not implemented.
if(Demod.thisBit > 0) {
Demod.metric += Demod.thisBit;
} else {
Demod.metric -= Demod.thisBit;
}
(Demod.metricN)++;
*/
Demod.shiftReg >>= 1;
if(Demod.thisBit > 0) { // logic '1'
Demod.shiftReg |= 0x200;
}
Demod.bitCount++;
if(Demod.bitCount == 10) {
uint16_t s = Demod.shiftReg;
if((s & 0x200) && !(s & 0x001)) { // stop bit == '1', start bit == '0'
uint8_t b = (s >> 1);
Demod.output[Demod.len] = b;
Demod.len++;
Demod.state = DEMOD_AWAITING_START_BIT;
} else {
Demod.state = DEMOD_UNSYNCD;
LED_C_OFF();
if(s == 0x000) {
// This is EOF (start, stop and all data bits == '0'
return TRUE;
}
}
}
Demod.posCount = 0;
}
break;
default:
Demod.state = DEMOD_UNSYNCD;
LED_C_OFF();
break;
}
return FALSE;
}
static void DemodReset()
{
// Clear out the state of the "UART" that receives from the tag.
Demod.len = 0;
Demod.state = DEMOD_UNSYNCD;
Demod.posCount = 0;
memset(Demod.output, 0x00, MAX_FRAME_SIZE);
}
static void DemodInit(uint8_t *data)
{
Demod.output = data;
DemodReset();
}
/*
* Demodulate the samples we received from the tag, also log to tracebuffer
* quiet: set to 'TRUE' to disable debug output
*/
static void GetSamplesFor14443bDemod(int n, bool quiet)
{
int max = 0;
bool gotFrame = FALSE;
int lastRxCounter, ci, cq, samples = 0;
// Allocate memory from BigBuf for some buffers
// free all previous allocations first
BigBuf_free();
// The response (tag -> reader) that we're receiving.
uint8_t *receivedResponse = BigBuf_malloc(MAX_FRAME_SIZE);
// The DMA buffer, used to stream samples from the FPGA
int8_t *dmaBuf = (int8_t*) BigBuf_malloc(ISO14443B_DMA_BUFFER_SIZE);
// Set up the demodulator for tag -> reader responses.
DemodInit(receivedResponse);
// Setup and start DMA.
FpgaSetupSscDma((uint8_t*) dmaBuf, ISO14443B_DMA_BUFFER_SIZE);
int8_t *upTo = dmaBuf;
lastRxCounter = ISO14443B_DMA_BUFFER_SIZE;
// Signal field is ON with the appropriate LED:
LED_D_ON();
// And put the FPGA in the appropriate mode
FpgaWriteConfWord(FPGA_MAJOR_MODE_HF_READER_RX_XCORR | FPGA_HF_READER_RX_XCORR_848_KHZ);
for(;;) {
int behindBy = lastRxCounter - AT91C_BASE_PDC_SSC->PDC_RCR;
if(behindBy > max) max = behindBy;
while(((lastRxCounter-AT91C_BASE_PDC_SSC->PDC_RCR) & (ISO14443B_DMA_BUFFER_SIZE-1)) > 2) {
ci = upTo[0];
cq = upTo[1];
upTo += 2;
if(upTo >= dmaBuf + ISO14443B_DMA_BUFFER_SIZE) {
upTo = dmaBuf;
AT91C_BASE_PDC_SSC->PDC_RNPR = (uint32_t) upTo;
AT91C_BASE_PDC_SSC->PDC_RNCR = ISO14443B_DMA_BUFFER_SIZE;
}
lastRxCounter -= 2;
if(lastRxCounter <= 0) {
lastRxCounter += ISO14443B_DMA_BUFFER_SIZE;
}
samples += 2;
if(Handle14443bSamplesDemod(ci, cq)) {
gotFrame = TRUE;
break;
}
}
if(samples > n || gotFrame) {
break;
}
}
AT91C_BASE_PDC_SSC->PDC_PTCR = AT91C_PDC_RXTDIS;
if (!quiet) Dbprintf("max behindby = %d, samples = %d, gotFrame = %d, Demod.len = %d, Demod.sumI = %d, Demod.sumQ = %d", max, samples, gotFrame, Demod.len, Demod.sumI, Demod.sumQ);
//Tracing
if (tracing && Demod.len > 0) {
uint8_t parity[MAX_PARITY_SIZE];
LogTrace(Demod.output, Demod.len, 0, 0, parity, FALSE);
}
}
//-----------------------------------------------------------------------------
// Transmit the command (to the tag) that was placed in ToSend[].
//-----------------------------------------------------------------------------
static void TransmitFor14443b(void)
{
int c;
FpgaSetupSsc();
while(AT91C_BASE_SSC->SSC_SR & (AT91C_SSC_TXRDY)) {
AT91C_BASE_SSC->SSC_THR = 0xff;
}
// Signal field is ON with the appropriate Red LED
LED_D_ON();
// Signal we are transmitting with the Green LED
LED_B_ON();
FpgaWriteConfWord(FPGA_MAJOR_MODE_HF_READER_TX | FPGA_HF_READER_TX_SHALLOW_MOD);
for(c = 0; c < 10;) {
if(AT91C_BASE_SSC->SSC_SR & (AT91C_SSC_TXRDY)) {
AT91C_BASE_SSC->SSC_THR = 0xff;
c++;
}
if(AT91C_BASE_SSC->SSC_SR & (AT91C_SSC_RXRDY)) {
volatile uint32_t r = AT91C_BASE_SSC->SSC_RHR;
(void)r;
}
WDT_HIT();
}
c = 0;
for(;;) {
if(AT91C_BASE_SSC->SSC_SR & (AT91C_SSC_TXRDY)) {
AT91C_BASE_SSC->SSC_THR = ToSend[c];
c++;
if(c >= ToSendMax) {
break;
}
}
if(AT91C_BASE_SSC->SSC_SR & (AT91C_SSC_RXRDY)) {
volatile uint32_t r = AT91C_BASE_SSC->SSC_RHR;
(void)r;
}
WDT_HIT();
}
LED_B_OFF(); // Finished sending
}
//-----------------------------------------------------------------------------
// Code a layer 2 command (string of octets, including CRC) into ToSend[],
// so that it is ready to transmit to the tag using TransmitFor14443b().
//-----------------------------------------------------------------------------
static void CodeIso14443bAsReader(const uint8_t *cmd, int len)
{
int i, j;
uint8_t b;
ToSendReset();
// Establish initial reference level
for(i = 0; i < 40; i++) {
ToSendStuffBit(1);
}
// Send SOF
for(i = 0; i < 10; i++) {
ToSendStuffBit(0);
}
for(i = 0; i < len; i++) {
// Stop bits/EGT
ToSendStuffBit(1);
ToSendStuffBit(1);
// Start bit
ToSendStuffBit(0);
// Data bits
b = cmd[i];
for(j = 0; j < 8; j++) {
if(b & 1) {
ToSendStuffBit(1);
} else {
ToSendStuffBit(0);
}
b >>= 1;
}
}
// Send EOF
ToSendStuffBit(1);
for(i = 0; i < 10; i++) {
ToSendStuffBit(0);
}
for(i = 0; i < 8; i++) {
ToSendStuffBit(1);
}
// And then a little more, to make sure that the last character makes
// it out before we switch to rx mode.
for(i = 0; i < 24; i++) {
ToSendStuffBit(1);
}
// Convert from last character reference to length
ToSendMax++;
}
/**
Convenience function to encode, transmit and trace iso 14443b comms
**/
static void CodeAndTransmit14443bAsReader(const uint8_t *cmd, int len)
{
CodeIso14443bAsReader(cmd, len);
TransmitFor14443b();
if (tracing) {
uint8_t parity[MAX_PARITY_SIZE];
LogTrace(cmd,len, 0, 0, parity, TRUE);
}
}
//-----------------------------------------------------------------------------
// Read a SRI512 ISO 14443B tag.
//
// SRI512 tags are just simple memory tags, here we're looking at making a dump
// of the contents of the memory. No anticollision algorithm is done, we assume
// we have a single tag in the field.
//
// I tried to be systematic and check every answer of the tag, every CRC, etc...
//-----------------------------------------------------------------------------
void ReadSTMemoryIso14443b(uint32_t dwLast)
{
FpgaDownloadAndGo(FPGA_BITSTREAM_HF);
clear_trace();
set_tracing(TRUE);
uint8_t i = 0x00;
// Make sure that we start from off, since the tags are stateful;
// confusing things will happen if we don't reset them between reads.
LED_D_OFF();
FpgaWriteConfWord(FPGA_MAJOR_MODE_OFF);
SetAdcMuxFor(GPIO_MUXSEL_HIPKD);
FpgaSetupSsc();
// Now give it time to spin up.
// Signal field is on with the appropriate LED
LED_D_ON();
FpgaWriteConfWord(FPGA_MAJOR_MODE_HF_READER_RX_XCORR | FPGA_HF_READER_RX_XCORR_848_KHZ);
SpinDelay(200);
// First command: wake up the tag using the INITIATE command
uint8_t cmd1[] = {0x06, 0x00, 0x97, 0x5b};
CodeAndTransmit14443bAsReader(cmd1, sizeof(cmd1));
GetSamplesFor14443bDemod(RECEIVE_SAMPLES_TIMEOUT, TRUE);
if (Demod.len == 0) {
DbpString("No response from tag");
return;
} else {
Dbprintf("Randomly generated Chip ID (+ 2 byte CRC): %02x %02x %02x",
Demod.output[0], Demod.output[1], Demod.output[2]);
}
// There is a response, SELECT the uid
DbpString("Now SELECT tag:");
cmd1[0] = 0x0E; // 0x0E is SELECT
cmd1[1] = Demod.output[0];
ComputeCrc14443(CRC_14443_B, cmd1, 2, &cmd1[2], &cmd1[3]);
CodeAndTransmit14443bAsReader(cmd1, sizeof(cmd1));
GetSamplesFor14443bDemod(RECEIVE_SAMPLES_TIMEOUT, TRUE);
if (Demod.len != 3) {
Dbprintf("Expected 3 bytes from tag, got %d", Demod.len);
return;
}
// Check the CRC of the answer:
ComputeCrc14443(CRC_14443_B, Demod.output, 1 , &cmd1[2], &cmd1[3]);
if(cmd1[2] != Demod.output[1] || cmd1[3] != Demod.output[2]) {
DbpString("CRC Error reading select response.");
return;
}
// Check response from the tag: should be the same UID as the command we just sent:
if (cmd1[1] != Demod.output[0]) {
Dbprintf("Bad response to SELECT from Tag, aborting: %02x %02x", cmd1[1], Demod.output[0]);
return;
}
// Tag is now selected,
// First get the tag's UID:
cmd1[0] = 0x0B;
ComputeCrc14443(CRC_14443_B, cmd1, 1 , &cmd1[1], &cmd1[2]);
CodeAndTransmit14443bAsReader(cmd1, 3); // Only first three bytes for this one
GetSamplesFor14443bDemod(RECEIVE_SAMPLES_TIMEOUT, TRUE);
if (Demod.len != 10) {
Dbprintf("Expected 10 bytes from tag, got %d", Demod.len);
return;
}
// The check the CRC of the answer (use cmd1 as temporary variable):
ComputeCrc14443(CRC_14443_B, Demod.output, 8, &cmd1[2], &cmd1[3]);
if(cmd1[2] != Demod.output[8] || cmd1[3] != Demod.output[9]) {
Dbprintf("CRC Error reading block! Expected: %04x got: %04x",
(cmd1[2]<<8)+cmd1[3], (Demod.output[8]<<8)+Demod.output[9]);
// Do not return;, let's go on... (we should retry, maybe ?)
}
Dbprintf("Tag UID (64 bits): %08x %08x",
(Demod.output[7]<<24) + (Demod.output[6]<<16) + (Demod.output[5]<<8) + Demod.output[4],
(Demod.output[3]<<24) + (Demod.output[2]<<16) + (Demod.output[1]<<8) + Demod.output[0]);
// Now loop to read all 16 blocks, address from 0 to last block
Dbprintf("Tag memory dump, block 0 to %d", dwLast);
cmd1[0] = 0x08;
i = 0x00;
dwLast++;
for (;;) {
if (i == dwLast) {
DbpString("System area block (0xff):");
i = 0xff;
}
cmd1[1] = i;
ComputeCrc14443(CRC_14443_B, cmd1, 2, &cmd1[2], &cmd1[3]);
CodeAndTransmit14443bAsReader(cmd1, sizeof(cmd1));
GetSamplesFor14443bDemod(RECEIVE_SAMPLES_TIMEOUT, TRUE);
if (Demod.len != 6) { // Check if we got an answer from the tag
DbpString("Expected 6 bytes from tag, got less...");
return;
}
// The check the CRC of the answer (use cmd1 as temporary variable):
ComputeCrc14443(CRC_14443_B, Demod.output, 4, &cmd1[2], &cmd1[3]);
if(cmd1[2] != Demod.output[4] || cmd1[3] != Demod.output[5]) {
Dbprintf("CRC Error reading block! Expected: %04x got: %04x",
(cmd1[2]<<8)+cmd1[3], (Demod.output[4]<<8)+Demod.output[5]);
// Do not return;, let's go on... (we should retry, maybe ?)
}
// Now print out the memory location:
Dbprintf("Address=%02x, Contents=%08x, CRC=%04x", i,
(Demod.output[3]<<24) + (Demod.output[2]<<16) + (Demod.output[1]<<8) + Demod.output[0],
(Demod.output[4]<<8)+Demod.output[5]);
if (i == 0xff) {
break;
}
i++;
}
}
//=============================================================================
// Finally, the `sniffer' combines elements from both the reader and
// simulated tag, to show both sides of the conversation.
//=============================================================================
//-----------------------------------------------------------------------------
// 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.
//-----------------------------------------------------------------------------
/*
* Memory usage for this function, (within BigBuf)
* Last Received command (reader->tag) - MAX_FRAME_SIZE
* Last Received command (tag->reader) - MAX_FRAME_SIZE
* DMA Buffer - ISO14443B_DMA_BUFFER_SIZE
* Demodulated samples received - all the rest
*/
void RAMFUNC SnoopIso14443b(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 = TRUE; // TODO: set and evaluate trigger condition
FpgaDownloadAndGo(FPGA_BITSTREAM_HF);
BigBuf_free();
clear_trace();
set_tracing(TRUE);
// The DMA buffer, used to stream samples from the FPGA
int8_t *dmaBuf = (int8_t*) BigBuf_malloc(ISO14443B_DMA_BUFFER_SIZE);
int lastRxCounter;
int8_t *upTo;
int ci, cq;
int maxBehindBy = 0;
// Count of samples received so far, so that we can include timing
// information in the trace buffer.
int samples = 0;
DemodInit(BigBuf_malloc(MAX_FRAME_SIZE));
UartInit(BigBuf_malloc(MAX_FRAME_SIZE));
// Print some debug information about the buffer sizes
Dbprintf("Snooping buffers initialized:");
Dbprintf(" Trace: %i bytes", BigBuf_max_traceLen());
Dbprintf(" Reader -> tag: %i bytes", MAX_FRAME_SIZE);
Dbprintf(" tag -> Reader: %i bytes", MAX_FRAME_SIZE);
Dbprintf(" DMA: %i bytes", ISO14443B_DMA_BUFFER_SIZE);
// Signal field is off, no reader signal, no tag signal
LEDsoff();
// And put the FPGA in the appropriate mode
FpgaWriteConfWord(FPGA_MAJOR_MODE_HF_READER_RX_XCORR | FPGA_HF_READER_RX_XCORR_848_KHZ | FPGA_HF_READER_RX_XCORR_SNOOP);
SetAdcMuxFor(GPIO_MUXSEL_HIPKD);
// Setup for the DMA.
FpgaSetupSsc();
upTo = dmaBuf;
lastRxCounter = ISO14443B_DMA_BUFFER_SIZE;
FpgaSetupSscDma((uint8_t*) dmaBuf, ISO14443B_DMA_BUFFER_SIZE);
uint8_t parity[MAX_PARITY_SIZE];
bool TagIsActive = FALSE;
bool ReaderIsActive = FALSE;
// And now we loop, receiving samples.
for(;;) {
int behindBy = (lastRxCounter - AT91C_BASE_PDC_SSC->PDC_RCR) &
(ISO14443B_DMA_BUFFER_SIZE-1);
if(behindBy > maxBehindBy) {
maxBehindBy = behindBy;
}
if(behindBy < 2) continue;
ci = upTo[0];
cq = upTo[1];
upTo += 2;
lastRxCounter -= 2;
if(upTo >= dmaBuf + ISO14443B_DMA_BUFFER_SIZE) {
upTo = dmaBuf;
lastRxCounter += ISO14443B_DMA_BUFFER_SIZE;
AT91C_BASE_PDC_SSC->PDC_RNPR = (uint32_t) dmaBuf;
AT91C_BASE_PDC_SSC->PDC_RNCR = ISO14443B_DMA_BUFFER_SIZE;
WDT_HIT();
if(behindBy > (9*ISO14443B_DMA_BUFFER_SIZE/10)) { // TODO: understand whether we can increase/decrease as we want or not?
Dbprintf("blew circular buffer! behindBy=%d", behindBy);
break;
}
if(!tracing) {
DbpString("Reached trace limit");
break;
}
if(BUTTON_PRESS()) {
DbpString("cancelled");
break;
}
}
samples += 2;
if (!TagIsActive) { // no need to try decoding reader data if the tag is sending
if(Handle14443bUartBit(ci & 0x01)) {
if(triggered && tracing) {
LogTrace(Uart.output, Uart.byteCnt, samples, samples, parity, TRUE);
}
/* 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();
}
if(Handle14443bUartBit(cq & 0x01)) {
if(triggered && tracing) {
LogTrace(Uart.output, Uart.byteCnt, samples, samples, parity, TRUE);
}
/* 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_GOT_FALLING_EDGE_OF_SOF);
}
if(!ReaderIsActive) { // no need to try decoding tag data if the reader is sending - and we cannot afford the time
if(Handle14443bSamplesDemod(ci | 0x01, cq | 0x01)) {
//Use samples as a time measurement
if(tracing)
{
uint8_t parity[MAX_PARITY_SIZE];
LogTrace(Demod.output, Demod.len, samples, samples, parity, FALSE);
}
triggered = TRUE;
// And ready to receive another response.
DemodReset();
}
TagIsActive = (Demod.state > DEMOD_GOT_FALLING_EDGE_OF_SOF);
}
}
FpgaDisableSscDma();
LEDsoff();
AT91C_BASE_PDC_SSC->PDC_PTCR = AT91C_PDC_RXTDIS;
DbpString("Snoop statistics:");
Dbprintf(" Max behind by: %i", maxBehindBy);
Dbprintf(" Uart State: %x", Uart.state);
Dbprintf(" Uart ByteCnt: %i", Uart.byteCnt);
Dbprintf(" Uart ByteCntMax: %i", Uart.byteCntMax);
Dbprintf(" Trace length: %i", BigBuf_get_traceLen());
}
/*
* Send raw command to tag ISO14443B
* @Input
* datalen len of buffer data
* recv bool when true wait for data from tag and send to client
* powerfield bool leave the field on when true
* data buffer with byte to send
*
* @Output
* none
*
*/
void SendRawCommand14443B(uint32_t datalen, uint32_t recv, uint8_t powerfield, uint8_t data[])
{
FpgaDownloadAndGo(FPGA_BITSTREAM_HF);
BigBuf_free();
SetAdcMuxFor(GPIO_MUXSEL_HIPKD);
FpgaSetupSsc();
set_tracing(TRUE);
CodeAndTransmit14443bAsReader(data, datalen);
if(recv) {
GetSamplesFor14443bDemod(RECEIVE_SAMPLES_TIMEOUT, TRUE);
uint16_t iLen = MIN(Demod.len, USB_CMD_DATA_SIZE);
cmd_send(CMD_ACK, iLen, 0, 0, Demod.output, iLen);
}
if(!powerfield) {
FpgaWriteConfWord(FPGA_MAJOR_MODE_OFF);
LED_D_OFF();
}
}
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