//----------------------------------------------------------------------------- // 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 //============================================================================= // 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_ERROR_WAIT } 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 int Handle14443bUartBit(int 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_ERROR_WAIT; } } 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. Uart.state = STATE_ERROR_WAIT; } 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_ERROR_WAIT; } } 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 Uart.posCnt = 0; Uart.state = STATE_ERROR_WAIT; } 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 if (Uart.byteCnt != 0) { return TRUE; } Uart.posCnt = 0; Uart.state = STATE_ERROR_WAIT; } else { // this is an error Uart.posCnt = 0; Uart.state = STATE_ERROR_WAIT; } } break; case STATE_ERROR_WAIT: // We're all screwed up, so wait a little while // for whatever went wrong to finish, and then // start over. Uart.posCnt++; if(Uart.posCnt > 10) { Uart.state = STATE_UNSYNCD; LED_A_OFF(); } break; default: Uart.state = STATE_UNSYNCD; break; } return FALSE; } //----------------------------------------------------------------------------- // 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, int *len, int maxLen) { uint8_t mask; int i, bit; // 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. 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; mask = 0x80; for(i = 0; i < 8; i++, mask >>= 1) { bit = (b & mask); if(Handle14443bUartBit(bit)) { *len = Uart.byteCnt; return TRUE; } } } } } //----------------------------------------------------------------------------- // Main loop of simulated tag: receive commands from reader, decide what // response to send, and send it. //----------------------------------------------------------------------------- void SimulateIso14443bTag(void) { // the only command we understand is REQB, AFI=0, Select All, N=0: static const uint8_t cmd1[] = { 0x05, 0x00, 0x08, 0x39, 0x73 }; // ... and we 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 }; uint8_t *resp; int respLen; // allocate command receive buffer BigBuf_free(); uint8_t *receivedCmd = BigBuf_malloc(MAX_FRAME_SIZE); int len; int i; int cmdsRecvd = 0; FpgaDownloadAndGo(FPGA_BITSTREAM_HF); // prepare the (only one) tag answer: CodeIso14443bAsTag(response1, sizeof(response1)); uint8_t *resp1 = BigBuf_malloc(ToSendMax); memcpy(resp1, ToSend, ToSendMax); uint16_t resp1Len = ToSendMax; // We need to listen to the high-frequency, peak-detected path. SetAdcMuxFor(GPIO_MUXSEL_HIPKD); FpgaSetupSsc(); cmdsRecvd = 0; for(;;) { uint8_t b1, b2; if(!GetIso14443bCommandFromReader(receivedCmd, &len, 100)) { Dbprintf("button pressed, received %d commands", cmdsRecvd); break; } // Good, look at the command now. if(len == sizeof(cmd1) && memcmp(receivedCmd, cmd1, len)==0) { resp = resp1; respLen = resp1Len; } else { Dbprintf("new cmd from reader: len=%d, cmdsRecvd=%d", len, cmdsRecvd); // And print whether the CRC fails, just for good measure 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(respLen <= 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(); // Transmit the response. i = 0; for(;;) { if(AT91C_BASE_SSC->SSC_SR & (AT91C_SSC_TXRDY)) { uint8_t b = resp[i]; AT91C_BASE_SSC->SSC_THR = b; i++; if(i > respLen) { break; } } if(AT91C_BASE_SSC->SSC_SR & (AT91C_SSC_RXRDY)) { volatile uint8_t b = (uint8_t)AT91C_BASE_SSC->SSC_RHR; (void)b; } } } } //============================================================================= // 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, DEMOD_ERROR_WAIT } 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(); } 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(); } /* * 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(DMA_BUFFER_SIZE); // Set up the demodulator for tag -> reader responses. DemodInit(receivedResponse); // Setup and start DMA. FpgaSetupSscDma((uint8_t*) dmaBuf, DMA_BUFFER_SIZE); int8_t *upTo = dmaBuf; lastRxCounter = 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) & (DMA_BUFFER_SIZE-1)) > 2) { ci = upTo[0]; cq = upTo[1]; upTo += 2; if(upTo >= dmaBuf + DMA_BUFFER_SIZE) { upTo = dmaBuf; AT91C_BASE_PDC_SSC->PDC_RNPR = (uint32_t) upTo; AT91C_BASE_PDC_SSC->PDC_RNCR = DMA_BUFFER_SIZE; } lastRxCounter -= 2; if(lastRxCounter <= 0) { lastRxCounter += 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]; //GetParity(Demod.output, Demod.len, parity); 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]; GetParity(cmd, len, parity); 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) { clear_trace(); set_tracing(TRUE); uint8_t i = 0x00; FpgaDownloadAndGo(FPGA_BITSTREAM_HF); // 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); SpinDelay(200); 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)); // LED_A_ON(); GetSamplesFor14443bDemod(RECEIVE_SAMPLES_TIMEOUT, TRUE); // LED_A_OFF(); if (Demod.len == 0) { DbpString("No response from tag"); return; } else { Dbprintf("Randomly generated UID from tag (+ 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)); // LED_A_ON(); GetSamplesFor14443bDemod(RECEIVE_SAMPLES_TIMEOUT, TRUE); // LED_A_OFF(); 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 // LED_A_ON(); GetSamplesFor14443bDemod(RECEIVE_SAMPLES_TIMEOUT, TRUE); // LED_A_OFF(); 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)); // LED_A_ON(); GetSamplesFor14443bDemod(RECEIVE_SAMPLES_TIMEOUT, TRUE); // LED_A_OFF(); 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 - 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(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", 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 = DMA_BUFFER_SIZE; FpgaSetupSscDma((uint8_t*) dmaBuf, 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) & (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 + DMA_BUFFER_SIZE) { upTo = dmaBuf; lastRxCounter += DMA_BUFFER_SIZE; AT91C_BASE_PDC_SSC->PDC_RNPR = (uint32_t) dmaBuf; AT91C_BASE_PDC_SSC->PDC_RNCR = DMA_BUFFER_SIZE; WDT_HIT(); if(behindBy > (9*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) { //GetParity(Uart.output, Uart.byteCnt, parity); 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) { //GetParity(Uart.output, Uart.byteCnt, parity); 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_UNSYNCD); } if(!ReaderIsActive) { // no need to try decoding tag data if the reader is sending - and we cannot afford the time if(Handle14443bSamplesDemod(ci, cq)) { //Use samples as a time measurement if(tracing) { uint8_t parity[MAX_PARITY_SIZE]; //GetParity(Demod.output, Demod.len, parity); 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); SetAdcMuxFor(GPIO_MUXSEL_HIPKD); FpgaSetupSsc(); set_tracing(TRUE); /* if(!powerfield) { // Make sure that we start from off, since the tags are stateful; // confusing things will happen if we don't reset them between reads. FpgaWriteConfWord(FPGA_MAJOR_MODE_OFF); LED_D_OFF(); SpinDelay(200); } */ // if(!GETBIT(GPIO_LED_D)) { // if field is off // FpgaWriteConfWord(FPGA_MAJOR_MODE_HF_READER_RX_XCORR | FPGA_HF_READER_RX_XCORR_848_KHZ); // // Signal field is on with the appropriate LED // LED_D_ON(); // SpinDelay(200); // } 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(); } }