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proxmark3/armsrc/pcf7931.c

530 lines
14 KiB
C
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#include "pcf7931.h"
#define T0_PCF 8 //period for the pcf7931 in us
#define ALLOC 16
size_t DemodPCF7931(uint8_t **outBlocks) {
uint8_t bits[256] = {0x00};
uint8_t blocks[8][16];
uint8_t *dest = BigBuf_get_addr();
int GraphTraceLen = BigBuf_max_traceLen();
if ( GraphTraceLen > 18000 )
GraphTraceLen = 18000;
int i, j, lastval, bitidx, half_switch;
int clock = 64;
int tolerance = clock / 8;
int pmc, block_done;
int lc, warnings = 0;
size_t num_blocks = 0;
int lmin=128, lmax=128;
uint8_t dir;
//clear read buffer
BigBuf_Clear_keep_EM();
LFSetupFPGAForADC(95, true);
DoAcquisition_default(0, true);
lmin = 64;
lmax = 192;
i = 2;
/* Find first local max/min */
if(dest[1] > dest[0]) {
while(i < GraphTraceLen) {
if( !(dest[i] > dest[i-1]) && dest[i] > lmax)
break;
i++;
}
dir = 0;
} else {
while(i < GraphTraceLen) {
if( !(dest[i] < dest[i-1]) && dest[i] < lmin)
break;
i++;
}
dir = 1;
}
lastval = i++;
half_switch = 0;
pmc = 0;
block_done = 0;
for (bitidx = 0; i < GraphTraceLen; i++) {
if ((dest[i-1] > dest[i] && dir == 1 && dest[i] > lmax) || (dest[i-1] < dest[i] && dir == 0 && dest[i] < lmin)) {
lc = i - lastval;
lastval = i;
// Switch depending on lc length:
// Tolerance is 1/8 of clock rate (arbitrary)
if (ABS(lc-clock/4) < tolerance) {
// 16T0
if((i - pmc) == lc) { /* 16T0 was previous one */
/* It's a PMC ! */
i += (128+127+16+32+33+16)-1;
lastval = i;
pmc = 0;
block_done = 1;
} else {
pmc = i;
}
} else if (ABS(lc-clock/2) < tolerance) {
// 32TO
if((i - pmc) == lc) { /* 16T0 was previous one */
/* It's a PMC ! */
i += (128+127+16+32+33)-1;
lastval = i;
pmc = 0;
block_done = 1;
} else if(half_switch == 1) {
bits[bitidx++] = 0;
half_switch = 0;
}
else
half_switch++;
} else if (ABS(lc-clock) < tolerance) {
// 64TO
bits[bitidx++] = 1;
} else {
// Error
if (++warnings > 10) {
Dbprintf("Error: too many detection errors, aborting.");
return 0;
}
}
if(block_done == 1) {
if(bitidx == 128) {
for(j = 0; j < 16; ++j) {
blocks[num_blocks][j] =
128 * bits[j*8 + 7]+
64*bits[j*8+6]+
32*bits[j*8+5]+
16*bits[j*8+4]+
8*bits[j*8+3]+
4*bits[j*8+2]+
2*bits[j*8+1]+
bits[j*8]
;
}
num_blocks++;
}
bitidx = 0;
block_done = 0;
half_switch = 0;
}
if(i < GraphTraceLen)
dir =(dest[i-1] > dest[i]) ? 0 : 1;
}
if(bitidx==255)
bitidx=0;
warnings = 0;
if(num_blocks == 4) break;
}
memcpy(outBlocks, blocks, 16*num_blocks);
return num_blocks;
}
bool IsBlock0PCF7931(uint8_t *block) {
// assuming all RFU bits are set to 0
// if PAC is enabled password is set to 0
if (block[7] == 0x01)
{
if (!memcmp(block, "\x00\x00\x00\x00\x00\x00\x00", 7) && !memcmp(block+9, "\x00\x00\x00\x00\x00\x00\x00", 7))
return true;
}
else if (block[7] == 0x00)
{
if (!memcmp(block+9, "\x00\x00\x00\x00\x00\x00\x00", 7))
return true;
}
return false;
}
bool IsBlock1PCF7931(uint8_t *block) {
// assuming all RFU bits are set to 0
if (block[10] == 0 && block[11] == 0 && block[12] == 0 && block[13] == 0)
if((block[14] & 0x7f) <= 9 && block[15] <= 9)
return true;
return false;
}
void ReadPCF7931() {
int found_blocks = 0; // successfully read blocks
int max_blocks = 8; // readable blocks
uint8_t memory_blocks[8][17]; // PCF content
uint8_t single_blocks[8][17]; // PFC blocks with unknown position
int single_blocks_cnt = 0;
size_t n = 0; // transmitted blocks
uint8_t tmp_blocks[4][16]; // temporary read buffer
uint8_t found_0_1 = 0; // flag: blocks 0 and 1 were found
int errors = 0; // error counter
int tries = 0; // tries counter
memset(memory_blocks, 0, 8*17*sizeof(uint8_t));
memset(single_blocks, 0, 8*17*sizeof(uint8_t));
int i = 0, j = 0;
do {
i = 0;
memset(tmp_blocks, 0, 4*16*sizeof(uint8_t));
n = DemodPCF7931((uint8_t**)tmp_blocks);
if(!n)
++errors;
// exit if no block is received
if (errors >= 10 && found_blocks == 0 && single_blocks_cnt == 0) {
Dbprintf("Error, no tag or bad tag");
return;
}
// exit if too many errors during reading
if (tries > 50 && (2*errors > tries)) {
Dbprintf("Error reading the tag");
Dbprintf("Here is the partial content");
goto end;
}
// our logic breaks if we don't get at least two blocks
if (n < 2) {
if (n == 0 || !memcmp(tmp_blocks[0], "\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00", 16))
continue;
if (single_blocks_cnt < max_blocks) {
for (i = 0; i < single_blocks_cnt; ++i) {
if (!memcmp(single_blocks[i], tmp_blocks[0], 16)) {
j = 1;
break;
}
}
if (j != 1) {
memcpy(single_blocks[single_blocks_cnt], tmp_blocks[0], 16);
single_blocks_cnt++;
}
j = 0;
}
++tries;
continue;
}
Dbprintf("(dbg) got %d blocks (%d/%d found) (%d tries, %d errors)", n, found_blocks, (max_blocks == 0 ? found_blocks : max_blocks), tries, errors);
i = 0;
if(!found_0_1) {
while (i < n - 1) {
if (IsBlock0PCF7931(tmp_blocks[i]) && IsBlock1PCF7931(tmp_blocks[i+1])) {
found_0_1 = 1;
memcpy(memory_blocks[0], tmp_blocks[i], 16);
memcpy(memory_blocks[1], tmp_blocks[i+1], 16);
memory_blocks[0][ALLOC] = memory_blocks[1][ALLOC] = 1;
// block 1 tells how many blocks are going to be sent
max_blocks = MAX((memory_blocks[1][14] & 0x7f), memory_blocks[1][15]) + 1;
found_blocks = 2;
Dbprintf("Found blocks 0 and 1. PCF is transmitting %d blocks.", max_blocks);
// handle the following blocks
for (j = i + 2; j < n; ++j) {
memcpy(memory_blocks[found_blocks], tmp_blocks[j], 16);
memory_blocks[found_blocks][ALLOC] = 1;
++found_blocks;
}
break;
}
++i;
}
} else {
// Trying to re-order blocks
// Look for identical block in memory blocks
while (i < n-1) {
// skip all zeroes blocks
if (memcmp(tmp_blocks[i], "\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00", 16)) {
for (j = 1; j < max_blocks - 1; ++j) {
if (!memcmp(tmp_blocks[i], memory_blocks[j], 16) && !memory_blocks[j+1][ALLOC]) {
memcpy(memory_blocks[j+1], tmp_blocks[i+1], 16);
memory_blocks[j+1][ALLOC] = 1;
if (++found_blocks >= max_blocks) goto end;
}
}
}
if (memcmp(tmp_blocks[i+1], "\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00", 16)) {
for (j = 0; j < max_blocks; ++j) {
if (!memcmp(tmp_blocks[i+1], memory_blocks[j], 16) && !memory_blocks[(j == 0 ? max_blocks : j) -1][ALLOC]) {
if (j == 0) {
memcpy(memory_blocks[max_blocks - 1], tmp_blocks[i], 16);
memory_blocks[max_blocks - 1][ALLOC] = 1;
} else {
memcpy(memory_blocks[j-1], tmp_blocks[i], 16);
memory_blocks[j-1][ALLOC] = 1;
}
if (++found_blocks >= max_blocks) goto end;
}
}
}
++i;
}
}
++tries;
if (BUTTON_PRESS()) {
Dbprintf("Button pressed, stopping.");
goto end;
}
}
while (found_blocks != max_blocks);
end:
Dbprintf("-----------------------------------------");
Dbprintf("Memory content:");
Dbprintf("-----------------------------------------");
for (i = 0; i < max_blocks; ++i) {
if (memory_blocks[i][ALLOC])
print_result("Block", memory_blocks[i], 16);
else
Dbprintf("<missing block %d>", i);
}
Dbprintf("-----------------------------------------");
if (found_blocks < max_blocks) {
Dbprintf("-----------------------------------------");
Dbprintf("Blocks with unknown position:");
Dbprintf("-----------------------------------------");
for (i = 0; i < single_blocks_cnt; ++i)
print_result("Block", single_blocks[i], 16);
Dbprintf("-----------------------------------------");
}
cmd_send(CMD_ACK,0,0,0,0,0);
}
static void RealWritePCF7931(uint8_t *pass, uint16_t init_delay, int32_t l, int32_t p, uint8_t address, uint8_t byte, uint8_t data) {
uint32_t tab[1024] = {0}; // data times frame
uint32_t u = 0;
uint8_t parity = 0;
bool comp = 0;
//BUILD OF THE DATA FRAME
//alimentation of the tag (time for initializing)
AddPatternPCF7931(init_delay, 0, 8192/2*T0_PCF, tab);
AddPatternPCF7931(8192/2*T0_PCF + 319*T0_PCF+70, 3*T0_PCF, 29*T0_PCF, tab);
//password indication bit
AddBitPCF7931(1, tab, l, p);
//password (on 56 bits)
AddBytePCF7931(pass[0], tab, l, p);
AddBytePCF7931(pass[1], tab, l, p);
AddBytePCF7931(pass[2], tab, l, p);
AddBytePCF7931(pass[3], tab, l, p);
AddBytePCF7931(pass[4], tab, l, p);
AddBytePCF7931(pass[5], tab, l, p);
AddBytePCF7931(pass[6], tab, l, p);
//programming mode (0 or 1)
AddBitPCF7931(0, tab, l, p);
//block adress on 6 bits
for (u = 0; u < 6; ++u) {
if (address&(1<<u)) { // bit 1
++parity;
AddBitPCF7931(1, tab, l, p);
} else{ // bit 0
AddBitPCF7931(0, tab, l, p);
}
}
//byte address on 4 bits
for (u = 0; u < 4; ++u)
{
if (byte&(1<<u)) { // bit 1
parity++;
AddBitPCF7931(1, tab, l, p);
}
else // bit 0
AddBitPCF7931(0, tab, l, p);
}
//data on 8 bits
for (u=0; u<8; u++)
{
if (data&(1<<u)) { // bit 1
parity++;
AddBitPCF7931(1, tab, l, p);
}
else //bit 0
AddBitPCF7931(0, tab, l, p);
}
//parity bit
if ((parity % 2) == 0)
AddBitPCF7931(0, tab, l, p); //even parity
else
AddBitPCF7931(1, tab, l, p);//odd parity
//time access memory
AddPatternPCF7931(5120+2680, 0, 0, tab);
//conversion of the scale time
for (u = 0; u < 500; ++u)
tab[u]=(tab[u] * 3)/2;
//compensation of the counter reload
while (!comp){
comp = 1;
for (u = 0; tab[u] != 0; ++u)
if(tab[u] > 0xFFFF){
tab[u] -= 0xFFFF;
comp = 0;
}
}
SendCmdPCF7931(tab);
}
/* Write on a byte of a PCF7931 tag
* @param address : address of the block to write
@param byte : address of the byte to write
@param data : data to write
*/
void WritePCF7931(uint8_t pass1, uint8_t pass2, uint8_t pass3, uint8_t pass4, uint8_t pass5, uint8_t pass6, uint8_t pass7, uint16_t init_delay, int32_t l, int32_t p, uint8_t address, uint8_t byte, uint8_t data) {
Dbprintf("Initialization delay : %d us", init_delay);
Dbprintf("Offsets : %d us on the low pulses width, %d us on the low pulses positions", l, p);
Dbprintf("Password (LSB first on each byte): %02x %02x %02x %02x %02x %02x %02x", pass1, pass2, pass3, pass4, pass5, pass6, pass7);
Dbprintf("Block address : %02x", address);
Dbprintf("Byte address : %02x", byte);
Dbprintf("Data : %02x", data);
uint8_t password[7] = {pass1, pass2, pass3, pass4, pass5, pass6, pass7};
RealWritePCF7931 (password, init_delay, l, p, address, byte, data);
}
/* Send a trame to a PCF7931 tags
* @param tab : array of the data frame
*/
void SendCmdPCF7931(uint32_t * tab){
uint16_t u=0, tempo=0;
Dbprintf("Sending data frame...");
FpgaDownloadAndGo(FPGA_BITSTREAM_LF);
FpgaSendCommand(FPGA_CMD_SET_DIVISOR, 95); //125Khz
FpgaWriteConfWord(FPGA_MAJOR_MODE_LF_PASSTHRU );
LED_A_ON();
// steal this pin from the SSP and use it to control the modulation
AT91C_BASE_PIOA->PIO_PER = GPIO_SSC_DOUT;
AT91C_BASE_PIOA->PIO_OER = GPIO_SSC_DOUT;
//initialization of the timer
AT91C_BASE_PMC->PMC_PCER |= (0x1 << AT91C_ID_TC0);
AT91C_BASE_TCB->TCB_BMR = AT91C_TCB_TC0XC0S_NONE | AT91C_TCB_TC1XC1S_TIOA0 | AT91C_TCB_TC2XC2S_NONE;
AT91C_BASE_TC0->TC_CCR = AT91C_TC_CLKDIS; // timer disable
AT91C_BASE_TC0->TC_CMR = AT91C_TC_CLKS_TIMER_DIV3_CLOCK; //clock at 48/32 MHz
AT91C_BASE_TC0->TC_CCR = AT91C_TC_CLKEN;
AT91C_BASE_TCB->TCB_BCR = 1;
tempo = AT91C_BASE_TC0->TC_CV;
for( u = 0; tab[u] != 0; u += 3){
// modulate antenna
HIGH(GPIO_SSC_DOUT);
while (tempo != tab[u])
tempo = AT91C_BASE_TC0->TC_CV;
// stop modulating antenna
LOW(GPIO_SSC_DOUT);
while (tempo != tab[u+1])
tempo = AT91C_BASE_TC0->TC_CV;
// modulate antenna
HIGH(GPIO_SSC_DOUT);
while (tempo != tab[u+2])
tempo = AT91C_BASE_TC0->TC_CV;
}
LED_A_OFF();
FpgaWriteConfWord(FPGA_MAJOR_MODE_OFF);
SpinDelay(200);
AT91C_BASE_TC0->TC_CCR = AT91C_TC_CLKDIS; // timer disable
LED(0xFFFF, 1000);
}
/* Add a byte for building the data frame of PCF7931 tags
* @param b : byte to add
* @param tab : array of the data frame
* @param l : offset on low pulse width
* @param p : offset on low pulse positioning
*/
bool AddBytePCF7931(uint8_t byte, uint32_t * tab, int32_t l, int32_t p){
uint32_t u;
for (u = 0; u < 8; ++u) {
if (byte & (1 << u)) { //bit is 1
if( AddBitPCF7931(1, tab, l, p)==1) return 1;
} else { //bit is 0
if (AddBitPCF7931(0, tab, l, p)==1) return 1;
}
}
return 0;
}
/* Add a bits for building the data frame of PCF7931 tags
* @param b : bit to add
* @param tab : array of the data frame
* @param l : offset on low pulse width
* @param p : offset on low pulse positioning
*/
bool AddBitPCF7931(bool b, uint32_t * tab, int32_t l, int32_t p){
uint8_t u = 0;
//we put the cursor at the last value of the array
for ( u = 0; tab[u] != 0; u += 3 ) { }
if ( b == 1 ) { //add a bit 1
if ( u == 0 )
tab[u] = 34 * T0_PCF + p;
else
tab[u] = 34 * T0_PCF + tab[u-1] + p;
tab[u+1] = 6 * T0_PCF + tab[u] + l;
tab[u+2] = 88 * T0_PCF + tab[u+1] - l - p;
return 0;
} else { //add a bit 0
if ( u == 0 )
tab[u] = 98 * T0_PCF + p;
else
tab[u] = 98 * T0_PCF + tab[u-1] + p;
tab[u+1] = 6 * T0_PCF + tab[u] + l;
tab[u+2] = 24 * T0_PCF + tab[u+1] - l - p;
return 0;
}
return 1;
}
/* Add a custom pattern in the data frame
* @param a : delay of the first high pulse
* @param b : delay of the low pulse
* @param c : delay of the last high pulse
* @param tab : array of the data frame
*/
bool AddPatternPCF7931(uint32_t a, uint32_t b, uint32_t c, uint32_t * tab){
uint32_t u = 0;
for(u = 0; tab[u] != 0; u += 3){} //we put the cursor at the last value of the array
tab[u] = (u == 0) ? a : a + tab[u-1];
tab[u+1] = b + tab[u];
tab[u+2] = c + tab[u+1];
return 0;
}
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