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proxmark3/armsrc/pcf7931.c

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#include "pcf7931.h"
#define T0_PCF 8 //period for the pcf7931 in us
#define ALLOC 16
int 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;
int 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
warnings++;
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;
}
int IsBlock0PCF7931(uint8_t *Block) {
// Assume RFU means 0 :)
if((memcmp(Block, "\x00\x00\x00\x00\x00\x00\x00\x01", 8) == 0) && memcmp(Block+9, "\x00\x00\x00\x00\x00\x00\x00", 7) == 0) // PAC enabled
return 1;
if((memcmp(Block+9, "\x00\x00\x00\x00\x00\x00\x00", 7) == 0) && Block[7] == 0) // PAC disabled, can it *really* happen ?
return 1;
return 0;
}
int IsBlock1PCF7931(uint8_t *Block) {
// Assume RFU means 0 :)
if( Block[10] == 0 &&
Block[11] == 0 &&
Block[12] == 0 &&
Block[13] == 0)
if ( (Block[14] & 0x7f) <= 9 && Block[15] <= 9)
return 1;
return 0;
}
void ReadPCF7931() {
uint8_t Blocks[8][17];
uint8_t tmpBlocks[4][16];
int i, j, ind, ind2, n;
int num_blocks = 0;
int max_blocks = 8;
int ident = 0;
int error = 0;
int tries = 0;
memset(Blocks, 0, 8*17*sizeof(uint8_t));
do {
memset(tmpBlocks, 0, 4*16*sizeof(uint8_t));
n = DemodPCF7931((uint8_t**)tmpBlocks);
if(!n)
error++;
if(error==10 && num_blocks == 0) {
Dbprintf("Error, no tag or bad tag");
return;
}
else if (tries==20 || error==10) {
Dbprintf("Error reading the tag");
Dbprintf("Here is the partial content");
goto end;
}
for(i=0; i<n; i++)
Dbprintf("(dbg) %02x %02x %02x %02x %02x %02x %02x %02x %02x %02x %02x %02x %02x %02x %02x %02x",
tmpBlocks[i][0], tmpBlocks[i][1], tmpBlocks[i][2], tmpBlocks[i][3], tmpBlocks[i][4], tmpBlocks[i][5], tmpBlocks[i][6], tmpBlocks[i][7],
tmpBlocks[i][8], tmpBlocks[i][9], tmpBlocks[i][10], tmpBlocks[i][11], tmpBlocks[i][12], tmpBlocks[i][13], tmpBlocks[i][14], tmpBlocks[i][15]);
if(!ident) {
for(i=0; i<n; i++) {
if(IsBlock0PCF7931(tmpBlocks[i])) {
// Found block 0 ?
if(i < n-1 && IsBlock1PCF7931(tmpBlocks[i+1])) {
// Found block 1!
// \o/
ident = 1;
memcpy(Blocks[0], tmpBlocks[i], 16);
Blocks[0][ALLOC] = 1;
memcpy(Blocks[1], tmpBlocks[i+1], 16);
Blocks[1][ALLOC] = 1;
max_blocks = MAX((Blocks[1][14] & 0x7f), Blocks[1][15]) + 1;
// Debug print
Dbprintf("(dbg) Max blocks: %d", max_blocks);
num_blocks = 2;
// Handle following blocks
for(j=i+2, ind2=2; j!=i; j++, ind2++, num_blocks++) {
if(j==n) j=0;
if(j==i) break;
memcpy(Blocks[ind2], tmpBlocks[j], 16);
Blocks[ind2][ALLOC] = 1;
}
break;
}
}
}
}
else {
for(i=0; i<n; i++) { // Look for identical block in known blocks
if(memcmp(tmpBlocks[i], "\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00", 16)) { // Block is not full of 00
for(j=0; j<max_blocks; j++) {
if(Blocks[j][ALLOC] == 1 && !memcmp(tmpBlocks[i], Blocks[j], 16)) {
// Found an identical block
for(ind=i-1,ind2=j-1; ind >= 0; ind--,ind2--) {
if(ind2 < 0)
ind2 = max_blocks;
if(!Blocks[ind2][ALLOC]) { // Block ind2 not already found
// Dbprintf("Tmp %d -> Block %d", ind, ind2);
memcpy(Blocks[ind2], tmpBlocks[ind], 16);
Blocks[ind2][ALLOC] = 1;
num_blocks++;
if(num_blocks == max_blocks) goto end;
}
}
for(ind=i+1,ind2=j+1; ind < n; ind++,ind2++) {
if(ind2 > max_blocks)
ind2 = 0;
if(!Blocks[ind2][ALLOC]) { // Block ind2 not already found
// Dbprintf("Tmp %d -> Block %d", ind, ind2);
memcpy(Blocks[ind2], tmpBlocks[ind], 16);
Blocks[ind2][ALLOC] = 1;
num_blocks++;
if(num_blocks == max_blocks) goto end;
}
}
}
}
}
}
}
tries++;
if (BUTTON_PRESS()) return;
} while (num_blocks != max_blocks);
end:
Dbprintf("-----------------------------------------");
Dbprintf("Memory content:");
Dbprintf("-----------------------------------------");
for(i=0; i<max_blocks; i++) {
if(Blocks[i][ALLOC]==1)
Dbprintf("%02x %02x %02x %02x %02x %02x %02x %02x %02x %02x %02x %02x %02x %02x %02x %02x",
Blocks[i][0], Blocks[i][1], Blocks[i][2], Blocks[i][3], Blocks[i][4], Blocks[i][5], Blocks[i][6], Blocks[i][7],
Blocks[i][8], Blocks[i][9], Blocks[i][10], Blocks[i][11], Blocks[i][12], Blocks[i][13], Blocks[i][14], Blocks[i][15]);
else
Dbprintf("<missing block %d>", i);
}
Dbprintf("-----------------------------------------");
cmd_send(CMD_ACK,0,0,0,0,0);
}
/* 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)
{
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);
//PMC
Dbprintf("Initialization delay : %d us", init_delay);
AddPatternPCF7931(8192/2*T0_PCF + 319*T0_PCF+70, 3*T0_PCF, 29*T0_PCF, tab);
Dbprintf("Offsets : %d us on the low pulses width, %d us on the low pulses positions", l, p);
//password indication bit
AddBitPCF7931(1, tab, l, p);
//password (on 56 bits)
Dbprintf("Password (LSB first on each byte) : %02x %02x %02x %02x %02x %02x %02x", pass1,pass2,pass3,pass4,pass5,pass6,pass7);
AddBytePCF7931(pass1, tab, l, p);
AddBytePCF7931(pass2, tab, l, p);
AddBytePCF7931(pass3, tab, l, p);
AddBytePCF7931(pass4, tab, l, p);
AddBytePCF7931(pass5, tab, l, p);
AddBytePCF7931(pass6, tab, l, p);
AddBytePCF7931(pass7, tab, l, p);
//programming mode (0 or 1)
AddBitPCF7931(0, tab, l, p);
//block adress on 6 bits
Dbprintf("Block address : %02x", address);
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
Dbprintf("Byte address : %02x", byte);
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
Dbprintf("Data : %02x", data);
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);
}
/* 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 <20> 1
if( AddBitPCF7931(1, tab, l, p)==1) return 1;
} else { //bit <20> 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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