//-----------------------------------------------------------------------------
// Copyright (C) 2010 iZsh <izsh at fail0verflow.com>
//
// 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.
//-----------------------------------------------------------------------------
// Low frequency TI commands
//-----------------------------------------------------------------------------
#include <stdio.h>
#include <stdlib.h>
#include <inttypes.h>
#include "crc16.h"
#include "proxmark3.h"
#include "ui.h"
#include "graph.h"
#include "cmdparser.h"
#include "cmdlfti.h"
#include "cmdmain.h"
static int CmdHelp(const char *Cmd);
static int CmdTIDemod(const char *Cmd) {
(void)Cmd; // Cmd is not used so far
/* MATLAB as follows:
f_s = 2000000; % sampling frequency
f_l = 123200; % low FSK tone
f_h = 134200; % high FSK tone
T_l = 119e-6; % low bit duration
T_h = 130e-6; % high bit duration
l = 2*pi*ones(1, floor(f_s*T_l))*(f_l/f_s);
h = 2*pi*ones(1, floor(f_s*T_h))*(f_h/f_s);
l = sign(sin(cumsum(l)));
h = sign(sin(cumsum(h)));
*/
// 2M*16/134.2k = 238
static const int LowTone[] = {
1, 1, 1, 1, 1, 1, 1, 1, 1, -1, -1, -1, -1, -1, -1, -1, -1,
1, 1, 1, 1, 1, 1, 1, 1, -1, -1, -1, -1, -1, -1, -1, -1,
1, 1, 1, 1, 1, 1, 1, 1, -1, -1, -1, -1, -1, -1, -1, -1,
1, 1, 1, 1, 1, 1, 1, 1, -1, -1, -1, -1, -1, -1, -1, -1,
1, 1, 1, 1, 1, 1, 1, 1, 1, -1, -1, -1, -1, -1, -1, -1, -1,
1, 1, 1, 1, 1, 1, 1, 1, -1, -1, -1, -1, -1, -1, -1, -1,
1, 1, 1, 1, 1, 1, 1, 1, -1, -1, -1, -1, -1, -1, -1, -1,
1, 1, 1, 1, 1, 1, 1, 1, -1, -1, -1, -1, -1, -1, -1, -1,
1, 1, 1, 1, 1, 1, 1, 1, 1, -1, -1, -1, -1, -1, -1, -1, -1,
1, 1, 1, 1, 1, 1, 1, 1, -1, -1, -1, -1, -1, -1, -1, -1,
1, 1, 1, 1, 1, 1, 1, 1, -1, -1, -1, -1, -1, -1, -1, -1,
1, 1, 1, 1, 1, 1, 1, 1, -1, -1, -1, -1, -1, -1, -1, -1,
1, 1, 1, 1, 1, 1, 1, 1, 1, -1, -1, -1, -1, -1, -1, -1, -1,
1, 1, 1, 1, 1, 1, 1, 1, -1, -1, -1, -1, -1, -1, -1, -1,
1, 1, 1, 1, 1, 1, 1, 1, -1, -1
};
// 2M*16/123.2k = 260
static const int HighTone[] = {
1, 1, 1, 1, 1, 1, 1, 1, -1, -1, -1, -1, -1, -1, -1,
1, 1, 1, 1, 1, 1, 1, 1, -1, -1, -1, -1, -1, -1, -1,
1, 1, 1, 1, 1, 1, 1, -1, -1, -1, -1, -1, -1, -1, -1,
1, 1, 1, 1, 1, 1, 1, -1, -1, -1, -1, -1, -1, -1, -1,
1, 1, 1, 1, 1, 1, 1, -1, -1, -1, -1, -1, -1, -1, -1,
1, 1, 1, 1, 1, 1, 1, -1, -1, -1, -1, -1, -1, -1,
1, 1, 1, 1, 1, 1, 1, 1, -1, -1, -1, -1, -1, -1, -1,
1, 1, 1, 1, 1, 1, 1, 1, -1, -1, -1, -1, -1, -1, -1,
1, 1, 1, 1, 1, 1, 1, -1, -1, -1, -1, -1, -1, -1, -1,
1, 1, 1, 1, 1, 1, 1, -1, -1, -1, -1, -1, -1, -1, -1,
1, 1, 1, 1, 1, 1, 1, -1, -1, -1, -1, -1, -1, -1,
1, 1, 1, 1, 1, 1, 1, 1, -1, -1, -1, -1, -1, -1, -1,
1, 1, 1, 1, 1, 1, 1, 1, -1, -1, -1, -1, -1, -1, -1,
1, 1, 1, 1, 1, 1, 1, 1, -1, -1, -1, -1, -1, -1, -1,
1, 1, 1, 1, 1, 1, 1, -1, -1, -1, -1, -1, -1, -1, -1,
1, 1, 1, 1, 1, 1, 1, -1, -1, -1, -1, -1, -1, -1, -1,
1, 1, 1, 1, 1, 1, 1, -1, -1, -1, -1, -1, -1, -1,
1, 1, 1, 1, 1, 1, 1, 1
};
save_restoreGB(GRAPH_SAVE);
int lowLen = sizeof(LowTone) / sizeof(int);
int highLen = sizeof(HighTone) / sizeof(int);
int convLen = (highLen > lowLen) ? highLen : lowLen;
uint16_t crc;
int i, j, TagType;
int lowSum = 0, highSum = 0;;
int lowTot = 0, highTot = 0;
int retval = PM3_ESOFT;
for (i = 0; i < GraphTraceLen - convLen; i++) {
lowSum = 0;
highSum = 0;;
for (j = 0; j < lowLen; j++) {
lowSum += LowTone[j] * GraphBuffer[i + j];
}
for (j = 0; j < highLen; j++) {
highSum += HighTone[j] * GraphBuffer[i + j];
}
lowSum = abs((100 * lowSum) / lowLen);
highSum = abs((100 * highSum) / highLen);
lowSum = (lowSum < 0) ? -lowSum : lowSum;
highSum = (highSum < 0) ? -highSum : highSum;
GraphBuffer[i] = (highSum << 16) | lowSum;
}
for (i = 0; i < GraphTraceLen - convLen - 16; i++) {
lowTot = 0;
highTot = 0;
// 16 and 15 are f_s divided by f_l and f_h, rounded
for (j = 0; j < 16; j++) {
lowTot += (GraphBuffer[i + j] & 0xffff);
}
for (j = 0; j < 15; j++) {
highTot += (GraphBuffer[i + j] >> 16);
}
GraphBuffer[i] = lowTot - highTot;
}
GraphTraceLen -= (convLen + 16);
RepaintGraphWindow();
// TI tag data format is 16 prebits, 8 start bits, 64 data bits,
// 16 crc CCITT bits, 8 stop bits, 15 end bits
// the 16 prebits are always low
// the 8 start and stop bits of a tag must match
// the start/stop prebits of a ro tag are 01111110
// the start/stop prebits of a rw tag are 11111110
// the 15 end bits of a ro tag are all low
// the 15 end bits of a rw tag match bits 15-1 of the data bits
// Okay, so now we have unsliced soft decisions;
// find bit-sync, and then get some bits.
// look for 17 low bits followed by 6 highs (common pattern for ro and rw tags)
int max = 0, maxPos = 0;
for (i = 0; i < 6000; i++) {
int dec = 0;
// searching 17 consecutive lows
for (j = 0; j < 17 * lowLen; j++) {
dec -= GraphBuffer[i + j];
}
// searching 7 consecutive highs
for (; j < 17 * lowLen + 6 * highLen; j++) {
dec += GraphBuffer[i + j];
}
if (dec > max) {
max = dec;
maxPos = i;
}
}
// place a marker in the buffer to visually aid location
// of the start of sync
GraphBuffer[maxPos] = 800;
GraphBuffer[maxPos + 1] = -800;
// advance pointer to start of actual data stream (after 16 pre and 8 start bits)
maxPos += 17 * lowLen;
maxPos += 6 * highLen;
// place a marker in the buffer to visually aid location
// of the end of sync
GraphBuffer[maxPos] = 800;
GraphBuffer[maxPos + 1] = -800;
PrintAndLogEx(DEBUG, "actual data bits start at sample %d", maxPos);
PrintAndLogEx(DEBUG, "length %d/%d", highLen, lowLen);
uint8_t bits[1 + 64 + 16 + 8 + 16];
bits[sizeof(bits) - 1] = '\0';
uint32_t shift3 = 0x7e000000, shift2 = 0, shift1 = 0, shift0 = 0;
for (i = 0; i < ARRAYLEN(bits) - 1; i++) {
int high = 0, low = 0;
for (j = 0; j < lowLen; j++) {
low -= GraphBuffer[maxPos + j];
}
for (j = 0; j < highLen; j++) {
high += GraphBuffer[maxPos + j];
}
if (high > low) {
bits[i] = '1';
maxPos += highLen;
// bitstream arrives lsb first so shift right
shift3 |= (1u << 31);
} else {
bits[i] = '.';
maxPos += lowLen;
}
// 128 bit right shift register
shift0 = (shift0 >> 1) | (shift1 << 31);
shift1 = (shift1 >> 1) | (shift2 << 31);
shift2 = (shift2 >> 1) | (shift3 << 31);
shift3 >>= 1;
// place a marker in the buffer between bits to visually aid location
GraphBuffer[maxPos] = 800;
GraphBuffer[maxPos + 1] = -800;
}
RepaintGraphWindow();
PrintAndLogEx(DEBUG, "TI tag : raw tag bits | %s", bits);
TagType = (shift3 >> 8) & 0xFF;
if (TagType != ((shift0 >> 16) & 0xFF)) {
PrintAndLogEx(DEBUG, "TI tag : Error: start and stop bits do not match!");
goto out;
} else if (TagType == 0x7E) {
PrintAndLogEx(INFO, "Readonly TI tag detected.");
retval = PM3_SUCCESS;
goto out;
} else if (TagType == 0xFE) {
PrintAndLogEx(INFO, "Rewriteable TI tag detected.");
// put 64 bit data into shift1 and shift0
shift0 = (shift0 >> 24) | (shift1 << 8);
shift1 = (shift1 >> 24) | (shift2 << 8);
// align 16 bit crc into lower half of shift2
shift2 = ((shift2 >> 24) | (shift3 << 8)) & 0x0FFFF;
// align 16 bit "end bits" or "ident" into lower half of shift3
shift3 >>= 16;
// only 15 bits compare, last bit of ident is not valid
if ((shift3 ^ shift0) & 0x7FFF) {
PrintAndLogEx(WARNING, "Error: Ident mismatch!");
}
// WARNING the order of the bytes in which we calc crc below needs checking
// i'm 99% sure the crc algorithm is correct, but it may need to eat the
// bytes in reverse or something
// calculate CRC
crc = 0;
crc = update_crc16(crc, (shift0 >> 0) & 0xFF);
crc = update_crc16(crc, (shift0 >> 8) & 0xFF);
crc = update_crc16(crc, (shift0 >> 16) & 0xFF);
crc = update_crc16(crc, (shift0 >> 24) & 0xFF);
crc = update_crc16(crc, (shift1 >> 0) & 0xFF);
crc = update_crc16(crc, (shift1 >> 8) & 0xFF);
crc = update_crc16(crc, (shift1 >> 16) & 0xFF);
crc = update_crc16(crc, (shift1 >> 24) & 0xFF);
//crc = crc16_ccitt(message, sizeof(message);
const char *crcStr = (crc == (shift2 & 0xFFFF)) ? _GREEN_("Passed") : _RED_("Fail");
PrintAndLogEx(INFO, "Tag data = %08X%08X [Crc %04X %s]", shift1, shift0, crc, crcStr);
if (crc != (shift2 & 0xFFFF))
PrintAndLogEx(WARNING, "Error: CRC mismatch, calculated %04X, got %04X", crc, shift2 & 0xFFFF);
retval = PM3_SUCCESS;
goto out;
} else {
PrintAndLogEx(WARNING, "Unknown tag type.");
}
out:
if (retval != PM3_SUCCESS)
save_restoreGB(GRAPH_RESTORE);
return retval;
}
// read a TI tag and return its ID
static int CmdTIRead(const char *Cmd) {
(void)Cmd; // Cmd is not used so far
clearCommandBuffer();
SendCommandNG(CMD_READ_TI_TYPE, NULL, 0);
return PM3_SUCCESS;
}
// write new data to a r/w TI tag
static int CmdTIWrite(const char *Cmd) {
int res = 0;
uint64_t arg0, arg1, arg2;
res = sscanf(Cmd, "%012" SCNx64 " %012" SCNx64 " %012" SCNx64 "", &arg0, &arg1, &arg2);
if (res == 2)
arg2 = 0;
if (res < 2) {
PrintAndLogEx(WARNING, "Please specify the data as two hex strings, optionally the CRC as a third");
return PM3_EINVARG;
}
clearCommandBuffer();
SendCommandMIX(CMD_WRITE_TI_TYPE, arg0, arg1, arg2, NULL, 0);
return PM3_SUCCESS;
}
static command_t CommandTable[] = {
{"help", CmdHelp, AlwaysAvailable, "This help"},
{"demod", CmdTIDemod, AlwaysAvailable, "Demodulate raw bits for TI-type LF tag from the GraphBuffer"},
{"read", CmdTIRead, IfPm3Lf, "Read and decode a TI 134 kHz tag"},
{"write", CmdTIWrite, IfPm3Lf, "Write new data to a r/w TI 134 kHz tag"},
{NULL, NULL, NULL, NULL}
};
static int CmdHelp(const char *Cmd) {
(void)Cmd; // Cmd is not used so far
CmdsHelp(CommandTable);
return PM3_SUCCESS;
}
int CmdLFTI(const char *Cmd) {
clearCommandBuffer();
return CmdsParse(CommandTable, Cmd);
}
int demodTI(void) {
return CmdTIDemod("");
}