//-----------------------------------------------------------------------------
// 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 EM4x commands
//-----------------------------------------------------------------------------
#include <stdio.h>
#include <string.h>
#include "proxusb.h"
#include "ui.h"
#include "graph.h"
#include "cmdparser.h"
#include "cmddata.h"
#include "cmdlf.h"
#include "cmdlfem4x.h"
static int CmdHelp(const char *Cmd);
/* Read the ID of an EM410x tag.
* Format:
* 1111 1111 1 <-- standard non-repeatable header
* XXXX [row parity bit] <-- 10 rows of 5 bits for our 40 bit tag ID
* ....
* CCCC <-- each bit here is parity for the 10 bits above in corresponding column
* 0 <-- stop bit, end of tag
*/
int CmdEM410xRead(const char *Cmd)
{
int i, j, clock, header, rows, bit, hithigh, hitlow, first, bit2idx, high, low;
int parity[4];
char id[11];
int retested = 0;
uint8_t BitStream[MAX_GRAPH_TRACE_LEN];
high = low = 0;
/* Detect high and lows and clock */
for (i = 0; i < GraphTraceLen; i++)
{
if (GraphBuffer[i] > high)
high = GraphBuffer[i];
else if (GraphBuffer[i] < low)
low = GraphBuffer[i];
}
/* get clock */
clock = GetClock(Cmd, high, 0);
/* parity for our 4 columns */
parity[0] = parity[1] = parity[2] = parity[3] = 0;
header = rows = 0;
/* manchester demodulate */
bit = bit2idx = 0;
for (i = 0; i < (int)(GraphTraceLen / clock); i++)
{
hithigh = 0;
hitlow = 0;
first = 1;
/* Find out if we hit both high and low peaks */
for (j = 0; j < clock; j++)
{
if (GraphBuffer[(i * clock) + j] == high)
hithigh = 1;
else if (GraphBuffer[(i * clock) + j] == low)
hitlow = 1;
/* it doesn't count if it's the first part of our read
because it's really just trailing from the last sequence */
if (first && (hithigh || hitlow))
hithigh = hitlow = 0;
else
first = 0;
if (hithigh && hitlow)
break;
}
/* If we didn't hit both high and low peaks, we had a bit transition */
if (!hithigh || !hitlow)
bit ^= 1;
BitStream[bit2idx++] = bit;
}
retest:
/* We go till 5 before the graph ends because we'll get that far below */
for (i = 1; i < bit2idx - 5; i++)
{
/* Step 2: We have our header but need our tag ID */
if (header == 9 && rows < 10)
{
/* Confirm parity is correct */
if ((BitStream[i] ^ BitStream[i+1] ^ BitStream[i+2] ^ BitStream[i+3]) == BitStream[i+4])
{
/* Read another byte! */
sprintf(id+rows, "%x", (8 * BitStream[i]) + (4 * BitStream[i+1]) + (2 * BitStream[i+2]) + (1 * BitStream[i+3]));
rows++;
/* Keep parity info */
parity[0] ^= BitStream[i];
parity[1] ^= BitStream[i+1];
parity[2] ^= BitStream[i+2];
parity[3] ^= BitStream[i+3];
/* Move 4 bits ahead */
i += 4;
}
/* Damn, something wrong! reset */
else
{
PrintAndLog("Thought we had a valid tag but failed at word %d (i=%d)", rows + 1, i);
/* Start back rows * 5 + 9 header bits, -1 to not start at same place */
i -= 9 + (5 * rows) - 5;
rows = header = 0;
}
}
/* Step 3: Got our 40 bits! confirm column parity */
else if (rows == 10)
{
/* We need to make sure our 4 bits of parity are correct and we have a stop bit */
if (BitStream[i] == parity[0] && BitStream[i+1] == parity[1] &&
BitStream[i+2] == parity[2] && BitStream[i+3] == parity[3] &&
BitStream[i+4] == 0)
{
/* Sweet! */
PrintAndLog("EM410x Tag ID: %s", id);
/* Stop any loops */
return 1;
}
/* Crap! Incorrect parity or no stop bit, start all over */
else
{
rows = header = 0;
/* Go back 59 bits (9 header bits + 10 rows at 4+1 parity) */
i -= 59;
}
}
/* Step 1: get our header */
else if (header < 9)
{
/* Need 9 consecutive 1's */
if (BitStream[i] == 1)
header++;
/* We don't have a header, not enough consecutive 1 bits */
else
header = 0;
}
}
/* if we've already retested after flipping bits, return */
if (retested++)
return 0;
/* if this didn't work, try flipping bits */
for (i = 0; i < bit2idx; i++)
BitStream[i] ^= 1;
goto retest;
}
/* emulate an EM410X tag
* Format:
* 1111 1111 1 <-- standard non-repeatable header
* XXXX [row parity bit] <-- 10 rows of 5 bits for our 40 bit tag ID
* ....
* CCCC <-- each bit here is parity for the 10 bits above in corresponding column
* 0 <-- stop bit, end of tag
*/
int CmdEM410xSim(const char *Cmd)
{
int i, n, j, h, binary[4], parity[4];
/* clock is 64 in EM410x tags */
int clock = 64;
/* clear our graph */
ClearGraph(0);
/* write it out a few times */
for (h = 0; h < 4; h++)
{
/* write 9 start bits */
for (i = 0; i < 9; i++)
AppendGraph(0, clock, 1);
/* for each hex char */
parity[0] = parity[1] = parity[2] = parity[3] = 0;
for (i = 0; i < 10; i++)
{
/* read each hex char */
sscanf(&Cmd[i], "%1x", &n);
for (j = 3; j >= 0; j--, n/= 2)
binary[j] = n % 2;
/* append each bit */
AppendGraph(0, clock, binary[0]);
AppendGraph(0, clock, binary[1]);
AppendGraph(0, clock, binary[2]);
AppendGraph(0, clock, binary[3]);
/* append parity bit */
AppendGraph(0, clock, binary[0] ^ binary[1] ^ binary[2] ^ binary[3]);
/* keep track of column parity */
parity[0] ^= binary[0];
parity[1] ^= binary[1];
parity[2] ^= binary[2];
parity[3] ^= binary[3];
}
/* parity columns */
AppendGraph(0, clock, parity[0]);
AppendGraph(0, clock, parity[1]);
AppendGraph(0, clock, parity[2]);
AppendGraph(0, clock, parity[3]);
/* stop bit */
AppendGraph(0, clock, 0);
}
/* modulate that biatch */
CmdManchesterMod("");
/* booyah! */
RepaintGraphWindow();
CmdLFSim("");
return 0;
}
/* Function is equivalent of loread + losamples + em410xread
* looped until an EM410x tag is detected */
int CmdEM410xWatch(const char *Cmd)
{
do
{
CmdLFRead("");
CmdSamples("2000");
} while ( ! CmdEM410xRead(""));
return 0;
}
/* Read the transmitted data of an EM4x50 tag
* Format:
*
* XXXXXXXX [row parity bit (even)] <- 8 bits plus parity
* XXXXXXXX [row parity bit (even)] <- 8 bits plus parity
* XXXXXXXX [row parity bit (even)] <- 8 bits plus parity
* XXXXXXXX [row parity bit (even)] <- 8 bits plus parity
* CCCCCCCC <- column parity bits
* 0 <- stop bit
* LW <- Listen Window
*
* This pattern repeats for every block of data being transmitted.
* Transmission starts with two Listen Windows (LW - a modulated
* pattern of 320 cycles each (32/32/128/64/64)).
*
* Note that this data may or may not be the UID. It is whatever data
* is stored in the blocks defined in the control word First and Last
* Word Read values. UID is stored in block 32.
*/
int CmdEM4x50Read(const char *Cmd)
{
int i, j, startblock, skip, block, start, end, low, high;
bool complete= false;
int tmpbuff[MAX_GRAPH_TRACE_LEN / 64];
char tmp[6];
high= low= 0;
memset(tmpbuff, 0, MAX_GRAPH_TRACE_LEN / 64);
/* first get high and low values */
for (i = 0; i < GraphTraceLen; i++)
{
if (GraphBuffer[i] > high)
high = GraphBuffer[i];
else if (GraphBuffer[i] < low)
low = GraphBuffer[i];
}
/* populate a buffer with pulse lengths */
i= 0;
j= 0;
while (i < GraphTraceLen)
{
// measure from low to low
while ((GraphBuffer[i] > low) && (i<GraphTraceLen))
++i;
start= i;
while ((GraphBuffer[i] < high) && (i<GraphTraceLen))
++i;
while ((GraphBuffer[i] > low) && (i<GraphTraceLen))
++i;
if (j>(MAX_GRAPH_TRACE_LEN/64)) {
break;
}
tmpbuff[j++]= i - start;
}
/* look for data start - should be 2 pairs of LW (pulses of 192,128) */
start= -1;
skip= 0;
for (i= 0; i < j - 4 ; ++i)
{
skip += tmpbuff[i];
if (tmpbuff[i] >= 190 && tmpbuff[i] <= 194)
if (tmpbuff[i+1] >= 126 && tmpbuff[i+1] <= 130)
if (tmpbuff[i+2] >= 190 && tmpbuff[i+2] <= 194)
if (tmpbuff[i+3] >= 126 && tmpbuff[i+3] <= 130)
{
start= i + 3;
break;
}
}
startblock= i + 3;
/* skip over the remainder of the LW */
skip += tmpbuff[i+1]+tmpbuff[i+2];
while (skip < MAX_GRAPH_TRACE_LEN && GraphBuffer[skip] > low)
++skip;
skip += 8;
/* now do it again to find the end */
end= start;
for (i += 3; i < j - 4 ; ++i)
{
end += tmpbuff[i];
if (tmpbuff[i] >= 190 && tmpbuff[i] <= 194)
if (tmpbuff[i+1] >= 126 && tmpbuff[i+1] <= 130)
if (tmpbuff[i+2] >= 190 && tmpbuff[i+2] <= 194)
if (tmpbuff[i+3] >= 126 && tmpbuff[i+3] <= 130)
{
complete= true;
break;
}
}
if (start >= 0)
PrintAndLog("Found data at sample: %i",skip);
else
{
PrintAndLog("No data found!");
PrintAndLog("Try again with more samples.");
return 0;
}
if (!complete)
{
PrintAndLog("*** Warning!");
PrintAndLog("Partial data - no end found!");
PrintAndLog("Try again with more samples.");
}
/* get rid of leading crap */
sprintf(tmp,"%i",skip);
CmdLtrim(tmp);
/* now work through remaining buffer printing out data blocks */
block= 0;
i= startblock;
while (block < 6)
{
PrintAndLog("Block %i:", block);
// mandemod routine needs to be split so we can call it for data
// just print for now for debugging
CmdManchesterDemod("i 64");
skip= 0;
/* look for LW before start of next block */
for ( ; i < j - 4 ; ++i)
{
skip += tmpbuff[i];
if (tmpbuff[i] >= 190 && tmpbuff[i] <= 194)
if (tmpbuff[i+1] >= 126 && tmpbuff[i+1] <= 130)
break;
}
while (GraphBuffer[skip] > low)
++skip;
skip += 8;
sprintf(tmp,"%i",skip);
CmdLtrim(tmp);
start += skip;
block++;
}
return 0;
}
int CmdEM410xWrite(const char *Cmd)
{
uint64_t id = 0;
unsigned int card;
sscanf(Cmd, "%lx %d", &id, &card);
if (id >= 0x10000000000) {
PrintAndLog("Error! Given EM410x ID is longer than 40 bits.\n");
return 0;
}
if (card > 1) {
PrintAndLog("Error! Bad card type selected.\n");
return 0;
}
PrintAndLog("Writing %s tag with UID 0x%010lx", card ? "T55x7":"T5555", id);
UsbCommand c = {CMD_EM410X_WRITE_TAG, {card, (uint32_t)(id >> 32), (uint32_t)id}};
SendCommand(&c);
return 0;
}
static command_t CommandTable[] =
{
{"help", CmdHelp, 1, "This help"},
{"em410xread", CmdEM410xRead, 1, "[clock rate] -- Extract ID from EM410x tag"},
{"em410xsim", CmdEM410xSim, 0, "<UID> -- Simulate EM410x tag"},
{"em410xwatch", CmdEM410xWatch, 0, "Watches for EM410x tags"},
{"em410xwrite", CmdEM410xWrite, 1, "<UID> <'0' T5555> <'1' T55x7> -- Write EM410x UID to T5555(Q5) or T55x7 tag"},
{"em4x50read", CmdEM4x50Read, 1, "Extract data from EM4x50 tag"},
{NULL, NULL, 0, NULL}
};
int CmdLFEM4X(const char *Cmd)
{
CmdsParse(CommandTable, Cmd);
return 0;
}
int CmdHelp(const char *Cmd)
{
CmdsHelp(CommandTable);
return 0;
}