+bool EM_EndParityTest(uint8_t *BitStream, size_t size, uint8_t rows, uint8_t cols, uint8_t pType)
+{
+ if (rows*cols>size) return false;
+ uint8_t colP=0;
+ //assume last col is a parity and do not test
+ for (uint8_t colNum = 0; colNum < cols-1; colNum++) {
+ for (uint8_t rowNum = 0; rowNum < rows; rowNum++) {
+ colP ^= BitStream[(rowNum*cols)+colNum];
+ }
+ if (colP != pType) return false;
+ }
+ return true;
+}
+
+bool EM_ByteParityTest(uint8_t *BitStream, size_t size, uint8_t rows, uint8_t cols, uint8_t pType)
+{
+ if (rows*cols>size) return false;
+ uint8_t rowP=0;
+ //assume last row is a parity row and do not test
+ for (uint8_t rowNum = 0; rowNum < rows-1; rowNum++) {
+ for (uint8_t colNum = 0; colNum < cols; colNum++) {
+ rowP ^= BitStream[(rowNum*cols)+colNum];
+ }
+ if (rowP != pType) return false;
+ }
+ return true;
+}
+
+uint32_t OutputEM4x50_Block(uint8_t *BitStream, size_t size, bool verbose, bool pTest)
+{
+ if (size<45) return 0;
+ uint32_t code = bytebits_to_byte(BitStream,8);
+ code = code<<8 | bytebits_to_byte(BitStream+9,8);
+ code = code<<8 | bytebits_to_byte(BitStream+18,8);
+ code = code<<8 | bytebits_to_byte(BitStream+27,8);
+ if (verbose || g_debugMode){
+ for (uint8_t i = 0; i<5; i++){
+ if (i == 4) PrintAndLog(""); //parity byte spacer
+ PrintAndLog("%d%d%d%d%d%d%d%d %d -> 0x%02x",
+ BitStream[i*9],
+ BitStream[i*9+1],
+ BitStream[i*9+2],
+ BitStream[i*9+3],
+ BitStream[i*9+4],
+ BitStream[i*9+5],
+ BitStream[i*9+6],
+ BitStream[i*9+7],
+ BitStream[i*9+8],
+ bytebits_to_byte(BitStream+i*9,8)
+ );
+ }
+ if (pTest)
+ PrintAndLog("Parity Passed");
+ else
+ PrintAndLog("Parity Failed");
+ }
+ return code;
+}
+/* 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.
+ */
+ //completed by Marshmellow
+int EM4x50Read(const char *Cmd, bool verbose)
+{
+ uint8_t fndClk[] = {8,16,32,40,50,64,128};
+ int clk = 0;
+ int invert = 0;
+ int tol = 0;
+ int i, j, startblock, skip, block, start, end, low, high, minClk;
+ bool complete = false;
+ int tmpbuff[MAX_GRAPH_TRACE_LEN / 64];
+ uint32_t Code[6];
+ char tmp[6];
+ char tmp2[20];
+ int phaseoff;
+ high = low = 0;
+ memset(tmpbuff, 0, MAX_GRAPH_TRACE_LEN / 64);
+
+ // get user entry if any
+ sscanf(Cmd, "%i %i", &clk, &invert);
+
+ // save GraphBuffer - to restore it later
+ save_restoreGB(1);
+
+ // 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];
+ }
+
+ i = 0;
+ j = 0;
+ minClk = 255;
+ // get to first full low to prime loop and skip incomplete first pulse
+ while ((GraphBuffer[i] < high) && (i < GraphTraceLen))
+ ++i;
+ while ((GraphBuffer[i] > low) && (i < GraphTraceLen))
+ ++i;
+ skip = i;
+
+ // populate tmpbuff buffer with pulse lengths
+ 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;
+ if (i-start < minClk && i < GraphTraceLen) {
+ minClk = i - start;
+ }
+ }
+ // set clock
+ if (!clk) {
+ for (uint8_t clkCnt = 0; clkCnt<7; clkCnt++) {
+ tol = fndClk[clkCnt]/8;
+ if (minClk >= fndClk[clkCnt]-tol && minClk <= fndClk[clkCnt]+1) {
+ clk=fndClk[clkCnt];
+ break;
+ }
+ }
+ if (!clk) return 0;
+ } else tol = clk/8;
+
+ // look for data start - should be 2 pairs of LW (pulses of clk*3,clk*2)
+ start = -1;
+ for (i= 0; i < j - 4 ; ++i) {
+ skip += tmpbuff[i];
+ if (tmpbuff[i] >= clk*3-tol && tmpbuff[i] <= clk*3+tol) //3 clocks
+ if (tmpbuff[i+1] >= clk*2-tol && tmpbuff[i+1] <= clk*2+tol) //2 clocks
+ if (tmpbuff[i+2] >= clk*3-tol && tmpbuff[i+2] <= clk*3+tol) //3 clocks
+ if (tmpbuff[i+3] >= clk-tol) //1.5 to 2 clocks - depends on bit following
+ {
+ start= i + 4;
+ break;
+ }
+ }
+ startblock = i + 4;
+
+ // skip over the remainder of LW
+ skip += tmpbuff[i+1] + tmpbuff[i+2] + clk;
+ if (tmpbuff[i+3]>clk)
+ phaseoff = tmpbuff[i+3]-clk;
+ else
+ phaseoff = 0;
+ // now do it again to find the end
+ end = skip;
+ for (i += 3; i < j - 4 ; ++i) {
+ end += tmpbuff[i];
+ if (tmpbuff[i] >= clk*3-tol && tmpbuff[i] <= clk*3+tol) //3 clocks
+ if (tmpbuff[i+1] >= clk*2-tol && tmpbuff[i+1] <= clk*2+tol) //2 clocks
+ if (tmpbuff[i+2] >= clk*3-tol && tmpbuff[i+2] <= clk*3+tol) //3 clocks
+ if (tmpbuff[i+3] >= clk-tol) //1.5 to 2 clocks - depends on bit following
+ {
+ complete= true;
+ break;
+ }
+ }
+ end = i;
+ // report back
+ if (verbose || g_debugMode) {
+ if (start >= 0) {
+ PrintAndLog("\nNote: one block = 50 bits (32 data, 12 parity, 6 marker)");
+ } else {
+ PrintAndLog("No data found!, clock tried:%d",clk);
+ PrintAndLog("Try again with more samples.");
+ PrintAndLog(" or after a 'data askedge' command to clean up the read");
+ return 0;
+ }
+ } else if (start < 0) return 0;
+ start = skip;
+ snprintf(tmp2, sizeof(tmp2),"%d %d 1000 %d", clk, invert, clk*47);
+ // get rid of leading crap
+ snprintf(tmp, sizeof(tmp), "%i", skip);
+ CmdLtrim(tmp);
+ bool pTest;
+ bool AllPTest = true;
+ // now work through remaining buffer printing out data blocks
+ block = 0;
+ i = startblock;
+ while (block < 6) {
+ if (verbose || g_debugMode) PrintAndLog("\nBlock %i:", block);
+ skip = phaseoff;
+
+ // look for LW before start of next block
+ for ( ; i < j - 4 ; ++i) {
+ skip += tmpbuff[i];
+ if (tmpbuff[i] >= clk*3-tol && tmpbuff[i] <= clk*3+tol)
+ if (tmpbuff[i+1] >= clk-tol)
+ break;
+ }
+ if (i >= j-4) break; //next LW not found
+ skip += clk;
+ if (tmpbuff[i+1]>clk)
+ phaseoff = tmpbuff[i+1]-clk;
+ else
+ phaseoff = 0;
+ i += 2;
+ if (ASKDemod(tmp2, false, false, 1) < 1) {
+ save_restoreGB(0);
+ return 0;
+ }
+ //set DemodBufferLen to just one block
+ DemodBufferLen = skip/clk;
+ //test parities
+ pTest = EM_ByteParityTest(DemodBuffer,DemodBufferLen,5,9,0);
+ pTest &= EM_EndParityTest(DemodBuffer,DemodBufferLen,5,9,0);
+ AllPTest &= pTest;
+ //get output
+ Code[block] = OutputEM4x50_Block(DemodBuffer,DemodBufferLen,verbose, pTest);
+ if (g_debugMode) PrintAndLog("\nskipping %d samples, bits:%d", skip, skip/clk);
+ //skip to start of next block
+ snprintf(tmp,sizeof(tmp),"%i",skip);
+ CmdLtrim(tmp);
+ block++;
+ if (i >= end) break; //in case chip doesn't output 6 blocks
+ }
+ //print full code:
+ if (verbose || g_debugMode || AllPTest){
+ if (!complete) {
+ PrintAndLog("*** Warning!");
+ PrintAndLog("Partial data - no end found!");
+ PrintAndLog("Try again with more samples.");
+ }
+ PrintAndLog("Found data at sample: %i - using clock: %i", start, clk);
+ end = block;
+ for (block=0; block < end; block++){
+ PrintAndLog("Block %d: %08x",block,Code[block]);
+ }
+ if (AllPTest) {
+ PrintAndLog("Parities Passed");
+ } else {
+ PrintAndLog("Parities Failed");
+ PrintAndLog("Try cleaning the read samples with 'data askedge'");
+ }
+ }
+
+ //restore GraphBuffer
+ save_restoreGB(0);
+ return (int)AllPTest;
+}
+
+int CmdEM4x50Read(const char *Cmd)
+{
+ return EM4x50Read(Cmd, true);
projects / proxmark3-svn / blobdiff