modified the autocorrelate part in lf search -1u command. It should be a more informative output and better bytes length reporting

CHANGELOG.md

@@ -3,10 +3,11 @@ All notable changes to this project will be documented in this file.
 This project uses the changelog in accordance with [keepchangelog](http://keepachangelog.com/). Please use this to write notable changes, which is not the same as git commit log...
 
 ## [unreleased][unreleased]
+ - Changed `lf search -1u` - improved the autocorrelation detection for unknown signals (@iceman1001)
  - Fixed `hf emrtd dump` stack smashing on device side (@iceman1001)
- - Change `dbprint` on device side to use max 200 chars strings. (@iceman1001)
+ - Changed `dbprint` on device side to use max 200 chars strings. (@iceman1001)
  - Fixed bootloader to correctly clear bss segment on start. Fixes USB serial number sometimes not working in the bootloader (@nvx)
- - Change `notes on downgrade attacks` - reworked the original text follow repo style (@iceman1001)
+ - Changed `notes on downgrade attacks` - reworked the original text follow repo style (@iceman1001)
  - Added `hf mf info` command and static encrypted nonce detection (@merlokk)
  - Added Saflok KDF - generate MFC keys (@h1kari)
  - Changed `lf fdx demod` - now raw bytes shows all data (@iceman1001)

client/src/cmddata.c

@@ -233,7 +233,7 @@ int printDemodBuff(uint8_t offset, bool strip_leading, bool invert, bool print_h
 
     uint8_t *buf = calloc(len, sizeof(uint8_t));
     if (buf == NULL) {
-        PrintAndLogEx(WARNING, "dail, cannot allocate memory");
+        PrintAndLogEx(WARNING, "fail, cannot allocate memory");
         return PM3_EMALLOC;
     }
     memcpy(buf, g_DemodBuffer, len);
@@ -870,24 +870,34 @@ int AutoCorrelate(const int *in, int *out, size_t len, size_t window, bool SaveG
     int foo = ABS(hi - hi_1);
     int bar = (int)((int)((hi + hi_1) / 2) * 0.04);
 
-    if (verbose && foo < bar) {
+    int retval = correlation;
-        distance = idx_1 - idx;
+
+    if (foo < bar) {
+        distance = (idx_1 - idx);
+        retval = distance;
+        if (verbose) {
             PrintAndLogEx(SUCCESS, "possible visible correlation "_YELLOW_("%4d") " samples", distance);
-    } else if (verbose && (correlation > 1)) {
-        PrintAndLogEx(SUCCESS, "possible correlation " _YELLOW_("%4zu") " samples", correlation);
-    } else {
-        PrintAndLogEx(FAILED, "no repeating pattern found, try increasing window size");
         }
 
-    int retval = correlation;
+    } else if (correlation > 1) {
+        if (verbose) {
+            PrintAndLogEx(SUCCESS, "possible correlation " _YELLOW_("%4zu") " samples", correlation);
+        }
+    } else {
+        PrintAndLogEx(HINT, "no repeating pattern found, try increasing window size");
+        // return value -1, indication to increase window size
+        return -1;
+    }
+
     if (SaveGrph) {
         //g_GraphTraceLen = g_GraphTraceLen - window;
         memcpy(out, correl_buf, len * sizeof(int));
         if (distance > 0) {
             setClockGrid(distance, idx);
             retval = distance;
-        } else
+        } else {
             setClockGrid(correlation, idx);
+        }
 
         g_CursorCPos = idx_1;
         g_CursorDPos = idx_1 + retval;

client/src/cmdlf.c

@@ -1504,7 +1504,7 @@ int CmdVchDemod(const char *Cmd) {
 }
 */
 
-static bool CheckChipType(bool getDeviceData) {
+static bool check_chiptype(bool getDeviceData) {
 
     bool retval = false;
 
@@ -1555,6 +1555,41 @@ out:
     return retval;
 }
 
+static int check_autocorrelate(int clock) {
+
+    PrintAndLogEx(NORMAL, "");
+    PrintAndLogEx(INFO, _CYAN_("Performing auto correlations..."));
+    for (int win = 4000; win < 30000; win += 2000) {
+        int ans = AutoCorrelate(g_GraphBuffer, g_GraphBuffer, g_GraphTraceLen, win, false, false);
+        if (ans == -1) {
+            continue;
+        }
+    
+        if (ans > 1) {
+            PrintAndLogEx(SUCCESS, "   " _YELLOW_("%d") " repeating samples", ans);
+
+            // If we got a field clock / bit rate from before
+            // we can use it for predict number of repeating bytes 
+            // this signal contain.
+            if (clock > 0) {
+                int bytes = ans / (8 * clock);
+                int mod = (bytes % 4);
+                int blocks  = (bytes / 4);
+
+                PrintAndLogEx(SUCCESS, "   " _YELLOW_("%u") " clock, " _YELLOW_("%d") " bytes repeating", clock, bytes);
+
+                if (mod == 0 && blocks < 7) {
+                    PrintAndLogEx(SUCCESS, "   " _YELLOW_("%d") " T5577 block%c needed", (bytes / 4), (mod == 1) ? ' ' : 's');
+                }
+            }
+            PrintAndLogEx(NORMAL, "");
+            return PM3_SUCCESS;
+        }
+    }
+    PrintAndLogEx(NORMAL, "");    
+    return PM3_EFAILED;
+}
+
 int CmdLFfind(const char *Cmd) {
 
     CLIParserContext *ctx;
@@ -1598,7 +1633,7 @@ int CmdLFfind(const char *Cmd) {
     PrintAndLogEx(INFO, "if it finds something that looks like a tag");
     PrintAndLogEx(INFO, "False Positives " _YELLOW_("ARE") " possible");
     PrintAndLogEx(INFO, "");
-    PrintAndLogEx(INFO, "Checking for known tags...");
+    PrintAndLogEx(INFO, _CYAN_("Checking for known tags..."));
     PrintAndLogEx(INFO, "");
 
     // only run these tests if device is online
@@ -1872,21 +1907,17 @@ int CmdLFfind(const char *Cmd) {
     }
 
     if (search_unk) {
-        //test unknown tag formats (raw mode)
-        PrintAndLogEx(INFO, "\nChecking for unknown tags:\n");
-        int ans = AutoCorrelate(g_GraphBuffer, g_GraphBuffer, g_GraphTraceLen, 8000, false, false);
-        if (ans > 0) {
 
-            PrintAndLogEx(INFO, "Possible auto correlation of %d repeating samples", ans);
+        // test unknown tag formats (raw mode)
+        PrintAndLogEx(INFO, _CYAN_("Checking for unknown tags...") "\n");
 
-            if (ans % 8 == 0)
+        // FSK
-                PrintAndLogEx(INFO, "Possible %d bytes", (ans / 8));
+        int clock = GetFskClock("", false);
-        }
+        if (clock) {
-
-        //fsk
-        if (GetFskClock("", false)) {
             if (FSKrawDemod(0, 0, 0, 0, true) == PM3_SUCCESS) {
-                PrintAndLogEx(INFO, "Unknown FSK Modulated Tag found!");
+                PrintAndLogEx(INFO, _GREEN_("FSK") " modulation detected!");
+                check_autocorrelate(clock);
+
                 if (search_cont) {
                     found++;
                 } else {
@@ -1895,31 +1926,58 @@ int CmdLFfind(const char *Cmd) {
             }
         }
 
+        // ASK
+        clock = GetAskClock("", false);
+        if (clock) {
             bool st = true;
             if (ASKDemod_ext(0, 0, 0, 0, false, true, false, 1, &st) == PM3_SUCCESS) {
-            PrintAndLogEx(INFO, "Unknown ASK Modulated and Manchester encoded Tag found!");
+                PrintAndLogEx(INFO, _GREEN_("ASK") " modulation / Manchester encoding detected!");
                 PrintAndLogEx(INFO, "if it does not look right it could instead be ASK/Biphase - try " _YELLOW_("'data rawdemod --ab'"));
+                check_autocorrelate(clock);
+
                 if (search_cont) {
                     found++;
                 } else {
                     goto out;
                 }
             }
+        }
 
+        // NZR
+        clock = GetNrzClock("", false);
+        if (clock) {
+            if (NRZrawDemod(0, 0, 0,false) == PM3_SUCCESS) {
+                PrintAndLogEx(INFO, _GREEN_("NRZ") " modulation detected!");
+                check_autocorrelate(clock);
+
+                if (search_cont) {
+                    found++;
+                } else {
+                    goto out;
+                }
+            }
+        }
+
+        // PSK
+        clock = GetPskClock("", false);
+        if (clock) {
             if (CmdPSK1rawDemod("") == PM3_SUCCESS) {
-            PrintAndLogEx(INFO, "Possible unknown PSK1 Modulated Tag found above!");
+                PrintAndLogEx(INFO, "Possible " _GREEN_("PSK1") " modulation detected!");
                 PrintAndLogEx(INFO, "    Could also be PSK2 - try " _YELLOW_("'data rawdemod --p2'"));
                 PrintAndLogEx(INFO, "    Could also be PSK3 - [currently not supported]");
                 PrintAndLogEx(INFO, "    Could also be  NRZ - try " _YELLOW_("'data rawdemod --nr"));
+                check_autocorrelate(clock);
+
                 if (search_cont) {
                     found++;
                 } else {
                     goto out;
                 }
             }
+        }
 
         if (found == 0) {
-            PrintAndLogEx(FAILED, _RED_("No data found!"));
+            PrintAndLogEx(FAILED, _RED_("Failed to determine any modulations or patterns"));
         }
     }
 
@@ -1929,7 +1987,7 @@ int CmdLFfind(const char *Cmd) {
 
 out:
     // identify chipset
-    if (CheckChipType(is_online) == false) {
+    if (check_chiptype(is_online) == false) {
         PrintAndLogEx(DEBUG, "Automatic chip type detection " _RED_("failed"));
     }
     return retval;