From: iceman1001 <iceman@iuse.se>
Date: Sat, 4 Feb 2017 11:41:30 +0000 (+0100)
Subject: ADD: 'lf search' - @marshmellow42 's check if signal is noice.
X-Git-Url: https://git.zerfleddert.de/cgi-bin/gitweb.cgi/proxmark3-svn/commitdiff_plain/3f84d473698a65e37504ec873905d248edef0f5d

ADD: 'lf search' - @marshmellow42 's check if signal is noice.
---

diff --git a/client/cmdlf.c b/client/cmdlf.c
index 2bbb9567..f2a9bb38 100644
--- a/client/cmdlf.c
+++ b/client/cmdlf.c
@@ -1004,6 +1004,7 @@ int CmdVchDemod(const char *Cmd) {
 //by marshmellow
 int CmdLFfind(const char *Cmd) {
 	int ans = 0;
+	size_t minLength = 1000;
 	char cmdp = param_getchar(Cmd, 0);
 	char testRaw = param_getchar(Cmd, 1);
 	if (strlen(Cmd) > 3 || cmdp == 'h' || cmdp == 'H') return usage_lf_find();
@@ -1011,21 +1012,38 @@ int CmdLFfind(const char *Cmd) {
 	if (!offline && (cmdp != '1')){
 		CmdLFRead("s");
 		getSamples("30000", false);
-	} else if (GraphTraceLen < 1000) {
+	} else if (GraphTraceLen < minLength) {
 		PrintAndLog("Data in Graphbuffer was too small.");
 		return 0;
 	}
 	if (cmdp == 'u' || cmdp == 'U') testRaw = 'u';
 
-	// if ( justNoise(GraphBuffer, GraphTraceLen) ) {
-		// PrintAndLog("Signal looks just like noise. Quitting.");
-		// return 0;
-	// }
-	
 	PrintAndLog("NOTE: some demods output possible binary\n  if it finds something that looks like a tag");
 	PrintAndLog("False Positives ARE possible\n");  
 	PrintAndLog("\nChecking for known tags:\n");
 
+	size_t testLen = minLength;
+	
+	// only run these tests if device is online
+	if (!offline && (cmdp != '1')){
+
+		// only run if graphbuffer is just noise as it should be for hitag/cotag
+		if (graphJustNoise(GraphBuffer, testLen)) {
+			
+			ans=CmdLFHitagReader("26");
+			if (ans==0)
+				return 1;
+
+			ans=CmdCOTAGRead("");
+			if (ans>0){
+				PrintAndLog("\nValid COTAG ID Found!");
+				return 1;
+			}
+			PrintAndLog("Signal looks just like noise. Quitting.");
+		    return 0;
+		}
+	}
+
 	ans=CmdFSKdemodIO("");
 	if (ans>0) {
 		PrintAndLog("\nValid IO Prox ID Found!");
@@ -1116,24 +1134,8 @@ int CmdLFfind(const char *Cmd) {
 		PrintAndLog("\nValid Presco ID Found!");
 		return 1;
 	}
-	// ICEMAN;  always call save_restorGB for COTAG. Will break graphbuffer
-	save_restoreGB(1);
-	ans=CmdCOTAGRead("");
-	if (ans>0){
-		PrintAndLog("\nValid COTAG ID Found!");
-		return 1;
-	}
-	save_restoreGB(0);
-	// TIdemod?
 
-/*	
-	if (!offline && (cmdp != '1')){
-		ans=CmdLFHitagReader("26");
-		if (ans==0) {
-			return 1;
-		}
-	}
-*/
+	// TIdemod?
 	PrintAndLog("\nNo Known Tags Found!\n");
 	if (testRaw=='u' || testRaw=='U'){
 		//test unknown tag formats (raw mode)
diff --git a/client/graph.c b/client/graph.c
index c22b7a3d..17aa3ae4 100644
--- a/client/graph.c
+++ b/client/graph.c
@@ -268,3 +268,16 @@ uint8_t fskClocks(uint8_t *fc1, uint8_t *fc2, uint8_t *rf1, bool verbose)
 	}
 	return 1;
 }
+
+// test samples are not just noise
+bool graphJustNoise(int *BitStream, int size)
+{
+	//might not be high enough for noisy environments
+	#define THRESHOLD 15; 
+
+	bool isNoise = TRUE;
+	for(int i=0; i < size && isNoise; i++){
+		isNoise = BitStream[i] < THRESHOLD;
+	}
+	return isNoise;
+}
diff --git a/client/graph.h b/client/graph.h
index 8deeb386..6f3f600d 100644
--- a/client/graph.h
+++ b/client/graph.h
@@ -22,6 +22,7 @@ uint8_t GetPskCarrier(const char str[], bool printAns, bool verbose);
 uint8_t GetNrzClock(const char str[], bool printAns, bool verbose);
 uint8_t GetFskClock(const char str[], bool printAns, bool verbose);
 uint8_t fskClocks(uint8_t *fc1, uint8_t *fc2, uint8_t *rf1, bool verbose);
+bool graphJustNoise(int *BitStream, int size);
 void setGraphBuf(uint8_t *buff, size_t size);
 void save_restoreGB(uint8_t saveOpt);