From: iceman1001 <iceman@iuse.se>
Date: Tue, 1 Mar 2016 05:57:02 +0000 (+0100)
Subject: FIX: Added @marshmellow42 's fix for ASK/Biphase simulation on deviceside.
X-Git-Url: https://git.zerfleddert.de/cgi-bin/gitweb.cgi/proxmark3-svn/commitdiff_plain/c728b2b4cf2ce9fe4eebf0e46d74ef8542e56c16

FIX: Added @marshmellow42 's fix for ASK/Biphase simulation on deviceside.
CHG: Added @marshmellow42 's refactoring of "gprox-II" demod.
---

diff --git a/armsrc/lfops.c b/armsrc/lfops.c
index 7f61c78d..54800f49 100644
--- a/armsrc/lfops.c
+++ b/armsrc/lfops.c
@@ -628,7 +628,7 @@ static void biphaseSimBit(uint8_t c, int *n, uint8_t clock, uint8_t *phase)
 		memset(dest+(*n), c ^ *phase, clock);
 		*phase ^= 1;
 	}
-
+	*n += clock;
 }
 
 // args clock, ask/man or askraw, invert, transmission separator
@@ -646,7 +646,7 @@ void CmdASKsimTag(uint16_t arg1, uint16_t arg2, size_t size, uint8_t *BitStream)
 		for (i=0; i<size; i++){
 			biphaseSimBit(BitStream[i]^invert, &n, clk, &phase);
 		}
-		if (BitStream[0]==BitStream[size-1]){ //run a second set inverted to keep phase in check
+		if (phase==1) { //run a second set inverted to keep phase in check
 			for (i=0; i<size; i++){
 				biphaseSimBit(BitStream[i]^invert, &n, clk, &phase);
 			}
diff --git a/client/cmddata.c b/client/cmddata.c
index 311e5b32..967fa28f 100644
--- a/client/cmddata.c
+++ b/client/cmddata.c
@@ -592,7 +592,7 @@ int Cmdaskbiphdemod(const char *Cmd)
 int CmdG_Prox_II_Demod(const char *Cmd)
 {
 	if (!ASKbiphaseDemod(Cmd, FALSE)){
-		if (g_debugMode) PrintAndLog("ASKbiphaseDemod failed 1st try");
+		if (g_debugMode) PrintAndLog("Error gProxII: ASKbiphaseDemod failed 1st try");
 		return 0;
 	}
 	size_t size = DemodBufferLen;
@@ -602,46 +602,32 @@ int CmdG_Prox_II_Demod(const char *Cmd)
 		if (g_debugMode) PrintAndLog("Error gProxII_Demod");
 		return 0;
 	}
-	//got a good demod
-	uint32_t ByteStream[65] = {0x00};
+	//got a good demod of 96 bits
+	uint8_t ByteStream[8] = {0x00};
 	uint8_t xorKey=0;
-	uint8_t keyCnt=0;
-	uint8_t bitCnt=0;
-	uint8_t ByteCnt=0;
-	size_t startIdx = ans + 6; //start after preamble
-	for (size_t idx = 0; idx<size-6; idx++){
-		if ((idx+1) % 5 == 0){
-			//spacer bit - should be 0
-			if (DemodBuffer[startIdx+idx] != 0) {
-				if (g_debugMode) PrintAndLog("Error spacer not 0: %u, pos: %u", (unsigned int)DemodBuffer[startIdx+idx],(unsigned int)(startIdx+idx));
+	size_t startIdx = ans + 6; //start after 6 bit preamble
+
+	uint8_t bits_no_spacer[90];
+	//so as to not mess with raw DemodBuffer copy to a new sample array
+	memcpy(bits_no_spacer, DemodBuffer + startIdx, 90);
+	// remove the 18 (90/5=18) parity bits (down to 72 bits (96-6-18=72))
+	size_t bitLen = removeParity(bits_no_spacer, 0, 5, 3, 90); //source, startloc, paritylen, ptype, length_to_run
+	if (bitLen != 72) {
+		if (g_debugMode) PrintAndLog("Error gProxII: spacer removal did not produce 72 bits: %u, start: %u", bitLen, startIdx);
 				return 0;
 			}
-			continue;
-		} 
-		if (keyCnt<8){ //lsb first
-			xorKey |=  (DemodBuffer[startIdx+idx]<<keyCnt);
-			keyCnt++;
-			if (keyCnt==8 && g_debugMode) PrintAndLog("xorKey Found: %02x", xorKey);
-			continue;
-		}
-		//lsb first
-		ByteStream[ByteCnt] |=  (DemodBuffer[startIdx+idx]<<bitCnt);
-		bitCnt++;
-		if (bitCnt % 8 == 0){
-			if (g_debugMode) PrintAndLog("byte %u: %02x", (unsigned int)ByteCnt, ByteStream[ByteCnt]);
-			bitCnt=0;
-			ByteCnt++;
-		}
-	}
-	for (uint8_t i = 0; i < ByteCnt; i++){
-		ByteStream[i] ^= xorKey; //xor
-		if (g_debugMode) PrintAndLog("byte %u after xor: %02x", (unsigned int)i, ByteStream[i]);
+	// get key and then get all 8 bytes of payload decoded
+	xorKey = (uint8_t)bytebits_to_byteLSBF(bits_no_spacer, 8);
+	for (size_t idx = 0; idx < 8; idx++) {
+		ByteStream[idx] = ((uint8_t)bytebits_to_byteLSBF(bits_no_spacer+8 + (idx*8),8)) ^ xorKey;
+		if (g_debugMode) PrintAndLog("byte %u after xor: %02x", (unsigned int)idx, ByteStream[idx]);
 	}
-	//now ByteStream contains 64 bytes of decrypted raw tag data
+	//now ByteStream contains 8 Bytes (64 bits) of decrypted raw tag data
 	// 
 	uint8_t fmtLen = ByteStream[0]>>2;
 	uint32_t FC = 0;
 	uint32_t Card = 0;
+	//get raw 96 bits to print
 	uint32_t raw1 = bytebits_to_byte(DemodBuffer+ans,32);
 	uint32_t raw2 = bytebits_to_byte(DemodBuffer+ans+32, 32);
 	uint32_t raw3 = bytebits_to_byte(DemodBuffer+ans+64, 32);
@@ -649,13 +635,14 @@ int CmdG_Prox_II_Demod(const char *Cmd)
 	if (fmtLen==36){
 		FC = ((ByteStream[3] & 0x7F)<<7) | (ByteStream[4]>>1);
 		Card = ((ByteStream[4]&1)<<19) | (ByteStream[5]<<11) | (ByteStream[6]<<3) | (ByteStream[7]>>5);
-		PrintAndLog("G-Prox-II Found: FmtLen %d, FC %d, Card %d",fmtLen,FC,Card);
+		PrintAndLog("G-Prox-II Found: FmtLen %d, FC %u, Card %u", (int)fmtLen, FC, Card);
 	} else if(fmtLen==26){
 		FC = ((ByteStream[3] & 0x7F)<<1) | (ByteStream[4]>>7);
 		Card = ((ByteStream[4]&0x7F)<<9) | (ByteStream[5]<<1) | (ByteStream[6]>>7);
-		PrintAndLog("G-Prox-II Found: FmtLen %d, FC %d, Card %d",fmtLen,FC,Card);    
+		PrintAndLog("G-Prox-II Found: FmtLen %d, FC %u, Card %u", (int)fmtLen, FC, Card);
 	} else {
-		PrintAndLog("Unknown G-Prox-II Fmt Found: FmtLen %d",fmtLen);
+		PrintAndLog("Unknown G-Prox-II Fmt Found: FmtLen %d",(int)fmtLen);
+		PrintAndLog("Decoded Raw: %s", sprint_hex(ByteStream, 8)); 
 	}
 	PrintAndLog("Raw: %08x%08x%08x", raw1,raw2,raw3);
 	setDemodBuf(DemodBuffer+ans, 96, 0);
diff --git a/client/cmdlfguard.c b/client/cmdlfguard.c
index 05975eea..686ada27 100644
--- a/client/cmdlfguard.c
+++ b/client/cmdlfguard.c
@@ -48,7 +48,7 @@ int GetGuardBits(uint32_t fc, uint32_t cn, uint8_t *guardBits) {
 	time_t t;
 	srand((unsigned) time(&t));
 	//uint8_t xorKey = rand() % 0xFF;
-	uint8_t xorKey = 0x6b;
+	uint8_t xorKey = 0x66;
 	uint8_t i;
 	
 	
diff --git a/common/lfdemod.c b/common/lfdemod.c
index edebe456..862d05ba 100644
--- a/common/lfdemod.c
+++ b/common/lfdemod.c
@@ -68,7 +68,7 @@ uint8_t parityTest(uint32_t bits, uint8_t bitLen, uint8_t pType)
 
 //by marshmellow
 // takes a array of binary values, start position, length of bits per parity (includes parity bit),
-//   Parity Type (1 for odd; 0 for even; 2 Always 1's), and binary Length (length to run) 
+//   Parity Type (1 for odd; 0 for even; 2 for Always 1's; 3 for Always 0's), and binary Length (length to run) 
 size_t removeParity(uint8_t *BitStream, size_t startIdx, uint8_t pLen, uint8_t pType, size_t bLen)
 {
 	uint32_t parityWd = 0;
@@ -80,10 +80,11 @@ size_t removeParity(uint8_t *BitStream, size_t startIdx, uint8_t pLen, uint8_t p
 		}
 		j--; // overwrite parity with next data
 		// if parity fails then return 0
-		if (pType == 2) { // then marker bit which should be a 1
-			if (!BitStream[j]) return 0;
-		} else {
-			if (parityTest(parityWd, pLen, pType) == 0) return 0;			
+		switch (pType) {
+			case 3: if (BitStream[j]==1) return 0; break; //should be 0 spacer bit
+			case 2: if (BitStream[j]==0) return 0; break; //should be 1 spacer bit
+			default: //test parity
+				if (parityTest(parityWd, pLen, pType) == 0) return 0; break;
 		}
 		bitCnt+=(pLen-1);
 		parityWd = 0;
@@ -96,6 +97,7 @@ size_t removeParity(uint8_t *BitStream, size_t startIdx, uint8_t pLen, uint8_t p
 // by marshmellow
 // takes a array of binary values, length of bits per parity (includes parity bit),
 //   Parity Type (1 for odd; 0 for even; 2 Always 1's; 3 Always 0's), and binary Length (length to run)
+//   Make sure *dest is long enough to store original sourceLen + #_of_parities_to_be_added
 size_t addParity(uint8_t *BitSource, uint8_t *dest, uint8_t sourceLen, uint8_t pLen, uint8_t pType)
 {
 	uint32_t parityWd = 0;
@@ -114,7 +116,6 @@ size_t addParity(uint8_t *BitSource, uint8_t *dest, uint8_t sourceLen, uint8_t p
 				dest[j++] = parityTest(parityWd, pLen-1, pType) ^ 1;
 				break;
 		}
-		
 		bitCnt += pLen;
 		parityWd = 0;
 	}