Implemented data hex2bin and data bin2hex as per suggestion in http://www.proxmark.org/forum/viewtopic.php?pid=17504

CHANGELOG.md

@@ -9,6 +9,7 @@ This project uses the changelog in accordance with [keepchangelog](http://keepac
 - AWID26 command context added as 'lf awid' containing realtime demodulation as well as cloning/simulation based on tag numbers (Craig Young)
 - Added 'hw status'. This command makes the ARM print out some runtime information. (holiman) 
 - Added 'hw ping'. This command just sends a usb packets and checks if the pm3 is responsive. Can be used to abort certain operations which supports abort over usb. (holiman)
+- Added `data hex2bin` and `data bin2hex` for command line conversion between binary and hexadecimal (holiman)
 
 ### Changed
 - Revised workflow for StandAloneMode14a (Craig Young)

client/cmddata.c

@@ -24,6 +24,7 @@
 #include "usb_cmd.h"
 #include "crc.h"
 #include "crc16.h"
+#include "loclass/cipherutils.h"
 
 uint8_t DemodBuffer[MAX_DEMOD_BUF_LEN];
 uint8_t g_debugMode=0;
@@ -1943,26 +1944,14 @@ int CmdHpf(const char *Cmd)
 	RepaintGraphWindow();
 	return 0;
 }
-typedef struct {
-	uint8_t * buffer;
-	uint32_t numbits;
-	uint32_t position;
-}BitstreamOut;
 
-bool _headBit( BitstreamOut *stream)
-{
-	int bytepos = stream->position >> 3; // divide by 8
-	int bitpos = (stream->position++) & 7; // mask out 00000111
-	return (*(stream->buffer + bytepos) >> (7-bitpos)) & 1;
-}
-
-uint8_t getByte(uint8_t bits_per_sample, BitstreamOut* b)
+uint8_t getByte(uint8_t bits_per_sample, BitstreamIn* b)
 {
 	int i;
 	uint8_t val = 0;
 	for(i =0 ; i < bits_per_sample; i++)
 	{
-		val |= (_headBit(b) << (7-i));
+		val |= (headBit(b) << (7-i));
 	}
 	return val;
 }
@@ -2002,7 +1991,7 @@ int getSamples(const char *Cmd, bool silent)
 	if(bits_per_sample < 8)
 	{
 		PrintAndLog("Unpacking...");
-		BitstreamOut bout = { got, bits_per_sample * n,  0};
+		BitstreamIn bout = { got, bits_per_sample * n,  0};
 		int j =0;
 		for (j = 0; j * bits_per_sample < n * 8 && j < n; j++) {
 			uint8_t sample = getByte(bits_per_sample, &bout);
@@ -2265,6 +2254,99 @@ int CmdZerocrossings(const char *Cmd)
 	return 0;
 }
 
+int usage_data_bin2hex(){
+		PrintAndLog("Usage: data bin2hex <binary_digits>");
+		PrintAndLog("       This function will ignore all characters not 1 or 0 (but stop reading on whitespace)");
+		return 0;
+}
+
+/**
+ * @brief Utility for conversion via cmdline.
+ * @param Cmd
+ * @return
+ */
+int Cmdbin2hex(const char *Cmd)
+{
+	int bg =0, en =0;
+	if(param_getptr(Cmd, &bg, &en, 0))
+	{
+		return usage_data_bin2hex();
+	}
+	//Number of digits supplied as argument
+	size_t length = en  - bg +1;
+	size_t bytelen = (length+7) / 8;
+	uint8_t* arr = (uint8_t *) malloc(bytelen);
+	memset(arr, 0, bytelen);
+	BitstreamOut bout = { arr, 0, 0 };
+
+	for(; bg <= en ;bg++)
+	{
+		char c = Cmd[bg];
+		if( c == '1')	pushBit(&bout, 1);
+		else if( c == '0')	pushBit(&bout, 0);
+		else PrintAndLog("Ignoring '%c'", c);
+	}
+
+	if(bout.numbits % 8 != 0)
+	{
+		printf("[padded with %d zeroes]\n", 8-(bout.numbits % 8));
+	}
+
+	//Uses printf instead of PrintAndLog since the latter
+	// adds linebreaks to each printout - this way was more convenient since we don't have to
+	// allocate a string and write to that first...
+	for(size_t x = 0; x  < bytelen ; x++)
+	{
+		printf("%02X", arr[x]);
+	}
+	printf("\n");
+	free(arr);
+	return 0;
+}
+
+int usage_data_hex2bin(){
+
+	PrintAndLog("Usage: data bin2hex <binary_digits>");
+	PrintAndLog("       This function will ignore all non-hexadecimal characters (but stop reading on whitespace)");
+	return 0;
+
+}
+
+int Cmdhex2bin(const char *Cmd)
+{
+	int bg =0, en =0;
+	if(param_getptr(Cmd, &bg, &en, 0))
+	{
+		return usage_data_hex2bin();
+	}
+
+
+	while(bg <= en )
+	{
+		char x = Cmd[bg++];
+		// capitalize
+		if (x >= 'a' && x <= 'f')
+			x -= 32;
+		// convert to numeric value
+		if (x >= '0' && x <= '9')
+			x -= '0';
+		else if (x >= 'A' && x <= 'F')
+			x -= 'A' - 10;
+		else
+			continue;
+
+		//Uses printf instead of PrintAndLog since the latter
+		// adds linebreaks to each printout - this way was more convenient since we don't have to
+		// allocate a string and write to that first...
+
+		for(int i= 0 ; i < 4 ; ++i)
+			printf("%d",(x >> (3 - i)) & 1);
+	}
+	printf("\n");
+
+	return 0;
+}
+
 static command_t CommandTable[] =
 {
 	{"help",            CmdHelp,            1, "This help"},
@@ -2287,6 +2369,9 @@ static command_t CommandTable[] =
 	{"getbitstream",    CmdGetBitStream,    1, "Convert GraphBuffer's >=1 values to 1 and <1 to 0"},
 	{"grid",            CmdGrid,            1, "<x> <y> -- overlay grid on graph window, use zero value to turn off either"},
 	{"hexsamples",      CmdHexsamples,      0, "<bytes> [<offset>] -- Dump big buffer as hex bytes"},
+	{"bin2hex",         Cmdbin2hex,         1, "bin2hex <digits>     -- Converts binary to hexadecimal"},
+	{"hex2bin",         Cmdhex2bin,         1, "hex2bin <hexadecimal> -- Converts hexadecimal to binary"},
+	{"hexsamples",      CmdHexsamples,      0, "<bytes> [<offset>] -- Dump big buffer as hex bytes"},
 	{"hide",            CmdHide,            1, "Hide graph window"},
 	{"hpf",             CmdHpf,             1, "Remove DC offset from trace"},
 	{"load",            CmdLoad,            1, "<filename> -- Load trace (to graph window"},

client/util.h

@@ -47,6 +47,7 @@ char * printBits(size_t const size, void const * const ptr);
 uint8_t *SwapEndian64(const uint8_t *src, const size_t len, const uint8_t blockSize);
 
 char param_getchar(const char *line, int paramnum);
+int param_getptr(const char *line, int *bg, int *en, int paramnum);
 uint8_t param_get8(const char *line, int paramnum);
 uint8_t param_get8ex(const char *line, int paramnum, int deflt, int base);
 uint32_t param_get32ex(const char *line, int paramnum, int deflt, int base);