add LEGIC decoder (submitted by Sourcerer, untested by me)

client/cmdhflegic.c

@@ -3,6 +3,11 @@
 #include "proxusb.h"
 #include "cmdparser.h"
 #include "cmdhflegic.h"
+#include "cmdmain.h"
+#include "data.h"
+#include "ui.h"
+#include <string.h>
+#include <stdio.h>
 
 static int CmdHelp(const char *Cmd);
 
@@ -21,6 +26,7 @@ static command_t CommandTable[] =
 {
   {"help",        CmdHelp,        1, "This help"},
   {"reader",      CmdLegicRFRead, 0, "[offset [length]] -- read bytes from a LEGIC card"},
+  {"decode",      CmdLegicDecode, 0, "Display deobfuscated and decoded LEGIC RF tag data (use after hf legic reader)"},
   {NULL, NULL, 0, NULL}
 };
 
@@ -35,3 +41,180 @@ int CmdHelp(const char *Cmd)
   CmdsHelp(CommandTable);
   return 0;
 }
+
+/*
+ *  Output BigBuf and deobfuscate LEGIC RF tag data.
+ *   This is based on information given in the talk held
+ *  by Henryk Ploetz and Karsten Nohl at 26c3
+ *  FIXME: will crash if sample buffer does not contain valid legic data
+ */
+int CmdLegicDecode(const char *Cmd)
+{
+  int h, i, j, k, n;
+  int segment_len = 0;
+  int segment_flag = 0;
+  int stamp_len = 0;
+  int crc = 0;
+  int wrp = 0;
+  int wrc = 0;
+  int data_buf[1032]; // receiver buffer
+  char out_string[3076]; // just use big buffer - bad practice
+  char token_type[4];
+  int delivered = 0;
+
+  h = 0;
+  
+  // copy data from proxmark into buffer
+  for (i = 0; i < 256; i += 12, h += 48) {
+    UsbCommand c = {CMD_DOWNLOAD_RAW_ADC_SAMPLES_125K, {i, 0, 0}};
+    SendCommand(&c);
+    WaitForResponse(CMD_DOWNLOADED_RAW_ADC_SAMPLES_125K);
+    
+    for (j = 0; j < 48; j += 8) {
+      for (k = 0; k < 8; k++) {
+        data_buf[h+j+k] = sample_buf[j+k];
+      }
+      delivered += 8;
+      if (delivered >= 1024)
+        break;
+    }
+  }
+    
+  // Output CDF System area (9 bytes) plus remaining header area (12 bytes)
+  
+  PrintAndLog("\nCDF: System Area");
+  
+  PrintAndLog("MCD: %02x, MSN: %02x %02x %02x, MCC: %02x",
+    data_buf[0],
+    data_buf[1],
+    data_buf[2],
+    data_buf[3],
+    data_buf[4]
+  );
+  
+  crc = data_buf[4];
+ 
+  switch (data_buf[5]&0x7f) {
+    case 0x00 ... 0x2f:
+      strncpy(token_type, "IAM",sizeof(token_type));
+      break;
+    case 0x30 ... 0x6f:
+      strcpy(token_type, "SAM");
+      break;
+    case 0x70 ... 0x7f:
+      strcpy(token_type, "GAM");
+      break;
+    default:
+      strcpy(token_type, "???");
+      break;
+  }
+  
+  stamp_len = 0xfc - data_buf[6];
+  
+  PrintAndLog("DCF: %02x %02x, Token_Type=%s (OLE=%01u), Stamp_len=%02u",
+    data_buf[5],
+    data_buf[6],
+    token_type,
+    (data_buf[5]&0x80)>>7,
+    stamp_len
+  );
+  
+  PrintAndLog("WRP=%02u, WRC=%01u, RD=%01u, raw=%02x, SSC=%02x",
+    data_buf[7]&0x0f,
+    (data_buf[7]&0x70)>>4,
+    (data_buf[7]&0x80)>>7,
+    data_buf[7],
+    data_buf[8]
+  );
+  
+  PrintAndLog("Remaining Header Area");
+  
+  PrintAndLog("%02x %02x %02x %02x %02x %02x %02x %02x %02x %02x %02x %02x %02x",
+      data_buf[9],
+    data_buf[10],
+    data_buf[11],
+    data_buf[12],
+    data_buf[13],
+    data_buf[14],
+    data_buf[15],
+    data_buf[16],
+    data_buf[17],
+    data_buf[18],
+    data_buf[19],
+    data_buf[20],
+    data_buf[21]
+  );
+  
+  PrintAndLog("\nADF: User Area");
+  
+    i = 22;  
+  for (n=0; n<64; n++) {
+    segment_len = ((data_buf[i+1]^crc)&0x0f) * 256 + (data_buf[i]^crc);
+    segment_flag = ((data_buf[i+1]^crc)&0xf0)>>4;
+    
+    wrp = (data_buf[i+2]^crc);
+    wrc = ((data_buf[i+3]^crc)&0x70)>>4;
+    
+     PrintAndLog("Segment %02u: raw header=%02x %02x %02x %02x, flag=%01x (valid=%01u, last=%01u), len=%04u, WRP=%02u, WRC=%02u, RD=%01u, CRC=%02x",
+      n,
+      data_buf[i]^crc,
+      data_buf[i+1]^crc,
+      data_buf[i+2]^crc,
+      data_buf[i+3]^crc,
+      segment_flag,
+      (segment_flag&0x4)>>2,
+      (segment_flag&0x8)>>3,
+      segment_len,
+      wrp,
+      wrc,
+      ((data_buf[i+3]^crc)&0x80)>>7,
+      (data_buf[i+4]^crc)
+    );
+    
+    i+=5;
+    
+    if (wrc>0) {
+      PrintAndLog("WRC protected area:");
+      for (k=0, j=0; k < wrc; k++, i++, j += 3) {
+        sprintf(&out_string[j], "%02x", (data_buf[i]^crc));
+        out_string[j+2] = ' ';
+      };
+        
+      out_string[j] = '\0';
+    
+      PrintAndLog("%s", out_string);
+    }
+    
+    if (wrp>wrc) {
+      PrintAndLog("Remaining write protected area:");
+      
+      for (k=0, j=0; k < (wrp-wrc); k++, i++, j += 3) {
+        sprintf(&out_string[j], "%02x", (data_buf[i]^crc));
+        out_string[j+2] = ' ';
+      };
+    
+      out_string[j] = '\0';
+    
+      PrintAndLog("%s", out_string);
+      if((wrp-wrc) == 8) {
+        sprintf(out_string,"Card ID: %2X%02X%02X",data_buf[i-4]^crc,data_buf[i-3]^crc,data_buf[i-2]^crc);
+        PrintAndLog("%s", out_string);
+      }
+    }
+    
+    PrintAndLog("Remaining segment payload:");
+    for (k=0, j=0; k < (segment_len - wrp - 5); k++, i++, j += 3) {
+      sprintf(&out_string[j], "%02x", (data_buf[i]^crc));
+      out_string[j+2] = ' ';
+    };
+    
+    out_string[j] = '\0';
+    
+    PrintAndLog("%s", out_string);
+    
+    // end with last segment
+    if (segment_flag & 0x8)
+      return 0;
+  };
+  return 0;
+}

client/cmdhflegic.h

@@ -4,5 +4,6 @@
 int CmdHFLegic(const char *Cmd);
 
 int CmdLegicRFRead(const char *Cmd);
+int CmdLegicDecode(const char *Cmd);
 
 #endif