More work on iclass

[proxmark3-svn] / common / iso14443crc.c

diff --git a/common/iso14443crc.c b/common/iso14443crc.c
index 250a4ee500eaac62d4e66c2d53e18ac95079b04e..a6def1a91be2df84675660c67ec636ecc3ba4b55 100644 (file)
--- a/common/iso14443crc.c
+++ b/common/iso14443crc.c
@@ -1,31 +1,48 @@
-#include "iso14443crc.h"\r
-\r
-static unsigned short UpdateCrc14443(unsigned char ch, unsigned short *lpwCrc)\r
-{\r
-    ch = (ch ^ (unsigned char) ((*lpwCrc) & 0x00FF));\r
-    ch = (ch ^ (ch << 4));\r
-    *lpwCrc = (*lpwCrc >> 8) ^ ((unsigned short) ch << 8) ^\r
-              ((unsigned short) ch << 3) ^ ((unsigned short) ch >> 4);\r
-    return (*lpwCrc);\r
-}\r
-\r
-void ComputeCrc14443(int CrcType,\r
-                     unsigned char *Data, int Length,\r
-                     unsigned char *TransmitFirst,\r
-                     unsigned char *TransmitSecond)\r
-{\r
-    unsigned char chBlock;\r
-    unsigned short wCrc=CrcType;\r
-\r
-  do {\r
-        chBlock = *Data++;\r
-        UpdateCrc14443(chBlock, &wCrc);\r
-    } while (--Length);\r
-\r
-    if (CrcType == CRC_14443_B)\r
-        wCrc = ~wCrc;                /* ISO/IEC 13239 (formerly ISO/IEC 3309) */\r
-\r
-    *TransmitFirst = (unsigned char) (wCrc & 0xFF);\r
-    *TransmitSecond = (unsigned char) ((wCrc >> 8) & 0xFF);\r
-    return;\r
-}\r
+//-----------------------------------------------------------------------------
+// This code is licensed to you under the terms of the GNU GPL, version 2 or,
+// at your option, any later version. See the LICENSE.txt file for the text of
+// the license.
+//-----------------------------------------------------------------------------
+// ISO14443 CRC calculation code.
+//-----------------------------------------------------------------------------
+
+#include "iso14443crc.h"
+
+static unsigned short UpdateCrc14443(unsigned char ch, unsigned short *lpwCrc)
+{
+    ch = (ch ^ (unsigned char) ((*lpwCrc) & 0x00FF));
+    ch = (ch ^ (ch << 4));
+    *lpwCrc = (*lpwCrc >> 8) ^ ((unsigned short) ch << 8) ^
+              ((unsigned short) ch << 3) ^ ((unsigned short) ch >> 4);
+    return (*lpwCrc);
+}
+
+void ComputeCrc14443(int CrcType,
+                     const unsigned char *Data, int Length,
+                     unsigned char *TransmitFirst,
+                     unsigned char *TransmitSecond)
+{
+    unsigned char chBlock;
+    unsigned short wCrc=CrcType;
+
+  do {
+        chBlock = *Data++;
+        UpdateCrc14443(chBlock, &wCrc);
+    } while (--Length);
+
+    if (CrcType == CRC_14443_B)
+        wCrc = ~wCrc;                /* ISO/IEC 13239 (formerly ISO/IEC 3309) */
+
+    *TransmitFirst = (unsigned char) (wCrc & 0xFF);
+    *TransmitSecond = (unsigned char) ((wCrc >> 8) & 0xFF);
+    return;
+}
+
+int CheckCrc14443(int CrcType, const unsigned char *Data, int Length) {
+       unsigned char b1;
+       unsigned char b2;
+       if (Length < 3) return 0;
+       ComputeCrc14443(CrcType, Data, Length - 2, &b1, &b2);
+       if ((b1 == Data[Length - 2]) && (b2 == Data[Length - 1])) return 1;
+       return 0;
+}