CRC32: Prevent decompression of data used in CRC32 calculation on host. This leads to false negatives with TrueCrypt/VeraCrypt keyfiles

docs/changes.txt

@@ -29,6 +29,7 @@
 - UTF8-to-UTF16: Replaced naive UTF8 to UTF16 conversion with true conversion for RAR3, AES Crypt, MultiBit HD (scrypt) and Umbraco HMAC-SHA1
 - AES Crypt Plugin: Reduced max password length from 256 to 128 which improved performance by 22%
 - RAR3-p (Compressed): Fix workaround in unrar library in AES constant table generation to enable multi-threading support
+- CRC32: Prevent decompression of data used in CRC32 calculation on host. This leads to false negatives with TrueCrypt/VeraCrypt keyfiles
 
 ##
 ## Technical

include/filehandling.h

@@ -16,6 +16,7 @@ int    _wopen       (const char *path, int oflag, ...);
 #endif
 
 bool   hc_fopen       (HCFILE *fp, const char *path, char *mode);
+bool   hc_fopen_nozip (HCFILE *fp, const char *path, char *mode);
 int    hc_fscanf      (HCFILE *fp, const char *format, void *ptr);
 int    hc_fprintf     (HCFILE *fp, const char *format, ...);
 int    hc_vfprintf    (HCFILE *fp, const char *format, va_list ap);

src/cpu_crc32.c

@@ -94,7 +94,7 @@ int cpu_crc32 (const char *filename, u8 keytab[64])
 
   HCFILE fp;
 
-  hc_fopen (&fp, filename, "rb");
+  hc_fopen_nozip (&fp, filename, "rb");
 
   #define MAX_KEY_SIZE (1024 * 1024)
 

src/filehandling.c

@@ -113,6 +113,68 @@ bool hc_fopen (HCFILE *fp, const char *path, char *mode)
   return true;
 }
 
+bool hc_fopen_nozip (HCFILE *fp, const char *path, char *mode)
+{
+  if (path == NULL || mode == NULL) return false;
+
+  int oflag = -1;
+
+  int fmode = S_IRUSR|S_IWUSR;
+
+  if (strncmp (mode, "a", 1) == 0 || strncmp (mode, "ab", 2) == 0)
+  {
+    oflag = O_WRONLY | O_CREAT | O_APPEND;
+
+    #if defined(MSDOS) || defined(OS2) || defined(WIN32) || defined(_WIN32) || defined(__CYGWIN__)
+    if (strncmp (mode, "ab", 2) == 0) oflag |= O_BINARY;
+    #endif
+  }
+  else if (strncmp (mode, "r", 1) == 0 || strncmp (mode, "rb", 2) == 0)
+  {
+    oflag = O_RDONLY;
+    fmode = -1;
+
+    #if defined(MSDOS) || defined(OS2) || defined(WIN32) || defined(_WIN32) || defined(__CYGWIN__)
+    if (strncmp (mode, "rb", 2) == 0) oflag |= O_BINARY;
+    #endif
+  }
+  else if (strncmp (mode, "w", 1) == 0 || strncmp (mode, "wb", 2) == 0)
+  {
+    oflag = O_WRONLY | O_CREAT | O_TRUNC;
+
+    #if defined(MSDOS) || defined(OS2) || defined(WIN32) || defined(_WIN32) || defined(__CYGWIN__)
+    if (strncmp (mode, "wb", 2) == 0) oflag |= O_BINARY;
+    #endif
+  }
+  else
+  {
+    // ADD more strncmp to handle more "mode"
+    return false;
+  }
+
+  fp->pfp = NULL;
+  fp->is_gzip = false;
+  fp->is_zip = false;
+
+  if (fmode == -1)
+  {
+    fp->fd = open (path, oflag);
+  }
+  else
+  {
+    fp->fd = open (path, oflag, fmode);
+  }
+
+  if (fp->fd == -1 && fp->is_zip == false) return false;
+
+  if ((fp->pfp = fdopen (fp->fd, mode)) == NULL)  return false;
+
+  fp->path = path;
+  fp->mode = mode;
+
+  return true;
+}
+
 size_t hc_fread (void *ptr, size_t size, size_t nmemb, HCFILE *fp)
 {
   size_t n = -1;