diff --git a/pokerth_lib.pro b/pokerth_lib.pro
index d89d8461..540c1693 100644
--- a/pokerth_lib.pro
+++ b/pokerth_lib.pro
@@ -43,8 +43,8 @@ HEADERS += \
 		src/playerdata.h \
 		src/gamedata.h \
 		src/config/configfile.h \
-		src/core/rand.h \
 		src/core/thread.h \
+		src/core/crypthelper.h \
 		src/engine/boardinterface.h \
 		src/engine/enginefactory.h \
 		src/engine/handinterface.h \
@@ -105,6 +105,7 @@ SOURCES += \
 		src/engine/berointerface.cpp \
 		src/gui/guiinterface.cpp \
 		src/core/common/thread.cpp \
+		src/core/common/crypthelper.cpp \
 		src/core/tinyxml/tinystr.cpp \
 		src/core/tinyxml/tinyxml.cpp \
 		src/core/tinyxml/tinyxmlerror.cpp \
diff --git a/src/core/common/crypthelper.cpp b/src/core/common/crypthelper.cpp
new file mode 100644
index 00000000..24e45e1b
--- /dev/null
+++ b/src/core/common/crypthelper.cpp
@@ -0,0 +1,121 @@
+/***************************************************************************
+ *   Copyright (C) 2007 by Lothar May                                      *
+ *                                                                         *
+ *   This program is free software; you can redistribute it and/or modify  *
+ *   it under the terms of the GNU General Public License as published by  *
+ *   the Free Software Foundation; either version 2 of the License, or     *
+ *   (at your option) any later version.                                   *
+ *                                                                         *
+ *   This program is distributed in the hope that it will be useful,       *
+ *   but WITHOUT ANY WARRANTY; without even the implied warranty of        *
+ *   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the         *
+ *   GNU General Public License for more details.                          *
+ *                                                                         *
+ *   You should have received a copy of the GNU General Public License     *
+ *   along with this program; if not, write to the                         *
+ *   Free Software Foundation, Inc.,                                       *
+ *   59 Temple Place - Suite 330, Boston, MA  02111-1307, USA.             *
+ ***************************************************************************/
+
+#include "crypthelper.h"
+
+
+#include <openssl/md5.h>
+#include <cstring>
+#include <cstdio>
+
+using namespace std;
+
+// Helper function.
+static int
+fromHex(int ch)
+{
+	int retVal = -1;
+
+	if (ch >= '0' && ch <= '9')
+		retVal = ch - '0';
+	else if (ch >= 'a' && ch <= 'f')
+		retVal = ch - 'a' + 10;
+	else if (ch >= 'A' && ch <= 'F')
+		retVal = ch - 'A' + 10;
+
+	return retVal;
+}
+
+
+MD5Buf::MD5Buf()
+{
+	memset(data, 0, sizeof(data));
+}
+
+
+std::string
+MD5Buf::ToString() const
+{
+	// Create a hex-based string from the MD5 data.
+	string retValue;
+	char tmpBuf[2 + 1];
+	tmpBuf[sizeof(tmpBuf) - 1] = 0;
+	for (int i = 0; i < MD5_DATA_SIZE; i++)
+	{
+		sprintf(tmpBuf, "%02x", data[i]);
+		retValue += tmpBuf;
+	}
+	return retValue;
+}
+
+bool
+MD5Buf::FromString(const std::string &text)
+{
+	// Convert hex-based string to MD5 data.
+	bool retVal = false;
+	if (text.size() == 2 * MD5_DATA_SIZE)
+	{
+		unsigned char *tmpData = data;
+		const char *t = text.c_str();
+		int i = 0;
+		for (; i < MD5_DATA_SIZE; i++) {
+			int part1 = fromHex(*t++);
+			if (part1 == -1)
+				break;
+			int part2 = fromHex(*t++);
+			if (part2 == -1)
+				break;
+			*tmpData++ = (part1<<4) + part2;
+		}
+		retVal = i == MD5_DATA_SIZE;
+	}
+	return retVal;
+}
+
+bool
+MD5Buf::operator==(const MD5Buf &other)
+{
+	return memcmp(data, other.data, MD5_DATA_SIZE) == 0;
+}
+
+
+bool
+CryptHelper::MD5Sum(const std::string &fileName, MD5Buf &buf)
+{
+	bool retVal = false;
+	FILE *file = fopen(fileName.c_str(), "rb");
+
+	if (file)
+	{
+		// Calculate MD5 sum of file.
+		unsigned char readBuf[8192];
+		MD5_CTX context;
+		int numBytes;
+
+		MD5_Init(&context);
+		while ((numBytes = fread(readBuf, 1, sizeof(readBuf), file)) > 0)
+			MD5_Update(&context, readBuf, numBytes);
+		MD5_Final(buf.data, &context);
+		retVal = ferror(file) == 0;
+
+		fclose(file);
+	}
+	return retVal;
+}
+
diff --git a/src/core/crypthelper.h b/src/core/crypthelper.h
new file mode 100644
index 00000000..b5dea316
--- /dev/null
+++ b/src/core/crypthelper.h
@@ -0,0 +1,47 @@
+/***************************************************************************
+ *   Copyright (C) 2007 by Lothar May                                      *
+ *                                                                         *
+ *   This program is free software; you can redistribute it and/or modify  *
+ *   it under the terms of the GNU General Public License as published by  *
+ *   the Free Software Foundation; either version 2 of the License, or     *
+ *   (at your option) any later version.                                   *
+ *                                                                         *
+ *   This program is distributed in the hope that it will be useful,       *
+ *   but WITHOUT ANY WARRANTY; without even the implied warranty of        *
+ *   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the         *
+ *   GNU General Public License for more details.                          *
+ *                                                                         *
+ *   You should have received a copy of the GNU General Public License     *
+ *   along with this program; if not, write to the                         *
+ *   Free Software Foundation, Inc.,                                       *
+ *   59 Temple Place - Suite 330, Boston, MA  02111-1307, USA.             *
+ ***************************************************************************/
+/* Helper class for crypt functions. */
+
+#ifndef _CRYPTHELPER_H_
+#define _CRYPTHELPER_H_
+
+#include <string>
+
+#define MD5_DATA_SIZE		16
+
+struct MD5Buf
+{
+	MD5Buf();
+
+	std::string ToString() const;
+	bool FromString(const std::string &text);
+
+	bool operator==(const MD5Buf &other);
+
+	unsigned char data[MD5_DATA_SIZE];
+};
+
+class CryptHelper
+{
+public:
+
+	static bool MD5Sum(const std::string &fileName, MD5Buf &buf);
+};
+
+#endif