diff --git a/rdr/RandomStream.cxx b/rdr/RandomStream.cxx
new file mode 100644
index 0000000..7f62e09
--- /dev/null
+++ b/rdr/RandomStream.cxx
@@ -0,0 +1,118 @@
+/* Copyright (C) 2002-2003 RealVNC Ltd.  All Rights Reserved.
+ *    
+ * This 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 software 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 software; if not, write to the Free Software
+ * Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA  02111-1307,
+ * USA.
+ */
+
+#include <rdr/RandomStream.h>
+#include <rdr/Exception.h>
+#include <time.h>
+#include <stdlib.h>
+#ifndef WIN32
+#include <unistd.h>
+#include <errno.h>
+#else
+#define getpid() GetCurrentProcessId()
+#endif
+
+using namespace rdr;
+
+const int DEFAULT_BUF_LEN = 256;
+
+unsigned int RandomStream::seed;
+
+RandomStream::RandomStream()
+  : offset(0)
+{
+  ptr = end = start = new U8[DEFAULT_BUF_LEN];
+
+#ifdef WIN32
+  provider = 0;
+  if (!CryptAcquireContext(&provider, 0, 0, PROV_RSA_FULL, 0)) {
+    if (GetLastError() == NTE_BAD_KEYSET) {
+      if (!CryptAcquireContext(&provider, 0, 0, PROV_RSA_FULL, CRYPT_NEWKEYSET)) {
+        fprintf(stderr, "RandomStream: unable to create keyset\n");
+        provider = 0;
+      }
+    } else {
+      fprintf(stderr, "RandomStream: unable to acquire context\n");
+      provider = 0;
+    }
+  }
+  if (!provider) {
+#else
+  fp = fopen("/dev/urandom", "r");
+  if (!fp)
+    fp = fopen("/dev/random", "r");
+  if (!fp) {
+#endif
+    fprintf(stderr,"RandomStream: warning: no OS supplied random source - using rand()\n");
+    seed += (unsigned int) time(0) + getpid() + getpid() * 987654 + rand();
+    srand(seed);
+  }
+}
+
+RandomStream::~RandomStream() {
+  delete [] start;
+
+#ifdef WIN32
+  if (provider) {
+    CryptReleaseContext(provider, 0);
+  }
+#else
+  if (fp) fclose(fp);
+#endif
+}
+
+int RandomStream::pos() {
+  return offset + ptr - start;
+}
+
+int RandomStream::overrun(int itemSize, int nItems, bool wait) {
+  if (itemSize > DEFAULT_BUF_LEN)
+    throw Exception("RandomStream overrun: max itemSize exceeded");
+
+  if (end - ptr != 0)
+    memmove(start, ptr, end - ptr);
+
+  end -= ptr - start;
+  offset += ptr - start;
+  ptr = start;
+
+  int length = start + DEFAULT_BUF_LEN - end;
+
+#ifdef WIN32
+  if (provider) {
+    if (!CryptGenRandom(provider, length, (U8*)end))
+      throw rdr::SystemException("unable to CryptGenRandom", GetLastError());
+    end += length;
+#else
+  if (fp) {
+    int n = fread((U8*)end, length, 1, fp);
+    if (n != 1)
+      throw rdr::SystemException("reading /dev/urandom or /dev/random failed",
+                                 errno);
+    end += length;
+#endif
+  } else {
+    for (int i=0; i<length; i++)
+      *(U8*)end++ = (int) (256.0*rand()/(RAND_MAX+1.0));
+  }
+
+  if (itemSize * nItems > end - ptr)
+    nItems = (end - ptr) / itemSize;
+
+  return nItems;
+}