diff --git a/src/privfile.cpp b/src/privfile.cpp
new file mode 100644
index 0000000..670598a
--- /dev/null
+++ b/src/privfile.cpp
@@ -0,0 +1,61 @@
+
+/*
+ * This file is part of Codecrypt.
+ *
+ * Copyright (C) 2013-2016 Mirek Kratochvil <exa.exa@gmail.com>
+ *
+ * Codecrypt is free software: you can redistribute it and/or modify it
+ * under the terms of the GNU Lesser General Public License as published by
+ * the Free Software Foundation, either version 3 of the License, or (at
+ * your option) any later version.
+ *
+ * Codecrypt 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 Lesser General Public
+ * License for more details.
+ *
+ * You should have received a copy of the GNU Lesser General Public License
+ * along with Codecrypt. If not, see <http://www.gnu.org/licenses/>.
+ */
+
+#include "privfile.h"
+
+#include <sys/stat.h>
+#include <sys/types.h>
+#include <sys/file.h>
+#include <fcntl.h>
+#include <unistd.h>
+#include <errno.h>
+
+bool put_private_file (const std::string&fn,
+                       const std::string&contents, bool force_perms)
+{
+	struct stat st;
+	if (stat (fn.c_str(), &st)) {
+		if (errno != ENOENT)
+			return false;
+
+		//if it simply doesn't exist, create it
+		int fd;
+		fd = creat (fn.c_str(), S_IRUSR | S_IWUSR);
+		if (fd < 0) return false;
+		ssize_t res = write (fd, contents.c_str(),
+		                     contents.length());
+		if (close (fd)) return false;
+		if ( (size_t) res != contents.length()) return false;
+
+	} else {
+		if (!S_ISREG (st.st_mode))
+			return false;
+
+		//remove others' read/write. group r/w is untouched.
+		if (force_perms && (st.st_mode & 07)) {
+			if (chmod (fn.c_str(), st.st_mode & ~07))
+				return false;
+		}
+	}
+
+	if (access (fn.c_str(), R_OK | W_OK)) return false;
+
+	return true;
+}
diff --git a/src/privfile.h b/src/privfile.h
new file mode 100644
index 0000000..41d5979
--- /dev/null
+++ b/src/privfile.h
@@ -0,0 +1,30 @@
+
+/*
+ * This file is part of Codecrypt.
+ *
+ * Copyright (C) 2013-2016 Mirek Kratochvil <exa.exa@gmail.com>
+ *
+ * Codecrypt is free software: you can redistribute it and/or modify it
+ * under the terms of the GNU Lesser General Public License as published by
+ * the Free Software Foundation, either version 3 of the License, or (at
+ * your option) any later version.
+ *
+ * Codecrypt 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 Lesser General Public
+ * License for more details.
+ *
+ * You should have received a copy of the GNU Lesser General Public License
+ * along with Codecrypt. If not, see <http://www.gnu.org/licenses/>.
+ */
+
+#ifndef _ccr_privfile_h_
+#define _ccr_privfile_h_
+
+#include <string>
+
+bool put_private_file (const std::string&fn,
+                       const std::string&contents,
+                       bool force_permissions);
+
+#endif