diff -r 7d6f2526244a -r 197a85a35cba app/src/main/java/com/isode/stroke/stringcodecs/PBKDF2.java
--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/app/src/main/java/com/isode/stroke/stringcodecs/PBKDF2.java	Sun Mar 15 18:03:03 2015 +0100
@@ -0,0 +1,29 @@
+/*
+ * Copyright (c) 2010, Isode Limited, London, England.
+ * All rights reserved.
+ */
+/*
+ * Copyright (c) 2010, Remko Tronçon.
+ * All rights reserved.
+ */
+package com.isode.stroke.stringcodecs;
+
+import com.isode.stroke.base.ByteArray;
+
+public class PBKDF2 {
+
+    public static ByteArray encode(ByteArray password, ByteArray salt, int iterations) {
+        ByteArray u = HMACSHA1.getResult(password, ByteArray.plus(salt, new ByteArray("\0\0\0\1")));
+        ByteArray result = new ByteArray(u);
+        byte[] resultData = result.getData();
+        int i = 1;
+        while (i < iterations) {
+            u = HMACSHA1.getResult(password, u);
+            for (int j = 0; j < u.getSize(); ++j) {
+                resultData[j] ^= u.getData()[j];
+            }
+            ++i;
+        }
+        return result;
+    }
+}