diff -r 7d6f2526244a -r 197a85a35cba app/src/main/java/com/isode/stroke/stringcodecs/SHA1.java
--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/app/src/main/java/com/isode/stroke/stringcodecs/SHA1.java	Sun Mar 15 18:03:03 2015 +0100
@@ -0,0 +1,27 @@
+/*
+ * 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;
+import java.security.MessageDigest;
+import java.security.NoSuchAlgorithmException;
+
+public class SHA1 {
+
+    public static ByteArray getHash(ByteArray data) {
+        MessageDigest md;
+        try {
+            md = MessageDigest.getInstance("SHA-1");
+        } catch (NoSuchAlgorithmException ex) {
+            throw new IllegalStateException("JRE doesn't have an SHA hash function", ex);
+        }
+        md.update(data.getData());
+        return new ByteArray(md.digest());
+    }
+}