diff --git a/authentication/source/java/ch/systemsx/cisd/authentication/Principal.java b/authentication/source/java/ch/systemsx/cisd/authentication/Principal.java
index 0c370e8d828d72a3f985578866ee1b3a45efbbae..62d35c94b04048f0df92a54bafd7a4aacf789aa2 100644
--- a/authentication/source/java/ch/systemsx/cisd/authentication/Principal.java
+++ b/authentication/source/java/ch/systemsx/cisd/authentication/Principal.java
@@ -23,6 +23,8 @@ import java.util.Set;
 
 import org.apache.commons.lang.builder.ToStringBuilder;
 
+import ch.systemsx.cisd.common.utilities.AbstractHashable;
+
 /**
  * This class defines in its constructor minimum information that we must know about a
  * <code>Principal</code>.
@@ -33,7 +35,7 @@ import org.apache.commons.lang.builder.ToStringBuilder;
  * 
  * @author Christian Ribeaud
  */
-public class Principal implements Serializable
+public class Principal extends AbstractHashable implements Serializable 
 {
     private static final long serialVersionUID = 1L;