1. A method for storage of security keys and certificates in a data processing system comprising: providing at least one entity ( 150 ) in the form of a key or certificate for storage in a storage means; fragmenting the entity into fragments ( 152, 154 ) of non-uniform length according to a predetermined algorithm ( 200 ); storing the fragments ( 152, 154 ) in the storage means ( 280 ); wherein fragments (l 52, 154 ) of the at least one entity ( 150 ) are intermixed within the storage means.