t trends in distributed encrypted i.e. locked with the secret key. Both the hashed message processing, is to run a single global service with distributed, co- and the original message are passed to the receiver who uses his operating nodes. This is an expensive approach, out of reach for all different key to unlock (decrypt) the hashed message. but the largest players, but it does have significant benefits. The unhashed message is compared to the original message. If the Instead of franchising the service so that each node is an island or results are the same then the message must have come from the long-lining into a single central point the distributed nodes all originator since he is the only one who could have created the co-operate. This means that each node may host mailboxes and locked message as his key is private. processing for another to facilitate load balancing or disaster re- Data integrity can also be achieved using the above method, but covery and only a single registration is required for an account to be may also be achieved using symmetric keys. Note that symmetric directly accessible via any node world wide. This allows the global keys can guarantee data integrity but since by definition they are management of a multi-national company's account from the most known by at least two people they cannot guarantee authenticity. appropriate regional centre. Confidentiality can be achieved simply by encrypting the contents The global distributed approach matches both the structure of the of the P1 envelope. The standards do not specify any particular standards bodies and the trends in computing which are driving the encryption method, which is left free to the implementors of the end development of standards such as X.400 and X.500. systems. Further security features are typically provided by the VANS. These include audit trails and notifications, both positive and nega- 38.9 Future trends tive. Full support for notifications is not mandatory, however com- The current round of standards work concerns 