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A protection model is presented for a general purpose computing system based on tags attached as seals and signatures to values exchanged among processes. A tag attached to a value as a seal does not prevent that value from being propagated to any place within the system; rather., it guarantees that the value and any information derived from it cannot leave the system unless a matching tag is presented. A tag attached to a value as a signature is used by a process to verify the origin of the received data. Solutions to problems from the areas of interprocess communication and proprietary services are given. [ABSTRACT FROM AUTHOR]

Controlled sharing of information is needed and desirable for many applications and is supported in operating systems by access control mechanisms. This paper shows how to extend programming languages to provide controlled sharing. The extension permits expression of access constraints on shared data. Access constraints can apply both to simple objects. and to objects that are components of larger objects, such as bank account records in a bank's data base. The constraints are stated declaratively, and can be enforced by static checking similar to type checking. The approach can he used to extend any strongly-typed language, but is particularly suitable for extending languages that support the notion of abstract data types. [ABSTRACT FROM AUTHOR]

Presents a technique on signature authentication using public key encryption. Proposition of elaborate mechanism without using network clock; Application of secret key by the receiver; Effectiveness of the technique.

Presents a method of user password authentication with insecure communication. Description of the method on security tampering; Assumption of secure on-way encryption function; Implementation of encryption function on microcomputer in user's terminal.