SYSTEMATIC DESIGN OF A FAMILY OF ATTACK-RESISTANT AUTHENTICATION PROTOCOLS

The extensive use of open networks and distributed systems poses serio us threats to the security of end-to-end communications and network co mponents themselves. A necessary foundation for securing a network is the ability to reliably authenticate communication partners and other network entities. One-way password-based authentication techniques are not sufficient to cope with the issues at hand. Modern designs rely o n two-way cryptographic authentication protocols. However, most existi ng designs suffer from one or more limitations: they require synchroni zation of local clocks, they are subject to export restrictions becaus e of the way they use cryptographic functions, they are not amenable t o use in lower layers of network protocols because of the size and com plexity of messages they use, etc. Designing suitable cryptographic pr otocols that cater to large and dynamic network communities but do not suffer from the above problems presents substantial challenges in ter ms of ease of use, efficiency, flexibility, and above all security. Th is paper discusses the above challenges; shows how a few simple protoc ols, including one proposed by ISO, can easily be broken; and derives a series of desirable properties that authentication protocols should exhibit to meet the requirements of future large and dynamic network c ommunities. Then the paper describes a methodology that was developed to systematically build and test the security of a family of cryptogra phic two-way authentication protocols that are as simple as possible y et resistant to a wide class of attacks, efficient, easy to implement and use, and amenable to many different networking environments. It al so discusses several concrete examples of protocols of that family tha t presents various advantages in specific distributed system scenarios .