Showing papers on "Cryptography published in 1974"

A user authentication scheme not requiring secrecy in the computer

Abstract: In many computer operating systems a user authenticates himself by entering a secret password known solely to himself and the system. The system compares this password with one recorded in a Password Table which is available to only the authentication program. The integrity of the system depends on keeping the table secret. In this paper a password scheme is presented which does not require secrecy in the computer. All aspects of the system, including all relevant code and data bases, may be known by anyone attempting to intrude.The scheme is based on using a function H which the would-be intruder is unable to invert. This function is applied to the user's password and the result compared to a table entry, a match being interpreted as authentication of the user. The intruder may know all about H and have access to the table, but he can penetrate the system only if he can invert H to determine an input that produces a given output.This paper discusses issues surrounding selection of a suitable H. Two different plausible arguments are given that penetration would be exceedingly difficult, and it is then argued that more rigorous results are unlikely. Finally, some human engineering problems relating to the scheme are discussed.

A high security log-in procedure

Abstract: The protection of time sharing systems from unauthorized users is often achieved by the use of passwords. By using one-way ciphers to code the passwords, the risks involved with storing the passwords in the computer can be avoided. We discuss the selection of a suitable one-way cipher and suggest that for this purpose polynomials over a prime modulus are superior to one-way ciphers derived from Shannon codes.

Privacy Systems for Telecommunication Networks

Abstract: : There is an increasing need for providing privacy and security in telecommunication and teleprocessing networks. This paper presents a brief survey of privacy systems--the techniques that can be used to provide communications security in commercial systems--and then examines in qualitative terms the protective characteristics of several classes of privacy transformations (encryption techniques). The emphasis is on the level of protection that can be expected and the effects of the telecommunication network characteristics on the performance of the privacy system, and vice versa. (Author)