A High Security Log-in Procedure 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 Sannon codes. CACM August, 1974 Purdy, G. B. operating systems, time sharing systems, security, cryptography 4.35 CA740803 JB January 17, 1978 10:10 AM 2621 5 2621 2621 5 2621 2621 5 2621