Showing papers by "Chris J. Mitchell published in 1987"
TL;DR: Some formal requirements for a key distribution scheme are listed and it is shown that one of the proposed schemes fails to satisfy them.
8 citations
TL;DR: A method is described which, for any n, generates a rearrangeably nonblocking network for a bidirectional telephone system containing 2n subscribers, which is the minimum possible for two-stage networks of this type.
Abstract: A method is described which, for any n, generates a rearrangeably nonblocking network for a bidirectional telephone system containing 2n subscribers. The number of switches is always n2+2n?1, which is the minimum possible for two-stage networks of this type. This generalises earlier work of Newbury and Raby.
2 citations
TL;DR: In this article, a new method is given for evaluating the permanent of an n by $n (0, 1)$ circulant matrix, which gives as corollaries many of the previously known results.
Abstract: The permanent of an n by $n (0,1)$ circulant matrix is known to be equal to the number of permutations on n objects satisfying certain positional restrictions. The size of this number is of major importance for the design of certain analogue speech scramblers, as well as being a generalisation of certain “classical” enumeration problems. In this paper a new method is given for evaluating this permanent, which gives as corollaries many of the previously known results. The analogue speech scrambling scheme is also used to motivate a second enumeration problem, about which little seems to be known.
1 citations