Phillip G. Bradford

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Sensors are tiny computers with limited computational capability and physical resources. The implementation of secure protocols for sensor network is a big challenge. In order to provide high security for sensor networks, it is very important to choose a small, efficient and effiective encryption algorithm as a security primitive. The TEA (Tiny Encryption(More)
In this paper we discuss a variation of the classical Huffman coding problem: finding optimal prefix-free codes for unequal letter costs. Our problem consists of finding a minimal cost prefix-free code in which the encoding alphabet consists of unequal cost (length) letters, with lengths α and β. The most efficient algorithm known previously required O(n)(More)
The problem of matching nuts and bolts is the following Given a collection of n nuts of distinct sizes and n bolts such that there is a one to one correspondence between the nuts and the bolts nd for each nut its corresponding bolt We can only compare nuts to bolts That is we can neither compare nuts to nuts nor bolts to bolts This humble restriction on the(More)
This paper proposes a new scheduling policy for cluster-based servers called DAS (Deferred Assignment Scheduling). The main idea in DAS is to defer scheduling as much as possible in order to make better use of the accumulated information on job sizes. In broad outline, DAS operates as follows: (1) incoming jobs are held by the dispatcher in a buffer; (2)(More)
An <i>insider threat</i> is caused by authorized users potentially performing unsanctioned or inappropriate actions that endanger the computer security of an organization. This paper describes a novel approach that employs the ideas of <i>Role-Based Access Control (RBAC)</i> to initiate role-action mapping rules in line with organization specific security(More)
This paper gives a O(lg n) time and n=lgn processor algorithm for solving the matrix chain ordering problem and for nding optimal triangulations of a convex polygon on the Common CRCW PRAM model. This algorithm works by nding shortest paths in special digraphs modeling dynamic programming tables. These shortest paths are found cheaply using new and e cient(More)
This paper shows how to allocate a limited supply of inventory in a centralized distribution system with multiple retailers subject to minimal supply commitments and maximum delivery limits for each retailer. The objective is to maximize the number of units sold by all retailers in one time period. The analysis is done by building on a classical result of(More)