Choosing the security architecture and policies for a system is a demanding task that must be informed by an understanding of user behavior. We investigate the hypothesis that adding visible security features to a system increases user confidence in the security of a system and thereby causes users to reduce how much effort they spend in other security areas. In our study, 96 volunteers each created a pair of accounts, one secured only by a password and one secured by both a password and a fingerprint reader. Our results strongly support our hypothesis - on average. When using the fingerprint reader, users created passwords that would take one three-thousandth as long to break, thereby potentially negating the advantage two-factor authentication could have offered.

Reverse engineering compiled executables is a task with a steep learning curve. It is complicated by the task of translating assembly into a series of abstractions that represent the overall flow of a program. Most of the steps involve finding interesting areas of an executable and determining their overall functionality. This paper presents a method using dynamic analysis of program execution to visually represent the overall flow of a program. We use the Ether hypervisor framework to covertly monitor a program. The data is processed and presented for the reverse engineer. Using this method the amount of time needed to extract key features of an executable is greatly reduced, improving productivity. A preliminary user study indicates that the tool is useful for both new and experienced users.

Abstract This research defines and analyzes a methodology for deriving a performance model for SPMD hybrid parallel applications. Hybrid parallelism combines shared memory and message passing computing models. This work extends the current practice of application performance modelling by development of a methodology for hybrid applications with these procedures. Creation of a model based on complexity analysis of an application code and its data structures. Enhancement of a static complexity model by dynamic factors to capture execution time phenomena, such as memory hierarchy effects. Quantitative analysis of model characteristics and the effects of perturbations in measured parameters. These research results are presented in the context of a hybrid parallel implementation of a sparse linear algebra kernel. A model for this kernel is derived and analyzed using the methodology. Application of the model on two large parallel computing platforms provides case studies for the methodology. Operating system issues, machine balance factor, and memory hierarchy effects on model accuracy are examined. Copyright © 2007 John Wiley & Sons, Ltd.

Summary form only given. Automatic data distribution for composite grid applications requires that meshes be mapped to a parallel machine in a manner that balances the load while minimizing communication. To provide beginning support for mapping to computational grids, the automatic data distribution toolkit (ADDT) supports heterogeneous environments with varying communication and computational capabilities. This paper describes the applications supported by ADDT, the mapping techniques used, the Web interface for the toolkit, as well as planned future developments.

Composite grid problems arise in important application areas, e.g. reactor simulation. Related physical phenomena are inherently parallel and their simulations are computationally intensive. Unfortunately, parallel languages, such as High Performance Fortran, provide little support for these problems. We illustrate topological connections via a coupling statement, develop a programming style and transformation system to support composite grid code development, and develop an algorithm that automatically determines distributions for composite grid problems with small meshes. A mesh is classified as small if the amount of computational work associated with the mesh is less than the amount of work to be assigned to a single processor. Precompiler transformations, such as cloning for alignment specification, are described. Excerpts from a High Performance Fortran program before and after transformation illustrate user programming style and transformation issues. Our distribution algorithm's alignment and distribution specifications are input to the transformed High Performance Fortran programs which applies the mapping for execution of the simulation code. Some advantages of this approach are: transformations are applied before compilation and allow communication optimization; data distribution may be determined for any number of problems without recompilation; user determined distribution for parallelization is unnecessary; portability is improved. We validate the topology-based data distribution algorithm using a number of reactor configurations. Two random distribution algorithms provide a basis of comparison with measures of load balance and communication cost. Experiments show that the topology-based distribution algorithm almost always obtains load balance at least as good as, and often significantly better than, random algorithms while reducing the total communication per iteration from 50% to as much as a factor of ten.