Stephen Michell

State based key hop protocol: a lightweight security protocol for wireless networks

State Based Key Hop (SBKH) protocol provides a strong, lightweight encryption scheme for battery operated devices, such as the sensors in a wireless sensor network, as well as small office home office (SOHO) users. Although SBKH can be applied to many underlying protocols, in this paper, we focus on integrating SBKH with 802.11. Hence we compare SBKH with other 802.11 security protocols and show that SBKH eliminates all the issues with wired equivalent privacy (WEP) protocol, using the existing hardware and software as much as possible at a power and processing cost that is much lower than WiFi Protected Access (WPA) 1.0 or 2.0, and is cheaper than WE.

Tasklettes – a Fine Grained Parallelism for Ada on Multicores

The widespread use of multi-CPU computers is challenging programming languages, which need to adapt to be able to express potential parallelism at the language level. In this paper we propose a new model for fine grained parallelism in Ada, putting forward a syntax based on aspects, and the corresponding semantics to integrate this model with the existing Ada tasking capabilities. We also propose a standard interface and show how it can be extended by the user or library writers to implement their own parallelization strategies.

Safe parallel programming in ada with language extensions

The increased presence of parallel computing platforms brings concerns to the general purpose domain that were previously prevalent only in the specific niche of high-performance computing. As parallel programming technologies become more prevalent in the form of new emerging programming languages and extensions of existing languages, additional safety concerns arise as part of the paradigm shift from sequential to parallel behaviour. In this paper, we propose various syntax extensions to the Ada language, which provide mechanisms whereby the compiler is given the necessary semantic information to enable the implicit and explicit parallelization of code. The model is based on earlier work, which separates parallelism specification from concurrency implementation, but proposes an updated syntax with additional mechanisms to facilitate the development of safer parallel programs.

An Execution Model for Fine-Grained Parallelism in Ada

This paper extends the authors earlier proposal for providing Ada with support for fine-grained parallelism with an execution model based on the concept of abstract executors, detailing the progress guarantees that these executors must provide and how these can be assured even in the presence of potentially blocking operations. The paper also describes how this execution model can be applied to real-time systems.

Parallelism in Ada: Status and Prospects

Recently, a semantic and runtime model for parallel programming was proposed for addition to Ada. The proposal uses program annotations (expressed as Ada 2012 aspects) to inform the compiler of opportunities for parallel computation, and also offers the ability to specify details of parallel execution. The proposal includes support for specialized behaviors via dedicated libraries and a runtime environment that builds on pools of worker tasks. This paper extends that work by adding notations for data types and parallel blocks, simplifying some of the parallel notations and eliminating obstructions to the implementation of efficient parallel algorithms.

Real-Time Fine-Grained Parallelism in Ada

The approach for fine-grained parallelism in Ada presented at the last Real-Time Ada Workshop has been revised, both in terms of the language mechanisms to specify parallelism, as well as in terms of the underlying execution model. This paper summarizes the current state of the proposal, further detailing how programmers can control the behavior of the parallel execution, and discussing the issues which are still open.

Parallelism in Ada: general model and ravenscar

Parallel programming is expected to become more the norm as multi-core and many-core processors gain more widespread use. Ada has always had excellent concurrency support, but could be improved in the area of parallel programming. Specifically, divide and conquer parallelism via parallel loops and subprograms are difficult to write without some sort of library support. In this paper we describe a proposal that combines the use of task pools and parallelism managers to provide parallelism capabilities to real-time Ada applications, including Ravenscar applications. This work complements the syntax enhancements that we previously proposed, so that together they facilitate the writing of parallel applications.

Performance of state based key hop (SBKH) protocol for security on wireless networks

State based key hop (SBKH) protocol is a novel, simple encryption scheme that uses RC4 encryption technique in a way that provides robust security with reduced processing cost, compared to 802.11 security protocols: wired equivalent privacy (WEP) and wireless fidelity (Wi-Fi) protected access (WPA). Low processing cost makes SBKH suitable for battery-operated devices, such as wireless sensors, and ease of implementation and maintenance make it suitable for small office home office (SOHO) user nodes. We present a performance analysis of the SBKH protocol and compare it with a performance analysis of WEP and WPA. The analysis reveals that SBKH is significantly more power efficient in terms of processing compared to WEP, WPA 1.0 and WPA 2.0 for all packet sizes.

Conclusions of the 14th international real-time Ada workshop

The last session of IRTAW-14 was devoted to concluding on the results of the workshop, with the goal of prioritizing and selecting Ada Issues (AIs) to be produced and sent to the ISO/IEC JTC1/SC22/WG9 Ada Rapporteur Group (ARG). It allowed time for closing some open issues. In this report, Sections 2 to 4 summarize the final discussion around some open issues. Section 5 reflects the list of AIs to be produced by the workshop. The plan for next meeting is considered in Section 6. There is a final consideration about concurrency vulnerabilities in Section 7. Finally, Section 8 concludes with the closing of IRTAW-14.

Session Summary: Fine-grained parallelism

The main goals of this session were to: Present an overview of a model for fine-grained parallelism in Ada based on the notion of tasklets; Present and discuss a general execution model that would support parallelism constructs being considered for possible inclusion in a future version of the Ada standard; Present and discuss a real-time model that provides consistency with the general model while providing enough flexibility to accommodate a wide range of real-time systems with the intent of supporting real-time analysis and maintaining or improving the safety features of the language.