Model Checking Security Protocols

The formal analysis of security protocols is a prime example of a domain where model checking has been successfully applied. Although security protocols are typically small, analysis by hand is difficult as a protocol should work even when arbitrarily many runs are interleaved and in the presence of an adversary. Specialized model-checking techniques have been developed that address both the problems of unbounded, interleaved runs and a prolific, highly nondeterministic adversary.These techniques have been implemented in model-checking tools that now scale to protocols of realistic size and can be used to aid protocol design and standardization.In this chapter, we provide an overview of the main applications of model checking in security protocol analysis. We explain the central concepts involved in the analysis of security protocols: the abstraction of messages, protocols as role automata, the adversary model, and property specification. We explain and relate the main algorithms used and describe systems based on them. We also give examples of the successful applications of model checking to protocol standards. Finally, we provide an outlook on the field: What is possible with the state of the art and what are the future challenges

Prevention of colorectal cancer by combining early detection and chemoprevention

Colorectal cancer is a major cause of cancer-related mortality. Most colorectal cancers arise in precursor lesions over a number of years. The carcinogenetic pathway is modulated by a wide array of genetic and epigenetic factors. Two major approaches to halting carcinogenesis are chemoprevention and early detection. Chemoprevention is an attractive emerging option-advances in understanding the carcinogenetic pathways and progress in evaluating various putative agents are promising. However, several issues regarding efficacy, safety, and acceptability require answers before an ideal agent can come into widespread use. Early detection and removal of precursor lesions show promise in reducing disease burden. Although the concept has been around and has been widely advocated for several years, participation in screening remains low. The ideal test in terms of practicality, accuracy, and safety is still debated. This article reviews the recent literature related to screening and chemoprevention of colorectal cancer. Copyright © 2009 by Current Medicine Group LLC