E.P. de Vink

Virtual Analysis and Reduction of Side-Channel Vulnerabilities of Smartcards

This paper focuses on the usability of the PINPAS tool. The PINPAS tool is an instruction-level interpreter for smartcard assembler languages, augmented with facilities to study side-channel vulnerabilities. The tool can simulate side-channel leakage and has a suite of utilities to analyze this. The usage of the tool, for the analysis of a cryptographic algorithm is illustrated using the standard AES and RSA. Vulnerabilities of the implementations are identified and protective measures added. It is argued, that the tool can be instrumental for the design and realization of secure smartcard implementations in a systematic way.

Metric Semantics and Full Abstractness for Action Refinement and Probabilistic Choice

This paper provides a case-study in the field of metric semantics for probabilistic programming. Both an operational and a denotational semantics are presented for an abstract process language L_pr, which features action refinement and probabilistic choice. The two models are constructed in the setting of complete ultrametric spaces, here based on probability measures of compact support over sequences of actions. It is shown that the standard toolkit for metric semantics works well in the probabilistic context of L_pr, e.g. in establishing the correctness of the denotational semantics with respect to the operational one. In addition, it is shown how the method of proving full abstraction --as proposed recently by the authors for a nondeterministic language with action refinement-- can be adapted to deal with the probabilistic language L_pr as well.

Transactions on Computational Systems Biology XIV

We formalise a continuous-time Markov chain with multidimensional discrete state space model of the AKAP scaffold protein as a crosstalk mediator between two biochemical signalling pathways. The analysis by temporal properties of the AKAP model requires reasoning about whether the counts of individuals of the same type (species) are increasing or decreasing. For this purpose we propose the concept of stochastic trends based on formulating the probabilities of transitions that increase (resp. decrease) the counts of individuals of the same type, and express these probabilities as formulae such that the state space of the model is not altered. We define a number of stochastic trend formulae (e.g. weakly increasing, strictly increasing, weakly decreasing, etc.) and use them to extend the set of state formulae of Continuous Stochastic Logic. We show how stochastic trends can be implemented in a guarded-command style specification language for transition systems. We illustrate the application of stochastic trends with numerous small examples and then we analyse the AKAP model in order to characterise and show causality and pulsating behaviours in this biochemical system.