Aspect] is a simple and practical aspect-oriented extension to Java With just a few new constructs, AspectJ provides support for modular implementation of a range of crosscutting concerns. In AspectJ's dynamic join point model, join points are well-defined points in the execution of the program; pointcuts are collections of join points; advice are special method-like constructs that can be attached to pointcuts; and aspects are modular units of crosscutting implementation, comprising pointcuts, advice, and ordinary Java member declarations. AspectJ code is compiled into standard Java bytecode. Simple extensions to existing Java development environments make it possible to browse the crosscutting structure of aspects in the same kind of way as one browses the inheritance structure of classes. Several examples show that AspectJ is powerful, and that programs written using it are easy to understand.

An overview of AspectJ

The objective of this paper is to give a comprehensive introduction to applied cryptography with an engineer or computer scientist in mind. The emphasis is on the knowledge needed to create practical systems which supports integrity, confidentiality, or authenticity. Topics covered includes an introduction to the concepts in cryptography, attacks against cryptographic systems, key use and handling, random bit generation, encryption modes, and message authentication codes. Recommendations on algorithms and further reading is given in the end of the paper. This paper should make the reader able to build, understand and evaluate system descriptions and designs based on the cryptographic components described in the paper.

[서평]「Applied Cryptography」

Current standard security practices do not provide substantial assurance that the end-to-end behavior of a computing system satisfies important security policies such as confidentiality. An end-to-end confidentiality policy might assert that secret input data cannot be inferred by an attacker through the attacker's observations of system output; this policy regulates information flow. Conventional security mechanisms such as access control and encryption do not directly address the enforcement of information-flow policies. Previously, a promising new approach has been developed: the use of programming-language techniques for specifying and enforcing information-flow policies. In this paper, we survey the past three decades of research on information-flow security, particularly focusing on work that uses static program analysis to enforce information-flow policies. We give a structured view of work in the area and identify some important open challenges.

/pdf/language-based-information-flow-security-34hjiqf6qq.pdf

Language-based information-flow security

In comparative concurrency semantics, one usually distinguishes between linear time and branching time semantic equivalences. Milner's notion of observatin equivalence is often mentioned as the standard example of a branching time equivalence. In this paper we investigate whether observation equivalence really does respect the branching structure of processes, and find that in the presence of the unobservable action t of CCS this is not the case.Therefore, the notion of branching bisimulation equivalence is introduced which strongly preserves the branching structure of processes, in the sense that it preserves computations together with the potentials in all intermediate states that are passed through, even if silent moves are involved. On closed CCS-terms branching bisimulation congruence can be completely axiomatized by the single axion scheme: a.(t.(y+z)+y)=a.(y+z) (where a ranges over all actions) and the usual loaws for strong congruence.We also establish that for sequential processes observation equivalence is not preserved under refinement of actions, whereas branching bisimulation is.For a large class of processes, it turns out that branching bisimulation and observation equivalence are the same. As far as we know, all protocols that have been verified in the setting of observation equivalence happen to fit in this class, and hence are also valid in the stronger setting of branching bisimulation equivalence.

/pdf/branching-time-and-abstraction-in-bisimulation-semantics-4i7zl85i25.pdf

Branching time and abstraction in bisimulation semantics

One obtains in this paper a process algebra RCCS, in the style of CCS, where processes can backtrack. Backtrack, just as plain forward computation, is seen as a synchronization and incurs no additional cost on the communication structure. It is shown that, given a past, a computation step can be taken back if and only if it leads to a causally equivalent past.

/pdf/reversible-communicating-systems-43j3i8ss9x.pdf

Reversible communicating systems

We introduce the νSPI-calculus that strengthens the notion of "perfect symmetric cryptography" of the spi-calculus by taking time into account. This involves defining an operational semantics, defining a control flow analysis (CFA) in the form of a flow logic, and proving semantic correctness. Our first result is that secrecy in the sense of Dolev-Yao can be expressed in terms of the CFA. Our second result is that also non-interference in the sense of Abadi can be expressed in terms of the CFA; unlike Abadi we find the non-interference property to be an extension of the Dolev-Yao property.

/pdf/static-analysis-for-secrecy-and-non-interference-in-networks-4pv2ytxpjd.pdf

Static Analysis for Secrecy and Non-interference in Networks of Processes

This article surveys the definition and application of an enhancement of structural operational semantics in the field of concurrent systems, and also addresses issues of distribution and mobility ...

Enhanced operational semantics

http://cs.sookmyung.ac.kr/~chang/lecture/popa05/sdarticle.pdf

Static Analysis for Stack Inspection

We study causality in the π-calculus. Our notion of causality combines the dependencies given by the syntactic structure of processes with those originated by passing names. It turns out that two transitions not causally related may although occur in a fixed ordering in any computation, i.e., π-calculus may express implicitly a priority between actions. Our causality relation still induces the same partial order of transitions for all the computations that are obtained by shuffling transitions that are concurrent (= related neither by causality nor by priority). The presentation takes advantage from a parametric definition of process behaviour that highlights the essence of the topic. All the results on bisimulation based equivalences, congruences, axiomatizations and logics are taken (almost) for free from the interleaving theory.

Causality for Mobile Processes

We use a structural operational semantics which drives us in inferring quantitative measures on system evolution. The transitions of the system are labeled and we assign rates to them by only looking at these labels. The rates reflect the possibly distributed architecture on which applications run. We then map transition systems to Markov chains, and performance evaluation is carried out using standard tools. As a working example, we compare the performance of a conventional uniprocessor with a prefetch pipeline machine. We also consider two case studies from the literature involving mobile computation to show that our framework is feasible.

/pdf/performance-evaluation-of-mobile-processes-via-abstract-19ykdgniav.pdf

Pierpaolo Degano

Papers

Static Analysis for Secrecy and Non-interference in Networks of Processes

Enhanced operational semantics

Static Analysis for Stack Inspection

Causality for Mobile Processes

Performance evaluation of mobile processes via abstract machines