Proof appendix to accompany the paper, "From MinX to MinC: Semantics-Driven Decompilation of Recursive Datatypes"

Proof appendix to accompany the paper, "From MinX to MinC: Semantics-Driven Decompilation of Recursive Datatypes

Solvers for Type Recovery and Decompilation of Binaries

Reconstructing the meaning of a program from its binary is known as reverse engineering. Since reverse engineering is ultimately a search for meaning, there is growing interest in inferring a type (a meaning) for the elements of a binary in a consistent way. Currently there is no consensus on how best to achieve this, with the few existing approaches utilising ad-hoc techniques which lack any formal basis. Moreover, previous work does not answer (or even ask) the fundamental question of what it means for recovered types to be correct. This thesis demonstrates how solvers for Satisfiability Modulo Theories (SMT) and Constraint Handling Rules (CHR) can be leveraged to solve the type reconstruction problem. In particular, an approach based on a new SMT theory of rational tree constraints is developed and evaluated. The resulting solver, based on the reification mechanisms of Prolog, is shown to scale well, and leads to a reification driven SMT framework that supports rapid implementation of SMT solvers for different theories in just a few hundred lines of code. The question of how to guarantee semantic relevance for reconstructed types is answered with a new and semantically-founded approach that provides strong guarantees for the reconstructed types. Key to this approach is the derivation of a witness program in a type safe high-level language alongside the reconstructed types. This witness has the same semantics as the binary, is type correct by construction, and it induces a (justifiable) type assignment on the binary. Moreover, the approach, implemented using CHR, yields a type-directed decompiler. Finally, to evaluate the flexibility of reificiation-based SMT solving, the SMT framework is instantiated with theories of general linear inequalities, integer difference problems and octagons. The integer difference solver is shown to perform competitively with state-of-the-art SMT solvers. Two new algorithms for incremental closure of the octagonal domain are presented and proven correct. These are shown to be both conceptually simple, and offer improved performance over existing algorithms. Although not directly related to reverse engineering, these results follow from the work on SMT solver construction

Handbook of remote working for social innovators

No abstract available.publishe

The Ursinus Weekly, October 29, 1962

Founders Day affair Sunday features theologian McCord • Student concert series opens in Philadelphia • Cub and Key men meet at Millers • Juniors plan turnabout dance • Pi Nu welcomes seven new pledges • Improved Main Street is becoming auto speedway • Saturday\u27s Innkeepers concert delights and enchants audience • Pre-medicals hear Hudock lecture on electrocardiograph • Foreign students speak at recent reception • Young GOP meeting scheduled for Tuesday • Tense Cuban situation draws profs\u27 comments • UC represented at WAC program • Library display depicts internationality of UC • The Rail will open soon • Chamberlin will speak next week in Y program • Editorial: An alarming issue; Campus post office sets new hours • Conclusion of Dr. Miller\u27s talk on India in recent Forum program • Renovations in off-campus dorms praised by long-suffering women • Coed continues social work tale of reform school • The Weekly interviews three more foreign students • Soccermen succumb to Swarthmore, St. Joe\u27s in consecutive matches • UC suffers football defeat in Wagner heartbreaker 14-8 • Player of the week: Doubly dangerous is Degenhardt • Next week\u27s opponent: Haverford • Unbeaten Curtis I first in league • Greek gleaningshttps://digitalcommons.ursinus.edu/weekly/1279/thumbnail.jp

From MinX to MinC: Semantics-Driven Decompilation of Recursive Datatypes

Reconstructing the meaning of a program from its binary executable is known as reverse engineering; it has a wide range of applications in software security, exposing piracy, legacy systems, etc. Since reversing is ultimately a search for meaning, there is much interest in inferring a type (a meaning) for the elements of a binary in a consistent way. Unfortunately existing approaches do not guarantee any semantic relevance for their reconstructed types. This paper presents a new and semantically-founded approach that provides strong guarantees for the reconstructed types. Key to our approach is the derivation of a witness program in a high-level language alongside the reconstructed types. This witness has the same semantics as the binary, is type correct by construction, and it induces a (justifiable) type assignment on the binary. Moreover, the approach effectively yields a type-directed decompiler. We formalise and implement the approach for reversing Minx, an abstraction of x86, to MinC, a type-safe dialect of C with recursive datatypes. Our evaluation compiles a range of textbook C algorithms to MinX and then recovers the original structures

Not fitting in and getting out : psychological type and congregational satisfaction among Anglican churchgoers in England

Listening to the motivations reported by individuals for ceasing church attendance and becoming church leavers, Francis and Richter identified high on the list the sense of "not fitting in". Drawing on psychological type theory, several recent studies have documented the way in which some psychological types are over-represented in church congregations and other psychological types are under-represented. Bringing these two observations together, the present study tested the hypothesis that church congregations have created type-alike communities within which individuals displaying the opposite type preferences are more likely to feel marginalised and to display lower levels of satisfaction with the congregations they attend. Data were provided by 1867 churchgoers who completed a measure of psychological type, together with measures of frequency of attendance and congregational satisfaction. These data confirmed that congregations were weighted towards preferences for introversion, sensing, feeling and judging, and that individuals displaying the opposite preferences (especially intuition, thinking and perceiving) recorded lower levels of congregational satisfaction. The implications of these findings are discussed for promoting congregational retention by enhancing awareness of psychological type preferences among those who attend

PhD Annual Yearbook New Series Volume 1 October 2009

An edited volume with contributions from six PhD researchers in the school of Humanities and Social Sciences at the University of East London. Each contributor details their research work in progress. Topics in this volume include: Gypsy/Traveller children in England, refugee experiences in Education, Atget at Bercy, The textile self re/collected and a virtual conceptualization of the digital. This edition also includes two book reviews: Pitcher, B., (2009), The Politics Of Multiculturalism: Race and Racism in Contemporary Britain, Hampshire, Palgrave Macmillan and Back, L., (2007), The Art of Listening, Oxford, Berg

On the canonically invariant calculation of Maslov indices

After a short review of various ways to calculate the Maslov index appearing in semiclassical Gutzwiller type trace formulae, we discuss a coordinate-independent and canonically invariant formulation recently proposed by A Sugita (2000, 2001). We give explicit formulae for its ingredients and test them numerically for periodic orbits in several Hamiltonian systems with mixed dynamics. We demonstrate how the Maslov indices and their ingredients can be useful in the classification of periodic orbits in complicated bifurcation scenarios, for instance in a novel sequence of seven orbits born out of a tangent bifurcation in the H\'enon-Heiles system.Comment: LaTeX, 13 figures, 3 tables, submitted to J. Phys.