A logic is presented for formalizing properties of specifications in the Edinburgh Logical Framework or LF. In this logic, typing judgments in LF serve as atomic formulas and quantification is permitted over LF terms and contexts. Quantifiers of the first variety are qualified by simple types that describe the functional structure associated with the variables they bind. Quantifiers over contexts are typed by context schemas that constrain their instantiations to adhere to a regular structure. The semantics of the logic is based ultimately on an understanding of derivability in LF. As such, valid formulas in the logic represent meta-theoretic properties of object systems that are encoded via LF signatures. The logic is complemented by a proof system that is briefly discussed. There are two categories to the rules in this proof system. One collection of rules captures the meanings of logical connectives and quantifiers. Another collection provides a means for analyzing atomic formulas based on an understanding of derivability in LF; these rules build in the capability for a case-analysis style reasoning about LF judgements and for induction over the heights of LF derivations.

In this paper, we present an approach to detecting novel cyber attacks though a form of program diversification, similar to the use of n-version programming for fault tolerant systems. Building on extensive previous and ongoing work by others on the use of code clones in a wide variety of areas, our Functionally Equivalent Variants using Information Synchronization (FEVIS) system automatically generates program variants to berun in parallel, seeking to detect attacks through divergence in behavior. Unlike approaches to diversification that only change program memory layout and behavior, FEVIS can detect attacks exploiting vulnerabilities in execution timing, string processing, and other logic errors. We are in the early stages of research and development for this approach, but have made sufficient progress to provide a proof of concept and some lessons learned. In this paper we describe FEVIS and its application to diversifying an open-source webserver, with results on several different example classes of attack which FEVIS will detect.

The two-level logic approach (2LL) to reasoning about computational specifications, as implemented by the Abella theorem prover, represents derivations of a specification language as an inductive definition in a reasoning logic. This approach has traditionally been formulated with the specification and reasoning logics having the same type system, and only the formulas being translated. However, requiring identical type systems limits the approach in two important ways: (1) every change in the specification language's type system requires a corresponding change in that of the reasoning logic, and (2) the same reasoning logic cannot be used with two specification languages at once if they have incompatible type systems. We propose a technique based on adequate encodings of the types and judgements of a typed specification language in terms of a simply typed higher-order logic program, which is then used for reasoning about the specification language in the usual 2LL. Moreover, a single specification logic implementation can be used as a basis for a number of other specification languages just by varying the encoding. We illustrate our technique with an implementation of the LF dependent type theory as a new specification language for Abella, co-existing with its current simply typed higher-order hereditary Harrop specification logic, without modifying the type system of its reasoning logic.