The practical application of Secure Two-Party Computation is hindered by the difficulty to implement secure computation protocols. While recent work has proposed very simple programming languages which can be used to specify secure computations, it is still difficult for practitioners to use them, and cumbersome to translate existing source code into this format. Similarly, the manual construction of two-party computation protocols, in particular ones based on the approach of garbled circuits, is labor intensive and error-prone.The central contribution of the current paper is a tool which achieves Secure Two-Party Computation for ANSI C. Our work is based on a combination of model checking techniques and two-party computation based on garbled circuits.Our key insight is a nonstandard use of the bit-precise model checker CBMC which enables us to translate C programs into equivalent Boolean circuits. To this end, we modify the standard CBMC translation from programs into Boolean formulas whose variables correspond to the memory bits manipulated by the program. As CBMC attempts to minimize the size of the formulas, the circuits obtained by our tool chain are also size efficient; to improve the efficiency of the garbled circuit evaluation, we perform optimizations on the circuits. Experimental results with the new tool CBMC-GC demonstrate the practical usefulness of our approach.

Secure two-party computation (STC) is a computer security paradigm where two parties can jointly evaluate a program with sensitive input data, provided in parts from both parties. By the security guarantees of STC, neither party can learn any information on the other party's input while performing the STC task. For a long time thought to be impractical, until recently, STC has only been implemented with domain-specific languages or hand-crafted Boolean circuits for specific computations. Our open-source compiler CBMC-GC is the first ANSI C compiler for STC. It turns C programs into Boolean circuits that fit the requirements of garbled circuits, a generic STC approach based on circuits. Here, the size of the resulting circuits plays a crucial role since each STC step involves encryption and network transfer and is therefore extremely slow when compared to computations performed on modern hardware architectures. We report on newly implemented circuit optimization techniques that substantially reduce the circuit sizes compared to the original release of CBMC-GC.

Although the principal analogy between counterexample generation and white box testing has been repeatedly addressed, the usage patterns and performance requirements for software testing are quite different from formal verification. Our tool FSHELL provides a versatile testing environment for C programs which supports both interactive explorative use and a rich scripting language. More than a frontend for software model checkers, FSHELL is designed as a database engine which dispatches queries about the program to program analysis tools. We report on the integration of CBMC into FSHELL and describe architectural modifications which support efficient test case generation.

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In this paper, we describe (con) 2 colic testing -a systematic testing approach for concurrent software. Based on concrete and symbolic executions of a concurrent program, (con) 2 colic testing derives inputs and schedules such that the execution space of the program under investigation is systematically explored. We introduce interference scenarios as key concept in (con) 2 colic testing. Interference scenarios capture the flow of data among different threads and enable a unified representation of path and interference constraints. We have implemented a (con) 2 colic testing engine and demonstrate the effectiveness of our approach by experiments.