We present Program Demultiplexing (PD), an execution paradigm that creates concurrency in sequential programs by "demultiplexing " methods (functions or subroutines). Call sites of a demultiplexed method in the program are associated with handlers that allow the method to be separated from the sequential program and executed on an auxiliary processor. The demultiplexed execution of a method (and its handler) is speculative and occurs when the inputs of the method are (speculatively) available, which is typically far in advance of when the method is actually called in the sequential execution. A trigger, composed of predicates that are based on program counters and memory write addresses, launches the speculative execution of the method on another processor. Our implementation of PD is based on a full-system execution-based chip multi-processor simulator with software to generate triggers and handlers from an x86program binary. We evaluate eight integer benchmarks from the SPEC2000 suite ⎯programs written in C with no explicit concurrency and/or motivation to create concurrency ⎯ and achieve a harmonic mean speedup of 1.8x with our implementation of PD. 1.

Code obfuscation makes it harder for a security analyst to understand the malicious payload of a program. In most cases an analyst needs to study the program at the machine code level, with little or no extra information available, apart from his experience. An unexperienced analyst is confronted with a steep learning curve, as understanding unobfuscated machine code already requires some skills. We have built LOCO, a graphical, interactive environment to help a security analyst improving his skills in understanding obfuscated code.

This paper presents LOCO, a graphical, interactive environment to experiment with code obfuscation and deobfuscation transformations, which can be applied automatically, semi-automatically and by hand. LOCO is an extension of the multi-platform visualization tool LANCET, combined with an obfuscation infrastructure in the underlying link-time program rewriter DIABLO. By use of LOCO, a developer can easily navigate through the control flow graph of a program and do fine-grained obfuscation, test new obfuscation transformations, test the robustness of existing transformations or improve existing transformations.

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