Secure Optimization Through Opaque Observations
Abstract
Secure applications implement protections against side-channel and physical attacks. Such protections embed input/output side-effects preventing optimizing compilers from altering the protection. These side-effects are error-prone and compiler-dependent, and the current practice involves analyzing the generated machine code to make sure security or privacy properties are still enforced. Vu et al. recently demonstrated how to automate the insertion of volatile side-effects in a compiler [30], but these may be too expensive in fine-grained protections such as control-flow integrity. We introduce observations of the program state that are intrinsic to the correct execution of security protections, along with means to specify and preserve observations across the compilation flow. Such observations complement the traditional input/output-preservation contract of compilers. We show how to guarantee their preservation without modifying compilation passes and with as little performance impact as possible. We validate our approach on a range of benchmarks, expressing the secure compilation of these applications in terms of observations to be made at specific program points.