Cryptology ePrint Archive: Report 2021/650

Structured Leakage and Applications to Cryptographic Constant-Time and Cost

Gilles Barthe and Benjamin Gregoire and Vincent Laporte and Swarn Priya

Abstract: Many security properties of interest are captured by instrumented semantics that model the functional behavior and the leakage of programs. For several important properties, including cryptographic constant-time (CCT), leakage models are sufficiently abstract that one can define instrumented semantics for high-level and low-level programs. One important goal is then to relate leakage of source programs and leakage of their compilation---this can be used, e.g.\, to prove preservation of CCT. To simplify this task, we put forward the idea of structured leakage. In contrast to the usual modeling of leakage as a sequence of observations, structured leakage is tightly coupled with the operational semantics of programs. This coupling greatly simplifies the definition of leakage transformers that map the leakage of source programs to leakage of their compilation and yields more precise statements about the preservation of security properties. We illustrate our methods on the Jasmin compiler and prove preservation results for two policies of interest: CCT and cost.

Category / Keywords: foundations / Secure Compilation, Cryptographic Constant-Time, Cost

Date: received 18 May 2021, last revised 21 May 2021

Contact author: gjbarthe at gmail com, benjamin gregoire at inria fr, vincent laporte at inria fr, swarn priya at inria fr

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Version: 20210521:092618 (All versions of this report)

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