Work in Progress: Thwarting Timing Attacks in Microcontrollers using Fine-grained Hardware Protections

Timing side-channels are an identified threat for security critical software. Existing countermeasures have a cost either on the hardware requirements or execution time. We focus on low-cost microcontrollers that have a very low computational capacity. Although these processors do not feature out-of-order execution or speculation, they remain vulnerable to timing attacks exploiting the varying latencies of ALU operations or memory accesses. We propose to augment the RISC-V ISA with security primitives that have a guaranteed timing behavior. These primitives allow constant time ALU operations and memory accesses that do not alter the state of the cache. Our approach has a low overhead in terms of hardware cost, binary code size, and execution time both for the constant time secure program and other programs running concurrently on the same hardware.

Conference paper

In SILM - IEEE Euro S&P workshop