Paper 2026/131

Root-Cause Analysis of Power Side-Channel Leaks in RISC-V Cryptographic Implementations

Abraham Basurto-Becerra, Radboud University Nijmegen

Lejla Batina, Radboud University Nijmegen

Ileana Buhan, Radboud University Nijmegen

Durba Chatterjee, Radboud University Nijmegen

Abstract

Masking is the standard defense against power-based side-channel analysis (SCA) for cryptographic software, in which sensitive variables are split into independent shares. Although prior work often attributes leakage to microarchitectural effects, architectural interactions alone can already introduce subtle leaks that remain poorly understood. In this work, we propose ISALeak, a target-agnostic framework for analyzing full masked implementations to precisely identify and attribute the root causes of side-channel leakage at the instruction-set (ISA) level. ISALeak complements statistical tests such as TVLA by not only detecting leakage, but also localizing and explaining its source. We evaluate our approach on masked AES and masked Ascon across multiple compiler versions and optimizations. Using power measurements from ASIC (PicoRV32) and FPGA (Ibex) RISC-V cores, we show that 20-40% of the leaks detected by TVLA for masked AES originate from architectural register interactions. For masked Ascon, 17-23% of the observed leakage likewise stems from ISA-level effects and consistently manifests in physical power traces.

@misc{cryptoeprint:2026/131,
      author = {Asmita Adhikary and Abraham Basurto-Becerra and Lejla Batina and Ileana Buhan and Durba Chatterjee},
      title = {Root-Cause Analysis of Power Side-Channel Leaks in {RISC}-V Cryptographic Implementations},
      howpublished = {Cryptology {ePrint} Archive, Paper 2026/131},
      year = {2026},
      url = {https://eprint.iacr.org/2026/131}
}