Paper 2019/349

Spin Me Right Round: Rotational Symmetry for FPGA-specific AES

Felix Wegener, Lauren De Meyer, and Amir Moradi


The effort in reducing the area of AES implementations has largely been focused on Application-Specific Integrated Circuits (ASICs) in which a tower field construction leads to a small design of the AES S-box. In contrast, a naive implementation of the AES S-box has been the status-quo on Field-Programmable Gate Arrays (FPGAs). A similar discrepancy holds for masking schemes - a well-known side-channel analysis countermeasure - which are commonly optimized to achieve minimal area in ASICs. In this paper we demonstrate a representation of the AES S-box exploiting rotational symmetry which leads to a 50% reduction of the area footprint on FPGA devices. We present new AES implementations which improve on the state of the art and explore various trade-offs between area and latency. For instance, at the cost of increasing 4.5 times the latency, one of our design variants requires 25% less look-up tables (LUTs) than the smallest known AES on Xilinx FPGAs by Sasdrich and Güneysu at ASAP 2016. We further explore the protection of such implementations against side-channel attacks. We introduce a generic methodology for masking any n-bit Boolean functions of degree t with protection order d. The methodology is exact for first-order and heuristic for higher orders. Its application to our new construction of the AES S-box allows us to improve previous results and introduce the smallest first-order masked AES implementation on Xilinx FPGAs, to-date.

Available format(s)
Publication info
A major revision of an IACR publication in TCHES 2018
AESSCADPARotational SymmetryThreshold Implementationsd+1 MaskingFPGA
Contact author(s)
lauren demeyer @ esat kuleuven be
felix wegener @ rub de
amir moradi @ rub de
2019-10-09: revised
2019-04-03: received
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Creative Commons Attribution


      author = {Felix Wegener and Lauren De Meyer and Amir Moradi},
      title = {Spin Me Right Round: Rotational Symmetry for FPGA-specific AES},
      howpublished = {Cryptology ePrint Archive, Paper 2019/349},
      year = {2019},
      note = {\url{}},
      url = {}
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