Paper 2021/1252

Complete Practical Side-Channel-Assisted Reverse Engineering of AES-Like Ciphers

Andrea Caforio, Fatih Balli, and Subhadeep Banik


Public knowledge about the structure of a cryptographic system is a standard assumption in the literature and algorithms are expected to guarantee security in a setting where only the encryption key is kept secret. Nevertheless, undisclosed proprietary cryptographic algorithms still find widespread use in applications both in the civil and military domains. Even though side-channel-based reverse engineering attacks that recover the hidden components of custom cryptosystems have been demonstrated for a wide range of constructions, the complete and practical reverse engineering of AES-128-like ciphers remains unattempted. In this work, we close this gap and propose the first practical reverse engineering of AES-128-like custom ciphers, i.e., algorithms that deploy undisclosed SubBytes, ShiftRows and MixColumns functions. By performing a side-channel-assisted differential power analysis, we show that the amount of traces required to fully recover the undisclosed components are relatively small, hence the possibility of a side-channel attack remains as a practical threat. The results apply to both 8-bit and 32-bit architectures and were validated on two common microcontroller platforms.

Available format(s)
Publication info
Published elsewhere. CARDIS-2021
side-channelDPAreverse engineeringAES
Contact author(s)
andrea caforio @ epfl ch
fatih balli @ csem ch
subhadeep banik @ epfl ch
2021-09-20: received
Short URL
Creative Commons Attribution


      author = {Andrea Caforio and Fatih Balli and Subhadeep Banik},
      title = {Complete Practical Side-Channel-Assisted Reverse Engineering of AES-Like Ciphers},
      howpublished = {Cryptology ePrint Archive, Paper 2021/1252},
      year = {2021},
      note = {\url{}},
      url = {}
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