Paper 2025/308
ChiLow and ChiChi: New Constructions for Code Encryption
, Radboud University Nijmegen, Univ Rennes, Inria, CNRS, IRISA, France, University of Haifa, French Institute for Research in Computer Science and Automation, Ruhr University Bochum, Radboud University Nijmegen, French Institute for Research in Computer Science and Automation, Ruhr University Bochum, Ruhr University Bochum, University of Chinese Academy of Sciences, State Key Laboratory of Cryptology, STMicroelectronics (Belgium), CSEMAbstract
We study the problem of embedded code encryption, i.e., encryption for binary software code for a secure microcontroller that is stored in an insecure external memory. As every single instruction must be decrypted before it can be executed, this scenario requires an extremely low latency decryption. We present a formal treatment of embedded code encryption security definitions, propose three constructions, namely ACE1, ACE2 and ACE3, and analyze their security. Further, we present ChiLow, a family of tweakable block ciphers and a related PRF specifically designed for embedded code encryption. At the core of ChiLow, there is ChiChi, a new family of non-linear layers of even dimension based on the well-known χ function. Our fully unrolled hardware implementation of ChiLow, using the Nangate 15nm Open Cell Library, achieves a decryption latency of less than 280 picoseconds.
Metadata
- Available format(s)
-
PDF
- Category
- Secret-key cryptography
- Publication info
- A major revision of an IACR publication in EUROCRYPT 2025
- Keywords
- symmetric cryptographylightweight cryptographymemory encryptionlow latency encryption
- Contact author(s)
-
yanis belkheyar @ ru nl
patrick derbez @ inria fr
shibam ghosh @ inria fr
gregor leander @ rub de
silvia mella @ ru nl
leo perrin @ inria fr
shahram rasoolzadeh @ rub de
lukas stennes @ rub de
siweisun isaac @ gmail com
gilles vanassche @ st com
damian vizar @ csem ch - History
- 2025-02-21: approved
- 2025-02-20: received
- See all versions
- Short URL
- https://ia.cr/2025/308
- License
-
CC BY
BibTeX
@misc{cryptoeprint:2025/308,
author = {Yanis Belkheyar and Patrick Derbez and Shibam Ghosh and Gregor Leander and Silvia Mella and Léo Perrin and Shahram Rasoolzadeh and Lukas Stennes and Siwei Sun and Gilles Van Assche and Damian Vizár},
title = {{ChiLow} and {ChiChi}: New Constructions for Code Encryption},
howpublished = {Cryptology {ePrint} Archive, Paper 2025/308},
year = {2025},
url = {https://eprint.iacr.org/2025/308}
}
