CryptoDB
Yanis Belkheyar
Publications
Year
Venue
Title
2025
EUROCRYPT
ChiLow and ChiChi: New Constructions for Code Encryption
Abstract
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.
2022
TCHES
BipBip: A Low-Latency Tweakable Block Cipher with Small Dimensions
Abstract
Recently, a memory safety concept called Cryptographic Capability Computing (C3) has been proposed. C3 is the first memory safety mechanism that works without requiring extra storage for metadata and hence, has the potential to significantly enhance the security of modern IT-systems at a rather low cost. To achieve this, C3 heavily relies on ultra-low-latency cryptographic primitives. However, the most crucial primitive required by C3 demands uncommon dimensions. To partially encrypt 64-bit pointers, a 24-bit tweakable block cipher with a 40-bit tweak is needed. The research on low-latency tweakable block ciphers with such small dimensions is not very mature. Therefore, designing such a cipher provides a great research challenge, which we take on with this paper. As a result, we present BipBip, a 24-bit tweakable block cipher with a 40-bit tweak that allows for ASIC implementations with a latency of 3 cycles at a 4.5 GHz clock frequency on a modern 10 nm CMOS technology.
Coauthors
- Gilles Van Assche (1)
- Yanis Belkheyar (2)
- Joan Daemen (1)
- Patrick Derbez (1)
- Christoph Dobraunig (1)
- Shibam Ghosh (1)
- Santosh Ghosh (1)
- Gregor Leander (1)
- Silvia Mella (1)
- Léo Perrin (1)
- Shahram Rasoolzadeh (2)
- Lukas Stennes (1)
- Siwei Sun (1)
- Damian Vizár (1)