The BipBip Low-Latency Tweakable Block Cipher

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 took on with the design of BipBip. BipBip is 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.

Resources:

• The TCHES paper containing specifications and design rationale
• Reference code in C++

Authors (in alphabetical order):

• Yanis Belkheyar
• Joan Daemen
• Christoph Dobraunig
• Santosh Ghosh
• Shahram Rasoolzadeh