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.