Light-Weight Instruction Set Extensions for Bit-Sliced Cryptography

Bit-slicing is a non-conventional implementation technique for cryptographic software where an n-bit processor is considered as a collection of n 1-bit execution units operating in SIMD mode. Particularly when implementing symmetric ciphers, the bit-slicing approach has several advantages over more conventional alternatives: it often allows one to reduce memory footprint by eliminating large look-up tables, and it permits more predictable performance characteristics that can foil time based side-channel attacks. Both features are attractive for mobile and embedded processors, but the performance overhead that results from bit-sliced implementation often represents a significant disadvantage. In this paper we describe a set of light-weight Instruction Set Extensions (ISEs) that can improve said performance while retaining all advantages of bit-sliced implementation. Contrary to other crypto-ISE, our design is generic and allows for a high degree of algorithm agility: we demonstrate appl...

• Type: Conference
• Year: 2008
• Where: CHES
• Authors: Philipp Grabher, Johann Großschädl, Dan Page
• Keywords: Bit-sliced Implementation, CHES 2008, Cryptology, Non-conventional Implementation Technique, Predictable Performance Characteristics