Mercy: A fast large block cipher for disk sector encryption

Abstract

We discuss the special requirements imposed on the under-lying cipher of systems which encrypt each sector of a disk partition in-dependently, and demonstrate a certificational weakness in some existing block ciphers including Bellare and Rogaway’s 1999 proposal, proposing a new quantitative measure of avalanche. To address these needs, we present Mercy, a new block cipher accepting large (4096-bit) blocks, which uses a key-dependent state machine to build a bijective F function for a Feistel cipher. Mercy achieves 9 cycles/byte on a Pentium compatible processor.