XCRUSH: A Family of ARX Block Ciphers

The XCRUSH family of non-Feistel, ARX block ciphers is designed to make efficient use of modern 64-bit general-purpose processors using a small number of encryption rounds which are simple to implement in software. The avalanche function, which applies one data-dependent, key-dependent rotation per 64-bit word of plaintext per round, allows XCRUSH to produce an almost totally diffuse 256-bit block after just the first two rounds. Designed for speed in software, the reference implementation for 3-round XCRUSH is measured at ∼7.3 cycles/byte single-threaded on an Intel Haswell processor. A deterministic random bit generator, constructed using the avalanche function, serves as a key scheduling algorithm. No security claims are made in this paper.