Faster 64-bit universal hashing using carry-less multiplications

Abstract

Intel and AMD support the carry-less multiplication (CLMUL) instruction set in their x64 processors. We use CLMUL to implement an almost universal 64-bit hash family (CLHASH). We compare this new family with what might be the fastest almost universal family on x64 processors (VHASH). We find that CLHASH is at least 60 % faster. We also compare CLHASH with a popular hash function designed for speed (Google’s CityHash). We find that CLHASH is 40 % faster than CityHash on inputs larger than 64 bytes and just as fast otherwise.