Abstract
This paper introduces VMAC, a message authentication algorithm (MAC) optimized for high performance in software on 64-bit architectures. On the Athlon 64 processor, VMAC authenticates 2KB cache-resident messages at a cost of about 0.5 CPU cycles per message byte (cpb) — significantly faster than other recent MAC schemes such as UMAC (1.0 cpb) and Poly1305 (3.1 cpb). VMAC is a MAC in the Wegman-Carter style, employing a “universal” hash function VHASH, which is fully developed in this paper. VHASH employs a three-stage hashing strategy, and each stage is developed with the goal of optimal performance in 64-bit environments.