Engineering Aspects of Hash Functions

Hash functions have numerous applications in cryptography, from public key to cryptographic protocols and cryptosystems. Evidently, substantial effort was invested on designing "secure" hash functions, unintentionally over-looking other engineering aspects that may affect their use in practice. However, we argue that in some applications, the efficiency of hash functions is as important as their security. Unlike most of the existing related works in the literature (which merely report on efficiency figures of some popular hash functions without discussing how and why these results were obtained), we not only discuss how to carry out efficiency evaluations, we also provide a set of optimization guidelines to assist implementers in optimizing their implementations. We demonstrate this by adopting an existing SHA-1/SHA-2 implementation and show how minor optimization can lead to significant efficiency gain.