The Definition And Software Performance Of Hashstream, A Fast Length-Flexible Prf

Two of the fastest types of cryptographic algorithms are the stream cipher and the almost-universal hash function. There are secure examples of each that process data in software using less than one CPU cycle per byte. Hashstream combines the two types of algorithms in a straightforward manner yielding a PRF that can both consume inputs of and produce pseudorandom outputs of any desired length. The result is an object useful in many contexts: authentication, encryption, authenticated encryption, random generation, mask generation, etc. The HS1-SIV authenticated-encryption algorithm-a CAESAR competition second round selection-was based on Hashstream and showed the promise of such an approach by having provable security and topping the speed charts in several test configurations.