FRMAC, a Fast Randomized Message Authentication Code

We revisit the randomized approach followed in the design of the RMAC message authentication code in order to construct a MAC with similar properties, but based on WegmanCarter’s ε-universal hash families instead of a classical CBC chain. This yields a new message authentication code called FRMAC whose security bounds are, as in RMAC, beyond the birthday paradox limit. With efficient hash functions in software, the performance of FRMAC for large messages is similar to those of the fastest previously known schemes. FRMAC can also be more efficient for small messages. Furthermore, due to relaxed requirements about the nonces in the security proof, the implementation of FRMAC in real applications tends to be easier.