MISRs for Fast Authentication of Long Messages

In this paper we investigate the performance of using Multiple Input Shift Registers (MISRs) for message authentication. Linear Feedback Shift Registers (LFSRs) have been shown to be an efficient mechanism for authentication. Inspired by literature in digital system testing we present the use of MISRs for authentication. Such schemes are useful in sensor networks, the smart-grid, and multimedia authentication. n-bit MISRs have n, s-bit input streams while LFSRs have only one input bit stream. Therefore, MISRs present a potential for an n-fold speedup while maintaining similar hardware complexity as an LFSR. We first show that the MISR is a hash function that is epsilon-almost universal, epsilon-opt secure, and epsilon-balanced. We then use a pseudorandom function along with an MISR to generate a message authentication code (MAC) that is provably secure. We compare the software and hardware implementation of our MAC with other schemes. In software our scheme requires 8ms to compute a tag for a message of size 4MB (megabytes). In hardware our method results in a speedup of at least 10 over other methods.