Efficient calculation of message authentication codes for related data

摘要

A method of computing a message authentication code (MAC) for a message having a common part and an independent part using a constrained processor, including: performing a MAC function on the common part of the message using a first secret key to produce a first output; performing a pseudorandom function on the independent part of the message using a second key to produce a second output, wherein the computation time of the pseudorandom function is significantly less than the computation time of the MAC function; and combining the first output and the second output to produce a computed MAC for the message.