Implementation and Performance of the Simon and Speck Lightweight Block Ciphers on ASICs

Simon and Speck are families of lightweight block ciphers proposed in June 2013 by the US National Security Agency. Here we discuss ASIC implementations of these algorithms, presenting in some detail how one implements the smallest bit-serial versions of the algorithms. We also give area and throughput results for a variety of implementations—bit serial, iterated, and partially and fully pipelined. To the best of our knowledge, each version of Simon admits implementations with the smallest area of any comparable block cipher with a flexible key, and Speck is close behind: at the 64-bit block/128-bit key size, for example, both can be realized in under 1000 GE. More surprisingly, however, since they were intended for use on constrained platforms, Simon and Speck allow for extremely high efficiency and high-throughput implementations; each version of Simon, in particular, has the highest efficiency (throughput divided by area) of any comparably sized block cipher we’ve seen—lightweight or not.