SIMON and SPECK: New NSA Encryption Algorithms

The NSA has published some new symmetric algorithms:

Abstract: In this paper we propose two families of block ciphers, SIMON and SPECK, each of which comes in a variety of widths and key sizes. While many lightweight block ciphers exist, most were designed to perform well on a single platform and were not meant to provide high performance across a range of devices. The aim of SIMON and SPECK is to fill the need for secure, flexible, and analyzable lightweight block ciphers. Each offers excellent performance on hardware and software platforms, is flexible enough to admit a variety of implementations on a given platform, and is amenable to analysis using existing techniques. Both perform exceptionally well across the full spectrum of lightweight applications, but SIMON is tuned for optimal performance in hardware, and SPECK for optimal performance in software.

It’s always fascinating to study NSA-designed ciphers. I was particularly interested in the algorithms’ similarity to Threefish, and how they improved on what we did. I was most impressed with their key schedule. I am always impressed with how the NSA does key schedules. And I enjoyed the discussion of requirements. Missing, of course, is any cryptanalytic analysis.

I don’t know anything about the context of this paper. Why was the work done, and why is it being made public? I’m curious.

Posted on July 1, 2013 at 6:24 AM • 34 Comments