Marking a new path in the world of encryption, MISTY is a cryptosystem that offers several innovative features, such as verifiable security and high-speed processing on multiple platforms. It has brought about a paradigm shift in which encryption is now seen as an integral part of the infrastructure for a digital society. Not surprisingly, this unique technology has an interesting background. Let’s take a look at the challenges faced by the people involved in developing MISTY and the steps it took to create a new market for this innovative product.

Let’s go back to 1993 when a researcher came across a scientific paper written by an encryption specialist in Israel. It centered on a new method for dramatically reducing the number of calculations required to break a cipher: differential cryptanalysis. Simple principles combined in precise order to create an awesome tool for decryption. The researcher was fascinated by the sheer beauty of the mathematics.

That man is Mitsuru Matsui, an engineer working in the Information Technology R&D Center at Mitsubishi Electric. He had studied mathematics in graduate school and had once considered a career as a mathematician. However, he had been attracted to the world of encryption and from then on his days were taken up with research into creating and breaking codes. Although this was not considered a main job responsibility, he was fortunate that Mitsubishi Electric has a tradition of allowing researchers a certain amount of free rein in pursuing research at their own discretion. Moreover, Matsui’s boss, a section chief called Atsuhiro Yamagishi, knew that “The most significant results are achieved when a researcher pursues something that he himself finds interesting.”

It was not long before his research produced results. At a conference, Matsui announced his linear cryptanalysis method, capable of breaking a cipher with even fewer calculations then required by differential cryptanalysis. This caused quite a stir. Furthermore, to demonstrate his theory, he started work on breaking a commercial cryptosystem that was already in use: the US Data Encryption Standard (DES). DES had a reputation for being unbreakable; indeed, for fifteen years it had withstood the combined challenges by crypto research facilities and veteran cryptographers from all over the world.