Application Specific Block Ciphers and a Focus on the Linear Layer

• Applicant: Professor Dr. Gregor Leander
• Subject Area: Theoretical Computer Science
• Term: from 2015 to 2021
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 267225567

We are in the midst of an evolutionary change with respect to computing and information technologies. For a few years the computing world has begun to move towards the "many computers- one user" paradigm, in which the "computers" are often every day devices. This situation is frequently referred to as the Internet of Things (IoT). At the same time, security has become an increasingly important issue for many IoT applications. In the near future we will see more revolutionary new IoT applications which require strong security and privacy mechanisms. Examples include vehicle-to-vehicle communication, networked medical implants and payment with NFC-enabled wireless tokens.Virtually all modern security solutions are based on cryptographic primitives, with block ciphers as the by far most widely used primitives. It is thus of crucial importance to have strong cryptosystems available for today's and future IoT applications. While the need for cryptography for small devices has been known in industry for at least 15 years, it only became an active research area in academia over the last 6-7 years. This imbalance of supply and demand has forced industry to deploy several proprietary, self-made algorithms. Many of those have been critically broken, resulting in major losses, both in terms of real money and in trust for the companies involved. The situation started to change with the introduction of several dedicated crypto algorithms over the last few years. This field has been one of the hottest fields of research in symmetric cryptography recently, with new research results appearing in almost every major conference. However, almost all proposed lightweight ciphers have been optimized with respect to one metric, namely chip area if implemented in hardware. It is my strong belief that it is time to significantly broaden the area of lightweight cryptography by designing a variety of new lightweight ciphers, seeking to optimize other, more relevant, optimization criteria such as code size, energy consumption, timing, side-channel resistance, and ease of implementation. It is my belief that this line of research not only has the obvious merit of producing new optimized ciphers, but on top will help to increase our fundamental understanding of ciphers. The project is exceptionally interesting from a scientific perspective, since these design goals enlarge the design space significantly. Thus these new challenges come along with great opportunities for new, innovative design approaches.

• DFG Programme: Research Grants