Speck-R: An ultra light-weight cryptographic scheme for Internet of Things

Lightweight cryptography (LWC) is an interesting research area in the field of information security. Some limitations like: increased components usage, time consumption, power consumption and memory requirement mandate the need for lightweight cryptography. One of the proposed algorithms in this field is Speck which was designed by the National Security Agency (NSA) in June 2013. In this paper, we propose a new ultra-lightweight cryptographic algorithm based on Speck known as Speck-R. Speck-R is a hybrid cipher, combining ARX architecture with a dynamic substitution layer. The novelty in this paper resides in adding a key-dynamic substitution layer that changes according to a dynamic key. With this modification, the number of rounds can be reduced from 26 (in Speck) to 7 (in Speck-R). Thus, the main contribution of this paper consists in reducing the execution time of Speck by at least 18% on limited devices to reach a reduction of 77% while keeping a high level of security. To backbone Speck-R's security, different security and statistical tests are exerted on Speck-R. In addition, a real hardware implementation on three different famous IoT devices is also presented where Speck-R outperformed Speck in terms of execution times. Finally, extensive tests show that Speck-R possesses the necessary criteria to be considered as a good cipher scheme that is suitable for lightweight devices.