Security Cryptanalysis of NUX for the Internet of Things

Abstract EN

In order to adopt the restricted environment, such as radio frequency identification technology or sensor networking, which are the important components of the Internet of Things, lightweight block ciphers are designed.

NUX is a 31-round iterative ultralightweight cipher proposed by Bansod et al.

In this paper, we examine the resistance of NUX to differential and linear analysis and search for 1~31-round differential characteristics and linear approximations.

In design specification, authors claimed that 25-round NUX is resistant to differential and linear attack.

However, we can successfully perform 29-round differential attack on NUX with the 22-round differential characteristic found in this paper, which is 4 rounds more than the limitation given by authors.

Furthermore, we present the key recovery attack on 22-round NUX using a 19-round linear approximation determined in this paper.

Besides, distinguishing attack, whose distinguisher is built utilizing the property of differential propagation through NUX, is implemented on full NUX with data complexity 8.