Security analysis of mCrypton proper to low-cost ubiquitous computing devices and applications

mCrypton, which is a mini-version of Crypton, is a 64-bit block cipher with three key size options (64bits, 96 bits, 128 bits). It was designed for use in low-cost ubiquitous wireless devices and resourceconstrained tiny devices such as low-cost Radio-Frequency Identification tags and sensors in Ubiquitous Sensor Network. In this paper we show that 8-round mCrypton with 128-bit key is vulnerable to relatedkey rectangle attack. We first describe how to construct two related-key truncated differentials on which 7-round related-key rectangle distinguisher is based and then we exploit it to attack 8-round mCrypton. This attack requires 246 dada and 246 time complexities, which is faster than exhaustive search. This is the first known cryptanalytic result on mCrypton.