The boomerang attack on the 4-round LILLIPUT-TBC-II-256 cipher

Lilliput-AE is a tweakable block cipher submitted as a candidate to the NIST lightweight cryptography standardization process. It is an OCB based authenticated encryption scheme using the block cipher Lilliput with a tweakey schedule (LILLIPUT-TBC). It has 128-bit blocks and supports key sizes of 128, 192, and 256 bits. Lilliput-AE has two particular authenticated encryption modes: Lilliput-I and Lilliput-II based respectively on a nonce-respecting mode and a nonce-misuse resistant mode. In this paper, we present an attack on the 4-round LILLIPUT-TBC-II-256 cipher with 256-bit security level using boomerang technique based on Yoyo tricks, which were firstly presented at ASIACRYPT 2017 to attack the AES block cipher. The attack requires $2^{180}$ encryptions. The data complexity is $2^{24}$ texts and the memory complexity is $2^{24{,}3}$ bit. The main result is obtained due to the simultaneous use of boomerang technique and the property of the diffusion transformation.