## Cryptology ePrint Archive: Report 2019/727

Iterative Differential Characteristic of TRIFLE-BC

Fukang Liu and Takanori Isobe

Abstract: TRIFLE is a Round 1 candidate of the NIST Lightweight Cryptography Standardization process. In this paper, we present an interesting 1-round iterative differential characteristic of the underlying block cipher TRIFLE-BC used in TRIFLE, which holds with probability of $2^{-3}$. Consequently, it allows to mount distinguishing attack on TRIFLE-BC for up to 43 (out of 50) rounds with data complexity $2^{124}$ and time complexity $2^{124}$. Most importantly, with such an iterative differential characteristic, the forgery attack on TRIFLE can reach up to 21 (out of 50) rounds with data complexity $2^{63}$ and time complexity $2^{63}$. Finally, to achieve key recovery attack on reduced TRIFLE, we construct a differential characteristic covering three blocks by carefully choosing the positions of the iterative differential characteristic. As a result, we can mount key-recovery attack on TRIFLE for up to 11 rounds with data complexity $2^{63}$ and time complexity $2^{104}$. Although the result in this paper cannot threaten the security margin of TRIFLE, we hope it can help further understand the security of TRIFLE.

Category / Keywords: secret-key cryptography / AEAD, TRIFLE, differential attack, distinguisher, forgery

Original Publication (with minor differences): SAC 2019

Date: received 19 Jun 2019, last revised 8 Jul 2019

Contact author: liufukangs at 163 com, takanori isobe at ai u-hyogo ac jp

Available format(s): PDF | BibTeX Citation

Note: Correct some editorial mistakes.

Short URL: ia.cr/2019/727

[ Cryptology ePrint archive ]