Linear Forgery Attacks on the Authenticated Encryption Cipher ACORN-Like  

作　　者：Yunqiang Li Ting Cui 

机构地区：[1]PLA SSF Information Engineering University,Zhengzhou 450004,China

出　　处：《Chinese Journal of Electronics》2025年第1期257-265,共9页电子学报(英文版)

基　　金：supported by the National Natural Science Foundation of China(Grant No.61772547)。

摘　　要：The authenticated encryption stream cipher ACORN is one of the finalists of the Competition for Authenticated Encryption:Security,Applicability,and Robustness(CAESAR)and is intended for lightweight applications.Because of structural weaknesses in the state update function of ACORN,we can introduce a linear function to analyze conditions and differential trails of the state collision and present a linear method to construct forgery messages under the condition that the key and initialization vector are known or the register state at a certain time is known.The attack method is suitable for three versions of ACORN and may be also extended to any ACORN-like,of which the linear feedback shift register(LFSR)can be replaced by other LFSRs and the feedback function can be replaced by other nonlinear functions.For continuous l(l>293)bits of new input data,we can construct 2^(l-294)forgery messages for any given message of ACORN.Using a standard personal computer,a concrete forgery message can be constructed almost instantly and the required central processing unit time and memory are equivalent to the required resources for solving a system of 293 linear equations over the binary field.These attacks in this paper make that the sender and receiver may easily cheat each other,which is not a desirable property for an ideal cipher and casts some doubt on the necessary authentication security requirements of ACORN.

关 键 词：CAESAR ACORN Authenticated encryption Collision attack Forgery attack State collision differential trail 

分 类 号：TP309[自动化与计算机技术—计算机系统结构] TN918.4[自动化与计算机技术—计算机科学与技术]