对简化版MORUS算法的改进动态立方攻击  

Improved Dynamic Cube Attack on Reduced MORUS

作　　者：李俊志[1] 关杰[1] LI Jun-Zhi;GUAN Jie(Information Engineering University,Zhengzhou 450001,China)

机构地区：[1]信息工程大学,河南郑州450001

出　　处：《软件学报》2020年第6期1829-1838,共10页Journal of Software

基　　金：国家自然科学基金(61572516,61602514)。

摘　　要：MORUS算法是Wu等人设计的认证加密算法,现已进入CAESAR竞赛的第三轮.动态立方攻击是Dinur等人2011年提出的针对迭代型序列密码的分析方法.提出了一种改进的动态立方攻击方法,优化了动态立方攻击的立方集合的选取规则,提出了优先猜测关键值并恢复相应的关键秘密信息的方法,据此给出了成功率更高的秘密信息恢复方法.利用该方法分析了初始化5步的简化版MORUS算法,最终以O(295.05)的复杂度恢复所有128比特密钥,攻击的成功率大于92%.MORUS is a third-round candidate authenticated cipher of CAESAR designed by H.Wu et al.Dynamic cube attack presented by Itai Dinur et al.recovers the secret key of a cryptosystem by exploiting distinguishers given by cube testers.This study proposes an improved dynamic cube attack by optimizing standard of choosing cubes and method of recovering secret expressions.Based on which,a technique is presented for recovering crucial secret expressions preferentially with high successful rate.Then,MORUS of reduced to 5 steps is attacked utilizing improved dynamic cube attack,and the key of 128-bit is recovered with data complexity of O(295.05)and the successful rate of 92%at least.

关 键 词：MORUS 动态立方攻击 认证加密 流密码 CAESAR 

分 类 号：TP309[自动化与计算机技术—计算机系统结构]