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《计算机技术与发展》[ISSN:1006-6977/CN:61-1281/TN]

卷:

期数:

2025年02期

页码:

63-69

栏目:

网络空间安全

出版日期:

2025-02-10

文章信息/Info

Title:

An Improved Meet-in-the-middle Attack on 6-Round Square

文章编号:

1673-629X(2025)02-0063-07

作者:

何峰1; 董晓丽2; 韦永壮1

1. 桂林电子科技大学 广西密码学与信息安全重点实验室,广西 桂林 541004;

2. 西安邮电大学 网络空间安全学院,陕西 西安 710121

Author(s):

HE Feng1; DONG Xiao-li2; WEI Yong-zhuang1

1. Guangxi Key Laboratory of Cryptography & Information Security,Guilin University of Electronic Technology,Guilin 541004,China;

2. School of Cyberspace Security,Xi’an University of Posts & Telecommunications,Xi’an 710121,China

关键词:

分组密码; Square算法; 中间相遇攻击; 差分枚举技术; 密钥桥技术

Keywords:

block cipher; Square; meet-in-the-middle attack; differential enumeration technique; key bridge technique

分类号:

TP309

DOI:

10.20165/j.cnki.ISSN1673-629X.2024.0313

摘要:

Square 分组密码算法是由 Daemen 等人设计,并在 1997 年快速软件加密(FSE)国际会议上首次公布。 该密码算法基于 SPN(Substitution-Permutation Network)结构,其分组长度和密钥长度均为 128 比特;具有设计新颖、实现高效等优点,也是高级加密标准(AES)算法的前身,在密码学界备受关注。 中间相遇攻击作为分组密码算法的重要分析方法之一,如何研究 Square 算法抵抗中间相遇攻击一直是业内讨论的热点问题。 该文基于 Square 算法的结构特点和截断差分特征,利用差分枚举技术,构造了一个 3. 5 轮中间相遇区分器。 通过密钥桥技术及 Square 算法的密钥编排特点,推演出了主密钥与子密钥之间的部分线性关系。 由此,将 3. 5 轮区分器向前扩展 1 轮,向后扩展 1. 5 轮,实现了对 6 轮 Square 算法的中间相遇攻击。 该攻击所需数据复杂度为 2105 个选择明文,时间复杂度为2105 次6 轮加密,存储复杂度为285 个分组。 与已有攻击结果相比,新的攻击有效地降低了所需的数据复杂度、时间复杂度和存储复杂度。

Abstract:

The Square block cipher was proposed by Daemen et al. at the Fast Software Encryption (FSE) conference in 1997. It uses the Substitution Permutation Network (SPN) structure,and its block length and key length are all 128-bit. Because of its novel design and efficient implementation,also as the predecessor of AES,Square are extensively received attention by cryptographic community. Mo-reover,the meet-in-the-middle attack is one of the important cryptanalytic methods. How to research the security of Square block cipher against the meet- in - the - middle attack appears to be an interesting topic. In this paper, a new 3. 5 - round meet - in - the - middle distinguisher is constructed by using the structural characteristics, truncated differentials of the Square and differential enumeration technique. In particular,the partial linear relationship between the subkey and master key in the key schedule is deduced via key bridge technique. Therefore,a new meet - in - the - middle attack on 6 - round Square is proposed by adding 1 round ( forward encryption operation) and 1. 5 round (backward encryption operations) on 3. 5-round meet-in-the-middle distinguisher. This attack requires the data complexity of 2105 chosen plaintexts,the time complexity of 2105 6-rounds encryption operations,and the memory complexity of 285 blocks. Compared with previous attacks,this attack can effectively reduce the data complexity,time complexity,and memory complexity.

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更新日期/Last Update: 2025-02-10