电子学报 ›› 2013, Vol. 41 ›› Issue (8): 1569-1573.DOI: 10.3969/j.issn.0372-2112.2013.08.018

• 科研通信 • 上一篇    下一篇

Cobra-H64/128算法的相关密钥-差分攻击

罗伟, 郭建胜   

  1. 解放军信息工程大学, 河南郑州 450004
  • 收稿日期:2012-11-02 修回日期:2013-03-18 出版日期:2013-08-25
    • 通讯作者:
    • 郭建胜
    • 作者简介:
    • 罗 伟 男,1987年生,硕士研究生,研究方向为分组密码设计与分析. E-mail:luowei.crypt@gmail.com

Related-Key Differential Attacks on Cobra-H64/128

LUO Wei, GUO Jian-sheng   

  1. The PLA Information Engineering University, Zhengzhou, Henan 450004, China
  • Received:2012-11-02 Revised:2013-03-18 Online:2013-08-25 Published:2013-08-25

摘要: 本文研究了Cobra-H64/128分组密码算法在相关密钥-差分攻击下的安全性.针对Cobra-H64算法,利用新构造的相关密钥-差分路径和CP逆变换存在的信息泄露规律给出攻击算法1,恢复出了全部128bit密钥,相应的计算复杂度为2^40.5次Cobra-H64算法加密,数据复杂度为2^40.5个选择明文,存储复杂度为2^22bit,成功率约为1;针对Cobra-H128算法,利用新构造的相关密钥-差分路径给出攻击算法2,恢复出了全部256bit密钥,相应的计算复杂度为2^76次Cobra-H128算法加密,数据复杂度为2^76个选择明文,存储复杂度为2^16.2bit.分析结果表明,Cobra-H64/128算法在相关密钥-差分攻击条件下是不安全的.

关键词: 密码分析, Cobra-H64/128算法, 相关密钥-差分攻击, 差分传递特性, 比特传递特性

Abstract: The security of Cobra-H64/128 block cipher under related-key differential cryptanalysis was studied.For Cobra-H64,we use related-key differential attack to get the whole 128 bits key with probability 1 based on the new constructed related-key differential and loopholes in CP box,and the corresponding computational complexity is 2^40.5 Cobra-H64 encryptions,the data complexity is 2^40.5 chosen-plaintexts,the memory complexity is 2^22 bits.To recover the whole 256 bits key of Cobra-H128,we need a computational complexity of 2^76 Cobra-H128 encryptions,a data complexity of 2^76 chosen-plaintexts,a memory complexity of 2^16.2 bits.The analysis results show that Cobra-H64/128 are unsafe under related-key differential attacks.

Key words: cryptanalysis, Cobra-H64/128 block cipher, related-key differential attack, differential transmission characteristic, bit transmission property

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