LBlock 算法的相关密钥－不可能差分攻击

摘要

该文研究了 LBlock 分组密码算法在相关密钥-不可能差分条件下的安全性．利用子密钥生成算法的差分信息泄漏规律，构造了多条低重量子密钥差分链，给出了15轮相关密钥-不可能差分区分器．通过扩展区分器，给出了23轮和24轮 LBlock 算法的相关密钥-不可能差分攻击方法．攻击所需的数据复杂度分别为265.2和265.6个选择明文，计算复杂度分别为266.2次23轮 LBlock 算法加密和266.6次24轮 LBlock 算法加密，存储复杂度分别为261.2和277.2字节存储空间．与已有结果相比，首次将针对 LBlock 算法的攻击扩展到了23轮和24轮．%In this paper,the strength of LBlock against related-key impossible differential attack is examined.Based on the differential information leakages in sub-key schedule,several sub-key differentials in low weight are constructed,and a 15-round re-lated-key impossible differential distinguisher of LBlock is presented.By extending the distinguisher,related-key impossible differen-tial attacks on 23-round LBlock and 24-round LBlock are presented.The data complexities of the attacks are 265.2 and 265.6 chosen-plain-text,respectively;the computing complexities of the attacks are 266.2 23-round LBlock encryptions and 266.6 24-round LBlock encryptions,respectively;the storage complexities of the attacks are 261 .2 and 277.2 bytes of memory space,respectively.The crypt-analysis of reduced-round LBlock are first extended to 23-round and 24-round in this paper.