基于MILP的11轮INLEC的中间相遇分析

MILP-Based for Meet-in-the-Middle Attack of 11-Round INLEC

摘要: INLEC是专为物联网环境设计的新的轻量级分组密码算法，为了保障它在物联网环境中的安全性，就必须研究其安全强度。本文提出了基于MILP的11轮INLEC的中间相遇分析。首先基于INLEC算法，建立了混合整数线性规划的搜索模型，找到若干条5轮INLEC中间相遇区分器；其次，根据分析过程中猜测密钥位数最少原则，选取1条中间相遇区分器，并往前扩展2轮，往后扩展4轮，构造出11轮INLEC中间相遇分析路径；最后基于该路径恢复出完全的密钥。整个分析过程的时间复杂度为2^115.17次加密，数据复杂度为2⁶¹个选择明文，存储复杂度为2⁸¹个64比特块。该结果为首个INLEC第三方安全性分析成果。

Abstract: INLEC is a lightweight block cipher for resource-constrained Internet of Things environments. Thus, it is essential to evaluate its security boundary further. Our research proposes a meet-in-the-middle attack on 11-round INLEC based on the MILP automated search algorithm. First, by studying the structure of INLEC, we construct an automated search model of INLEC based on Mixed Integer Linear Programming to find five-round meet-in-the-middle distinguishers of INLEC. Then, we exploit the redundancy of INLEC’s key schedule and select one good distinguisher according to the fewest guessed subkeys in the key recovery phase. Add one round and four rounds on the top and bottom of this distinguisher to construct a 11-round meet-in-the-middle attack path. Finally, we recover the master key with a time complexity of 2^115.17 encryptions, a data complexity of 2⁶¹ chosen plaintexts, and a memory complexity of 2⁸¹ 64-bit blocks. This work represents the first third-party security analysis result for INLEC.