改进的减轮MIBS-80密码的中间相遇攻击

MIBS密码算法是一个Feistel结构的轻量级分组密码，广泛适用于资源严格受限的环境。该文利用多重集和有效的差分枚举方法，构造了8轮MIBS中间相遇区分器，并在新区分器的基础上，实现了12轮和13轮MIBS-80密码的中间相遇攻击。攻击过程利用差分传递的性质筛选明文对，利用MIBS-80密钥扩展算法中主密钥和轮密钥的关系减少密钥的猜测量，攻击12轮MIBS-80的时间复杂度为2^53.2，攻击13轮MIBS-80的时间复杂度为2⁶²。与已有中间相遇攻击的结果相比，该文对MIBS-80中间相遇攻击的轮数提高了2轮。

Improved Meet-in-the-middle Attacks on Reduced-round MIBS-80 Cipher

MIBS is a Feistel structured lightweight block cipher aimed at extremely constrained resources environment. In this paper, an 8-round meet-in-the-middle distinguisher of MIBS is constructed by utilizing multiset and effective differential enumeration technique. Then, the meet-in-the-middle attacks on 12-round and 13-round MIBS-80 are proposed based on the new distinguisher. In the attack process, the plaintexts are filtered utilizing the differential properties and the guessed keys are reduced using the relation of master key and round key in the key expansion algorithm of MIBS-80. The time complexity of attacking 12-round and 13-round MIBS-80 is 253.2 and 262, respectively. Compared with the known results of the meet-in-the-middle attack, the number of rounds of meet-in-the-middle attack on MIBS-80 is increased by 2-round.