LBlock算法的相关密钥不可能飞来去器分析

Related-key impossible boomerang cryptanalysis on LBlock

研究了相关密钥不可能飞来去器分析方法及轻量级分组密码算法LBlock在该分析方法下的安全性。将不可能飞来去器分析方法和相关密钥分析方法相结合,针对22轮LBlock给出了新的攻击。构造了15轮的相关密钥不可能飞来去器区分器,通过向前扩展3轮,向后扩展4轮,成功攻击了22轮LBlock。该攻击的数据复杂度仅为2^(51.3)个明文,计算复杂度为2^(71.54)次22轮加密。与已有结果相比,攻击的数据复杂度和计算复杂度均有明显下降。

The related-key impossible boomerang cryptanalysis and the strength of the lightweight block cipher LBlock against this method were investigated. A new attack on 22-round LBlock was presented combining impossible boomerang attacks with related-key attacks. A 15-round related-key impossible boomerang distinguisher was constructed. Based on the new distinguisher, an attack on 22-round LBlock was mounted successfully by concatenating 3-round to the begin- ning and 4-round to the end. The attack on 22-round LBlock required data complexity of only 2 513 plaintexts and com- putational complexity of about 2 7154 22-round encryptions. Compared with published cryptanalysis results on 22-round LBlock, proposed attack has great advantages on data and computational complexities.