SPECK分组密码算法的立方测试与分析

摘要

SPECK类算法是一类轻量级分组密码算法，由于其出色的平台适用性和软件实现性能而备受关注。针对当前 SPECK类算法在抵御立方攻击以及算法内部结构对密钥比特的混淆和扩散方面存在安全隐患的问题，分别利用立方攻击结合二次测试和立方测试对 SPECK32／64算法进行分析，在选择明文攻击条件下，若算法简化到3轮，可直接恢复17 bit密钥，攻击时间复杂度约为247，若算法简化到5轮～7轮，通过立方测试均能捕获到密钥中比特。结果表明，SPECK32／64算法需经过8轮以上的迭代操作才能有效抵抗立方分析。%SPECK is a family of lightweight block cipher algorithms.SPECK cipher receives much attention due to its excellent performance on platform applicability and software implementation.Aiming at the security risk of the SPECK algorithm in resisting cube attack as well as the confusion and diffusion of key bits in the internal structure of the algorithm,this paper applies cube attack on the SPECK32/64 algorithm by combining quadraticity tests with cube test.It finds that 17 bit key can be recovered with a time complexity of about 247 when the SPECK32/64 algorithm is simplified into three rounds.Applying cube test on five to seven rounds of SPECK32/64 algorithm,it is found that the key neutral-bit can be captured.So result shows that cube analysis can be effectively resisted,only if iteration of more than 8 rounds is applied to SPECK32/64.