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PRIDE算法是2014年美密会上提出的一个轻量级密码算法.设计者声称此算法主要特点是其线性层具有良好的安全性和实现效率.滑动攻击是一类重要的密码分析方法,主要是利用密码加密算法和密钥扩展算法的自相似性来实现分析.本文从PRIDE算法的密钥扩展算法出发,研究PRIDE算法的滑动攻击.首先说明由密钥扩展算法生成的轮子密钥不具有周期性,从而证明PRIDE算法不存在单钥滑动攻击.进一步,通过分析密钥扩展算法中的非线性函数g_r~(i),寻找到相关密钥,并证明在相关密钥下存在滑动攻击,同时也提出对无白化密钥和全轮PRIDE算法的相关密钥滑动攻击.两个攻击算法所需要的数据都是233个明文,攻击所需要的计算复杂度分别为2~(60.7)和2~(124.7)次加密.针对密钥扩展算法的这个弱点,改进密钥扩展算法,即改进非线性函数g(i)r.在新的密钥扩展算法下,PRIDE算法不存在单钥和相关密钥滑动攻击.研究表明,密钥扩展算法影响密码算法的安全性,同时,设计一个好的、安全的密钥扩展算法是至关重要的.
The PRIDE algorithm is a lightweight cryptographic algorithm proposed at the Aesthetic Conference in 2014. The designer claims that the main feature of this algorithm is its linear layer with good security and efficiency of implementation.Sliding attacks are an important class of cryptanalysis methods, This paper analyzes the self-similarity of the key encryption algorithm and the key expansion algorithm.This paper starts with the key expansion algorithm of the PRIDE algorithm and studies the sliding attack of the PRIDE algorithm.First, it shows that the wheel key generated by the key expansion algorithm does not have a period Which proves that there is no single-key sliding attack in the PRIDE algorithm.Furthermore, by analyzing the nonlinear function g_r ~ (i) in the key expansion algorithm, we find the relevant key and prove that there is a sliding attack under the relevant key Also proposed a keyless sliding attack on the non-whitening key and the all round PRIDE algorithm.The data required by both attack algorithms is 233 plaintexts, the computational complexity required for the attack is respectively 2 ~ (60.7) and 2 ~ (124.7) times encryption.Aiming at the weakness of the key expansion algorithm, the key expansion algorithm is improved, that is to improve the nonlinear function g (i) r. Under the new key expansion algorithm, the PRIDE algorithm does not exist single-key and Related key sliding attacks.The research shows that the key expansion algorithm affects the security of the cryptographic algorithm, meanwhile, it is very important to design a good and secure key expansion algorithm.