高強度DES替換盒建構與檢測模型

Abstract

替換盒是DES編碼法中唯一能阻擋分析過程的運算。替換盒有什麼樣的性質、如何建立強固的替換盒函數，這三十餘年來一直受到密碼界廣泛的注意。建構一組替換盒必須考慮的性質十分複雜，傳統建構法常以數種重要的替換盒特性為建構法則，再調整所建構的替換盒，使其在其它性質上有所增進，但此種方法所建構的替換盒在高階性質上常存在著瓶頸。本篇論文採用90年代初所討論的替換盒差分分析法，實作暴力法替換盒建構模型，並且討論演化式差分攻擊的可能性。這個模型可以藉由設定性質的調整，快速並且大量建構符合這些性質的替換盒，並且避免傳統方法中對於次要及高階性質的不確定。另外，本論文所討論的演化式分析模型，利用基因演算法對於參數的最佳化，可以調整差分分析法過程中，難以尋找的特徵。

It is known that S-Box Operation is an effective substitution method, which has the advantages of defending cryptanalysis. In this thesis, we introduce two mechanisms to build and test S-Boxes. The criteria of building S-Boxes are complex and fuzzy. In the past 30 years, S-Box design criteria were discussed in many related cryptographic fields. Traditional construction methods were usually based on a set of basic properties. After these basic properties were satisfied, less important properties can be tuned by using other methods. The bottleneck of these construction methods usually emerged when considering higher order properties. In this thesis, we analyze the differential property discussed in Biham and Shamir’s paper and derive a brutal force construction model to execute high speed S-Box construction. We also introduce a Genetic Algorithms-based model to realize differential cryptanalysis.