一種動態背包密碼法的實行

Abstract

起初，背包密碼法(knapsackcipher)是發展為公開金匙加密法 (public- key encryption)的一環。然而在動態背包金匙產生法(Dynamic Knapsack Key Generation)中，為了發揮其彈性和實用性，便將背包金匙 運用在一種新的對稱金匙密碼系統(symmetric-keysystem)上。在本論文 中，實際運用了這種背包金匙產生法的概念，並提出加密和解密的演算法 。由於並沒有固定的副金匙(subkey)數目，所以可將尚未加密的訊息分為 三個部份，以便減少為了頭尾的零位元串而產生不必要的副金匙。在實際 運用中，產生的許多問題，也有很清楚的交待，例如：金匙產生的方式、 祕密金匙(private-key)的決定和資料擴大(data expansion)的問題。再 者，我們對於改進加密方法的可能方向也做了詳盡的探討。 Primarily, the knapsack cipher was developed for public-key encryption. In Dynamic Knapsack Key Generation, however, a new symmetric-key system applying the knapsack key is proposed because of the practicality and flexibility. In this thesis, we implement the concept of this knapsack key generation and give the algorithms concerning encipherment and decipherment. Since the benefit of the variable number of the subkeys, we partition the plaintext to three parts to reduce the waste of the production of the subkeys for heading and trailing zeros. The problems, the key generation, the decision of private keys and data expansion, occurring during implementation are also considered. Furthermore, we discuss the possible trend of the improvement.