遗传算法在密码学中的应用.doc

遗传算法在密码学中的应用 摘 要 遗传算法是一类借鉴生物界自然选择和自然遗传机制的随机有哪些信誉好的足球投注网站算法，它是一种利用遗传学发展的手段，即选择、交叉和变异构成对问题解答的算法。其应用优势在于处理传统有哪些信誉好的足球投注网站方法难以解决的复杂和非线性问题。 密码学是研究编制密码和破译密码的技术科学。密码分析是研究密码体制的破译问题，即破译者试图在不知道加密密钥的情况下，从截取到的密文恢复出明文消息或密钥。从密码学发展来看，可分为古典密码和现代密码。古典密码即是以字符为基本加密单元的密码。古典密码学主要有两大基本方法：替换密码和置换密码。本文基于遗传算法的基本思想，给出了一种对古典密码学中的替换密码进行密码分析的方法，并验证该方法的有效性。 本文首先通过随机获得的一个密钥对一段文章加密为密文，该密钥即为真正的密钥。遗传算法的有哪些信誉好的足球投注网站空间由种群中的个体组成，种群中的每个个体代表一个密钥，根据每个个体对该密文进行解密，以英文字母出现的频率对解密后的明文进行分析，利用遗传操作使这些密钥不断的进化，与真正的密钥越来越接近。 【关键词】遗传算法，替换密码，密钥，密文，密码分析 The Application of Genetic Algorithm in Cryptography Chen Zhaojun (School of mathematics, physics and information, Zhejiang Ocean University 316004) Abstract Genetic algorithm is a kind of random search algorithm based on biological natural selection and natural genetic mechanism. It is a kind of algorithm to resolve problems using genetics, such as selection, crossover and mutation. Its advantages lie in its application of the complex and nonlinear problems which traditional search method cant solve. Cryptography is a science studying the preparation and deciphering of code. Cryptanalysis is to study the deciphering cryptography issues, namely to decipher the encryption key from the interception of the cipher text to restore a specific message or key. Due to the development of cryptography, codes can be classified into two categories: classical codes and modern codes. Classical code is code taking character as basic unit of encryption. Classical cryptography can be talked in two basic methods: the password replacement and password substitution. This thesis based on the ideas of genetic algorithm presents us cryptanalysis in replacing the password by classical cryptography, and the verification of the effectiveness. In this paper, first, we encrypt cipher text by a randomly obtained encryption key, which is the real key. The searching space of genetic algorithm consists of the population of individuals. In the population, each individual is taken as a key. Decrypt the cipher text by individual. Anal