一种基于密文分析的密码识别技术

摘要

In fact, the details about the cryptographic algorithm applied in a cryptosystem are often unknown to one cryptanalyst. When a cryptanalyst works on cryptanalysis, he will have much trouble if he doesn’t know anything about which kind of cipher is used. In this paper, we introduce an approach to identifying cipher with no other information but ciphertext. Firstly, we present the whole implementation architecture of our identification system of cipher. Then we apply our identification system in identifying 5 common block ciphers, namely AES, Blowfish, 3DES, RC5 and DES. Through analyzing the experiment results, we conclude that the identification rate can obtain around 90%if keys are the same for training and testing ciphertexts. When we use different keys for training and testing ciphertexts, we can still identify AES from anyone of the other 4 ciphers with a high identification rate in one to one identification.%密码分析过程中，密码分析者往往不知道密码系统使用了哪一种密码，导致密码分析工作困难重重。因此，介绍一种基于密文分析的密码识别方法。首先介绍建立的密码识别系统的工作原理和过程，然后利用该系统对5类常见分组密码（AES、Blowfish、3DES、RC5和DES）进行识别。通过实验结果分析发现，当训练密文和测试密文的密钥一致时，识别率能达到90％左右；而当密钥不一致时，系统仍能够以较高的识别率对AES与其他四类密码进行两两识别。