An approach to identifying cryptographic algorithm from ciphertext

Cryptographic algorithm plays a significant role in a cryptosystem, which protects those sensitive and private data from been obtained by some malicious attackers. Actually, 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 the used cryptographic algorithm. In this paper, we introduce an approach to identifying the cryptographic algorithm with no other information but ciphertext. Firstly, we present the whole implementation architecture of our identification system. 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 cryptographic algorithms with a high identification rate in one to one identification.