Identification of Block Ciphers under CBC Mode

It has been challenging work to identify block ciphers under CBC mode over the past few decades. But we can still conduct the identification of block ciphers under CBC mode if enough ciphertext streams are available. In this paper, we consider the identification of 5 frequently used block ciphers, AES, DES, 3DES, RC5 and Blowfish. For multi-class identification, the identification rate of 5 block ciphers can reach above 90% as long as the size of ciphertext file is larger than 100 KB when same key and same IV for training and testing ciphertext files. For one to one identification, we identify AES from other 4 block ciphers on condition of different keys or different IVs for training and testing ciphertext files. We can obtain an identification rate of above 97% when the size of ciphertext file is equal to 100 KB. Besides, even if the size of ciphertext file is only 4 KB, the average identification rate is still higher than 80%.