Abstract: The security of verification code is an important part of securing the network. This paper uses deep learning to propose the long short-term memory (LSTM) network and connectionist temporal classification (CTC) model for intelligently recognizing the mainstream verification code images. The open source CAPTCHA verification code library is used to generate data sets, to simplify the verification code recognition model, to unify the speech recognition and text recognition methods, and to achieve the end-to-end model recognition. The proposed method has better performance under the condition of smaller training set.

Key words: CAPTCHA recognition, deep learning, long short-term memory network, connectionist temporal classification model