Biblio

With the widespread application of distributed information processing, information processing security issues have become one of the important research topics; CAPTCHA technology is often used as the first security barrier for distributed information processing and it prevents the client malicious programs to attack the server. The experiment proves that the existing “request / response” mode of CAPTCHA has great security risks. “The text-based CAPTCHA solution without network flow consumption” proposed in this paper avoids the “request / response” mode and the verification logic of the text-based CAPTCHA is migrated to the client in this solution, which fundamentally cuts off the client's attack facing to the server during the verification of the CAPTCHA and it is a high-security text-based CAPTCHA solution without network flow consumption.

As a multimedia security mechanism, CAPTCHAs are completely automated public turing test to tell computers and humans apart. Although cracking CAPTCHA has been explored for many years, it is still a challenging problem for real practice. In this demo, we present a text based CAPTCHA cracking system by using convolutional neural networks(CNN). To solve small sample problem, we propose to combine conditional deep convolutional generative adversarial networks(cDCGAN) and CNN, which makes a tremendous progress in accuracy. In addition, we also select multiple models with low pearson correlation coefficients for majority voting ensemble, which further improves the accuracy. The experimental results show that the system has great advantages and provides a new mean for cracking CAPTCHAs.