Study on Generation Technology of CAPTCHA Based on Multi-layer
Longlong Liao · Computer and Modernization · 2011
CAPTCHA has become a kind of tool that many Web sites use to prevent malicious programs from automatically registering or logging in,irrigation and other malicious network attack.However,the existing CAPTCHA is easy to be identified by computer malicious programs,but it is difficult to distinguish information of CAPTCHA in the image for user.Therefore,this paper studies a kind of CAPTCHA based on multi-layer.It is made of prospects layer and interference layer.The prospects layer is used to display random verification code and the interference layer is used to display interference Character.And.NET technology is used to implement the CAPTCHA.Finally,efficacy and safety of the CAPTCHA based on multi-layer is analyzed by using PWNtcha.The algorithm not only has high efficiency and safety,but also users can more easily identify.