基于多图层的图形验证码生成技术研究

图形验证码已成为许多网站系统常用的一种防止恶意程序自动注册或登录、恶意灌水等网络攻击的工具,但当前的图形验证码存在容易被恶意程序识别,甚至有时用户很难辨别验证码中的验证字符信息。本文研究一种基于多图层的图形验证码生成技术,由显示随机验证字符串的前景图层和显示干扰字符串的干扰图层构成图形验证码,并采用.NET技术实现了该图形验证码,最后通过验证码识别工具PWNtcha分析该验证码的有效性和安全性。实验证明,基于多图层的图形验证码不仅效率较高、安全性较强,而且能够比较容易被用户识别。

Study on Generation Technology of CAPTCHA Based on Multi-layer

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.