{"id":136,"date":"2006-12-08T19:27:47","date_gmt":"2006-12-08T17:27:47","guid":{"rendered":"https:\/\/alax.info\/blog\/136"},"modified":"2009-03-24T11:46:12","modified_gmt":"2009-03-24T09:46:12","slug":"captcha-for-asp","status":"publish","type":"post","link":"https:\/\/alax.info\/blog\/136","title":{"rendered":"CAPTCHA for ASP"},"content":{"rendered":"

CAPTCHA stands for “Completely Automated Public Turing test to tell Computers and Humans Apart<\/em>” which is more known to public as a verification code one needs to enter in order to proceed with certain action. The challenge is aimed to prevent from automated operation, such as, for instance, user registration, spam or data mining.<\/p>\n

Alax.Info Captcha Module offers a COM object to generate CAPTCHA PNG (Portable Network Graphics)<\/a> images:<\/p>\n

\"08-image001.png\"<\/p>\n

<\/p>\n

The images are generated using a few lines of code:<\/p>\n

<%@Language=”JScript”%>
\n<%
\n…
\nCaptchaText = (1000 + Math.random() * 9000).toFixed(0);
\nCaptchaImage = Server.CreateObject(“Alax.Info.Captcha.Image”);
\nCaptchaImage.Text = CaptchaText;
\nCaptchaImageFileName = “image.png”; \/\/ TODO: Choose random name, esp. per-session
\nCaptchaFileStream = Server.CreateObject(“Alax.Info.Captcha.FileStream”);
\nCaptchaFileStream.Path = Server.MapPath(CaptchaImageFileName);
\nCaptchaImage.Create(CaptchaFileStream);
\n…
\n%>
\n…
\n< img xsrc=”<%=CaptchaImageFileName%>?rand<%=Math.random().toString()%>” \/><\/p><\/blockquote>\n

Alax.Info.Captcha.Image<\/span> COM object exposes the following properties and methods:<\/p>\n