重要提示：reCAPTCHA API 1.0 版已不再受支持，请升级到 2.0 版。了解详情
reCAPTCHA ASP 指南提供了一种在 ASP 页面上添加人机识别系统的简单方法，可帮助您阻止漫游器滥用该功能。以下代码封装了 reCAPTCHA API。
注册 API 密钥后，您可以将以下代码粘贴到 ASP 页面顶部，从而将 reCAPTCHA 添加到传统版 ASP 网站中：
<%
recaptcha_challenge_field = Request("recaptcha_challenge_field")
recaptcha_response_field = Request("recaptcha_response_field")
recaptcha_public_key = "your_public_key" ' your public key
recaptcha_private_key = "your_private_key" ' your private key
' returns the HTML for the widget
function recaptcha_challenge_writer()
recaptcha_challenge_writer = _
"<script type=""text/javascript"">" & _
"var RecaptchaOptions = {" & _
" theme : 'red'," & _
" tabindex : 0" & _
"};" & _
"</script>" & _
"<script type=""text/javascript"" src=""http://www.google.com/recaptcha/api/challenge?k=" & recaptcha_public_key & """></script>" & _
"<noscript>" & _
"<iframe src=""http://www.google.com/recaptcha/api/noscript?k=" & recaptcha_public_key & """ frameborder=""1""></iframe><>" & _
"<textarea name=""recaptcha_challenge_field"" rows=""3"" cols=""40""></textarea>" & _
"<input type=""hidden"" name=""recaptcha_response_field""value=""manual_challenge"">" & _
"</noscript>"
end function
' returns "" if correct, otherwise it returns the error response
function recaptcha_confirm(rechallenge,reresponse)
Dim VarString
VarString = _
"privatekey=" & recaptcha_private_key & _
"&remoteip=" & Request.ServerVariables("REMOTE_ADDR") & _
"&challenge=" & rechallenge & _
"&response=" & reresponse
Dim objXmlHttp
Set objXmlHttp = Server.CreateObject("Msxml2.ServerXMLHTTP")
objXmlHttp.open "POST", "https://www.google.com/recaptcha/api/verify", False
objXmlHttp.setRequestHeader "Content-Type", "application/x-www-form-urlencoded"
objXmlHttp.send VarString
Dim ResponseString
ResponseString = split(objXmlHttp.responseText, vblf)
Set objXmlHttp = Nothing
if ResponseString(0) = "true" then
'They answered correctly
recaptcha_confirm = ""
else
'They answered incorrectly
recaptcha_confirm = ResponseString(1)
end if
end function
server_response = ""
newCaptcha = True
if (recaptcha_challenge_field <> "" or recaptcha_response_field <> "") then
server_response = recaptcha_confirm(recaptcha_challenge_field, recaptcha_response_field)
newCaptcha = False
end if
%>
此时，每当网页加载时，系统都会设置 server_response 和 newCaptcha 变量，以便您确定网页的状态。
您可以使用以下 HTML 作为框架：
<html>
<body>
<% if server_response <> "" or newCaptcha then %>
<% if newCaptcha = False then %>
<!-- An error occurred -->
Wrong!
<% end if %>
<!-- Generating the form -->
<form action="recaptcha.asp" method="post">
<%=recaptcha_challenge_writer()%>
</form>
<% else %>
<!-- The solution was correct -->
Correct!
<%end if%>
</body>
</html>