一、ASP产生随机验证码图片:
<%
randomize
i=0
num1=int(9*rnd)
numimage="<img src=images/num/"&num1&".bmp>"
numi=numi&numimage
i=i+1
loop
session("numi")=numi
%>
<br>
<%=session("numi")%>'注意这裏,运行后就是随机图片
'备注说明:
<img src=images/num/"&num1&".bmp>
以上images放置图片资料夹
num放置随机图片资料夹
"&num1&"产生随机图片

'/////////////////////////////////////////////

二、ASP数字验证码:
<%
randomize
i=0
do while i<6'随机产生6位验证码,可以变更数值为4
num1=int(9*rnd)
num=num&num1
i=i+1
loop
session("num")=num
%>
<br>
<%=session("num")%>

三、写个简单测试一下:
<%
Response.Expires = 0
Response.Expiresabsolute = Now() - 1
Response.AddHeader "pragma","no-cache"
Response.AddHeader "cache-control","private"
Response.CacheControl = "no-cache"
dim s
randomize timer
s=Int((9999)*Rnd +1000)
session("s")=s
%>
<tr>
<td width="294" bgcolor="#96C5DE" align="center" height="30" valign="middle"><font color="#FFFFFF">认证码： 
<input class="flat1" style="color: #4D9CC8; background-color: #FFFFFF; border: 1px solid #000000" size="15" name="yanzhengma"></font></td>
</tr>

然后在reg_save.asp 里加

<%
if session("s")<>Request.Form("yanzhengma") then
Response.Write ("<script>alert('n验证错误!码');javascript:history.back();</script>")
Response.end
end If
%>

%>