WEB上的“校验码”（图）是生成原理是什么？

[ANSARS]

现在CSDN.NET也用“校验码”（图）了，有的网站（如HOTMAIL）用的“校验码”是不规则字体，这些“校验码”（图）是怎么生成的？

[笨笨兔兔兔兔兔]

***************************************************************
' ************************** ASPCanvas **************************
' ***************************************************************
'
' Drawing and presentation object for ASP
'
' Chris Read (aka Centurix/askdaquack/captainscript)
'
' Thanks to Richard Deeming (www.trinet.co.uk) for improving
' the arc drawing algorithm
' Thanks to Daniel Hasan for bezier curve adjustments
' Thanks to Tony Stefano for his extra font packs
'
' Updated 23/02/2003
'
' ASPCanvas home: http://users.bigpond.net.au/mrjolly/

[3573745]

凑合用就是了！
某些东西没必要懂那么多！

[lovebanyi]

随机数 加一个session就可以实现了
已前是好几个图片拼的,,现在是用一个图片的,,

[h2yang]

如果是我，用最笨的办法：用10000个图，用一个随机数，再<img src="">就可以了……

[ANSARS]

h2yang(小青) :你的办法我想到了，是万不得已。有好的方法吗？

[ygjwjj]

<%
Response.Buffer = True
With Response
.Expires = -1
.AddHeader "Pragma","no-cache"
.AddHeader "cache-ctrol","no-cache"
End With
Dim a(10,10)

a(0,1) = "0x3c" '数字0
a(0,2) = "0x66"
a(0,3) = "0xc3"
a(0,4) = "0xc3"
a(0,5) = "0xc3"
a(0,6) = "0xc3"
a(0,7) = "0xc3"
a(0,8) = "0xc3"
a(0,9) = "0x66"
a(0,10)= "0x3c"

a(1,1) = "0x18" '数字1
a(1,2) = "0x1c"
a(1,3) = "0x18"
a(1,4) = "0x18"
a(1,5) = "0x18"
a(1,6) = "0x18"
a(1,7) = "0x18"
a(1,8) = "0x18"
a(1,9) = "0x18"
a(0,10)= "0x7e"

a(2,1) = "0x3c" '数字2
a(2,2) = "0x66"
a(2,3) = "0x60"
a(2,4) = "0x60"
a(2,5) = "0x30"
a(2,6) = "0x18"
a(2,7) = "0x0c"
a(2,8) = "0x06"
a(2,9) = "0x06"
a(2,10)= "0x7e"

a(3,1) = "0x3c" '数字3
a(3,2) = "0x66"
a(3,3) = "0xc0"
a(3,4) = "0x60"
a(3,5) = "0x1c"
a(3,6) = "0x60"
a(3,7) = "0xc0"
a(3,8) = "0xc0"
a(3,9) = "0x66"
a(3,10)= "0x38"

a(4,1) = "0x38" '数字4
a(4,2) = "0x3c"
a(4,3) = "0x36"
a(4,4) = "0x33"
a(4,5) = "0x33"
a(4,6) = "0x33"
a(4,7) = "0xff"
a(4,8) = "0x30"
a(4,9) = "0x30"
a(4,10)= "0xfe"

a(5,1) = "0xfe" '数字5
a(5,2) = "0xfe"
a(5,3) = "0x06"
a(5,4) = "0x06"
a(5,5) = "0x3e"
a(5,6) = "0x60"
a(5,7) = "0xc0"
a(5,8) = "0xc3"
a(5,9) = "0x66"
a(5,10)= "0x3c"

a(6,1) = "0x60" '数字6
a(6,2) = "0x30"
a(6,3) = "0x18"
a(6,4) = "0x0c"
a(6,5) = "0x3e"
a(6,6) = "0x63"
a(6,7) = "0xc3"
a(6,8) = "0xc3"
a(6,9) = "0x66"
a(6,10) ="0x3c"

a(7,1) = "0xff" '数字7
a(7,2) = "0xc0"
a(7,3) = "0x60"
a(7,4) = "0x30"
a(7,5) = "0x18"
a(7,6) = "0x18"
a(7,7) = "0x18"
a(7,8) = "0x18"
a(7,9) = "0x18"
a(7,10)= "0x18"

a(8,1) = "0x3c" '数字8
a(8,2) = "0x66"
a(8,3) = "0xc3"
a(8,4) = "0x66"
a(8,5) = "0x3c"
a(8,6) = "0x66"
a(8,7) = "0xc3"
a(8,8) = "0xc3"
a(8,9) = "0x66"
a(8,10)= "0x3c"

a(9,1) = "0x3c" '数字9
a(9,2) = "0x66"
a(9,3) = "0xc3"
a(9,4) = "0xc3"
a(9,5) = "0x66"
a(9,6) = "0x3c"
a(9,7) = "0x18"
a(9,8) = "0x0c"
a(9,9) = "0x06"
a(9,10)= "0x03"
Dim num
Randomize
num = Int(7999 * Rnd + 2000)
Session("safenum") = num
Dim Image
Dim Width, Height
Dim digtal
Dim Length
Dim sort
Dim hc
Length = 4
hc = chr(13) & chr(10)
Redim sort(Length)
digital = ""
For I = 1 To Length - Len(num)
digital = digital & "0"
Next
For I = 1 To Len(num)
digital = digital & Mid(num, I, 1)
Next
For I = 1 To Len(digital)
sort(I) = Mid(digital, I, 1)
Next
Width = 8 * Len(digital)
Height = 10
Response.ContentType = "image/x-xbitmap"
Image = "#define counter_width " & Width & hc
Image = Image & "#define counter_height " & Height & hc
Image = Image & "static unsigned char counter_bits[] = {" & hc
For I = 1 To Height
For J = 1 To Length
Image = Image & a(sort(J),I) & ","
Next
Next
Image = Left(Image, Len(Image) - 1)
Image = Image & "};" & hc
Response.Write Image
%>

[liuyangxuan]

臭兔子。

[菜亲虫]

这是我刚刚用C#下的：
public System.IO.MemoryStream RndBitmap()
{//产生四位随机字母和数字，并将其写入Bitmap中
string strMother="ABCDEFGHIJKLMNPQRSTUVWXYZ23456789";//去除了1，数字0，字母O
string rt="";
System.Random rnd=new Random((int)System.DateTime.Now.Millisecond);
for(int i=0;i<4;i++)
rt+=strMother.Substring(rnd.Next(0,strMother.Length),1);
Session["vcode"]=rt;
vcode=(string)Session["vcode"];
Bitmap bt=new Bitmap(58,22);
bt.MakeTransparent(Color.White);
Graphics gr=Graphics.FromImage(bt);
gr.DrawString(rt,(new Font("宋体",16,FontStyle.Bold)),(new SolidBrush(Color.FromArgb(rnd.Next(200),rnd.Next(200),rnd.Next(200)))),0,0);
for(int j=0;j<80;j++)//随机产生80个点
bt.SetPixel(rnd.Next(0,58),rnd.Next(0,22),Color.FromArgb(rnd.Next(0,255),rnd.Next(0,255),rnd.Next(0,255)));
System.IO.MemoryStream ms=new System.IO.MemoryStream();
bt.Save(ms,System.Drawing.Imaging.ImageFormat.Png);
return ms;
}

[dsclub]

还是DotNet好，可以直接使用GDI/GDI+。

如果是ASP呢：
1、利用COM（论坛里记得三角猫大哥做过）
2、还有就是自己提前把一个图片文件按文档格式拆好了，最后再用ASP，以流的方式生成数据，让这个页面以image方式下载到客户端。（记不太清了，动网好像是这么做的）

[尚和空四]

哇

[ygjwjj]

数字的验证码早就不希奇了,现在都是带字体的中文验证码!

[jarraytan]

QQ注册时采用中文验证码了。。。

[jarraytan]

就用随机数加session得了，简单易行。

做那么花哨有必要吗？

[hbhbhbhbhb1021]

注意XP如果安装了SP2是不能显示ASP写的有些验证码的，要修改下注册表，具体怎么改，到GOOGLE上搜下，好多教的

[sadxu]

用十个图不能够满足需要吗？？？为什么用100000个呢？？？

[尚和空四]

十个图能够满足需要吗

[sbq79]

用十个失去意义了。还不如取消

[Mapleleaf123]

我喜歡註冊qq時的驗證,哪個會

[molocha]

qq垃圾，竟然用中文，顶区个肺！不会打中文怎么办，麻烦死了！！

[leenioa]

那个是用GDI+自动生成的
应该是用的字体不一样吧