罗霍曼联号码:谁知道阿里巴巴的注册页面表单验证效果是如何实现的？

实现文件:img.asp
<%
'Response.Expires = 0
Response.AddHeader "Pragma","no-cache"
Response.AddHeader "cache-ctrol","no-cache"
Response.ContentType = "Image/BMP"
Randomize Timer

Dim Text_Data(9),Text_Len,Int_Temp(),I,j,k,Int_Temp2

Text_Len = 4 '验证码长度(支持1-25位)

'**********************

ReDim Int_Temp( Text_Len - 1 )

Text_Data(0) = "00000000000001111000001100110000110111000011011100001100110000111011000011101100001100110000011110000000000000"
Text_Data(1) = "00000000000000011000000011100000111110000000011000000001100000000110000000011000000001100000000110000000000000"
Text_Data(2) = "00000000000001111000001100110000110011000000001100000001100000001100000001100000001100000000111111000000000000"
Text_Data(3) = "00000000000001111000001100110000110011000000001100000011100000000011000011001100001100110000011110000000000000"
Text_Data(4) = "00000000000001100000000110000000011011000001101100000110110000110011000011111110000000110000000011000000000000"
Text_Data(5) = "00000000000011111100001100000000110000000011000000001111100000000011000000001100000001100000111100000000000000"
Text_Data(6) = "00000000000000111000000011000000011000000011111000001100110000110011000011001100001100110000011110000000000000"
Text_Data(7) = "00000000000011111100000000110000000110000000011000000011000000001100000001100000000110000000011000000000000000"
Text_Data(8) = "00000000000001111000001100110000110011000011101100000111100000110111000011001100001100110000011110000000000000"
Text_Data(9) = "00000000000001111000001100110000110011000011001100001100110000011111000000011000000011000000011100000000000000"

Session("Num") = ""
For I = 0 To Text_Len - 1
Int_Temp(I) = Int(Rnd * 10)
Session("Num") = Session("Num") + Mid("0123456789",Int_Temp(I)+1,1)
Next

Int_Temp2 = (Text_Len - 1) \ 4 * 220 + ((Text_Len - 1) / 4 - (Text_Len - 1) \ 4 * 4) * 44
Response.BinaryWrite ChrB(&H42) & ChrB(&H4D)
Response.BinaryWrite ChrB(((Int_Temp2 + 206) / 256 - (Int_Temp2 + 206) \ 256) * 256) & ChrB((Int_Temp2 + 206) \ 256) '特殊位
Response.BinaryWrite ChrB(0) & ChrB(0) & ChrB(0) & ChrB(0) & ChrB(0) & ChrB(0) & ChrB(&H76) & ChrB(0) & ChrB(0) & ChrB(0) & ChrB(&H28) & ChrB(0) & ChrB(0) & ChrB(0)
Response.BinaryWrite ChrB(Text_Len * 10) '特殊位
Response.BinaryWrite ChrB(0) & ChrB(0) & ChrB(0) & ChrB(&HB) & ChrB(0) & ChrB(0) & ChrB(0) & ChrB(&H1) & ChrB(0) & ChrB(&H4) & ChrB(0) & ChrB(0) & ChrB(0) & ChrB(0) & ChrB(0)
Response.BinaryWrite ChrB(((Int_Temp2 + 88) / 256 - (Int_Temp2 + 88) \ 256) * 256) & ChrB((Int_Temp2 + 88) \ 256) '特殊位

Response.BinaryWrite ChrB(0) & ChrB(0) & ChrB(0) & ChrB(0) & ChrB(0) & ChrB(0) & ChrB(0) & ChrB(0) & ChrB(0) & ChrB(0) & ChrB(16) & ChrB(0) & ChrB(0) & ChrB(0) & ChrB(16) & ChrB(0) & ChrB(0) & ChrB(0) & ChrB(0) & ChrB(0) & ChrB(0) & ChrB(0) & ChrB(0) & ChrB(0) & ChrB(&H80) & ChrB(0) & ChrB(0) & ChrB(&H80) & ChrB(0) & ChrB(0) & ChrB(0) & ChrB(&H80) & ChrB(&H80) & ChrB(0) & ChrB(&H80) & ChrB(0) & ChrB(0) & ChrB(0) & ChrB(&H80) & ChrB(0) & ChrB(&H80) & ChrB(0)
Response.BinaryWrite ChrB(&H80) & ChrB(&H80) & ChrB(0) & ChrB(0) & ChrB(&H80) & ChrB(&H80) & ChrB(&H80) & ChrB(0) & ChrB(&HC0) & ChrB(&HC0) & ChrB(&HC0) & ChrB(0) & ChrB(0) & ChrB(0) & ChrB(&HFF) & ChrB(0) & ChrB(0) & ChrB(&HFF) & ChrB(0) & ChrB(0) & ChrB(0) & ChrB(&HFF) & ChrB(&HFF) & ChrB(0) & ChrB(&HFF) & ChrB(0) & ChrB(0) & ChrB(0) & ChrB(&HFF) & ChrB(0) & ChrB(&HFF) & ChrB(0) & ChrB(&HFF) & ChrB(&HFF) & ChrB(0) & ChrB(0) & ChrB(&HFF) & ChrB(&HFF) & ChrB(&HFF) & ChrB(0)

For i = 10 to 0 Step -1
For j = 0 to Text_Len - 1
For k = 1 to 9 Step 2
If Mid(Text_Data(Int_Temp(j)) , i * 10 + k , 1) = "0" Then Int_Temp2 = Get_BackColor() * 16 Else Int_Temp2 = Get_ForeColor() * 16
If Mid(Text_Data(Int_Temp(j)) , i * 10 + k + 1 , 1) = "0" Then Int_Temp2 = Int_Temp2 + Get_BackColor() Else Int_Temp2 = Int_Temp2 + Get_ForeColor()
Response.BinaryWrite ChrB(Int_Temp2)
Next
Next
Int_Temp2 = (Text_Len / 4 - Text_Len \ 4) * 4
Select Case Int_Temp2
Case 1
Response.BinaryWrite ChrB(0) & ChrB(0) & ChrB(0)
Case 2
Response.BinaryWrite ChrB(0) & ChrB(0)
Case 3
Response.BinaryWrite ChrB(0)
End Select
Next

Function Get_BackColor()
If Int(Rnd * 30) = 0 Then
Get_BackColor = CInt(Mid("00021209",Int(Rnd * 4) * 2 + 1,2))
Else
Get_BackColor = CInt(Mid("081515151515",Int(Rnd * 6) * 2 + 1,2))
End If
End Function

Function Get_ForeColor()
Get_ForeColor = CInt(Mid("00021209",Int(Rnd * 4) * 2 + 1,2))
End Function
%>

程序调用:
<script language="javascript">
document.write("<img src=img.asp>");
</script>