标题: ASP 验证码的程序及原理 [打印本页] 作者: 边走边看 时间: 2009-3-16 19:04 标题: ASP 验证码的程序及原理 一共4个页面：form.asp; chk.asp; num.asp; count.asp
得到一个随即数字。加密！
解密后成成XBM图片
利用session 判断
form.asp
<%
'### To encrypt/decrypt include this code in your page
'### strMyEncryptedString = EncryptString(strString)
'### strMyDecryptedString = DeCryptString(strMyEncryptedString)
'### You are free to use this code as long as credits remain in place
'### also if you improve this code let me know.
Private Function EncryptString(strString)
'####################################################################
'### Crypt Function (C) 2001 by Slavic Kozyuk grindkore@yahoo.com ###
'### Arguments: strString <--- String you wish to encrypt ###
'### Output: Encrypted HEX string ###
'####################################################################
Dim CharHexSet, intStringLen, strTemp, strRAW, i, intKey, intOffSet
Randomize Timer
intKey = Round((RND * 1000000) + 1000000) '##### Key Bitsize
intOffSet = Round((RND * 1000000) + 1000000) '##### KeyOffSet Bitsize
If IsNull(strString) = False Then
strRAW = strString
intStringLen = Len(strRAW)
For i = 0 to intStringLen - 1
strTemp = Left(strRAW, 1)
strRAW = Right(strRAW, Len(strRAW) - 1)
CharHexSet = CharHexSet & Hex(Asc(strTemp) * intKey)& Hex(intKey)
Next
EncryptString = CharHexSet & "|" & Hex(intOffSet + intKey) & "|" & Hex(intOffSet)
Else
EncryptString = ""
End If
End Function
Private Function DeCryptString(strCryptString)
'####################################################################
'### Crypt Function (C) 2001 by Slavic Kozyuk grindkore@yahoo.com ###
'### Arguments: Encrypted HEX stringt ###
'### Output: Decrypted ASCII string ###
'####################################################################
'### Note this function uses HexConv() and get_hxno() functions ###
'### so make sure they are not removed ###
'####################################################################
Dim strRAW, arHexCharSet, i, intKey, intOffSet, strRawKey, strHexCrypData
strRawKey = Right(strCryptString, Len(strCryptString) - InStr(strCryptString, "|"))
intOffSet = Right(strRawKey, Len(strRawKey) - InStr(strRawKey,"|"))
intKey = HexConv(Left(strRawKey, InStr(strRawKey, "|") - 1)) - HexConv(intOffSet)
strHexCrypData = Left(strCryptString, Len(strCryptString) - (Len(strRawKey) + 1))
arHexCharSet = Split(strHexCrypData, Hex(intKey))
For i=0 to UBound(arHexCharSet)
strRAW = strRAW & Chr(HexConv(arHexCharSet(i))/intKey)
Next
DeCryptString = strRAW
End Function
Private Function HexConv(hexVar)
Dim hxx, hxx_var, multiply
IF hexVar <> "" THEN
hexVar = UCASE(hexVar)
hexVar = StrReverse(hexVar)
DIM hx()
REDIM hx(LEN(hexVar))
hxx = 0
hxx_var = 0
FOR hxx = 1 TO LEN(hexVar)
IF multiply = "" THEN multiply = 1
hx(hxx) = mid(hexVar,hxx,1)
hxx_var = (get_hxno(hx(hxx)) * multiply) + hxx_var
multiply = (multiply * 16)
NEXT
hexVar = hxx_var
HexConv = hexVar
END IF
End Function
Private Function get_hxno(ghx)
If ghx = "A" Then
ghx = 10
ElseIf ghx = "B" Then
ghx = 11
ElseIf ghx = "C" Then
ghx = 12
ElseIf ghx = "D" Then
ghx = 13
ElseIf ghx = "E" Then
ghx = 14
ElseIf ghx = "F" Then
ghx = 15
End If
get_hxno = ghx
End Function
%>
<%
randomize
num = int(7999*rnd+2000) '计数器的值
num2 = EncryptString(num)
session("pwdt")=num
%>
<form action="chk.asp" method=post>
请输入验证码： <input type="text" name="pwds">
<img src="count.asp?sksid=<%=num2%>"> <input type=submit value=提交>
</form>
chk.asp
<%
if trim(request.form("pwds"))<>trim(session("pwdt")) then
%>
输入错误： 应该为：<%=session("pwdt")%>，可你输入的是:<%=request.form("pwds")%>
<%
else
%>
输入正确
<%end if%>
count.asp
<!--#include file="num.asp"-->
<%
'### To encrypt/decrypt include this code in your page
'### strMyEncryptedString = EncryptString(strString)
'### strMyDecryptedString = DeCryptString(strMyEncryptedString)
'### You are free to use this code as long as credits remain in place
'### also if you improve this code let me know.
Private Function EncryptString(strString)
'####################################################################
'### Crypt Function (C) 2001 by Slavic Kozyuk grindkore@yahoo.com ###
'### Arguments: strString <--- String you wish to encrypt ###
'### Output: Encrypted HEX string ###
'####################################################################
Dim CharHexSet, intStringLen, strTemp, strRAW, i, intKey, intOffSet
Randomize Timer
intKey = Round((RND * 1000000) + 1000000) '##### Key Bitsize
intOffSet = Round((RND * 1000000) + 1000000) '##### KeyOffSet Bitsize
If IsNull(strString) = False Then
strRAW = strString
intStringLen = Len(strRAW)
For i = 0 to intStringLen - 1
strTemp = Left(strRAW, 1)
strRAW = Right(strRAW, Len(strRAW) - 1)
CharHexSet = CharHexSet & Hex(Asc(strTemp) * intKey)& Hex(intKey)
Next
EncryptString = CharHexSet & "|" & Hex(intOffSet + intKey) & "|" & Hex(intOffSet)
Else
EncryptString = ""
End If
End Function
Private Function DeCryptString(strCryptString)
'####################################################################
'### Crypt Function (C) 2001 by Slavic Kozyuk grindkore@yahoo.com ###
'### Arguments: Encrypted HEX stringt ###
'### Output: Decrypted ASCII string ###
'####################################################################
'### Note this function uses HexConv() and get_hxno() functions ###
'### so make sure they are not removed ###
'####################################################################
Dim strRAW, arHexCharSet, i, intKey, intOffSet, strRawKey, strHexCrypData
strRawKey = Right(strCryptString, Len(strCryptString) - InStr(strCryptString, "|"))
intOffSet = Right(strRawKey, Len(strRawKey) - InStr(strRawKey,"|"))
intKey = HexConv(Left(strRawKey, InStr(strRawKey, "|") - 1)) - HexConv(intOffSet)
strHexCrypData = Left(strCryptString, Len(strCryptString) - (Len(strRawKey) + 1))
arHexCharSet = Split(strHexCrypData, Hex(intKey))
For i=0 to UBound(arHexCharSet)
strRAW = strRAW & Chr(HexConv(arHexCharSet(i))/intKey)
Next
DeCryptString = strRAW
End Function
Private Function HexConv(hexVar)
Dim hxx, hxx_var, multiply
IF hexVar <> "" THEN
hexVar = UCASE(hexVar)
hexVar = StrReverse(hexVar)
DIM hx()
REDIM hx(LEN(hexVar))
hxx = 0
hxx_var = 0
FOR hxx = 1 TO LEN(hexVar)
IF multiply = "" THEN multiply = 1
hx(hxx) = mid(hexVar,hxx,1)
hxx_var = (get_hxno(hx(hxx)) * multiply) + hxx_var
multiply = (multiply * 16)
NEXT
hexVar = hxx_var
HexConv = hexVar
END IF
End Function
Private Function get_hxno(ghx)
If ghx = "A" Then
ghx = 10
ElseIf ghx = "B" Then
ghx = 11
ElseIf ghx = "C" Then
ghx = 12
ElseIf ghx = "D" Then
ghx = 13
ElseIf ghx = "E" Then
ghx = 14
ElseIf ghx = "F" Then
ghx = 15
End If
get_hxno = ghx
End Function
%>
<%
Dim Image
Dim Width, Height
Dim num
Dim digtal
Dim Length
Dim sort
Length = 4 '自定计数器长度
Redim sort( Length )
num=cint(DeCryptString(request.querystring("sksid")))
digital = ""
For I = 1 To Length -Len( num ) '补0
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 ) '图像的宽度
Height = 10 '图像的高度，在本例中为固定值
Response.ContentType="image/x-xbitmap"
hc=chr(13) & chr(10)
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 ) '去掉最后一个逗号
Image = Image & "};" & hc
%>
<%
Response.Write Image
%>
num.asp
<%
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"