附加码技术讨论！高手请进！

大家讨论一下附加码的技术思路和实现方法！
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版权所有转载请保留谢谢合作

部分程序取自网络

作者：扬子

QQ: 21112856

WebSite: www.tingfo.net

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

  1   
  2'### To encrypt/decrypt include this code in your page   
  3'### strMyEncryptedString = EncryptString(strString)   
  4'### strMyDecryptedString = DeCryptString(strMyEncryptedString)   
  5'### You are free to use this code as long as credits remain in place   
  6'### also if you improve this code let me know.   
  7  
  8Private Function EncryptString(strString)   
  9'####################################################################   
 10'### Crypt Function (C) 2001 by Slavic Kozyuk [email protected] ###   
 11'### Arguments: strString <\--- String you wish to encrypt ###   
 12'### Output: Encrypted HEX string ###   
 13'####################################################################   
 14  
 15Dim CharHexSet, intStringLen, strTemp, strRAW, i, intKey, intOffSet   
 16Randomize Timer   
 17  
 18intKey = Round((RND * 1000000) + 1000000) '##### Key Bitsize   
 19intOffSet = Round((RND * 1000000) + 1000000) '##### KeyOffSet Bitsize   
 20  
 21If IsNull(strString) = False Then   
 22strRAW = strString   
 23intStringLen = Len(strRAW)   
 24  
 25For i = 0 to intStringLen - 1   
 26strTemp = Left(strRAW, 1)   
 27strRAW = Right(strRAW, Len(strRAW) - 1)   
 28CharHexSet = CharHexSet & Hex(Asc(strTemp) * intKey)& Hex(intKey)   
 29Next   
 30  
 31EncryptString = CharHexSet & " ¦" & Hex(intOffSet + intKey) & " ¦" & Hex(intOffSet)   
 32Else   
 33EncryptString = ""   
 34End If   
 35End Function   
 36  
 37  
 38  
 39\---------------------------------------------------------------   
 40  
 41  
 42  
 43  
 44  
 45Private Function DeCryptString(strCryptString)   
 46'####################################################################   
 47'### Crypt Function (C) 2001 by Slavic Kozyuk [email protected] ###   
 48'### Arguments: Encrypted HEX stringt ###   
 49'### Output: Decrypted ASCII string ###   
 50'####################################################################   
 51'### Note this function uses HexConv() and get_hxno() functions ###   
 52'### so make sure they are not removed ###   
 53'####################################################################   
 54  
 55Dim strRAW, arHexCharSet, i, intKey, intOffSet, strRawKey, strHexCrypData   
 56  
 57  
 58strRawKey = Right(strCryptString, Len(strCryptString) - InStr(strCryptString, " ¦"))   
 59intOffSet = Right(strRawKey, Len(strRawKey) - InStr(strRawKey," ¦"))   
 60intKey = HexConv(Left(strRawKey, InStr(strRawKey, " ¦") - 1)) - HexConv(intOffSet)   
 61strHexCrypData = Left(strCryptString, Len(strCryptString) - (Len(strRawKey) + 1))   
 62  
 63  
 64arHexCharSet = Split(strHexCrypData, Hex(intKey))   
 65  
 66For i=0 to UBound(arHexCharSet)   
 67strRAW = strRAW & Chr(HexConv(arHexCharSet(i))/intKey)   
 68Next   
 69  
 70DeCryptString = strRAW   
 71End Function   
 72  
 73  
 74  
 75Private Function HexConv(hexVar)   
 76Dim hxx, hxx_var, multiply   
 77IF hexVar <> "" THEN   
 78hexVar = UCASE(hexVar)   
 79hexVar = StrReverse(hexVar)   
 80DIM hx()   
 81REDIM hx(LEN(hexVar))   
 82hxx = 0   
 83hxx_var = 0   
 84FOR hxx = 1 TO LEN(hexVar)   
 85IF multiply = "" THEN multiply = 1   
 86hx(hxx) = mid(hexVar,hxx,1)   
 87hxx_var = (get_hxno(hx(hxx)) * multiply) + hxx_var   
 88multiply = (multiply * 16)   
 89NEXT   
 90hexVar = hxx_var   
 91HexConv = hexVar   
 92END IF   
 93End Function   
 94  
 95Private Function get_hxno(ghx)   
 96If ghx = "A" Then   
 97ghx = 10   
 98ElseIf ghx = "B" Then   
 99ghx = 11   
100ElseIf ghx = "C" Then   
101ghx = 12   
102ElseIf ghx = "D" Then   
103ghx = 13   
104ElseIf ghx = "E" Then   
105ghx = 14   
106ElseIf ghx = "F" Then   
107ghx = 15   
108End If   
109get_hxno = ghx   
110End Function   
111  
112

---------------------------------------------------------------

1   
2randomize   
3num = int(7999*rnd+2000) '计数器的值   
4num2 = EncryptString(num)   
5session("pwdt")=num

1<form action="chk.asp" method="post">   
2请输入验证码： <input name="pwds" type="text"/>
3<img src="count.asp?sksid=```
4=num2
5```"/> <input type="submit" value="提交"/>
6</form>

chk.asp

1   
2if 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

1输入正确

end if

1  
2count.asp
3<!--#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 [email protected] ###
'### 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 [email protected] ###
'### 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