[Resolvido] Erro na classe de encriptar e decriptar parâmetros na url

Pessoas,

A minha classe está dando pau numa variável. Creio que não está armazenado nenhum valor quando a inicio.

Onde está de vermelho aparece a mensagem:

O tamanho do argumento 'String' deve ser maior que zero.

Imports System.Web
Imports Microsoft.VisualBasic

' Classe para encryptar ou descriptar parâmetros da QueryString.

' Exemplos

' Para encriptar a QueryString a nível de página:
' Encryption_String = "?Var1=1&Var2=2&Var3=3"
' ENCRYPTED_CYPHERTEXT = "info=" & cl_encripta_decripta_querytstring.EnCrypt(Encryption_String)

'Para decriptar a QueryString a nível de página:
'Var1 = cl_encripta_decripta_querytstring.Request_eQueryString("Var1")
'Var2 = cl_encripta_decripta_querytstring.Request_eQueryString("Var2")
'Var3 = cl_encripta_decripta_querytstring.Request_eQueryString("CourseParentLevelID")

Public Class cl_encripta_decripta_querytstring

Private Shared Encryption_Key As String
Private Shared Encryption_KeyLocation As String
Private Shared DECRYPTED_CYPHERTEXT As String
Private Shared g_CryptThis As String
Private Shared Request As Web.HttpRequest = Web.HttpContext.Current.Request
Private Shared Server As Web.HttpServerUtility = System.Web.HttpContext.Current.Server
Private Shared Response As HttpResponse = System.Web.HttpContext.Current.Response

' Setar valores:
' Encryption_Key
' g_CryptThis
' DECRYPTED_CYPHERTEXT

Public Property PPEncryption_Key() As String
Get
Return Encryption_Key
End Get
Set(ByVal strValue As String)
Encryption_Key = strValue
End Set
End Property

Public Property PPg_CryptThis() As String
Get
Return g_CryptThis
End Get
Set(ByVal value As String)
value = Request.QueryString("info")
g_CryptThis = value
End Set
End Property

Public Property PPDECRYPTED_CYPHERTEXT() As String
Get
If Len(g_CryptThis) > 1 Then
DECRYPTED_CYPHERTEXT = DeCrypt(g_CryptThis)
End If
Return DECRYPTED_CYPHERTEXT
End Get
Set(ByVal strValue As String)
DECRYPTED_CYPHERTEXT = strValue
End Set
End Property

Shared Sub New()

 Encryption_Key = "RW1C]U`C8E(A_<H`I4WY76A_+QW._)?L[B\;D<$\S>^;RA`V%15F&K^-V^92]RQ[N>&.IT_R)[5);5AIV8C01Z]&I+/I0S1ZG=4\)1$HNQSKS)1[;<.UQ8G0[(`8M>%*\24KZ#5^#P&'U.;0*.[<C2&,(F=>3$7,,ML:Z;`9=LS:<W)(>?;%@\B;G:*^XT3AKB+,#L1795IHA7E&Q$3PAK(AT4R\:'`NXB7#,+/=/=1T\]XI>K.B@M^^*(`9P)M4-?[_0&$,9W2_K^08]+V<9647_E?5U.AS^,C'+OY&368.FLRQK1V@$V/,S@WRDGEOM9V8S<[L5I-=F8J:_QWN:BZ\[ISUTH%JOY@U';4BYD;RG3%P6?D-8IA0SR]>CB*'?@+B\_,*<YK0AO'9(+GXU@-DUO_OHF\E8\?@2<L$5;IU0`]UMFHWN7'<<1DK^)JGR$)P\#`R]X]GL8RGCC4+[@8;^*53@9:P*EO6Y$4XR(4FQ'P1#U2S7..`Y*YI'J8C"
 g_CryptThis = Request.QueryString("info")

 'Encryption_Key = Mid(ReadKeyFromFile(Encryption_KeyLocation), 1, Len(g_CryptThis))
 Encryption_Key = Mid(Encryption_Key, 1, Len(g_CryptThis))
	End Sub

	Public Property Encryption_KeyFull() As Int32
 Get
 Return Encryption_Key
 End Get
 Set(ByVal Value As Int32)
 Encryption_Key = Value
 End Set
	End Property

	Public Shared Function Request_eQueryString(ByVal GetQueryString)

 Dim i As Integer
 Dim Found_It As Integer
 Dim Chop_DECRYPTED_CYPHERTEXT As String
 Dim Found_It_Here As Integer
 Dim TrimExcess As Integer

 Found_It_Here = 0
 TrimExcess = 0
 Chop_DECRYPTED_CYPHERTEXT = ""

 For i = 0 To Len(GetQueryString)
 Found_It = InStr(1, DECRYPTED_CYPHERTEXT, "&" & GetQueryString & "=", 1)
 If CInt(Found_It) > 0 Then
 Found_It_Here = Found_It
 TrimExcess = 1
 End If

 If Found_It_Here < 1 Then
 Found_It = InStr(1, DECRYPTED_CYPHERTEXT, "?" & GetQueryString & "=", 1)
 If (CInt(Found_It) > 0) Then
 Found_It_Here = Found_It
 TrimExcess = 2
 End If
 End If

 If Found_It_Here > 0 Then
 Chop_DECRYPTED_CYPHERTEXT = Right(DECRYPTED_CYPHERTEXT, (Len(DECRYPTED_CYPHERTEXT)) - Found_It - Len(GetQueryString) - TrimExcess)
 Found_It = InStr(1, Chop_DECRYPTED_CYPHERTEXT, "&", 1)
 If CInt(Found_It) > 0 Then
 Chop_DECRYPTED_CYPHERTEXT = Left(Chop_DECRYPTED_CYPHERTEXT, Found_It - 1)
 End If
 End If

 Next

 Request_eQueryString = Chop_DECRYPTED_CYPHERTEXT

	End Function

	Public Shared Function EnCrypt(ByVal strCryptThis)

 strCryptThis = ChkString(strCryptThis)

 'Dim strChar As String
 Dim iKeyChar As Integer
 Dim iStringChar As Integer
 Dim i As Integer
 Dim iCryptChar As Integer
 Dim strEncrypted As String = Nothing

 For i = 1 To Len(strCryptThis)
 iKeyChar = Asc(Mid([color="#FF0000"]Encryption_Key[/color], i, 1))
 iStringChar = Asc(Mid(strCryptThis, i, 1))
 iCryptChar = iStringChar + iKeyChar

 If iCryptChar > 255 Then
 iCryptChar = iCryptChar - 256
 End If

 'iCryptChar = iKeyChar Xor iStringChar
 strEncrypted = strEncrypted & Chr(iCryptChar)
 Next
 EnCrypt = Server.UrlEncode(strEncrypted)
	End Function

	Private Shared Function DeCrypt(ByVal strEncrypted)

 'Dim strChar As String
 Dim iKeyChar As Integer
 Dim iStringChar As String
 Dim i As Integer
 Dim iDeCryptChar As Integer
 Dim strDecrypted As String = ""

 For i = 1 To Len(strEncrypted)
 iKeyChar = (Asc(Mid(Encryption_Key, i, 1)))
 iStringChar = Asc(Mid(strEncrypted, i, 1))
 iDeCryptChar = iStringChar - iKeyChar
 'iDeCryptChar = iKeyChar Xor iStringChar

 If iDeCryptChar < 0 Then
 iDeCryptChar = iDeCryptChar + 256
 End If

 If (iDeCryptChar = 34) Or (iDeCryptChar = 39) Then
 Response.Write("Ocorreu um erro na criptografia. Por favor verifique as configurações.")
 Response.End()
 Else
 strDecrypted = strDecrypted & Chr(iDeCryptChar)
 End If
 Next
 DeCrypt = strDecrypted
	End Function

	'Private Shared Function ReadKeyFromFile(ByVal strFileName)

	'	'keyFile
	'	ReadKeyFromFile = "RW1C]U`C8E(A_<H`I4WY76A_+QW._)?L[B\;D<$\S>^;RA`V%15F&K^-V^92]RQ[N>&.IT_R)[5);5AIV8C01Z]&I+/I0S1ZG=4\)1$HNQSKS)1[;<.UQ8G0[(`8M>%*\24KZ#5^#P&'U.;0*.[<C2&,(F=>3$7,,ML:Z;`9=LS:<W)(>?;%@\B;G:*^XT3AKB+,#L1795IHA7E&Q$3PAK(AT4R\:'`NXB7#,+/=/=1T\]XI>K.B@M^^*(`9P)M4-?[_0&$,9W2_K^08]+V<9647_E?5U.AS^,C'+OY&368.FLRQK1V@$V/,S@WRDGEOM9V8S<[L5I-=F8J:_QWN:BZ\[ISUTH%JOY@U';4BYD;RG3%P6?D-8IA0SR]>CB*'?@+B\_,*<YK0AO'9(+GXU@-DUO_OHF\E8\?@2<L$5;IU0`]UMFHWN7'<<1DK^)JGR$)P\#`R]X]GL8RGCC4+[@8;^*53@9:P*EO6Y$4XR(4FQ'P1#U2S7..`Y*YI'J8C"

	'End Function

	Shared Function ChkString(ByVal strQstring)

 If strQstring = "" Then
 strQstring = " "
 End If

 ChkString = Replace(strQstring, """", "")
 ChkString = Replace(ChkString, "'", "")

	End Function

End Class