Quote:Do not divide with 0!

(Aug 29, 2011 04:59 AM)0van Wrote:  Hey,
can someone help me with my XTEA Code?

Code

Public Class XTea
    Private Shared f_key As UInteger()

    Public Sub New(ByVal password As String)
  MsgBox(password)
  f_key = FormatKey(password)
    End Sub

    Public Function Encrypt(ByVal input As String) As String
  If input.Length = 0 Then
    Throw New ArgumentException("Invalid input length!")
  End If

  If input.Length Mod 2 <> 0 Then
    input += ControlChars.NullChar
  End If

  Dim dataBytes As Byte() = System.Text.ASCIIEncoding.ASCII.GetBytes(input)

  Dim cipher As String = String.Empty
  Dim tempData As UInteger() = New UInteger(1) {}
  For i As Integer = 0 To dataBytes.Length - 1 Step 2
    tempData(0) = dataBytes(i)
    tempData(1) = dataBytes(i + 1)
    code(tempData, f_key)
    cipher += ConvertUIntToString(tempData(0)) + ConvertUIntToString(tempData(1))
  Next

  Return cipher
    End Function

    Public Function Decrypt(ByVal Data As String) As String
  Dim x As Integer = 0
  Dim tempData As UInteger() = New UInteger(1) {}
  Dim dataBytes As Byte() = New Byte((Data.Length \ 8) * 2 - 1) {}
  For i As Integer = 0 To Data.Length - 1 Step 8
    tempData(0) = ConvertStringToUInt(Data.Substring(i, 4))
    tempData(1) = ConvertStringToUInt(Data.Substring(i + 4, 4))
    decode(tempData, f_key)
    dataBytes(x) = CByte(tempData(0))
    x += 1
    dataBytes(x) = CByte(tempData(1))
    x += 1
  Next
  Dim decipheredString As String = System.Text.ASCIIEncoding.ASCII.GetString(dataBytes, 0, dataBytes.Length)
  If decipheredString(decipheredString.Length - 1) = ControlChars.NullChar Then
    decipheredString = decipheredString.Substring(0, decipheredString.Length - 1)
  End If
  Return decipheredString
    End Function

    Private Shared Function FormatKey(ByVal Key As String) As UInteger()
  If Key.Length <= 5 Then
    Throw New ArgumentException("Key must be between 6 and 16 characters in length")
  End If

  Key = Key.PadRight(16, " "c).Substring(0, 16)

  Dim formattedKey As UInteger() = New UInteger(4) {}

  Dim j As Integer = 0
  For i As Integer = 0 To Key.Length - 1 Step 4
    formattedKey(j) = ConvertStringToUInt(Key.Substring(i, 4))
    j += 1
  Next
  Return formattedKey
    End Function

    Private Shared Sub code(ByVal v As UInteger(), ByVal k As UInteger())
  Dim y As UInteger = v(0)
  Dim z As UInteger = v(1)
  Dim sum As UInt64 = 0
  Dim delta As UInteger = &H9E3779B9UI

  For i = 0 To 31
    y += (z << 4 Xor z >> 5) + z Xor sum + k(sum And 3)
    sum += delta
    [color=#FF0000]z += (y << 4 Xor y >> 5) + y Xor sum + k(sum >> 11 And 3)[/color]
  Next

  v(0) = y
  v(1) = z
    End Sub

    Private Shared Sub decode(ByVal v As UInteger(), ByVal k As UInteger())
  Dim y As UInteger = v(0)
  Dim z As UInteger = v(1)
  Dim sum As UInteger = &HC6EF3720UI
  Dim delta As UInteger = &H9E3779B9UI

  For i = 0 To 31
    [color=#FF0000]z -= (y << 4 Xor y >> 5) + y Xor sum + k(sum >> 11 And 3)[/color]
    sum -= delta
    y -= (z << 4 Xor z >> 5) + z Xor sum + k(sum And 3)
  Next

  v(0) = y
  v(1) = z
    End Sub

    Private Shared Function ConvertStringToUInt(ByVal Input As String) As System.UInt32
  Dim output As UInt32
  output = Convert.ToUInt32(Input(0))
  output += (Convert.ToUInt32(Input(1)) << 8)
  output += (Convert.ToUInt32(Input(2)) << 16)
  output += (Convert.ToUInt32(Input(3)) << 24)
  Return output
    End Function
    Private Shared Function ConvertUIntToString(ByVal Input As System.UInt32) As String
  Dim output As New System.Text.StringBuilder()
  output.Append(Convert.ToChar(Input And &HFF))
  output.Append(Convert.ToChar((Input >> 8) And &HFF))
  output.Append(Convert.ToChar((Input >> 16) And &HFF))
  output.Append(Convert.ToChar((Input >> 24) And &HFF))
  Return output.ToString()
    End Function

End Class

Error: