.NET [VB.NET] XTEA Encryption [Source]

Code
Public Class XTea

    'Leave a thanks....



    '- decompiler



    Private Shared f_key As UInteger()



    Public Sub New(ByVal password As String)

  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 UInteger = 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

    z += (y << 4 Xor y >> 5) + y Xor sum + k(sum >> 11 And 3)

  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

    z -= (y << 4 Xor y >> 5) + y Xor sum + k(sum >> 11 And 3)

    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