Projekt Uge

Imports System.IO
Imports System.Security.Cryptography
Imports System.Text
Imports System.Runtime.Serialization.Formatters.Binary
Imports System.Text.RegularExpressions

Public Class Form1
    Public Function ReverseString(ByRef strToReverse As String) As String
        Dim result As String = ""
        For i As Integer = 0 To strToReverse.Length - 1
            result += strToReverse(strToReverse.Length - 1 - i)
        Next
        Return result
    End Function
    Public Function SimpleCrypt( _
       ByVal Text As String) As String
        ' Encrypts/decrypts the passed string using
        ' a simple ASCII value-swapping algorithm
        Dim strTempChar As String, i As Integer
        For i = 1 To Len(Text)
            If Asc(Mid$(Text, i, 1)) < 128 Then
                strTempChar = _
          CType(Asc(Mid$(Text, i, 1)) + 128, String)
            ElseIf Asc(Mid$(Text, i, 1)) > 128 Then
                strTempChar = _
          CType(Asc(Mid$(Text, i, 1)) - 128, String)
            End If
            Mid$(Text, i, 1) = _
                Chr(CType(strTempChar, Integer))
        Next i
        Return Text
    End Function

    Public Shared Function Crypt(ByVal Data As String, ByVal key As String) As String
        Return Encoding.Default.GetString(Crypt(Encoding.Default.GetBytes(Data), Encoding.Default.GetBytes(key)))
    End Function
    Public Shared Function Crypt(ByVal Data() As Byte, ByVal key() As Byte) As Byte()
        For i = 0 To (Data.Length * 2) + key.Length
            Data(i Mod Data.Length) = CByte(CInt((Data(i Mod Data.Length)) + CInt(Data((i + 1) Mod Data.Length))) Mod 256) Xor key(i Mod key.Length)
        Next
        Return Data
    End Function
    Public Shared Function DeCrypt(ByVal Data As String, ByVal key As String) As String
        Return Encoding.Default.GetString(DeCrypt(Encoding.Default.GetBytes(Data), Encoding.Default.GetBytes(key)))
    End Function
    Public Shared Function DeCrypt(ByVal Data() As Byte, ByVal key() As Byte) As Byte()
        For i = (Data.Length * 2) + key.Length To 0 Step -1
            Data(i Mod Data.Length) = CByte((CInt(Data(i Mod Data.Length) Xor key(i Mod key.Length)) - CInt(Data((i + 1) Mod Data.Length)) + 256) Mod 256)
        Next
        Return Data
    End Function
    Public Function XOREncrypt(ByVal CodeKey As String, ByVal DataIn As String) As String
        Dim lonDataPtr As Long
        Dim strDataOut As String
        Dim temp As Integer
        Dim tempstring As String
        Dim intXOrValue1 As Integer
        Dim intXOrValue2 As Integer
        For lonDataPtr = 1 To Len(DataIn)
            intXOrValue1 = Asc(Mid$(DataIn, lonDataPtr, 1))
            'The second value comes from the code key
            intXOrValue2 = Asc(Mid$(CodeKey, ((lonDataPtr Mod Len(CodeKey)) + 1), 1))
            temp = (intXOrValue1 Xor intXOrValue2)
            tempstring = Hex(temp)
            If Len(tempstring) = 1 Then tempstring = "0" & tempstring
            strDataOut = strDataOut + tempstring
        Next lonDataPtr
        XOREncrypt = strDataOut
    End Function
    'XOR Decryption
    Public Function XORDecrypt(ByVal CodeKey As String, ByVal DataIn As String) As String
        Dim lonDataPtr As Long
        Dim strDataOut As String
        Dim intXOrValue1 As Integer
        Dim intXOrValue2 As Integer
        For lonDataPtr = 1 To (Len(DataIn) / 2)
            intXOrValue1 = Val("&H" & (Mid$(DataIn, (2 * lonDataPtr) - 1, 2)))
            intXOrValue2 = Asc(Mid$(CodeKey, ((lonDataPtr Mod Len(CodeKey)) + 1), 1))
            strDataOut = strDataOut + Chr(intXOrValue1 Xor intXOrValue2)
        Next lonDataPtr
        XORDecrypt = strDataOut
    End Function


    Private Sub Form1_Load(sender As Object, e As EventArgs) Handles MyBase.Load

    End Sub

    Private Sub Button1_Click(sender As Object, e As EventArgs) Handles Button1.Click
        TextBox1.Text = Crypt(TextBox1.Text, 2345)
        TextBox1.Text = ReverseString(TextBox1.Text)
        TextBox1.Text = SimpleCrypt(TextBox1.Text)
        TextBox1.Text = XOREncrypt(TextBox2.Text, TextBox1.Text)

    End Sub
    Private Sub TextBox1_TextChanged(sender As Object, e As EventArgs) Handles TextBox1.TextChanged

    End Sub

    Private Sub Button2_Click(sender As Object, e As EventArgs) Handles Button2.Click
        ' TextBox1.Text = XORDecrypt(2345, TextBox1.Text)
        'TextBox1.Text = DeCrypt(TextBox1.Text, 2345)
        'TextBox1.Text = SimpleCrypt(TextBox1.Text)
    End Sub
End Class