Option Explicit On
Imports System.Security.Cryptography
Imports System.IO
Imports System.Text
 
 
    ''' <summary>
    ''' Diese Funktion dient zum Verschlüsseln des übergebenen Texts, anhand 
    ' des übergebenen Passworts.
    ''' </summary>
    ''' <param name="curKey"></param>
    ''' <param name="curText"></param>
    ''' <returns></returns>
    ''' <remarks></remarks>
    Public Function Rijndael_Verschluesseln(ByVal curKey As String, ByVal _
      curText As String) As String
        Dim Returntext As String = ""
        Try
            Dim rd As New RijndaelManaged
            Dim md5 As New MD5CryptoServiceProvider
            Dim key() As Byte = md5.ComputeHash(Encoding.UTF8.GetBytes(curKey))
 
            md5.Clear()
            rd.Key = key
            rd.GenerateIV()
 
            Dim iv() As Byte = rd.IV
            Dim ms As New MemoryStream
 
            ms.Write(iv, 0, iv.Length)
 
            Dim cs As New CryptoStream(ms, rd.CreateEncryptor, _
              CryptoStreamMode.Write)
            Dim data() As Byte = System.Text.Encoding.UTF8.GetBytes(curText)
 
            cs.Write(data, 0, data.Length)
            cs.FlushFinalBlock()
 
            Dim encdata() As Byte = ms.ToArray()
            Returntext = Convert.ToBase64String(encdata)
 
            cs.Close()
            rd.Clear()
 
        Catch ex As Exception
     MSGBOX(ex.message)
        End Try
 
        Return Returntext
    End Function
 
    ''' <summary>
    ''' Diese Funktion dient zum Entschlüsseln des übergebenen Texts, anhand 
    ' des übergebenen Passworts.
    ''' </summary>
    ''' <param name="curKey"></param>
    ''' <param name="curText"></param>
    ''' <returns></returns>
    ''' <remarks></remarks>
    Public Function Rijndael_Entschluesseln(ByVal curKey As String, ByVal _
      curText As String) As String
        Dim Returnstring As String = ""
        Try
            Dim rd As New RijndaelManaged
            Dim rijndaelIvLength As Integer = 16
            Dim md5 As New MD5CryptoServiceProvider
            Dim key() As Byte = md5.ComputeHash(Encoding.UTF8.GetBytes(curKey))
 
            md5.Clear()
 
            Dim encdata() As Byte = Convert.FromBase64String(curText)
            Dim ms As New MemoryStream(encdata)
            Dim iv(15) As Byte
 
            ms.Read(iv, 0, rijndaelIvLength)
            rd.IV = iv
            rd.Key = key
 
            Dim cs As New CryptoStream(ms, rd.CreateDecryptor, _
              CryptoStreamMode.Read)
 
            Dim data(CType(ms.Length, Integer) - rijndaelIvLength) As Byte
            Dim i As Integer = cs.Read(data, 0, data.Length)
 
            Returnstring = System.Text.Encoding.UTF8.GetString(data, 0, i)
            cs.Close()
            rd.Clear()
 
        Catch ex As Exception
MSGBOX(ex.message)
        End Try
        Return Returnstring
    End Function