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Hallo
Ich möchte eine Textdatei verschlüsseln (funktioniert bereits) und später wieder entschlüsseln.
Wie kann ich einen bestimmten Teil des Textes wieder entschlüsseln.

Code:

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Public Function Verschlüsseln()
        Dim RdM As New RijndaelManaged
        Dim fs1 As New FileStream(Pfad_Berechtigung, FileMode.Create)
        Dim CStream As New CryptoStream(fs1, RdM.CreateEncryptor, CryptoStreamMode.Write)
        Dim sw1 As New StreamWriter(CStream)
        sw1.WriteLine("[VB.Net, Frameworks 3.5]")
        sw1.WriteLine("Programmname")
        sw1.WriteLine("Nr=" & SerienNummer1())
        sw1.WriteLine("Ver=1.0")
        sw1.WriteLine("Dat=" & DateTime.Today)
        sw1.Close()
        CStream.Close()
        fs1.Close()
        Return ""
End Function

Public Function Entschlüsseln(ByVal Variable)
        Dim RdM As New RijndaelManaged
        Dim fs1 As New FileStream(Pfad_Berechtigung, FileMode.Open)
        Dim CStream As New CryptoStream(fs1, RdM.CreateDecryptor, CryptoStreamMode.Read)
        Dim sr1 As New StreamReader(CStream)
        Dim Textzeile As String
        Do Until sr1.Peek() = -1
            Textzeile = sr1.ReadLine()
            If Left(Textzeile, Len(Variable)) = Variable Then
                Entschlüsseln = Mid(Textzeile, Len(Variable) + 1)
                sr1.Close()
                CStream.Close()
                fs1.Close()
                Exit Function
            End If
        Loop
        sr1.Close()
        CStream.Close()
        fs1.Close()
        Return ""
End Function

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danke im voraus

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Hallo DrCNC,

Ich habe es mal so getestet und es funktioniert:

Code:

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    Sub Main()
        Dim SerienNummer1 = "TEST"

        Using Rijndael = RijndaelManaged.Create
            Dim content = "[VB.Net, Framework 3.5]" & vbCrLf &
                          "Programmname" & vbCrLf &
                          "Nr=" & SerienNummer1 & vbCrLf &
                          "Ver=1.0" & vbCrLf &
                          "Dat=" & DateTime.Today
            Encrypt(content, "C:\Users\Admin\Documents\Try\Crypt.txt", Rijndael.Key, Rijndael.IV)
            Console.WriteLine("Encrypted!")
            Console.ReadLine()
            Dim Cont = Decrypt("C:\Users\Raphael\Documents\Try\Crypt.txt", Rijndael.Key, Rijndael.IV)
            Console.WriteLine("Decrypted!")
            Console.ReadLine()
        End Using
    End Sub

    Public Sub Encrypt(plainText$, path$, Key() As Byte, IV() As Byte)
        Using rijAlg = Rijndael.Create()
            rijAlg.Key = Key
            rijAlg.IV = IV
            Using msEncrypt As New FileStream(path, FileMode.Create, FileAccess.Write, FileShare.Write)
                Using csEncrypt As New CryptoStream(msEncrypt, rijAlg.CreateEncryptor(rijAlg.Key, rijAlg.IV), CryptoStreamMode.Write)
                    Using swEncrypt As New StreamWriter(csEncrypt)
                        swEncrypt.Write(plainText)
                    End Using
                End Using
            End Using
        End Using
    End Sub
    Public Function Decrypt(path$, Key() As Byte, IV() As Byte) As String
        Dim plaintext = String.Empty
        Using rijAlg = Rijndael.Create()
            rijAlg.Key = Key
            rijAlg.IV = IV
            Dim decryptor As ICryptoTransform = rijAlg.CreateDecryptor(rijAlg.Key, rijAlg.IV)
            Using msDecrypt As New FileStream(path, FileMode.Open, FileAccess.Read, FileShare.Read)
                Using csDecrypt As New CryptoStream(msDecrypt, decryptor, CryptoStreamMode.Read)
                    Using srDecrypt As New StreamReader(csDecrypt)
                        Decrypt = srDecrypt.ReadToEnd()
                    End Using
                End Using
            End Using
        End Using
    End Function

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