Kryptering eller ?

Hej
Jeg har et lille problem som jeg håber nogen kan hjælpe mig med. Jeg har brug for at "kryptere" noget tekst, som skal gemmes i en database, og på den måde, hvis uvedkommende får adgang til databasen, skjule informationerne for dem. teksten skal kunne hentes ud igen og dekrypteres så man kan læse indholdet.
Jeg har fundet denne kode på nettet, og forsøgt at æbdre den så det passer til det jeg skal bruge det til. Men nu får jeg alle mulige fejl, når jeg forsøger at dekryptere teksten igen.
Jeg har forsøgt at lave teksten fra databasen om til byte igen, men det virker ikke helt efter hensigten.
Er der en anden måde at gøre det på. Og vil det gøre hele siden sløv hvis alt skal krypteres/dekrypteres hele tiden?

Dim myRijndael As New RijndaelManaged()

            ' Encrypt the string to an array of bytes.
            Dim encrypted As Byte() = encryptStringToBytes_AES(original, myRijndael.Key, myRijndael.IV)

            ' Decrypt the bytes to a string.
            Dim roundtrip As String = decryptStringFromBytes_AES(encrypted, myRijndael.Key, myRijndael.IV)

            'Display the original data and the decrypted data.
            'TextBox1.Text = encrypted
            'TextBox2.Text = roundtrip
            Dim str As String
            For i = 0 To encrypted.Length - 1
                str = str & (encrypted(i))
            Next
Function encryptStringToBytes_AES(ByVal plainText As String, ByVal Key() As Byte, ByVal IV() As Byte) As Byte()
        ' Check arguments.
        If plainText Is Nothing OrElse plainText.Length <= 0 Then
            Throw New ArgumentNullException("plainText")
        End If
        If Key Is Nothing OrElse Key.Length <= 0 Then
            Throw New ArgumentNullException("Key")
        End If
        If IV Is Nothing OrElse IV.Length <= 0 Then
            Throw New ArgumentNullException("Key")
        End If
        ' Declare the streams used
        ' to encrypt to an in memory
        ' array of bytes.
        Dim msEncrypt As MemoryStream = Nothing
        Dim csEncrypt As CryptoStream = Nothing
        Dim swEncrypt As StreamWriter = Nothing

        ' Declare the RijndaelManaged object
        ' used to encrypt the data.
        Dim aesAlg As RijndaelManaged = Nothing

        ' Declare the bytes used to hold the
        ' encrypted data.
        Dim encrypted As Byte() = Nothing

        Try
            ' Create a RijndaelManaged object
            ' with the specified key and IV.
            aesAlg = New RijndaelManaged()
            aesAlg.Key = Key
            aesAlg.IV = IV

            ' Create a decrytor to perform the stream transform.
            Dim encryptor As ICryptoTransform = aesAlg.CreateEncryptor(aesAlg.Key, aesAlg.IV)

            ' Create the streams used for encryption.
            msEncrypt = New MemoryStream()
            csEncrypt = New CryptoStream(msEncrypt, encryptor, CryptoStreamMode.Write)
            swEncrypt = New StreamWriter(csEncrypt)

            'Write all data to the stream.
            swEncrypt.Write(plainText)

        Finally
            ' Clean things up.
            ' Close the streams.
            If Not (swEncrypt Is Nothing) Then
                swEncrypt.Close()
            End If
            If Not (csEncrypt Is Nothing) Then
                csEncrypt.Close()
            End If
            If Not (msEncrypt Is Nothing) Then
                msEncrypt.Close()
            End If
            ' Clear the RijndaelManaged object.
            If Not (aesAlg Is Nothing) Then
                aesAlg.Clear()
            End If
        End Try
        ' Return the encrypted bytes from the memory stream.
        Return msEncrypt.ToArray()

    End Function


    Function decryptStringFromBytes_AES(ByVal cipherText() As Byte, ByVal Key() As Byte, ByVal IV() As Byte) As String
        ' Check arguments.
        If cipherText Is Nothing OrElse cipherText.Length <= 0 Then
            Throw New ArgumentNullException("cipherText")
        End If
        If Key Is Nothing OrElse Key.Length <= 0 Then
            Throw New ArgumentNullException("Key")
        End If
        If IV Is Nothing OrElse IV.Length <= 0 Then
            Throw New ArgumentNullException("Key")
        End If
        ' TDeclare the streams used
        ' to decrypt to an in memory
        ' array of bytes.
        Dim msDecrypt As MemoryStream = Nothing
        Dim csDecrypt As CryptoStream = Nothing
        Dim srDecrypt As StreamReader = Nothing

        ' Declare the RijndaelManaged object
        ' used to decrypt the data.
        Dim aesAlg As RijndaelManaged = Nothing

        ' Declare the string used to hold
        ' the decrypted text.
        Dim plaintext As String = Nothing

        Try
            ' Create a RijndaelManaged object
            ' with the specified key and IV.
            aesAlg = New RijndaelManaged()
            aesAlg.Key = Key
            aesAlg.IV = IV

            ' Create a decrytor to perform the stream transform.
            Dim decryptor As ICryptoTransform = aesAlg.CreateDecryptor(aesAlg.Key, aesAlg.IV)

            ' Create the streams used for decryption.
            msDecrypt = New MemoryStream(cipherText)
            csDecrypt = New CryptoStream(msDecrypt, decryptor, CryptoStreamMode.Read)
            srDecrypt = New StreamReader(csDecrypt)

            ' Read the decrypted bytes from the decrypting stream
            ' and place them in a string.
            plaintext = srDecrypt.ReadToEnd()
        Finally
            ' Clean things up.
            ' Close the streams.
            If Not (srDecrypt Is Nothing) Then
                srDecrypt.Close()
            End If
            If Not (csDecrypt Is Nothing) Then
                csDecrypt.Close()
            End If
            If Not (msDecrypt Is Nothing) Then
                msDecrypt.Close()
            End If
            ' Clear the RijndaelManaged object.
            If Not (aesAlg Is Nothing) Then
                aesAlg.Clear()
            End If
        End Try
        Return plaintext

    End Function