[RESOLVED] String properties (base64)

[Skatebone]

Hey guys, I am trying to send data from client to server (encypted) and the string sent from the client is not the same as recieved from the server. I've been killing my brain for hours to get this to work but I cant manage. Im converting everything to Base64 string.

Client:

    Public Sub SendMessage(ByVal msg As String)

        Try
            SyncLock myclient.GetStream
                sw = New IO.StreamWriter(myclient.GetStream)
                sw.Write(enc.EncryptString128Bit(msg, "key"))
                Debug.Print(enc.EncryptString128Bit(msg, "key"))
                sw.Flush()
            End SyncLock
        Catch ex As Exception
            MessageBox.Show("Unable to connect to Server!")
        End Try

    End Sub

Encyption Class:

Public Function EncryptString128Bit(ByVal vstrTextToBeEncrypted As String, _
                                        ByVal vstrEncryptionKey As String) As String

        Dim bytValue() As Byte
        Dim bytKey() As Byte
        Dim bytEncoded() As Byte
        Dim bytIV() As Byte = {121, 241, 10, 1, 132, 74, 11, 39, 255, 91, 45, 78, 14, 211, 22, 62}
        Dim intLength As Integer
        Dim intRemaining As Integer
        Dim objMemoryStream As New MemoryStream()
        Dim objCryptoStream As CryptoStream
        Dim objRijndaelManaged As RijndaelManaged


        vstrTextToBeEncrypted = StripNullCharacters(vstrTextToBeEncrypted)


        bytValue = Encoding.ASCII.GetBytes(vstrTextToBeEncrypted.ToCharArray)

        intLength = Len(vstrEncryptionKey)


        If intLength >= 32 Then
            vstrEncryptionKey = Strings.Left(vstrEncryptionKey, 32)
        Else
            intLength = Len(vstrEncryptionKey)
            intRemaining = 32 - intLength
            vstrEncryptionKey = vstrEncryptionKey & Strings.StrDup(intRemaining, "X")
        End If

        bytKey = Encoding.ASCII.GetBytes(vstrEncryptionKey.ToCharArray)

        objRijndaelManaged = New RijndaelManaged()


        Try

            objCryptoStream = New CryptoStream(objMemoryStream, _
              objRijndaelManaged.CreateEncryptor(bytKey, bytIV), _
              CryptoStreamMode.Write)
            objCryptoStream.Write(bytValue, 0, bytValue.Length)

            objCryptoStream.FlushFinalBlock()

            bytEncoded = objMemoryStream.ToArray
            objMemoryStream.Close()
            objCryptoStream.Close()
        Catch



        End Try


        Return Convert.ToBase64String(bytEncoded)

    End Function

Server:

 Private Sub doRead()

        Dim networkStream As NetworkStream = MyClient.GetStream()
        Do
            Dim readBuffer(Length - 1) As Byte
            Dim bytesRead As Integer = MyClient.GetStream.Read(readBuffer, 0, Length)
            
            Debug.Print(Convert.ToBase64String(readBuffer, Base64FormattingOptions.None, bytesRead))



        Loop
    End Sub

Thanks in advance!

[Sitten Spynne]

You should be using FromBase64String() on the receiving end. You'll also want to decrypt the bytes after doing that.

[Skatebone]

Thanks! I changed as u told me to but still i get nothing :/

Here:

Server:

    Private Sub doRead()

        Dim networkStream As NetworkStream = MyClient.GetStream()
        Do
            Dim readBuffer(Length - 1) As Byte
            Dim bytesRead As Integer = MyClient.GetStream.Read(readBuffer, 0, Length)
            

            Dim b As Byte() = Convert.FromBase64String(System.Text.Encoding.UTF8.GetString(readBuffer, 0, bytesRead))

            Debug.Print(System.Text.Encoding.UTF8.GetString(b))


        Loop
    End Sub

EDIT: Also I noticed that Client is sending 88 bytes of data, Server reading 88 bytes of data but b is returning 64 bytes of data Oo

[Sitten Spynne]

Decoding data needs to work in reverse order of how you encoded it. You aren't paying any attention to detail.

This is how the server encodes the string, ignoring the "strip null chars" step that can't be redone on the other end:

* Convert the string to ASCII bytes.
* Encrypt the bytes using Rijndael.
* Convert the encrypted data to a Base 64 string.

So whatever receives the data has a Base 64 string that represents encrypted bytes that represent an ASCII string. Here's how you decode it:

* Convert the bytes to a string using UTF-8. (Likely correct.)
* Decode the Base 64 string to an array of bytes. (Correct.)
* Convert the bytes to a string using UTF-8. (Incorrect.)

Once you decode from Base 64, what you've got is encrypted bytes. You have to decrypt them, then use ASCII to go from bytes to strings if you want to get the data that was sent. You should be doing this:

* Convert the bytes to a string.
* Decode the Base 64 string to the array of encrypted bytes.
* Decrypt the bytes using Rijndael with the same key and IV used for encryption.
* Convert the bytes to a string using ASCII.

[Skatebone]

Solved! Thanks alot )