Java symmetric encryption - server crushes

[mpampis Osirou]

Hello!
I am trying to make a java client-server application with symmetric encryption!! But I got this error!

This is my while from my server

 while ((inputLine = in.readLine()) != null) {
        AES_Cipher.init (Cipher.DECRYPT_MODE, AES_Key);


plaintext_decrypted = AES_Cipher.doFinal (inputLine.getBytes("UTF-8"));

        System.out.println("Server receive : "+ plaintext_decrypted);
        System.out.println("type message :");
        outputLine = stdIn.readLine();
        out.println(outputLine);
    }

Before I put this line

 plaintext_decrypted = AES_Cipher.doFinal (inputLine.getBytes("UTF-8"));

Everything works. But when I try to decrypt my message the server crushes :/

This is the error

Exception in thread "main" java.net.SocketException: Connection reset
at java.net.SocketInputStream.read(Unknown Source)
at java.net.SocketInputStream.read(Unknown Source)
at sun.nio.cs.StreamDecoder.readBytes(Unknown Source)
at sun.nio.cs.StreamDecoder.implRead(Unknown Source)
at sun.nio.cs.StreamDecoder.read(Unknown Source)
at java.io.InputStreamReader.read(Unknown Source)
at java.io.BufferedReader.fill(Unknown Source)
at java.io.BufferedReader.readLine(Unknown Source)
at java.io.BufferedReader.readLine(Unknown Source)
at Client.main(Client.java:58)

Could someone help me ?

[Richard Tookey]

By reading lines it looks to me like your are treating ciphertext bytes as characters which they are not. Bytes are not characters and Character streams cannot reliably be used to read binary data and ciphertext is most definitely not characters without first using something like Base64 or HEX encoding which you do not seem to be doing. Also, even if you change to using byte streams rather than character streams you cannot use doFinal() on a fragment of the input. You need to use update() on each fragment and then doFinal() when the input is complete. Also, you need to use AES as a stream cipher (yes it is possible to use a block cipher as a stream cipher) and not as a block cipher.

[mpampis Osirou]

Thanks bro I understand it now ;)