// set user name (same as used to login to the portal)
RSCPData authUser = RSCPData.builder()
        .tag(RSCPTag.TAG_RSCP_AUTHENTICATION_USER)
        .stringValue(user)
        .build();

// add password (same as used to login to the portal)
RSCPData authPwd = RSCPData.builder()
        .tag(RSCPTag.TAG_RSCP_AUTHENTICATION_PASSWORD)
        .stringValue(password)
        .build();

// combine user/password into a authentication request container
RSCPData authContainer = RSCPData.builder()
        .tag(RSCPTag.TAG_RSCP_REQ_AUTHENTICATION)
        .containerValues(Arrays.asList(authUser, authPwd))
        .build();

// put the authentication request into a frame
RSCPFrame authFrame = RSCPFrame.builder()
        .addData(authContainer)
        .timestamp(Instant.now())
        .build();

// get byte array ready to be encrypted and sent to the server
byte[] frame = authFrame.getAsByteArray();

// assuming we have the response byte array in byte[] response...
RSCPFrame frame = RSCPFrame.builder()
        .buildFromRawBytes(response);

// get the contents of the frame
List<RSCPData> dataList = frame.getData();
// an authentication response contains a single data set with the authentication level
// as CHAR8 value which fits into a Java short
RSCPData authData = dataList.get(0);
// read optional short (will be empty if the data cannot be expressed as short)
Optional<Short> authLevel = authData.getValueAsInt();