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    #1 
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\begin{document}


        
\begin{slide}
\begin{center}
\LARGE{{\bf}DTLS 1.2 Status}\\

\vspace{.3 in}
\large{Eric Rescorla}\\
\large{RTFM, Inc.}\\
\large{\texttt{ekr@networkresonance.com}}
\end{center}
\end{slide}


\begin{slide}
\heading{Current State}

\begin{itemize}
\item New draft: \url{draft-ietf-tls-rfc4347-bis-01.txt}
\item[]
\item Defined handling of invalid cookies
\item Fixed state machine for lost last flight
\item Clarified buffering of out of order packets
\item Editorial 
\end{itemize}

\end{slide}



\begin{slide}
\heading{Handling of Invalid Cookies}

\begin{itemize}
\item Issue raised by Pasi Eronen
\item Just dropping the \textsf{HelloRequest} creates deadlocks
\begin{itemize}
\item For instance, what happens is server changes keys
\end{itemize}
\item Resolution: treat as missing cookie
\end{itemize}
\end{slide}



\begin{slide}
\heading{Lost Last Flight}

\begin{minipage}[t]{2.5in}
\begin{itemize}
\item Issue raised by Robin Seggelman
\item What happens if the last flight is lost
\begin{itemize}
\item Other side retransmits
\item Does the sender retransmit?
\end{itemize}
\item Fixed state machine
\begin{itemize}
\item Required to hold last flight for 2MSL
\item Immediate retransmit in response to receive retransmit
\end{itemize}

\end{itemize}
\end{minipage}
\begin{minipage}[t]{1.5in}
\begin{verbatim}
  +-----------+                 
  |           |                 
  | FINISHED  | 
  |           |
  +-----------+
       |  /|\
       |   |
       |   |
       +---+

    Read retransmit
 Retransmit last flight
\end{verbatim}
\end{minipage}
\end{slide}



\begin{slide}
\heading{Buffering of Out of Order Packets (I)}

\vspace{-.2 in}
\begin{itemize}
\item Issue raised by Michael Tuexen
\item What happens about packets received before \textsf{Finished}
\begin{itemize}
\item Packet drops
\item Reordering
\end{itemize}
\item Clarified text to encourage buffering for reliable transports
\end{itemize}

{\small
\begin{verbatim}
                          Implementations MAY either buffer or
discard such packets, though when DTLS is used over reliable
transports (e.g., SCTP), they SHOULD be buffered and processed once
the handshake completes.  Note that TLS's restrictions on when
packets may be sent still apply, and the receiver treats the packets
as if they were sent in the right order.  In particular, it is still
impermissible to send data prior to completion of the first
handshake.
\end{verbatim}
}
\end{slide}


\begin{slide}
\heading{Buffering of Out of Order Packets (II)}

\begin{itemize}
\item Issue raised by Michael Tuexesn
\item What about reordering in rehandshakes?
\item There is potential for glitches in dataflow
\begin{itemize}
\item Data sent with new epoch
\item But not ready until \textsf{CSS}, \textsf{Finished} received
\end{itemize}
\item Proposal: implementations MAY accept packets before receiving
\textsf{CSS}, \textsf{Finished}
\begin{itemize}
\item Major vulnerability here is downgrade attack
\begin{itemize}
\item Epoch mostly replaces \textsf{ChangeCipherSpec}
\end{itemize}
\item SHOULD only do this during rehandshake?
\end{itemize}
\end{itemize}
\end{slide}


\begin{slide}
\heading{Trajectory}

\begin{itemize}
\item New version shortly
\item Hopefully get more input
\item Last call before PHL?
\end{itemize}

\end{slide}



\end{document}