Datagram Transport Level Security - DTLS

With the never ending onslaught of mobile technology and greater security awareness, I though it might be interesting to look at Datagram Transport Level Security (DTLS). The two main methods of securing internet communication are Transport Level Security (TLS) and IPSec. TLS is most obvious for its implementation in securing HTTP traffic i.e. HTTPS but is also used in other areas such as for secure IMAP and SMTP. Its main limitation is that it requires a reliable transport channel, normally TCP and hence is unsuitable for UDP traffic which today includes Voice Over IP and several gaming protocols. IPSec is suitable for UDP traffic but its implementation is far more complicated than TLS as it is designed for peer to peer communication rather than client server.

This led to the emergence of DTLS which as the name suggests is Transport Level Security with UDP as the transport channel. A very readable paper on its detail can be found here.

One widely available implementation of DTLS is Cisco’s Anyconnect Secure Mobility client. It doesn’t appear to follow the full goals of DTLS as the key exchange and handshaking is established over TLS which results in two channels needing to be maintained.

With the emerging popularity of VoIP clients on smart phones, I expect we shall be hearing more about DTLS over the coming months.