Securing Fax over IP for Business Communications

The recent controversy regarding NSA tracking of phone conversations has elevated concerns about security and privacy for business communications. Enterprises generally want to keep their communications private. Use of techniques such as private networks, firewalls and secured tunnels can help to protect internal communication from eavesdroppers, but there are also many exchanges which entail communication with third parties over public networks.

Facsimile is best known as a method of communicating images of printed pages over the Public Switched Telephone Network (PSTN) and many fax companies touted the PSTN as being much more secure than the public Internet, hence reducing the need for formal security approaches. But the circuit-switched network is rapidly being replaced by hybrid and all-IP networks, and a portion of business fax traffic is now sent over the Internet.

During the Nineties, the fax standards experts in the International Telecommunications Union (ITU-T) added annexes to the Group 3 fax T.30 protocol to protect against a variety of security threats. However, there was lack of consensus on how to proceed, so two different approaches were standardized. As attention turned to standardizing fax over higher speed V.34 links and over IP networks, the initial efforts to implement fax security using the new standard approaches fizzled out and never got traction in the marketplace.

Fast forward to 2013. Security and privacy now have a much higher profile. The NSA exposé and other security glitches like the Wikileaks exposures of government and corporate documents have increased awareness of the down side of unsecured documents and communication. In the meantime, as the phone network is being replaced by IP technology, most new sales of fax to the enterprise are for Fax over IP and the T.38 standard from the ITU is frequently used. Most applications of T.38 use a transport protocol called UDPTL (User Datagram Protocol Transport Layer) which is currently an unsecured protocol.

The conventional wisdom might have a “who cares?” attitude, since there’s a common perception that nobody uses fax anymore. However, fax still is used a great deal for a wide variety of business applications which include healthcare, financial and legal organizations, plus fax is integrated into a variety of business processes. Fax is also used for transmission of many normally confidential documents such as insurance claims, real estate transactions and legal notices, plus there are regulations such a HIPAA in the health care domain which require protection of documents from third parties.

For all of these reasons, the need for better security solutions for IP-based facsimile is becoming clear. In another realm of standardization, WebRTC is attracting a lot of attention as a next generation method for performing a wide variety of real time communications such as video and voice over web protocols. The original applications of the Session Initiation Protocol (SIP) were often implemented with little attention paid to security, so the WebRTC standards activities have examined the best approaches for addressing matters such as security and are recommending use of a relatively new security protocol known as Datagram Transport Layer Security (DTLS) to secure real time communications of media within WebRTC.

One advantage of DTLS is that it is relatively protocol agnostic and can be applied as a security layer for various different protocols. So this is a good time to consider how protocols planned for use in WebRTC might also have other applications. The Third Generation Partnership Program (3GPP) has recognized that IP fax is still an important application and wants to have a standard approach to secure faxes which are being transported over IP networks. As a result, there is now an Internet Draft being circulated for comments within the MMUSIC (Multiparty Multimedia Session Control) working group of the Internet Engineering Task Force (IETF) which proposes that DTLS be established as a transport layer that can be used to secure sessions of T.38 IP fax when running over the SIP protocol.

I’m personally enthusiastic about this direction and have made comments on the current draft. I find it ironic that the IETF is looking at adding security layer support to an ITU protocol, but in the world of standards, it’s useful for the work to be done by the experts who have the right domain expertise. In this case, the IETF created DTLS and there is interest in the combination of UDPTL and T.38 from the Fax over IP task group of the SIP Forum, so there is probably enough participation by the Internet and fax communities to produce a useful standard. At this writing, MMUSIC is considering adoption of this draft as an official working group item.

Stay tuned on this one. WebRTC is training a generation of engineers to use a new toolkit of various protocols, so the potential adoption of DTLS by the IP fax community may be a harbinger of a trend to re-purpose various components of the WebRTC initiative in innovative and surprising ways.