Our everlasting digital trails

Professor Raphael Phan

Facebook's Mark Zuckerberg recently published a post about his privacy-focussed vision for social networking.

Facebook currently also owns Instagram and WhatsApp, so this vision is likely to shape how we interact with our friends and family on social media in the near future.

The privacy-focused vision includes the so-called “permanence problem”, which is something we can't avoid with anything digital.

We humans naturally exist in this world for a finite period of time, yet traces of what we do could potentially remain ad infinitum. Physicists would say that we leave traces behind wherever we are, because as beings of matter, we necessarily interact with, and affect other matter in the physical realm.

In fact, our society now is such that we engage with others not just physically, but also virtually through cyberspace - via the Internet, social media, and instant messaging. These digital trails are even more perpetual, because unlike the physical world whose substances deteriorate over time, digital objects are unchanging. They can in fact be duplicated to produce identical copies.

This means that photos or videos we share digitally, could last forever in exactly the same detail and quality, as when they were first shared years ago. This so-called permanence aspect of the digital realm is why privacy advocates caution Internet users to be careful when posting any information online.

For instance, it has been reported that interviewers tend to trawl social media for personal information about job applicants. Some candidates were rejected based on inappropriate postings or even things they were involved in many years ago. It is true that teenagers do all kinds of things that they eventually grow out of; yet these past actions shouldn't really be used to assess them in their later stages of life.

So it's quite timely that social media giants such as Facebook have now made this digital permanence problem, their top priority. Actually, it's not the first to do so.

Snapchat emerged as a distinctive messaging app precisely because it highlighted itself as the solution to the digital everlasting problem - let messaging be ephemeral. Being ephemeral is a cool feature. It means that messages come with a default expiry, they automatically disappear after being viewed. Basically they self-destruct.

This addresses the permanence problem, and in essence, is fit for purpose - the aim of messaging is to communicate a message instantaneously to another.  Once it's been communicated, there is little reason for it to remain.  Analogously, once we've spoken and the intended listener has heard it, there is no point for it to be recorded for perpetual future playbacks.

The ephemeral solution is one way to solve the digital permanence problem. It ensures that what we've said during a specific conversation, cannot later be used against us in future situations.

Another solution to this digital everlasting problem is “off-the-record” messaging.  This idea was conceived by a team of researchers led by UC Berkeley. The enabling technology is based on the notion of deniable authentication, which is itself an intriguing concept.

Imagine during a conversation that your listener is convinced beyond any doubt, that it is really you speaking to him/her.  Yet after the conversation, s/he can't convince someone else that you said what you had said during that conversation. That is the gist of deniable authentication. So with this added feature, it means that during a messaging conversation, your recipient will know the message was sent by you. However, he/she will not be able to prove to anyone else that it was you who said it.

These solutions - ephemeral messaging, off-the-record messaging - safeguard privacy in face of the permanence problem.  Let messages from someone no longer exist or no longer be linked to that someone, after they have served their purpose; which makes perfect sense.  Indeed, when it comes to safeguarding privacy, we ought do no more than what is necessary.


Raphael Phan is a Professor at Monash University, and has a passion for problems caused by nosey individuals.