Mark Beech

2021-02-22: Redjacking

Over the weekend I was talking to a colleague about his patent pending system that uses IrDA/LiFi technologies, and it reminded me of a thing that happened long ago when in 2004 myself and a fellow University of Glamorgan student invented ‘redjacking’.

At the time Bluetooth was a new magic that was just starting to be included in mobile phones, and as more and more people were acquiring these bluetooth enabled phones (and not switching it off) the media popularized a new crazy called “Bluejacking”.

For more information on the phenomenon there is a wikipedia article but in simple terms it involved someone with a suitable phone creating a new contact with their message body as the contacts name and then using the send function to find another BT enabled phone to send it to unsolicited. The second party would get a notification of the incoming connection which would included the name / message payload. I witnessed the activity a few times on Valley Lines trains when the victim second party would typically look around confused.

A development in Bluejacking involved sending photos, but as they were not displayed until accepted and downloaded it was not so practical. If the media were top be believed it was frequently used to send explicit images and to arrange sexual encounters; but I never witnessed any of that.

So back to my part in this story, back then I did not have a phone with Bluetooth as it was an expensive new magic technology. I was rocking a Sony Ericsson T310, and whilst it did not have BT it did feature IrDA; a feature I often used with my PC to send SMS from a full sized keyboard.

At the time many laptops were fitted with IrDA, but needed to be actively switched into receive mode, so rather than the anonymous trolling that was possible with Bluejacking Redjacking required the consent of both parties – oh and a line of sight also.

So in one particularly boring class I worked out where to position my phone so it had a LoS to my friend’s laptop the other side of the room, and then proceeded to pass a few messages and memes (back then known as pictures) through the either.

Such a feat would have been completely unremarkable but for the media’s crazy over Bluejacking at the time leading to the obvious portmanteau of Redjacking.

Nowadays Bluetooth is better locked down, and infrared is practically extinct in consumer electronics limiting the opportunity for such fun, which is kind of sad.