When asked why he doesn't visit his local university or library to satisfy that desire, he answered, `in books, you only learn theory. It is not that I dislike the theory but computer security in real life is much different from theory'. Libraries also have trouble keeping pace with the rate of technological change, SKiMo said. `Possibly, it is also just the satisfaction of knowing that what I learn is proprietary—is "inside knowledge",' he added. There could, he said, be some truth in the statement that he likes learning in an adrenalin-inducing environment.
Is he addicted to computers? SKiMo says no, but the indications are there. By his own estimate, he has hacked between 3000 and 10000 computers in total. His parents—who have no idea what their son was up to day and night on his computer—worry about his behaviour. They pulled the plug on his machine many times. In SKiMo's own words, `they tried everything to keep me away from it'.
Not surprisingly, they failed. SKiMo became a master at hiding his equipment so they couldn't sneak in and take it away. Finally, when he got sick of battling them over it and he was old enough, he put his foot down. `I basically told them, "Diz is ma fuckin' life and none o' yer business, Nemo"—but not in those words.'
SKiMo says he hasn't suffered from any mental illnesses or instabilities—except perhaps paranoia. But he says that paranoia is justified in his case. In two separate incidents in 1996, he believed he was being followed. Try as he might, he couldn't shake the tails for quite some time. Perhaps it was just a coincidence, but he can never really be sure.
He described one hacking attack to me to illustrate his current interests. He managed to get inside the internal network of a German mobile phone network provider, DeTeMobil (Deutsche Telekom). A former state-owned enterprise which was transformed into a publicly listed corporation in January 1995, Deutsche Telekom is the largest telecommunications company in Europe and ranks number three in the world as a network operator. It employs almost a quarter of a million people. By revenue, which totalled about $A37 billion in 1995, it is one of the five largest companies in Germany.
After carefully researching and probing a site, SKiMo unearthed a method of capturing the encryption keys generated for DeTeMobil's mobile phone conversations.
He explained: `The keys are not fixed, in the sense that they are generated once and then stored in some database. Rather, a key is generated for each phone conversation by the company's AUC [authentication centre], using the "Ki" and a random value generated by the AUC. The Ki is the secret key that is securely stored on the smart card [inside the cellphone], and a copy is also stored in the AUC. When the AUC "tells" the cellphone the key for that particular conversation, the information passes through the company's MSC [mobile switching centre].
`It is possible to eavesdrop on a certain cellphone if one actively monitors either the handovers or the connection set-up messages from the OMC [operations and maintenance centre] or if one knows the Ki in the smart card.
`Both options are entirely possible. The first option, which relies on knowing the A5 encryption key, requires the right equipment. The second option, using the Ki, means you have to know the A3/A8 algorithms as well or the Ki is useless. These algorithms can be obtained by hacking the switch manufacturer, i.e. Siemens, Alcatel, Motorola …
`As a call is made from the target cellphone, you need to feed the A5 key into a cellphone which has been modified to let it eavesdrop on the channel used by the cellphone. Normally, this eavesdropping will only produce static—since the conversation is encrypted. However, with the keys and equipment, you can decode the conversation.'