When revelations about the US spying program 'Prism' had been causing a great stir for a week already, US President Barack Obama stepped in and tried to calm everybody down. In a TV interview he said the American secret service NSA (National Security Agency) consisted of "extraordinary professionals; they are dedicated to keeping the American people safe." But those extraordinary professionals are not tasked with analyzing the data - that's the job of computers. That's why the list of suspicious people does not just consist of terrorists. Ordinary people end up on it, too.

For you to become a target of the intelligence agencies it's enough if you have a neighbor who pursues suspicious activities, said Markus Beckedahl, an internet expert with German blog netzpolitik.org. "Your mobile phone will often be in use near where your neighbor uses his. That creates a certain pattern and it makes you suspicious, too." If your profile accidentally overlaps with others' that will also cause suspicion, for instance "if there's a terrorist somewhere who happens to order the same books as you and surf on the same websites," explained Beckedahl.

Links between people are the new keywords

Following the September 11 attacks in 2001, many political scientists were falsely suspected because as part of their job they conducted online searches about the Arab World. Since then, US intelligence agencies have not only seen a major budget increase, they have also improved their search methods. "People who are actually preparing a terror attack will neither communicate names, nor target areas nor their organization. That's why the agencies no longer focus on the content of communication - what has A said to B – but rather on communication patterns," said Wolfgang Krieger, an expert on intelligence agencies. The links between people are now the focus - in social networks but also in terms of money transfers through banks or via mobile phone connections.

There are reports that NSA and the British secret service GCHQ are capable of processing an exabyte of data. An exabyte is one billion gigabytes. Storage space is becoming cheaper, and internet expert Markus Beckedahl assumes that enormous amounts of data are already being stored permanently. Permanent storage, however, increases the risk that links can be established between individual people that result in a suspicious profile, he added.

Entry made difficult - not just into the US

"But you'll only find out about it when you can't access certain mobile phone tariffs any more simply because it's a provider that would have made it more difficult to eavesdrop on your phone talks - or when you're denied entry into the US because you're on a so-called ‘no-fly-list'," said Markus Beckedahl. There have been many cases where US bound planes were suddenly denied landing because they had a passenger on board whose name was on the secret ‘no fly list' - which means they're denied entry to the US. The most prominent example in recent times was singer Cat Stevens who a few years ago took on the name Yusuf Islam.

In Europe, customs controls are often a place for travelers to find out about data transfers they had no idea about. "I know people who took part in the protests against nuclear waste transports in Germany and who are thoroughly checked every time they are trying to enter England," said Markus Beckedahl. That's because on the one hand, environmental protests border on acts of terrorism in Britain and on the other because there is an international exchange on those activists.