Your smartphone knows where you’ve been – and that’s a problem

Oliver Herren

30-7-2025

Translation: Elicia Payne

Whether you’re driving to work, going to the gym or spending a Friday night in your favourite bar, your location reveals more about you than you think.

Everyone who uses a smartphone discloses endless data every day – often unknowingly. The particularly controversial one? Location data. According to a recent analysis by ETH Zurich, this is digital gold for data traders and cyber criminals. It not only reveals where you live and work, but also how you spend your free time, which doctors you visit or what political beliefs you might have.

Location data is digital gold

«I have nothing to hide.» Ever heard this sentence before? Maybe you said it yourself. Sounds logical: if you do nothing illegal, you have nothing to fear. But the argument is deceptive. Because it’s not about whether you have something to hide. It’s about what happens to the information you disclose.

Location data’s particularly valuable because it’s very personal. It not only reveals where you’ve been, but also how you lead your life. Your movement profile shows:

• Where you live and work.
• Whether you go to the gym regularly or prefer to go to the pub.
• Which doctors’ surgeries you visit.
• Whether you have a preference for expensive restaurants or fast food chains.

Data brokers use this information to create a detailed profile from your movements. This allows them to analyse your interests and habits – and sell this information at a high price.

From harmless to sensitive: why location data’s dangerous

In a perfect world, companies would only use our data for harmless purposes, such as personalised advertising. The reality is different. Location data can be used for much more problematic things. Insurance companies could charge customers higher rates if they regularly visit risky locations. Financial service providers could draw conclusions about your creditworthiness based on your place of residence. Your movement data could be analysed in order to tailor targeted election advertising or even disinformation to you. Scammers could use your behaviour pattern to manipulate you.

And all this without you ever saying «yes».

AI makes it even worse

You might be thinking: «Well, my location data isn’t accurate.» That’s right – GPS data often has an error tolerance of several metres. But AI models are now so good that they can still recognise reliable patterns from noisy data.

Researchers have shown that even location data with an error of 100 metres is enough to predict your behaviour ten times more accurately than pure guesswork. The data only loses its value when it’s distorted by more than one kilometre.

How to protect yourself

The good news? You’re not completely powerless. Here are some simple steps to better protect your location data:

1. Minimise location access: disable location services for apps (Apple, Android) that don’t necessarily need it.
2. Manually manage sharing: with some apps, you can just share the location for one session instead of permanently.
3. Restrict data sharing: check your app settings and deactivate personalised advertising.
4. Be informed, not indifferent: those who know the risks act more consciously. Talk to friends and family about it.

Everyone has something to hide

Even if you follow all the rules, you have a right to privacy. Your location is a reflection of your life and shouldn’t be easily given away. Companies and data traders have long recognised how valuable this information is. It’s up to us not to serve them everything on a silver platter.

Perhaps it’s time to remove the phrase «I have nothing to hide» from our vocabulary once and for all.

You can also find a good overview of how data tracking and trading works on SRF. I can recommend SRF Hintergrund’s podcast Die Cookiefalle as a starting point (links in German).

Oliver Herren

Chief Innovation Officer

Oliver.Herren@digitecgalaxus.ch

Cool: Creating interfaces between the real world and the world of pure information. Not cool: Driving by car to the mall to shop. My life happens online, the information age is where I feel at home.

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