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Security Bits — 21 June 2026

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A tip from Joop

This is not actually a listener question, but I’m gonna bend the rules a little 🙂

Nosillacastaway Joop asked if I’d seen the new open source iOS app Loupe, which shows all the data your iPhone makes available to apps (I had, but hadn’t taken the time to actually install it yet).

Inspired by Joop’s reminder, I installed it immediately and started exploring!

The app is free and open source, and extremely transparent about what it does and how it does it, and with good reason! The information it reveals is more than a little thought-provoking!

What the app does is show you every piece of information every iOS API makes available to apps installed on your device. Both the information apps can access without permission promts, and then with permission prompts.

The information is grouped by category, and by permission prompt, making it clear what extra information each prompt is protecting.

After spending quite some time exploring what the apps I choose to install onto my phone can access (if their developers choose to call the relevant APIs), I have some thoughts!

  1. Those annoying prompts are really important, they are protecting some very sensitive data!
  2. Apple have done their best to limit the data available to apps without additional permission to just what’s needed to facilitate the kinds of rich apps we expect on our iPhones. There was nothing that made me think “why on earth would you expose that!”
  3. The information available without additional permissions is directly concerning from a privacy point of view — there’s no way for developers to directly link your phone to you, the person.
  4. However, when you collect all the individually innocuous data points together, you can build a robust fingerprint, enough to be used as a so-called super cookie by unscrupulous developers. could sell to data brokers who could then start connecting the dots across every unscrupulous app you have installed!
    • The risk from these fingerprints generally doesn’t come from an individual developer using it to join the dots between your activities on two of their apps (there are simpler, more direct ways of doing that, like having you log in with the same account!)
    • The risk comes from data brokers and ad networks paying developers to share your data with them. This is how free apps generate income!
  5. The information being exposed without granting extra permissions is absolutely anonymous, so when you read an App Store nutrition label, and it says the app sends data “not associated with you”, it’s almost certainly sending a fingerprint to one or more data brokers as a revenue source!
  6. All ad-powered apps and many ad-free free apps declare that they share anonymous information — that’s how they monetise their otherwise free apps!

Thinking about it for just a few seconds, I could see immediately that I have a very unique fingerprint from these utterly sensible and innocuous data points! Apps on my phone can see that I have three keyboard languages installed — en-IE, nl-IE, and ga-IE (English, Dutch, and Irish with an Irish keyboard layout), and that my preferred locale for number and currency formatting is IE (Ireland). Other API calls reveal to apps that I’m currently using an orange iPhone 17 Pro Max with a specific disk capacity, and my current IP address, sampled over time, reveals that I spend most of my time on educational and residential ISPs in the greater Dublin area. How many Irish Orange iPhone 17 Pro Maxes with my storage capacity are there with those language preferences? I’d be prepared to wager there’s exactly one, mine!

There are hundreds of data points. I stand out because of my language preferences, but somewhere, in all those individually mundane data points, we’re all a little bit unusual in our own ways! For example — accessibility features only work well when apps obey them, so the APIs have to reveal your current settings in terms of contrast, animation level, font size, and so on. Of the people who enable at least one accessibility feature, you can rest (un)assured that few other people who share your ISP pattern have exactly those settings!

Do you have even one custom font installed?

I could go on, but you get the idea!

Great apps need these APIs, so Apple have done as much as it is possible to do, but nothing Apple do can change the reality that installing an app is an act of trust!

All in all, this little peek under the covers confirms my strong belief that the only way to avoid being tracked is to follow the money, read those nutrition labels, and pay for apps and services with your money rather than your privacy!

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Legend

When the textual description of a link is part of the link, it is the title of the page being linked to, when the text describing a link is not part of the link, it is a description written by Bart.

Emoji Meaning
🎧 A link to audio content, probably a podcast.
A call to action.
flag The story is particularly relevant to people living in a specific country, or, the organisation the story is about is affiliated with the government of a specific country.
📊 A link to graphical content, probably a chart, graph, or diagram.
🧯 A story that has been over-hyped in the media, or, “no need to light your hair on fire” 🙂
💵 A link to an article behind a paywall.
📌 A pinned story, i.e. one to keep an eye on that’s likely to develop into something significant in the future.
🎩 A tip of the hat to thank a member of the community for bringing the story to our attention.
🎦 A link to video content.

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