I guess the privacy advantage of a regular SIM is that as soon as you pop out the sim card out of your phone, towers can't track you anymore.
With eSIMs on the other hand, I can never truly trust that an eSIM is de-activated? Feels like you actually just have a permanent sim card in your phone and your phone can just be tracked no matter the status of your eSIM.
Or is this not technically possible?
One of the suspects in the Bali bombings was caught because while they frequently changed Sims, they didn't change devices. They were tracked by the IMEI.
That's correct. Iphones are especially vulnerable to that since they don't shut down all the way and always keep some radios enabled. Android devices will generally shut down properly.
But in any case, do you really need to worry about tracking by a carrier? Locating a phone is possible but not easy and usually only happens when it's specifically requested by the police.
If that's your threat level, you probably don't want to own a phone at all.
The SIM is just an identifier. There's nothing particularly special on a SIM card, that's why the switch to eSIM has happened so seamlessly. So, you're right; it's totally POSSIBLE that an eSIM could stick around if you delete. But it's also possible that your phone could save the info on a SIM card.
For the record, I don't think that's likely. Your phone's operating system (iPhone or Android) is built by a different company than the carriers that presumably want to track you. I doubt they're secretly colluding with carriers, because Apple and Google (especially Google) have enormous business models built around tracking you, and profiting off your data.
If a phone can track you with a deactivated eSIM then it can also track you without a SIM, by just also giving you a secret eSIM for use when your regular SIM is missing, and then simply lying to you about it.
I remember reading that for custom ROM developers it's complicated (or even not possible?) to implement eSIM support because the use of it requires google services.
As I understand it, it is not impossible, just too much effort to register an esim without google services. However, once registered, they are not needed anymore. So one solution is to register the esim on stock android before installing a custom ROM.
GrapheneOS has an even better solution where you can temporarily install google services in userspace and give them control of the esim module to register an esim and then remove the access and optionally uninstall them.
Afaik simcards run a simplified version of Java that has full hardware access and can be updated remotely. I don't see how it can possibly get any worse than that.
I'm no expert in the matter however this is what I understand from it.
Chips like the one in your debit card are fully fledged computers and do run software. When you plug it into something it receives power and interfaces with the other system. That's why it is secure, because like a pc it can use encryption etc.
Come to think of it, they must also be able to run with the low power provided by near field transmission, aka contactless payment.
Anyhoots the same kinda chip is on a simcard.
As far as I understand it they run a more limited version of Java, has full access to your hardware including being able to read all memory, and being updatable remotely.
You might also be interested to know that modern hardware commonly has such secondary computers with full access built in. Take the intel management engine for example, which is part of every modern intel cpu. However there are privacy oriented companies that disable these.
The real question is who has access to these things and what are their interests. It might not necessarily be a malevolent actor. It's one of the challenges of our time to answer questions related to these topics.
Nope, they are computers that run a Java-based OS.
If we want to talk about smartcards in general (contactless, chip-based, dongle-based) some of them only store/retrieve data, some only store a single unchangeble identifier, but others like banking cards & transit cards tend to run a small operating system that you can talk to, and even run applications on.
With a cheap USB card reader, you can actually interact with the operating system on a chip-based bank card using Linux
The only thing it improves is data security which can in some extent resist against identity theft, financial fraud, etc.
Does having an eSIM card improve my data security?
Yes, there are significant security benefits. An eSIM card cannot be stolen without stealing the phone, whereas removable SIM cards are sometimes stolen, and used in port out scams. That's when identity thieves fraudulently swap stolen SIM cards into different phones to gain access to the victim’s calls and text messages. The thieves may then try to reset credentials and gain access to the victim's financial and social media accounts.