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Comment by slimsag | Hacker News Reader

Also, make sure your TLS certificates are hard-coded/pinned in your application binary. Just like the network, you really cannot trust what is happening on the user's system.

This way you can ensure you as the developer have full control over your applications' network communication; by requiring client certificates issued by a CA you control, you can assert there is no MITM even if a sysadmin, user, or malware tries to install a proxy root CA on the system.

Finally, you can add binary obfuscation / anticheat mechanisms used commonly in video games to ensure that even if someone is familiar with the application in question they cannot alter the certificates your application will accept.

Lots of e.g. mobile banking apps, etc. do this for maximal security guarantees.

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In practice pinning tends to be very "best effort", if not outright disadvantageous.

All our apps had to auto-disable pinning less than a year after the build date, because if the user hadn't updated the app by the time we had to renew all our certs... they'd be locked out.

Also dealt with the fallout from a lovely little internet-of-things device that baked cert pinning into the firmware, but after a year on store shelves the clock battery ran out, so they booted up in 1970 and decided the pinned certs wouldn't become valid for ~50 years :D

Pinning is very complex, there is always the chance that you forget to update the pins and perform a denial of service against your own users. At the point where the device itself is compromised, you can’t really assert to anything. Furthermore, there is always the risk that your developers implement pinning incorrectly and introduce a chain validation failure.

Lots of apps use the anticheat/obfuscation mechanisms added by mobile apps are also trivial to bypass using instrumentation - ie frida codeshare. I know you aren’t implying that people should use client side controls to protect an app running on a device and an environment that they control, but in my experience even some technical folk will try and to do this

At some point you have to wonder if your app even matters that much.

The App probably not. The server maybe, the data probably.

This is way overkill, unless you are making a nuclear rocket launch application. If you can not trust the system root CA, the whole internet breaks down.

You will also increase the risk that your already understaffed ops-team messes up and creates even worse exposure or outages, while they are trying to figure out what ssl-keygen does.

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