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Comment by Nextgrid | Hacker News Reader

> with redundant power, cooling, etc

The doors the system controls don't have any of this. Hell, the whole building doesn't have any of this. And it definitely doesn't have redundant internet connections to the cloud-based control plane.

This is fear-mongering when a passive PC running a container image on boot will suffice plenty. For updates a script that runs on boot and at regular intervals that pulls down the latest image with a 30s timeout if it can't reach the server.

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What updates? That would be on a local network and have no internet connection, if done right.

And? That doesn't mean, especially for a system with security impact (like door access), that it should never be updated.

I am guessing the main attraction of such a system is that owners can set the cards remotely and get data about it (ie: who accessed and when)

Those devices can be trivially power cycled, and won’t have as many issues with dodgy power. Some PC somewhere with storage is a bigger problem.

> Some PC somewhere with storage is a bigger problem

Both an embedded microcontroller and a PC have storage. The reason you can power-cycle a microcontroller at will is because that storage is read-only and only a specific portion dedicated to state is writable (and the device can be reset if that ever gets corrupted).

Use a buildroot/yocto image on the PC with read-only partitions and a separate state partition that the system can rebuild on boot if it gets corrupted and you'll have something that can be power-cycled with no issues. Network hardware is internally often Linux-based and manages to do fine for exactly this reason.

PCs are orders of magnitude more complex, with a lot more to break. Sounds like a whole lot of work for… what?

Assuming the internet connection and AWS work of course. Which they won’t always, then oops.

If you're relying on AWS you either way have a "PC" to relay communication between AWS and the keycard readers & door latches.

There are IoT libraries that don’t require that.

A large number of embedded micro controllers are just PCs running Yocto linux configured as GP said. You can save money with a $.05 micro controller, but in most cases the development costs to make that entire system work are more than just buying an off the shelf raspberry pi.

You know what else would suffice plenty? Physical keys and mechanical locks. They worked (and still work) without electricity. The tech is mature and well-understood.

The reason for moving away from physical keys is that key management becomes a nightmare; you can't "revoke" a key without changing all the locks which is an expensive operation and requires distributing new keys to everyone else. Electronic access control solves that.

You might find Matt Blaze's paper on vulnerabilities in master-keyed physical locks interesting:

https://eprint.iacr.org/2002/160.pdf

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