[hamburgererror]

Let's admit for a second that the problem around computational cost is solved and using FHE is similar to using plaintext data.

My question might be very naive but I'd like to better understand the impact of FHE, discussions here seem to revolve very much around the use of FHE in ML, but are there other uses for FHE?

For example, could it be used for everyday work in an OS or a messaging app?

Also, is it the path for true obsfuscation?

[dcminter]

That's a big stretch for the premise, but...

There's no value to it in circumstances where you control all the hardware processing data, so "everyday work in an OS" - only if that OS is hosted on someone else's hardware, "a messaging app" - only if you expect some of the messages or metadata to undergo processing on someone else's hardware.

It seems wildly unlikely that the performance characteristics will improve dramatically, so in practice the uses are going to remain somewhat niche.

[hamburgererror]

> There's no value to it in circumstances where you control all the hardware processing data

But what about the case where you don't have so much control about what runs next to your program? Could it be possible for an attacker to run a program in order to extract some data when your program is run?

Also, could FHE offer some protection against vulnerabilities like Meltdown and Spectre?

> It seems wildly unlikely that the performance characteristics will improve dramatically

Why? Are there some specific signs for this already? I had the impression that everytime people tend to believe that with technology they get proven wrong later.

[GTP]

The tipical, and also most useful, example use case for FHE is running computational tasks on some cloud service without having to trust it. And yes, it would provide protection against Meltdown and Spectre (if performed on the hardware running the computation), as the attacker would be able to only extract encrypted data.

[dcminter]

The data has to be decrypted at some point in order to display it... unless we're envisioning FHME hardware in the monitor as well - honestly I think we're well across the threshold into fantasy already though.

[GTP]

Of course the data has to be decrypted, but in this case you would decrypt it on your client machine, so that you don't need to trust the cloud provider or other third parties using VMs on the same server (side channel attacks can sometimes be exploited from another VM running on the same hardware, although this is rarely considered as part of one's threat model).