I think the concern isn't necessarily that Bing would associate query X with person Y. The concern is that Bing would even know that query X exists. For example, if Bing saw a spike in searches for "Aramco IPO July 4, 2018" and were to reveal it to a human or store it, that might be a serious leak of non-public information. Many searches reveal private information, even when they aren't associated with a user.
> if Bing saw a spike in searches for "Aramco IPO July 4, 2018" and were to reveal it to a human or store it, that might be a serious leak of non-public information
Maybe I'm missing something obvious here, but how is that any different from Google or DuckDuckGo seeing the same spike?
Well you might trust DDG as a good actor but not a third party. To discover that this information is discoverable to a third party (even if un-attributable) would breach their trust in DDG. Whether that's reasonable or DDG are misleading people in that regard is another matter. Personally I still use them a lot, and will continue.
I just think there is a point to be made here. Even generally it's often opaque what third parties have what data and I don't really think GDPR has fixed that. It's surprising for people the Bing might have the contents of their DDG search history, somewhere in the huge dataset of DDG searches that pass through.
Also they might not want to help improve Bing search but I'm guessing they do inadvertently?
Intel SGX is only answer at the moment. The Signal messenger uses it, do address book matching is private. It requires the user to trust the server hardware vendor (Intel) instead of also the cloud provider.
That would not stop the Bing query matcher (or indeed the Signal address book matcher) from being able to look at the contents of its own secure enclave.
The trick is that every user uploads his own matcher. The server only sees encrypted matchers, feeds them data and returns the encrypted results. You as a user decrypt your results and nobody (except Intel) was able to see them.
