Comment by ls612
1 month ago
Because it turns out that mathematicians and computer scientists have devised schemes that allow for certain computational operations to be performed on encrypted data without revealing the data itself. You can do a+b=c and it doesn’t reveal anything about what a and b are is the intuition here. This has been mostly confined to the realm of theory and mathematics until very recently but Apple has operationalized it for the first time.
It’s not the first time Apple operationalized it, they did it for Caller ID awhile back.
And then when the system does the computation to determine your location (wait.what?)
The phone has intelligence to detect things that look like landmarks, and does cropping/normalization and converts to a mathematical form.
Apple has a database trained on multiple photos of each landmark (or part of a landmark), to give a likelihood of a match.
Homomorphic encryption means that the encrypted mathematical form of a potential landmark from the phone can be applied to the encrypted set of landmark data, to get an encrypted result set.
The phone can then decrypt this and see the result of the query. But anyone else sees this as noise being translated to new noise, including Apple's server.
The justification for this approach is storage - the data set of landmarks can only get larger as the data set gets more comprehensive. Imagine trying to match photos for inside castles, cathedrals and museums as examples.
> get an encrypted result set.
seems to me at that point, the server knows what segment of the overall dataset is being returned.
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