[Cryptography] Advances in homomorphic encryption

[Christian Huitema]

> cryptdb uses homomorphic encryption (as part of a larger system that leaks
more information that "pure" HE would, but that is an 
> irrelevant tangent).

Homomorphic encryption enables computations using additions and
multiplications, but I wonder about the domain of application. Whether you
consider projection and joint in a SQL database, or map/reduce, we need to
perform comparisons. For example, we may want to find all the sales that
happened last week and compute the average profit. That requires accessing
the date field and verifying that it falls within last week's  range. I
can't see how to do that if the date is encrypted in a way that provides
semantic security.

-- Christian Huitema