  We formulate a new secure distributed computation problem, where a simulation
center can require any linear combination of $ K $ users' data through a
caching layer consisting of $ N $ servers. The users, servers, and data
collector do not trust each other. For users, any data is required to be
protected from up to $ E $ servers; for servers, any more information than the
desired linear combination cannot be leaked to the data collector; and for the
data collector, any single server knows nothing about the coefficients of the
linear combination. Our goal is to find the optimal download cost, which is
defined as the size of message uploaded to the simulation center by the
servers, to the size of desired linear combination. We proposed a scheme with
the optimal download cost when $E < N-1$. We also prove that when $E\geq N-1$,
the scheme is not feasible.
