For distributed querying of confidential information, a querying data structure
is constructed from the confidential information on the computer at which the confidential
information resides. The querying data structure opaquely encapsulates queries
on the confidential information as a set of query hashes and answer pairs. The
querying data structure is distributed to other computers where the distributed
query processing is to be performed. The query is performed on such other computers
by hashing the query terms, using the resulting query hash as a look up index to
the associated answer in the querying data structure, and acting on the answer.
A strictly one-way hash is used to prevent recovery of the original inputs to the
query hashes in the query data structure by reverse hash.
