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.