Patent ID: 8261069

Claim:
A method for querying a database that contains data encrypted with key k B , comprising the steps of: a mediator party processor receiving {W} k A from a first party processor, which is a database query W that was encrypted with a first set of p encryption functions, said mediator party processor, employing a plurality of 1 or more ratio keys, to transform said {W} k A to a transformed query {W″} k B that results from encrypting W″ with a second set of q encryption functions; sending information that comprises said {W″} k B to a second party processor that has access to said database; said second party processor applying said information to said database and obtaining therefrom a result; and outputting said result for processing and delivery to said first party processor; where q>0 and q≦p, at least one of the encryption functions in the first set is different from the encryption function in the second set, said mediator party processor has no knowledge of the encryption functions that belong to said first set and has no knowledge of the encryption functions that belong to said second set, and said mediator processor, first party processor, and second party processor are distinct from each other.