Method of and device for querying of protected data structured in the form of a tree. A corresponding tree of node polynomials is constructed such that each node polynomial evaluates to zero for an input equal to an identifier assigned to a node name occurring in a branch of the data tree starting with the node in question. A tree of blinding polynomials and a tree of difference polynomials are constructed such that each polynomial in the tree of node polynomials equals the sum of the corresponding polynomial in the tree of blinding polynomials and the corresponding polynomial in the tree of difference polynomials. The blinding tree is given to a client, the difference tree to a server. By combining the outcomes of the evaluations of the client and the server, it is possible to identify nodes that match a given query.
|Published - 8 Dec 2005