Efficient tree search in encrypted data

Sometimes there is a need to store sensitive data on an untrusted database server. Song, Wagner and Perrig have introduced a way to search for the existence of a word in an encrypted textual document. The search speed is linear in the size of the document. It does not scale well for a large database. We have developed a tree search algorithm based on the linear search algorithm that is suitable for XML databases. It is more efficient since it exploits the structure of XML. We have built prototype implementations for both the linear and the tree search case. Experiments show a major improvement in search time