Partial Disclosure of Searchable Encrypted Data with Support for Boolean Queries

The setting in which Alice wishes to disclose log entries to Bob, only of which contain a keyword specified by him was studied. Suppose that Alice also wishes to keep other entries secret to Bob, even after the disclosure, then how could Alice convince Bob that the undisclosed entries surely do not contain the keyword? Such can be ensured with a variation of searchable encryption scheme; With Alice´s help, Bob can search through the encrypted log and specify the entries which contain the keyword. It is a common step to extend a simple search to a search with boolean queries, such as AND and OR. However, it is not simple to disclose entries which contain more than a single keyword, without leaking information on the undisclosed entries. In this paper, a scheme to disclose entries which match a boolean query is proposed. By using a Bloom filter as an encoded index, the scheme reduces the frequencies of comparison and the size of matching data, at the sacrifice of faultlessness.