Secure private database querying with content hiding bloom filters

Secure private database querying on a database for a query having a formula evaluation on at least two keywords A and B comprises: a server receiving a Bloom filter tree comprised of encrypted Bloom filters of encrypted keywords from the database, wherein each Bloom filter in the Bloom filter tree is separately masked by a random mask pad P; receiving an encrypted version of the keywords A and B from the client; and obtaining masked Bloom filter indices for the keywords A and B. The client and server participate in secure function evaluation (SFE) with the client. The server has an input comprising the masked Bloom filter indices for the keywords A and B and the client has an input comprising the random mask pad P. The secure function evaluation comprises: removing the random mask pad P from the masked Bloom filter indices input by the server; determining if there is a matching Bloom filter for each of the keywords A and B; and applying the formula evaluation to determine if the formula is satisfied.