Abstract: Encrypted information retrieval can include generating a database that is partitioned into shards each having a shard identifier, and database entries in each shard that are partitioned into buckets having a bucket identifier. A batch of client-encrypted queries are received. The batch of client-encrypted queries are processed using a set of server-encrypted data stored in a database. The processing includes grouping the client-encrypted queries according to shard identifiers of the client-encrypted queries, executing multiple queries in the group of client-encrypted queries for the shard together in a batch execution process, and generating multiple server-encrypted results to the multiple queries in the group of client-encrypted queries. The multiple server-encrypted results for each shard are transmitted to the client device.

Abstract: Methods, systems, and apparatus, including computer programs encoded on a computer storage medium for retrieving information from a server. Methods can include a server receiving a set of client-encrypted queries. The server identifies a set of server-encrypted decryption keys and transmits the set to the client device. The server receives a set of client-server-encrypted decryption keys that includes the set of server-encrypted decryption keys encrypted by the client device. The server also receives a set of client-encrypted/client-derived decryption keys that were derived by the client device. The server generates matching a map that specifies matches between the set of client-server-encrypted decryption keys and the set of client-encrypted/client-derived decryption keys. The server filters the set of client-encrypted queries using the map to create a set of filtered client-encrypted queries and generates a set of query results.

Abstract: Methods, systems, and computer readable medium facilitating encrypted information retrieval. Methods can include receiving a batch of queries that includes queries to special buckets in each database shard. Query results responsive to the batch of queries are transmitted to the client device. The query results includes server-encrypted secret shares obtained from the special buckets. Client-encrypted versions of the secret shares are received. A full set of server-encrypted secret shares is transmitted to the client device, which is encrypted by the client device to create a full set of client-server-encrypted secret shares. The client device is classified based on how many of the secret shares are included in both of the client-encrypted secret shares received from the client device and the full set of client-server-encrypted secret shares received from the client device.