Privacy-preserving Logarithmic-time Search on Encrypted Data in Cloud

Ideally, a privacy-preserving database-in-the-cloud environment would allow a database owner to outsource its encrypted database to a cloud server. The owner would retain control over what records can be queried and by whom, by granting each authorized user a search token and a decryption key. A user would then present this token to cloud server who would use it to find encrypted matching records, while learning nothing else. A user could then use its owner-issued decryption key to learn the actual matching