Controlling security in relational databases

A method comprising:

• controlling secure processing of queries in a relational database by:
• receiving, from a client device, a secure query in a format of an encrypted token generated using a structured query language (SQL) query in a conjunctive query form, the encrypted token including an arity value indicating a cardinality of tables included in a cross product portion of the query and a dimension value indicating dimensions of the tables included in the cross product;
• generating an encrypted response to the secure query using an encrypted database that comprises encrypted multi-maps corresponding to the relational database and an encrypted dictionary based on structured encryption, using structured encryption, in lieu of using property-preserving encryption (PPE), and in lieu of using fully homomorphic encryption (FHE);
• and
• sending the encrypted response to the client device.

A system comprising:

• at least one server that includes:
• at least one hardware device processor;
• an encrypted relational database that includes encrypted multi-maps corresponding to a relational database hosted at a client device, and an encrypted dictionary, the encrypted multimaps and the encrypted dictionary being encrypted using structured encryption in lieu of using property-preserving encryption (PPE) and in lieu of using fully homomorphic encryption (FHE);
• and
• a security controller that includes a computer-readable storage medium storing executable instructions that, when executed, cause one or more of the at least one hardware device processor to control secure processing of queries in the encrypted relational database, the security controller including:
• a query controller that receives, from the client device, a secure query in a format of an encrypted token generated using a structured query language (SQL) query in a conjunctive query form, and sends an encrypted response to the secure query to the client device, the query controller including:
• a search engine that generates the encrypted response to the secure query by initiating a search on the encrypted relational database, without decrypting the secure query and without decrypting the encrypted multi-maps.