A Multi-User Key and Data Exchange Protocol to Manage a Secure Database

We propose a multi-user key and data exchange protocol, which is able to manipulate stored encrypted data without need to decipher. This protocol can be used by several clients at any given time, which are connected to a server, for keys and data exchanges. The ciphered data located in client and that located in the server is exchanged, stored, compared and processed without the need to decipher. To clarify the protocol explanation we use it in a Database Management System (DBMS). The relational algebra operations, which include projection, selection, among others, are evaluated using the cryptographic protocol on encrypted data. Let us suppose a relation instance Is ciphered and stored on secondary memory. The protocol can evaluate queries such as selection σAi > v(Is) on the encrypted stored version. In this selection no data is deciphered onto main or secondary memory and therefore remains encrypted. Different users can submit queries, thus the protocol must have a strong key management.