Security and data confidentiality has become a critical issue for companies and
individuals. In a classical client-server network, the access control management is
performed on the server, relying on the assumption that the server is a trusted party. In
this paper, we focus on how to strengthen the data confidentiality in client-server
networks. We address the improving data confidentiality protocol by using symmetric
encryption based on different secret keys for each session derived from timestamp. This
key is generated in a local machine and without needing to exchange it between the client
and the server for encryption decryption process. We have to use symmetric encryption
without exchanging the secret key to ensure the security of information from attacks for
eavesdropping or modification.