Secure protocol with variable security level using secret sharing scheme

The security level of conventional secure protocols is fixed after security environment negotiation. However, communications differ in confidentiality in accordance with their contents. For this reason, a conventional protocol that always keeps the security level constant throughout the whole session is considered to be more secure than necessary. Since transmission efficiency is generally improved by lowering the security level, transmission efficiency is sacrificed when a conventional secure protocol is used. In this study, the secure protocol that dynamically and optimally changes the security level is proposed to solve this problem. Specifically, a variable security level is achieved by using a secret sharing scheme and multiple channels. Furthermore, the proposed protocol is theoretically evaluated.