Security and Quality-of-Service (QoS) issues have traditionally been considered separately, with different objectives and implementation architectures. No protocol has been designed and implemented so far to parameterize security as a QoS parameter. However, it has been noted recently that security and QoS are highly intertwined; security mechanisms may severely affect QoS mechanisms in terms of network performance and data confidentiality. In addition, users are not given the choices on which security services and mechanisms as well as which security level should be applied to their traffic. A security-enhanced quality of service-based (SQoS) network has been presented recently, with two major objectives. One objective is to offer the users elastic choices on the treatment of messages with appropriate security mechanisms with respect to their own QoS and budget requirements. Another objective is to facilitate interaction between security and QoS mechanisms in the most efficient manner by providing information to each other. In this paper, the network performance is investigated by defining the utility junctions and maximizing the user 's benefits subject to a set of constraints.