6.1 Introduction

In this chapter we examine an application that can potentially benefit from trusted computing, namely Single Sign-On (SSO). SSO gives the user the ability to log into systems and applications without the need to maintain separate authentication credentials for each such system and application. In other words, an SSO scheme allows the user to log into (ideally) all relevant systems and applications, using only one set of authentication credentials (e.g., only one username/password pair). In the remainder of the chapter, we will use the generic term Service Provider (SP) to refer to systems and/or applications in the context of SSO.

SSO has been the target of research for more than 20 years. During this period, many different SSO schemes have been proposed. Some of those have been implemented and deployed. However, none has been widely adopted (at least not in an open environment) and none has been able to provide a service to a large number of existing SPs. We examine the reasons behind this failure in Section 6.1.3 below. First, however, we outline the motivation behind SSO in Section 6.1.1, and explain how it works in Section 6.1.2. We then examine, in Section 6.2, how platforms that conform to the Trusted Computing Group (TCG) specifications could be used to enhance existing SSO schemes. Section 6.3 deals with the issue of privacy. Other issues that arise in the SSO context, such as associated costs and cross-platform mobility, are discussed in Section 6.4. Finally,...