5.1 Introduction

This chapter describes the Direct Anonymous Attestation (DAA) scheme in the context of its development and use within the TCG specification. This scheme was originated by Brickell, Camenisch and Chen and published in ^[9], ^[10]. It was adopted by the Trusted Computing Group [47] as the method for remote anonymous authentication of a Trusted Platform Module (TPM). In this chapter, we first talk about how the work of designing DAA started from a conflict between the need for security and the need for privacy in TPM authentication. In the historical context, we acknowledge various schemes which have been developed in response to this TCG problem, and which eventually led to the DAA scheme. In the context of a solution to the problem, we focus on explaining how the DAA scheme proposed in ^[9], ^[10] works. For more information on the security model of DAA, the security proof of the DAA scheme and its implementation analysis, we refer the reader to these two papers. In the context of further consideration, we discuss some options for the reissue of DAA keys and some possible improvements to increase the performance of the DAA scheme.