Introduction

The elements of security in computing begin with an identity. An identity is a computer representation of an active entity that can be physical (such as a human, a host system, or a network device) or can be a programming agent. Such an agent can be assigned a well-known system function (such as a running daemon) or a program delivering a business function on behalf of some entity. Modern systems adopt a fine level of identification sustainable even at the basic computing tasks and execution threads of an address space and may cross the boundaries of single computing systems with the advent of network and distributed computing.

The evolution of computing to automate more and more of the aspects of human interactions such as in business transactions led to the need of identity representation in computing that reflects that of real-life entities such as human beings. An identity therefore evolved from being simply an assigned identifier to an identifier that points to various attributes and entitlements, collectively referred to as a profile. Identity management has therefore emerged to address the issues surrounding the proliferation of identity profiles among various computing platforms within the boundaries of an enterprise and cross-enterprises and organizations to even the Internet. Foremost of these issues is the cross-referencing among profiles that represent the same identity as well as the synchronization of attributes among these profiles.

We begin by providing a taxonomy of identity models that is based on the scope of an identity,...