The Concepts of (Id)entity, Nymity and Authentication

Roger Clarke *

Principal, Xamax Consultancy Pty Ltd, Canberra

Invited Presentation to the Launch Workshop of the Research Project 'On the Identity Trail: Understanding the Importance and Impact of Anonymity and Authentication in a Networked Society', University of Ottawa, 10 June 2004

Version of 17 May 2004

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This paper examines key concepts underlying this major University of Ottawa research project. Central to the topic-area is the idea of identity, and the associated notions of identifier and identification. It is important to distinguish the entity 'person' from each person's multiple identities. That leads to notions of entity, 'entifier' (in particular, biometrics), and entification (in particular, the collection of biometrics).

The second cluster of ideas is usefully gathered under the generic term 'nymity'. The terms anonymity and pseudonymity need to be carefully distinguished, and pseudonym and anonym need to be defined, and used consistently.

The third general idea that needs to be considered is authentication. It relates to assertions of many kinds. The authentication of assertions of identity is important in some contexts. But it is vital that team-members not be blinded to the other vital forms of assertion. There are many circumstances in which assertions relating to value, attributes, location, and the ability to represent another person are considerably more relevant and important than the identity. Moreover, many discussions miss the point because they conflate identity authentication and entity authentication.

This paper and presentation survey the landscape of identity, nymity and authentication, and propose definitions that are intended to encourage cohesion and avoid mistaken assumptions.


An informal overview of the concepts is provided in 'Identification and Authentication Fundamentals'.

Indexes are provided to the author's works in the following areas:

The following are the key papers on which this presentation and paper draw:

Clarke R. (1994) 'Human Identification in Information Systems: Management Challenges and Public Policy Issues' Info. Technology & People 7,4 (December 1994). At

Clarke R. (1999) 'Anonymous, Pseudonymous and Identified Transactions: The Spectrum of Choice', Proc. IFIP User Identification & Privacy Protection Conference, Stockholm, June 1999, at

Clarke R. (2001) 'Authentication: A Sufficiently Rich Model to Enable e-Business' Review Draft of 26 December 2001, at

Clarke R. (2003) 'Authentication Re-visited: How Public Key Infrastructure Could Yet Prosper' Proc. 16th Bled Electronic Commerce Conf., Bled, Slovenia, 9-11 June 2003, at

Clarke R. (2004) 'Identity Management: The Technologies, Their Business Value, Their Problems, and Their Prospects' Xamax Consultancy Pty Ltd, March 2004, purchasable from

About the Author

Roger Clarke is Principal, Xamax Consultancy Pty Ltd, Canberra, which he established in 1982. His practice is primarily in strategic and policy aspects of eBusiness, information infrastructure, and dataveillance and privacy.

He has Honours and Masters degrees in Commerce, and a doctorate in information systems. He is also a Visiting Professor in the Baker & McKenzie Cyberspace Law & Policy Centre at the University of N.S.W., and in the E-Commerce Programme at the University of Hong Kong, and a Visiting Fellow in the Department of Computer Science, Australian National University.


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Created: 26 April 2004

Last Amended: 17 May 2004

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