Contents | Who Goes There? Authentication Through the Lens of Privacy | Committee on Authentication Technologies and Their Privacy Implications | Computer Science and Telecommunications Board | Division on Engineering and Physical Sciences | National Research Council of the National Academies | Stephen T. Kent and Lynette I. Millett, Editors

Questions? Call 888-624-8373

Title Page and Notice			i
National Academies Statement			iii
Committee			v
Preface			ix
Acknowledgment of Reviewers			xiii

EXECUTIVE SUMMARY			1

1	INTRODUCTION AND OVERVIEW		16
	Definitions and Terminology		18
	Authentication in Daily Life		21
	Current Tensions		28
	Four Overarching Privacy Concerns		30
	What This Report Does and Does Not Do		31

2	AUTHENTICATION IN THE ABSTRACT		33
	What Is Authentication and Why Is It Done?		33
		Three Parties to Authentication	36
		Authenticating to Authorize	37
		Authenticating to Hold Accountable	38
	What Do We Authenticate?		41
		Identifiers	42
		Attributes	43
		Statements	44
	How Do We Authenticate?		45
		Authenticating Physical Identity	47
		Authenticating Psychological Identity	47
		Authenticating Possession of an Artifact	49
	Identification		50
	The Relationship Between Authentication and Identification		51

3	PRIVACY CHALLENGES IN AUTHENTICATION SYSTEMS		55
	Privacy Impact of the Decision to Authenticate		56
	Access Control and Information Systems		57
	The Legal Foundations of Privacy		62
		Constitutional Roots of Privacy	63
		The Common Law Roots of Privacy Law	68
		Statutory Privacy Protections	69
	Information Privacy and Fair Information Practices		71
	Privacy of Communications		75
	Concluding Remarks		78

4	SECURITY AND USABILITY		80
	Threat Models		81
		Threats	81
		Dealing with Threats	84
	Authentication and People—User-Centered Design		86
		Lessons from User-Centered Design	87
		Lessons from Cognitive and Social Psychology	90
	Factors Behind the Technology Choice		95
	Systems and Secondary Use		97
	Concluding Remarks		101

5	AUTHENTICATION TECHNOLOGIES		104
	Technological Flavors of Authentication		104
	Basic Types of Authentication Mechanisms		106
		Something You Know	107
		Something You Have	110
		Something You Are	120
	Multifactor Authentication		123
	Centralized Versus Decentralized Authentication Systems		125
	Security Considerations for Individual Authentication Technologies		132
	Cost Considerations for Individual Authentication Technologies		135
	Concluding Remarks		136

6	AUTHENTICATION, PRIVACY, AND THE ROLES OF GOVERNMENT		138
	Regulator of Private Sector and Public Agency Behaviors and Processes		140
		Government-wide Law and Policy	141
		Agency- or Program-Specific Law and Policies	145
		Regulation of Private Sector Information Management Activity	149
		Policy Activity in the Early 2000s	151
		Summary	155
	Government as Issuer of Identity Documents		155
		The Tangled Web of Government-Issued Identity Documents	162
		Threats to Foundational Documents	165
	Government as Relying Party for Authentication Services		169
		Access Certificates for Electronic Services	170
		The Internal Revenue Service—Electronic Tax Filing	172
		The Social Security Administration and PEBES	175
	Nationwide Identity Systems		176
	Concluding Remarks		177

7	A TOOLKIT FOR PRIVACY IN THE CONTEXT OF AUTHENTICATION		179
	Privacy-Impact Toolkit		181
		Attribute Choice	182
		Identifier Selection	186
		Identity Selection	189
		The Authentication Phase	190
	Concluding Remarks		192

APPENDIXES
A	Biographies of Committee Members and Staff		197
B	Briefers to the Study Committee		207
C	Some Key Concepts		209

What Is CSTB?			213