AAA and Network Security for Mobile Access: Radius, Diameter, EAP, PKI and IP Mobility

Foreword xv

Preface xvii

About the Author xxi

Chapter 1 The 3 “A”s: Authentication, Authorization, Accounting 1

1.1 Authentication Concepts 1

1.1.1 Client Authentication 2

1.1.2 Message Authentication 4

1.1.3 Mutual Authentication 5

1.1.4 Models for Authentication Messaging 6

1.1.5 AAA Protocols for Authentication Messaging 7

1.2 Authorization 8

1.2.1 How is it Different from Authentication? 8

1.2.2 Administration Domain and Relationships with the User 9

1.2.3 Standardization of Authorization Procedures 10

1.3 Accounting 13

1.3.1 Accounting Management Architecture 13

1.3.2 Models for Collection of Accounting Data 15

1.3.3 Accounting Security 17

1.3.4 Accounting Reliability 17

1.3.5 Prepaid Service: Authorization and Accounting in Harmony 19

1.4 Generic AAA Architecture 19

1.4.1 Requirements on AAA Protocols Running on NAS 21

1.5 Conclusions and Further Resources 23

1.6 References 23

Chapter 2 Authentication 25

2.1 Examples of Authentication Mechanisms 25

2.1.1 User Authentication Mechanisms 26

2.1.2 Example of Device Authentication Mechanisms 31

2.1.3 Examples of Message Authentication Mechanisms 33

2.2 Classes of Authentication Mechanisms 36

2.2.1 Generic Authentication Mechanisms 41

2.3 Further Resources 44

2.4 References 45

Chapter 3 Key Management Methods 47

3.1 Key Management Taxonomy 47

3.1.1 Key Management Terminology 47

3.1.2 Types of Cryptographic Algorithms 49

3.1.3 Key Management Functions 50

3.1.4 Key Establishment Methods 51

3.2 Management of Symmetric Keys 54

3.2.1 EAP Key Management Methods 54

3.2.2 Diffie–Hellman Key Agreement for Symmetric Key Generation 58

3.2.3 Internet Key Exchange for Symmetric Key Agreement 61

3.2.4 Kerberos and Single Sign On 62

3.2.5 Kerberized Internet Negotiation of Keys (KINK) 66

3.3 Management of Public Keys and PKIs 67

3.4 Further Resources 68

3.5 References 69

Chapter 4 Internet Security and Key Exchange Basics 71

4.1 Introduction: Issues with Link Layer-Only Security 71

4.2 Internet Protocol Security 73

4.2.1 Authentication Header 74

4.2.2 Encapsulating Security Payload 74

4.2.3 IPsec Modes 75

4.2.4 Security Associations and Policies 77

4.2.5 IPsec Databases 78

4.2.6 IPsec Processing 78

4.3 Internet Key Exchange for IPsec 79

4.3.1 IKE Specifications 79

4.3.2 IKE Conversations 81

4.3.3 ISAKMP: The Backstage Protocol for IKE 83

4.3.4 The Gory Details of IKE 86

4.4 Transport Layer Security 91

4.4.1 TLS Handshake for Key Exchange 93

4.4.2 TLS Record Protocol 95

4.4.3 Issues with TLS 96

4.4.4 Wireless Transport Layer Security 96

4.5 Further Resources 96

4.6 References 97

Chapter 5 Introduction on Internet Mobility Protocols 99

5.1 Mobile IP 99

5.1.1 Mobile IP Functional Overview 102

5.1.2 Mobile IP Messaging Security 107

5.2 Shortcomings of Mobile IP Base Specification 109

5.2.1 Mobile IP Bootstrapping Issues 110

5.2.2 Mobile IP Handovers and Their Shortcomings 113

5.3 Seamless Mobility Procedures 117

5.3.1 Candidate Access Router Discovery 118

5.3.2 Context Transfer 120

5.4 Further Resources 125

5.5 References 126

Chapter 6 Remote Access Dial-In User Service (RADIUS) 127

6.1 RADIUS Basics 127

6.2 RADIUS Messaging 128

6.2.1 Message Format 129

6.2.2 RADIUS Extensibility 130

6.2.3 Transport Reliability for RADIUS 130

6.2.4 RADIUS and Security 131

6.3 RADIUS Operation Examples 135

6.3.1 RADIUS Support for PAP 135

6.3.2 RADIUS Support for CHAP 136

6.3.3 RADIUS Interaction with EAP 138

6.3.4 RADIUS Accounting 139

6.4 RADIUS Support for Roaming and Mobility 141

6.4.1 RADIUS Support for Proxy Chaining 142

6.5 RADIUS Issues 143

6.6 Further Resources 144

6.6.1 Commercial RADIUS Resources 144

6.6.2 Free Open Source Material 145

6.7 References 145

Chapter 7 Diameter: Twice the RADIUS? 147

7.1 Election for the Next AAA Protocol 147

7.1.1 The Web of Diameter Specifications 148

7.1.2 Diameter Applications 151

7.1.3 Diameter Node Types and their Roles 152

7.2 Diameter Protocol 153

7.2.1 Diameter Messages 153

7.2.2 Diameter Transport and Routing Concepts 157

7.2.3 Capability Negotiations 159

7.2.4 Diameter Security Requirements 160

7.3 Details of Diameter Applications 162

7.3.1 Accounting Message Exchange Example 162

7.3.2 Diameter-Based Authentication, NASREQ 163

7.3.3 Diameter Mobile IP Application 167

7.3.4 Diameter EAP Support 167

7.4 Diameter Versus RADIUS: A Factor 2? 168

7.4.1 Advantages of Diameter over RADIUS 168

7.4.2 Issues with Use of Diameter 170

7.4.3 Diameter-RADIUS Interactions (Translation Agents) 171

7.5 Further Resources 172

7.6 References 172

Chapter 8 AAA and Security for Mobile IP 175

8.1 Architecture and Trust Model 177

8.1.1 Timing Characteristics of Security Associations 178

8.1.2 Key Delivery Mechanisms 181

8.1.3 Overview of Use of Mobile IP-AAA in Key Generation 182

8.2 Mobile IPv4 Extensions for Interaction with AAA 184

8.2.1 MN-AAA Authentication Extension 184

8.2.2 Key Generation Extensions (IETF work in progress) 186

8.2.3 Keys to Mobile IP Agents? 187

8.3 AAA Extensions for Interaction with Mobile IP 187

8.3.1 Diameter Mobile IPv4 Application 188

8.3.2 Radius and Mobile IP Interaction: A CDMA2000 Example 196

8.4 Conclusion and Further Resources 200

8.5 References 201

Chapter 9 PKI: Public Key Infrastructure: Fundamentals and Support for IPsec and Mobility 203

9.1 Public Key Infrastructures: Concepts and Elements 204

9.1.1 Certificates 204

9.1.2 Certificate Management Concepts 205

9.1.3 PKI Elements 209

9.1.4 PKI Management Basic Functions 210

9.1.5 Comparison of Existing PKI Management Protocols 212

9.1.6 PKI Operation Protocols 221

9.2 PKI for Mobility Support 222

9.2.1 Identity Management for Mobile Clients: No IP Addresses! 222

9.2.2 Certification and Distribution Issues 225

9.3 Using Certificates in IKE 227

9.3.1 Exchange of Certificates within IKE 229

9.3.2 Identity Management for ISAKMP: No IP Address, Please! 231

9.4 Further Resources 232

9.5 References 232

9.6 Appendix A PKCS Documents 233

Chapter 10 Latest Authentication Mechanisms, EAP Flavors 235

10.1 Introduction 235

10.1.1 EAP Transport Mechanisms 237

10.1.2 EAP over LAN (EAPOL) 237

10.1.3 EAP over AAA Protocols 238

10.2 Protocol Overview 239

10.3 EAP-XXX 242

10.3.1 EAP-TLS (TLS over EAP) 244

10.3.2 EAP-TTLS 248

10.3.3 EAP-SIM 257

10.4 Use of EAP in 802 Networks 259

10.4.1 802.1X Port-Based Authentication 259

10.4.2 Lightweight Extensible Authentication Protocol (LEAP) 260

10.4.3 PEAP 262

10.5 Further Resources 262

10.6 References 263

Chapter 11 AAA and Identity Management for Mobile Access: The World of Operator Co-Existence 265

11.1 Operator Co-existence and Agreements 265

11.1.1 Implications for the User 266

11.1.2 Implications for the Operators 267

11.1.3 Bilateral Billing and Trust Agreements and AAA Issues 269

11.1.4 Brokered Billing and Trust Agreements 272

11.1.5 Billing and Trust Management through an Alliance 274

11.2 A Practical Example: Liberty Alliance 275

11.2.1 Building the Trust Network: Identity Federation 276

11.2.2 Support for Authentication/Sign On/Sign Off 279

11.2.3 Advantages and Limitations of the Liberty Alliance 282

11.3 IETF Procedures 283

11.4 Further Resources 285

11.5 References 285

Index 287