Scott B. Guthery CTO, Mobile-Mind Sguthery@mobile-mind

1. Extending the GSM/3G Key InfrastructureDIMACS Workshop on Mobile and Wireless SecurityNovember 3, 2004 Scott B. Guthery CTO, Mobile-Mind Sguthery@mobile-mind.com Mary J. Cronin Professor of Management Boston College Cronin@bc.edu

2. Outline • SIM for Mobile Network Authentication • SIM for Internet Authentication • SIM for Local Authentication

3. Subscriber Identity Module • Integral part of GSM security from the start • Holds secret key Ki • other copy held by subscriber’s network operator • 8-bit processor, 8KB EEPROM, file system, cryptographic algorithms Identity token with a wireless connection to an authentication and billing service

4. GSM/3G Authentication • Roaming is the stepping off point for extending the GSM/3G key infrastructure • Visited network authenticates without being in possession of Ki 1) Identity 2) Identity SIM Visited Network Home Network 3) Challenge & Response 4) Challenge 5) Response Ki Ki

5. SIM for Internet Authentication • EAP-SIM uses SIM for Internet authentication • visited network is an EAP authenticator • draft-haverinen-pppext-eap-sim-14.txt • Uses GSM/3G authentication but generates a stronger session key Internet Service SIM EAP Authenticator Home Network Ki Ki

6. SIM Toolkit • SIM gives commands to the handset • display text, get key hit, send SMS, block call • Operator controls loading of applications • GlobalPlatform architecture used to manage keys for non-operator applications Application 1 STK Handset Application 2 Application 3

7. SIM for Local Authentication • SIM-based authentication and authorization • visited network is a merchant or a door • SIM-based cryptographic services • session keys, certificates, signing, tickets, etc. Local Connections (IR, Bluetooth, etc.) Operator SIM Handset Other SIM 3G Network

8. User-Equipment Split • SIM is in the device needing signing and authentication services • All that’s left of the mobile communication network is the extended key infrastructure SIM A Network Operator Handset SIM B SIM C

9. Business Models for SIM Security ExtensionTheory, Reality and Lessons Learned • Theory: Compelling business and revenue opportunities based on leveraging SIM security • Enormous global installed base of active SIM cards • Over 800 million GSM and 3G handsets and subscribers • Well-established international standards for SIM applications and key infrastructure • Well documented architecture and tools for development using SIM Application Toolkit and Java Card™ platform • Multiple business models from different industries (banking, retail, media, IT, health, etc.) in search of strong mobile security solution will embrace the SIM

10. Three Potential Business Cases • SIM-hosted and authenticated non-telephony m-commerce applications and services • Allow trusted third parties to load applications onto the SIM card and share the existing key infrastructure to authenticate customers and authorize transactions via the wireless public network • SIM-enabled use of mobile handset for authenticated and authorized transactions via the wireless public network • Embedded SIMs for authorization of users or devices attached to any network, particularly WiFi

11. SIM-Hosted M-Commerce Applications • Business Model: Multiple applications are stored on a single SIM card to allow subscriber to conduct secure banking, make and pay for purchases, download and store value, tickets, etc to the SIM • Third party consumer and enterprise applications both supported • SIM application provider gets share of projected $60 billion plus in m-commerce transactions • Reality as of 2004 • Technical requirements are in place • Almost all recent SIMs are multi-application Java Card™ SIMs • Over 260 million of them are Global Platform compliant • SIM-hosted applications have been scarce • Limited to small mobile banking pilots in Europe and Asia • Majority of booming m-commerce business has moved to handset downloads and back end server-based security systems

12. SIM-Enabled Security for Mobile Devices • Business Model: Dual-slot handsets provide external slot for smart card to conduct secure transactions and move value via the SIM, making the mobile a cash dispenser, a ticket, a POS, etc. • 1999 launch of dual slot phones to great fanfare • Datamonitor projected over 32 million such phones in use by 2003 • All major handset makers announced plans to manufacture them • Reality as of 2004 • Dual slot phones are hard to find collectors’ items • Revival of the model via “add-on” module for standard GSM phone to create a mobile POS for developing markets • Way Systems has some initial traction with this approach for China

13. SIM Authentication in Non-Telephony Networks • Business Model: Embed SIM in WiFi and other networked devices or provide SIM-USB token to subscribers for authentication and payment for WiFi access and roaming • One solution for problems with 802.11 security • Potential for portability and roaming on different networks • Possible integration with wireless subscriber accounts • Reality as of 2004 • WLAN Smart Card Consortium attempting to define standards • Commercial deployments increasing but still in early stages • Transat solution launches with 3,500 hotspots in the UK (4/04) • Orange implements in Switzerland (3/04) • Tartara demonstrates solution with Verisign (3/04) • TSI demonstrates solution with Boingo Wireless (5/04)

14. Conclusion: Still Searching for Clear Business Case for SIM Extension • Limited applications to date outside of wireless telephony and some notable business failures such as dual-slot handsets • The combined business drivers of a billion SIMs, a rapidly growing m-commerce market and unsolved mobile security issues continue to bring new players and approaches to the table • Lesson learned: Wireless carriers have made controlling and guarding the SIM key infrastructure a priority over increasing revenues through extension • Carriers have the ability to cut off third party access to the SIM platform • WiFi and non-telephony network authentication looks like a good match for the SIM key infrastructure, but long-term models may require wireless carrier participation