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Security and PDAs in Mobile Computing Environments

Security and PDAs in Mobile Computing Environments. By Loo Tang Seet and Camilla Fjortoft. Today we will talk about . PDAs and their characteristics Security requirements Advantages and Limitations Operating Systems Authentication & Authorization (A&A) in Mobile Computing Environments

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Security and PDAs in Mobile Computing Environments

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  1. Security and PDAs in Mobile Computing Environments By Loo Tang Seet and Camilla Fjortoft

  2. Today we will talk about • PDAs and their characteristics • Security requirements • Advantages and Limitations • Operating Systems • Authentication & Authorization (A&A) in Mobile Computing Environments • A&A in Mobile Computing environment • Charon Architecture • Tiny SESAME Architecture ISRC Workshop, May 2002

  3. Personal Digital Assistants (PDAs) • Small, smaller, smallest • View, store and transmit data from a handheld device • New applications • FiloFax or Business/Enterprise applications? • Mix of personal and business data • Less personal • Access and store corporate data ISRC Workshop, May 2002

  4. PDAs cont.. • Extremely portable, huge advantage • Can be used as an access control device by a wireless network • The access to the device must be controlled • This control must be greater than that for your PC • Constitute Availability, Confidentiality and Integrity of data ISRC Workshop, May 2002

  5. Threats • Small, easy to run-away-with, forget, lose.. • Removable memory card with data • Wireless communication • IR, • data is being ‘beamed’ to another device via the IR port • Wireless network access points • Virus • Synchronizing with Host PC • Email attachments ISRC Workshop, May 2002

  6. Threats cont.. • Operating System • Four to seven digit PIN for accessing the device • Single user access • Input methods • I.e. by pen, choose simple passwords • Not all OS have support for data to be encrypted, need third party software  power consumption ISRC Workshop, May 2002

  7. Security Requirements • Secure access to device, data and network • Encryption of data • The device,or data, cannot be tampered with • OS integrity and file system security • Protection against virus and malicious code • Sufficient power supply and memory • Security policy involving handheld devices ISRC Workshop, May 2002

  8. Limitations of PDAs • Power • Battery only lasts for couple of hours when connected to wireless network • Reduces the amount of time to run applications • Power is a major limitation • Processing speed • Good enough for cryptographic operations • Memory • Memory no longer a limitation for new PDAs. Can get micro drivers with several GB of capacity ISRC Workshop, May 2002

  9. Operating Systems • Windows CE • 4 to 7 digit PIN, accessible by others • No support for data to be encrypted • Need third party software • Larger power consumption • PalmOS • For devices with restricted resources • Password for accessing the device • Single user OS, no file access based on user identity • Linux • Many different distribution available ISRC Workshop, May 2002

  10. PDA survey ISRC Workshop, May 2002

  11. Authentication & Authorization in Mobile Computing Environments Tiny SESAME Charon

  12. Overview • Authentication & authorization issues in mobile computing environments • Existing authentication and authorization security architectures • Adapting existing security architectures to mobile computing environments • Conclusions ISRC Workshop, May 2002

  13. Authentication & authorization Issues in Mobile Computing Environment • Two constraints presented by mobile computing environment: • Processing resource constraints on the mobile platform • Communication resource constraints in the mobile network • Two approach to providing A&A for mobile computing environment: • adapting existing security architecture or • design a whole new architecture ISRC Workshop, May 2002

  14. Existing A&A Security Architectures • Kerberos • Developed by MIT for Project Athena • Provides end-to-end mutual authentication between client and server with single sign on • Authorization is provided by the host OS • SESAME • An extension to Kerberos with additional services • Provides both authentication and authorization services and delegation of access rights • Supports both password and public key authentication • Supports RBAC ISRC Workshop, May 2002

  15. Charon – Indirect Authentication Using Kerberos IV – by UC at Berkeley • Migrating Kerberos into mobile computing platform • Displacing complexity from client to proxy • Only DES encryption/decryption on the client • Kerberos library shifted to proxy • Rewrites client and libdes library to run on the Sony MagicLink PDA with a total footprint of ~45kB ( 9% of the original size of kinit) • No modification to KDC and server is required ISRC Workshop, May 2002

  16. Kerberos Client AS TGS Phase I: Authentication & obtaining TGT 2 Service 1 Proxy 3 4 Charon Architecture ISRC Workshop, May 2002

  17. Charon Architecture Phase II: Obtaining ticket for proxy Kerberos Client AS 5,9 Proxy 6 8 TGS 7 Service ISRC Workshop, May 2002

  18. Charon Architecture Phase III: Accessing a Service via Proxy Kerberos Client 10,14 AS Proxy 11 13 TGS 12 16 15 Service ISRC Workshop, May 2002

  19. Charon vs Standard Kerberos • Inherits both the strength and shortcomings of Kerberos IV • Charon provides a lightweight client to accommodate the mobile computing devices with limited storage space • Additional protocol exchanges required to establish trust between client and proxy • No network performance advantage using Charon versus the unmodified Kerberos ISRC Workshop, May 2002

  20. Adapting PKINIT - By A. Harbitter & D. Menasce • PKINIT – Public key extension to Kerberos V initial authentication phase • Public key encryption requires more computational resources • General approaches to adapt PK based security systems: • Reduce the number of public/private key operations on the mobile client side • Choose the right public key algorithm that allows faster public/private key operation to be performed on the mobile client side (refer to next slide) • Use proxy to offload some processing from client ISRC Workshop, May 2002

  21. Relative Speeds of Public/Private Key Operations Using DSA and RSA Refer to “Applied Cryptography”, by Bruce Schneier ISRC Workshop, May 2002

  22. TINY SESAME- By UIUC • A lightweight SESAME implemented in Java using component-based architecture • Supports authentication, simple encryption, integrity checks and RBAC • Dynamic component loading ISRC Workshop, May 2002

  23. User Sponsor Client Application User Service Tiny SESAME Architecture Client Side Security Server AS APA Client PAS KDS GSS-API DCL SACM Communication Protocol Security Context Application Server APA-Client: Authentication & Privilege client. AS: Authentication Server. DCL: Dynamic Component Loader. GSS: Generic Security Services. KDS: Key Distribution Center. PAC: Privilege Attribute Certificate. PAS: Privilege Attribute Server. PVF: PAC Validation Facility. SACM: Secure Association Context Manager. DCL SACM GSS-API PVF ISRC Workshop, May 2002

  24. Conclusions • Current A&A security architectures trust the client to protect confidential keying information • PDAs are becoming less personal • PDA are small, portable and easily subverted • Better security is needed for PDA ISRC Workshop, May 2002

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