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Developing Secure Smartcard Systems for University Usage

Explore the implementation and potential of smartcards for secure authentication, internet access, and more at the University of Michigan. Discover the hardware's benefits, applications, and the current challenges in this innovative technology integration.

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Developing Secure Smartcard Systems for University Usage

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  1. Practical Security Systems with Smartcards Naomaru Itoi CITI University of Michigan

  2. Contents • Introduction • Related work • Three components • Future directions

  3. Project Goals • Develop, Build, and Deploy a secure system with smartcards in the University of Michigan. • Provide a smartcard which handles computer authentication, Internet access, identification, banking, payment, etc… in everybody’s pocket. • Feedback to computer science world

  4. Why? - Smartcard is good • Secure hardware • Tamper-resistance • Restricted communication (serial port) • File protection (PIN, cryptographic) • Cryptographic algorithms • Portability • Convenience • Security • Multi-functionality • One smartcard for several tasks

  5. Smartcard Applications • Telecommunication payment • Majority of smartcard used in Europe • Health care • Government applications • Store customer based information • Banking • Visa Cash, MasterCard • More secure than magnetic stripe credit card But these are in Europe

  6. No Killer-Application in the US Applications in the US? • Only 2% of smartcard product shipped to the US in 1995 • Telecommunication payment? • No global infrastructure • Health care? • Government? • No large centralized government application • Banking? • Customers and merchants are familiar with magnetic stripe credit card

  7. Information Technology Business • Demand for secure computer environment is large • Users are ready to new hardware Can be the Killer-Application in the US

  8. Computer environment goals • Security • Solve typical problems e.g. vulnerability of passwords • Secure authentication • Secure Internet access • Convenience • Store personal information in a smartcard • Single Sign-On

  9. Related Work • Secure coprocessor • Doug Tygar et al. in CMU • Build physically tamper-proof coprocessor • Build secure bootstrapping, etc. • Build an operating system to take advantage of it • Theoretical approach • Butler Lampson et al. in DEC • Develop theory of authentication in distributed systems • Build secure bootstrapping, etc. • Build an operating system, then prove it to be secure

  10. Our approach • Take existing secure hardware - smartcard • Integrate smartcards with existing infrastructure • Secrets in a smartcard remain secure even if hardware / software is compromised • Store critical information in a smartcard

  11. Three components • Smartcard development environment • Smartcard integration with the UNIX filesystem • Smartcard authentication • Smartcard integration with Kerberos V5 • Smartcard, Pluggable Authentication Module, and Windows NT

  12. Smartcard development toolkit current situation • ISO-7816 • Standard smartcard interface • Primitive message framing protocol • Too primitive to be useful • Vendor dependencies • Smartcard Programming Toolkit • IBM MFC, Microsoft PC/SC, OpenCard Framework, EMV’96, PKCS#11 … • Building everything over a smartcard - language, API, toolkit, library, application, etc. • Hassle to learn yet another new toolkit • Not interoperable

  13. SCFS goals • Implement VFS layer that handles smartcards • UNIX filesystem API • UNIX commands • Can handle any smartcard as long as it supports ISO-7816

  14. scfsd Smartcard Application XFS VFS SCFS design • Arla like 2-level architecture User level Kernel level • XFS handles application requests • Scfsd translates requests to smartcard commands • Scfsd pops up a Tk window to ask PIN when a file is protected

  15. arlad AFS server Application XFS VFS Arla - free AFS client • Written by Assar Westerlund et al. in Royal Institute of Technology, Sweden User level Kernel level

  16. SCFS implementation xfs_mount() Send a reset signal to a smartcard Choose smartcard type from the configuration table Mount the scfs filesystem xfs_read() Translate FID into a smartcard file Select the file Send “read” APDU Copy data to the user space with uiomove() ...

  17. SCFS performance (ms) Command Total Smartcard Scfs Overhead Read 8 Bytes 28.9 28.2 0.7 (2.4%) Read 128 Bytes 190.2 189.4 0.8 (0.4%) Write 8 Bytes 63.4 62.7 0.7 (1.1%) Write 128 Bytes 1259.5 1258.9 0.7 (0.1%) Start reading smartcard Read() call Finish reading smartcard Read() return Total Smartcard access Scfs overhead Scfs overhead

  18. SCFS conclusion • Smartcard files seem almost identical to UNIX files -- except the length of a file • UNIX filesystem API • UNIX commands ls, cd, pwd, etc. • Useful development toolkit • Secure storage can be implemented with symbolic links • User profiles, Netscape cookies, Kerberos tickets, etc. • Overhead is fairly small (up to 2.4%)

  19. Smartcard Integration with Kerberos • Kerberos - the most widely used network authentication protocol • U of M computer environment is protected by Kerberos V4 • Security limitations (Steven Bellovin et al.,AT&T): • Need for an external encryption device • Need for a secure key storage • Dictionary attack to passwords • Solve these problems with a smartcard

  20. Decrypt Need for encryption device Kerberos KDC 1) username Ku User password Workstation 2) {TGT}Ku Ku • A workstation decrypts TGT. • A workstation is a vulnerable secure storage. • A workstation may not be trusted.

  21. Need for secure storage • Keys are stored in a hard disk or in memory in a workstation. • Hard disks are not secure • Adversary with an administrator right can access keys. • Data in a hard disk may be backed up in a mass storage device. • Memory is not secure • Adversary can run memory scan. • Data in memory can be paged out to a hard disk.

  22. Dictionary Attack • Obtain a <plaintext, ciphertext> pair • Create a list of English words, names, etc. • Derive keys from the words in the list • Decrypt the ciphertext with the derived key • If the plaintext is recovered, the key used for decryption is the secret key in quest • Kerberos gives up <plaintext, ciphertext> pair easily • Real problem in U of M -- 4,000 accounts are compromised

  23. Decrypt Countermeasures - use a smartcard Kerberos KDC 1) username Ku • Ku is not exposed either a user, networks, or a workstation. • There is no password. Workstation 3) {TGT}Ku 2) {TGT}Ku Smartcard DES engine 4) TGT Ku

  24. Implementation • Smartcard called STARCOS v. 2.1 from Giesecke & Devrient • Modify Kerberos v5-1.0.5 by M.I.T. • Modify Kerberos client • Kerberos server remains unmodified

  25. Kerberos-Smartcard performance • The authentication protocol takes 2.51s. • Decryption is the bottleneck -- takes 2.09s. • Fine breakdown shows it is possible to improve performance with CBC-in-a-smartcard approach. Card reset Kinit start Start decryption End decryption Kinit finish (ms) 0 20 370 2460 2520

  26. Kerberos-Smartcard conclusion • Practical smartcard authentication method • Solve limitations of Kerberos • The protocol works fairly fast • There is still room to improve

  27. Smartcard, Pluggable Authentication Module, and Windows NT • Smartcard authentication in UNIX and NT • UNIX-PAM • Flexible authentication method • Single Sign-On • Need PAM in NT

  28. Design • Use PAM - standard security framework • Implement PAM in Windows NT • Integrate Kerberos-Smartcard protocol with PAM

  29. NT without PAM GINA AFS NT domain NetWare LSA Kerberos4 Kerberos5 NetWare • No Single Sign-On • Poor configuration method authenticated services authentication systems

  30. NT with PAM NI_PAM GINA Kerberos4 Kerberos5 NetWare LSA • Single Sign-On performed • Configuration centralized in Configuration Table authenticated service NT Local Kerberos4 Kerberos5 Netware authentication systems

  31. Implementation Winlogon WlxLoggedOffSAS() NI_GINA Config table in Registry NI_PAM NI_KRB4 NI_KRB5 NI_NW LSA Kerberos4 Kerberos5 Netware4.0

  32. NI_PAM Performance User Logon PAMStart K5 Start K5 End PAMEnd 0 0.05 0.82 299.82 299.91 (ms) • PAM is fast

  33. NI_PAM conclusion • First step to smartcard authentication in NT • Flexible and integrated security configuration method • Common method among Solaris, Linux, and Windows NT • Single Sign-On with Kerberos V4, Kerberos V5, and Netware 4.0

  34. NI_PAM contribution • Developed in summer of 1997 • Presented in 1998 USENIX Windows/NT symposium • ITD plans internal deployment in Fall/1998 • University-wide deployment in Winter/1999 term

  35. Conclusion - OverallGoals revisited • Security • Solve typical problems e.g. vulnerability of passwords -- Kerberos-Smartcard • Secure authentication -- Kerberos-Smartcard • Secure Internet access • Convenience • Store personal information in a smartcard -- Smartcard Filesystem • Single Sign-On -- PAM in NT • Improved development environment • Smartcard -- Smartcard Filesystem • Windows NT security -- PAM in NT

  36. Future Directions • Kerberos-Smartcard • Secure key storage for Kerberos servers • Decryption performance optimization • IP in a smartcard • A computer can talk with smartcards even if they are not directly connected to its serial ports • Secure bootstrapping with a smartcard • PAM • Single Sign-On with PAM and smartcards

  37. Related Work - comparison Secure computer system Secure operating system Secure bootstrapping Secure computer system Existing operating system Existing bootstrapping Secure hardware Authentication theory Existing hardware + Smartcard

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