Embedded Security

1. Embedded Security A.J. Han Vinck May 2003

2. content • Introduction • Embedded system • Embedded cryptography • Some problems in crypto • or: how to use/implement mathematics ? • Counter measures Han Vinck February 2003

3. embedded system • acomputing system as part of a larger system • may use • a ROM-based operating system • a disk-based system, like a PC • used to control, monitor or assist an operation Example:a P that controls an automobile engine Han Vinck February 2003

4. Source: Richard Newton Han Vinck February 2003

5. Components in embedded systems • Micro processors • no access to programm • Busses • Communication ports/modems • Hardware • Programmable hardware: FPGA • (P)ROM, RAM • Battery/Power supply • System clock Protect software Bus and port management needed Pin/memory protection; proper design Check variations Han Vinck February 2003

6. Embedded processor constraints • small amounts of memory (RAM, ROM) limit the amount of data a program can hold restrict the program code size • restriction on power consumption slower clock speeds  less processing power.  • An embedded processor is not subject to FIRMR Federal Information Resources Management Regulation regulation when used for control of communication devices, automobile diagnostics • Word length 8, 16, 32; speed XX MHz BUT: Cryptography is computationally intensive Han Vinck February 2003

7. Some interesting facts • Intel 4004 was an embedded application (a calculator) • Of todays microprocessors • 95% go into embedded applications • SSH3/4 (Hitachi): best selling RISC microprocessor • application area • Microcontrollers • DSPs • Media Processors • Graphics Processors • Network and Communication Processors Han Vinck February 2003

8. Embedded System Constraints cont‘d Less hardware more software lower speed parallel structure serial solutions Han Vinck February 2003

9. embedded cryptography • Cryptography engineered into an equipment or system whose basic function is not cryptographic Problem: if to be implemented later Han Vinck February 2003

10. ATTACKS • can be more difficult in customized (specialized) HW/SW • new possibilities: side-channel/tamper attacks • Power analysis; voltage variations; etc • easy access to nodes; reverse engineering available • easier because security depends on HW/SW/power constraints • Public key infrastructure is missing – no backbone Han Vinck February 2003

11. Why attack ? • Gain control ( power ) • Competition; 11.9 • Money(crime) • Pay TV, cell Phones, car stealing, misuse of information • Kick • hackers Han Vinck February 2003

12. Basic Cryptographic tools • Algorithms: • Symmetric-key: 3DES, AES • Public-key: RSA, Diffie-Hellman, ECC • Hashing: MD5 • Random Number Generation: • RC4 • Protocols: • SSL; SSH; Kerberos • Based on zero-knowledge; honest coin flipping • Certification; Arbitrating; Trusted center Han Vinck February 2003

13. example • Many tools based on discrete logarithm problem ax = y modulo n given x „easy“ to find y given y „hard“ to find x All integers of size > = 1024 bits! Han Vinck February 2003

14. discrete logarithm application • Secret key algorithm Pohlig-Hellman • Public key algorithm RSA; El Gamal • Random number generation • Key exchange Diffie-Hellman • Signatures; Hash functions *** • additional property used • when ed = 1 modulo p-1 aed = a modulo p • SLOW: Security based on numbers > 1024 bits Han Vinck February 2003

15. Interesting new approach • NTRU: • based on convolution product of two polynomials • Faster than usual algorithms like RSA, ECC • CEES embedded security standard • (IEEE P1363.1) CEES: consortium for efficient embedded security Han Vinck February 2003

16. Symmetric key systems • Stream cipher: simple and fast M M MR MR R R problem PRNG PRNG key stored at two locations! Han Vinck February 2003

17. Problems in cryptographic systems • Choise of parameters • Example: • bad numbers in Diffie-Hellman, • RSA key e d = 1 modulo (p-1)(q-1) • „own development“ • Example: • WiFI, Hash(M+d) = Hash(M) + Hash(d) • Avoid patents (IDEA) • Pseudo random number generation • not predictable; long period; dependability Han Vinck February 2003

18. Problems (cont) • protocol not complete • Man in the middle attack • Replay • complexity • Mathematics OK, size of parameters not • limited processing poweradditional risk • network speeds increasesecurity must also • network connections • Web-based applications; cell phone without protection Han Vinck February 2003

19. Problems (cont) • Internet connection security threats • Packet sniffing  use encryption • Avoids reading open messages, passwords, keys, etc. • Substitution  use signed Hash • Modifying data, commands or software • Impersonation  use authentication • Replay; man in the middle; masquerade • Key management  use key infrastructure • Who can do what and when • Insider attacks • Manufacturing, distribution, installation and operation Han Vinck February 2003

20. Problems (cont) • Physical security • Tamper-resistant • Side channel attack resistance • Timing-, power analysis Han Vinck February 2003

21. access to the system • via Internet or Internal • many candidate nodes • wireless is „open“ • downloading may start malicious programs • Illegal memory allocation or corruption • Reading for passwords  send to outside  attack Han Vinck February 2003

22. Counter measures (1) • Use secure Base • Log all activities • Utilize Access control • Assign privilage levels/rights • Careful downloading of SW • Allow only signed and authorized downloading • Fixed memory partitions • Encrypt sensitive content • Determine failure modes (what happens after?) Han Vinck February 2003

23. Counter measures (2) • Test at initialization • Test at operation if everything works properly • Example: Random Number generation • Logging of Deviations • Immediatly signaling of serious deviations Han Vinck February 2003

24. Research projects • Security in critical infrastructures • key management; compatibility; scalability • Security in embedded systems • best algorithm and architecture for specified resources • memory or computing power • Investigate the CEES proposal • Random number generation based on inverse source coding • easy to implement, but hard to analyze Han Vinck February 2003

25. conclusions • performance of cryptographic algorithms is crucial low speed  dissatisfaction and inconvenience needed at communication speed • programmability facilitates modifications and enhancements • make algorithm independentfrom the protocol • Key management protocol needed • Master keys, Session keys Han Vinck February 2003

26. Digital Signal Processor • fast arithmetic; strong integer arithmetic • specialized computational units and instructions for signal processing • real-time capabilities • highly parallel architecture •  lower clock speed  relatively lower power • relatively low price • programmability flexibility • programmer selects the units he needs • can be implemented as a co-processor  > speed Han Vinck February 2003

27. Example Field Programmable Array Type I two or more look-up tables and two or more flip-flops Type II two-input logic function or a 4-to-1 multiplexer and a flip-flop Han Vinck February 2003

28. FPGA Han Vinck February 2003