Transcript PUFx - CE Sharif

Physical Unclonable Functions
Farzane Salehi Minapour
Aida Miralaei
MohammadKazem Taram
Department of Computer Eng.
Sharif University of Technology
Spring 2014
Agenda
● Challenges in Hardware Security
● What is PUF ?
● Applications of PUFs
● Classification of PUFs
● PUF Circuits
● Summery
● References
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Challenges=>Conventional Authentication
 Conventional Authentication Schemes
 Need to store keys
 Power and area consuming
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Challenges => Store Secrets
.
 Conventional approach to embed secure secrets in IC
• Non-volatile memory(ROM, Fuse, Flash or EEPROM)
• Battery-backed RAM
 Non-volatile memory technologies are often vulnerable to invasive
and non-invasive attack
 Adversaries can physically extract secret keys from EEPROM while
processor is off
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Challenges=>expensive tamper proof packs
 Storing digital information in a device in a way that is
resistant to physical attacks is difficult and expensive.
IBM 4758
●
Tamper-proof package containing a
secure processor which has a secret
key and memory
●
Tens of sensors, resistance,
temperature, voltage, etc.
●
Continually battery-powered
●
~ $3500 for a 99 MHz processor and
128MB of memory
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Challenges=>Power and Area
 Power and Area are critical
RFID tag can afford a maximum of 2000 gates for
security features
 Passive RFIDs
A good cryptographic primitive should be
lightweight, occupy little area on silicon and
should have very low power consumption.
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What is PUF?
 Physical Unclonable Function (PUF)
 Process variations can be turned into a feature
rather than a problem
• Variation is inherent in fabrication process
•
Unique for each physical instance
• Hard to remove or predict
• Relative variation increases as the fab process
advances
• Non-silicon PUFs
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Types of PUFs
● Optical PUFs
● Coating and Acoustic PUFs
● Silicon PUFs(SPUF)
○ timing and delay information
○ easy integrate into ICs
Applications of PUF
1) Low cost authentication[1]
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Applications of PUF
2) Cryptographic Key Generator[1]
*ECC=Error Correction Code
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Applications of PUF
3) Software Licensing and Anonymous Computation[3]
*CPUF=Controlled PUF
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Applications of PUF
3) Software Licensing and Anonymous Computation
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Applications of PUF
4) Random Number Generation [2]
●0.1% of all challenges do not
return a consistent response
●These meta-stable challenges
generate responses which can
vary unpredictably
Classification of PUFs
● Strong PUFs
○ Large number of challenge response pairs
○ IC identification and secret key generation
○ E.g arbiter PUF and feed forward arbiter
● Weak PUFs
○ Limited number of challenge response pairs
(sometime just single)
○ Secret key generation
○ E.g SRAM PUF and butterfly PUF
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PUF Circuits
● Arbiter PUF[4]
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PUF Circuits
● Arbiter PUF
● delay paths with the same layout length
● Simple->attackers can construct a timing model
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PUF Circuits
● construct a k-bit response
● one circuit can be used k times with different inputs
● duplicate the single-output PUF circuit
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PUF Circuits
● Feed Forward Arbiter PUF
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PUF Circuits
● Lightweight Secure PUF[7]
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PUF Circuits
● Ring Oscillator PUF [1]
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PUF Circuits
● Ring Oscillator PUF
● Easier Implementation
● No need for careful layout and routing
● Slower, Larger, more power to generate bits
● Better for FPGAs and secure processors
● Hard to generate many challenge response pairs
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PUF Circuits
● Ring Oscillator PUF
● environmental conditions
● Choose ring oscillator pairs,
whose frequencies are far
apart=>remove key
generation error
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PUF Circuits SRAM
● SRAM PUF[5]
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PUF Circuits
● Butterfly PUF[6]
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Summery
●PUFs are innovative circuit primitives that extract
secrets from physical characteristics of
integrated circuits (ICs)
●PUFs can enable low-cost authentication of
individual ICs
●Generate volatile secret keys for cryptographic
operations both symmetric and asymmetric
cryptographic operations
●PUF applications and circuits
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References
[1] Suh, G.E., Devadas, S.: Physical unclonable functions for device authentication and
secret key generation. In: Design Automation Conference, pp. 9{14. ACM Press, New York,
NY, USA (2007)
[2] C. W. O’Donnell, G. E. Suh, and S. Devadas . PUF-based random number generation. In
MITCSAIL CSG Technical Memo 481, November 2004
[3] Gassend, Blaise, et al. "Controlled physical random functions and applications." ACM
Transactions on Information and System Security (TISSEC) 10.4 (2008): 3.
[4] J.W. Lee, D. Lim, B. Gassend, G. E. Suh, M. van Dijk and S. Devadas, “ A
technique to build a secret key in integrated circuits with identification and authentication
applications”, in Proceedings of the VLSI Circuits Symposium, June 2004.
[5] D. E. Holcomb, W. P. Burleson, and K. Fu, “ Power-up SRAM State as an
Identifying Fingerprint and Source of True Random Numbers”, in IEEE Transactions on
Computers, 58(9):1198-1210, 2009.
[6] S. S. Kumar, J. Guajardo, R. Maes, Geert-Jan Schrijen and P. Tuyls, “Extended Abstract: The
Butterfly PUF Protecting IP on every FPGA”, in IEEE International Workshop on HardwareOriented Security and Trust, HOST 2008.
[7] M. Majzoobi, F. Koushanfar and M. Potkonjak, “Lightweight Secure PUFs”, in IEEE
International Conference on Computer-Aided Design, 2008
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Thanks