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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
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Physical Unclonable Functions FarzaneSalehiMinapour Aida Miralaei MohammadKazemTaram 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 Hardware Security and Trust, CE, SUT
Challenges=>Conventional Authentication • Conventional Authentication Schemes • Need to store keys • Power and area consuming Hardware Security and Trust, CE, SUT
. 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 Hardware Security and Trust, CE, SUT
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 Hardware Security and Trust, CE, SUT
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. Hardware Security and Trust, CE, SUT
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 Hardware Security and Trust, CE, SUT
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] Hardware Security and Trust, CE, SUT
Applications of PUF 2) Cryptographic Key Generator[1] *ECC=Error Correction Code Hardware Security and Trust, CE, SUT
Applications of PUF 3) Software Licensing and Anonymous Computation[3] *CPUF=Controlled PUF Hardware Security and Trust, CE, SUT
Applications of PUF 3) Software Licensing and Anonymous Computation Hardware Security and Trust, CE, SUT
Applications of PUF • 0.1% of all challenges do not return a consistent response • These meta-stable challenges generate responses which can vary unpredictably • 4) Random Number Generation [2]
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 Hardware Security and Trust, CE, SUT
PUF Circuits • Arbiter PUF[4] Hardware Security and Trust, CE, SUT
PUF Circuits • Arbiter PUF • delay paths with the same layout length • Simple->attackers can construct a timing model Hardware Security and Trust, CE, SUT
PUF Circuits • construct a k-bit response • one circuit can be used k times with different inputs • duplicate the single-output PUF circuit Hardware Security and Trust, CE, SUT
PUF Circuits • Feed Forward Arbiter PUF Hardware Security and Trust, CE, SUT
PUF Circuits • Lightweight Secure PUF[7] Hardware Security and Trust, CE, SUT
PUF Circuits • Ring Oscillator PUF [1] Hardware Security and Trust, CE, SUT
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 Hardware Security and Trust, CE, SUT
PUF Circuits • Ring Oscillator PUF • environmental conditions • Choose ring oscillator pairs, whose frequencies are far apart=>remove key generation error Hardware Security and Trust, CE, SUT
PUF Circuits SRAM • SRAM PUF[5] Hardware Security and Trust, CE, SUT
PUF Circuits • Butterfly PUF[6] Hardware Security and Trust, CE, SUT
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 Hardware Security and Trust, CE, SUT
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 Hardware-Oriented 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 Hardware Security and Trust, CE, SUT