Design And Implementation Of On-chip SRAM PUF For Embedded SoC

With the wide application of embedded systems, embedded systems informationprotection is attracting more and more people to pay attention to, which produced a series ofcryptography and encryption algorithm, such as the common used DES, AES, RSA etc.These algorithms are foundations of modern cryptography system, established bymathematicians and computer scientists based on the algorithmic complexity theory, whichguaranteed their safety from mathematics. Besides, to ensure the algorithms themselvessecurity sufficiently, they were selected openly and undertook lots of analog attacks. Thesecurity of the cryptographic system is often depends on the safety of system keys ratherthan the confidentiality of the cipher algorithm, thus, once the system keys is leaked oftenmeans the invalidation of entire security mechanism.Aimed at the existing physical attack methods to system keys, this paper introducedsome system key security strategies and defense methods that mainly existed, analyzed thefunctions and their advantages and disadvantages. Based on the function of existing PUF(Physical Unclonable Functions), which preventing information from physical attacks, thispaper proposed an on-chip SRAM PUF (Static Random Access Memory PUF) systemsecurity key generation method, it uses power up characteristics of SRAM that integrated onthe CPU extracting system security keys, This design has the following characteristics:(1) System only needs to store a helper data that just have small amount informationentropy of SRAM power up initial value. We do not need to store the system keys orcryptographic keys, which effectively put an end to the physical attack on the system keys.(2) System keys we extracted from the SRAM power up value is highly uniqueness andhardware correlation. Even if the attackers get a system key of certain hardware, they can’tapply it to other similar platforms.(3) This system has a high degree of reliability. To the STM32F407platform we use, authentication and key generation success rate we designed up to99.99992%.In this paper, the key generation method we proposed was implemented on theSTM32F407platform. We have an analysis and test to the system we designed, the testresults show that, the designed on-chip SRAM PUF system work well to meet the designrequirements.