Emerging non-volatile memory based physical unclonable functions

Abstract

Cybersecurity has drawn tremendous attentions from academia and industry in the recent years, thanks to the proliferation of extensively connected devices and computers. While software-defined service has been demonstrated effective in many other applications, safeguarding sensitive information that virtually resides in the communication channels, computation nodes and data storage elements remains a critical issue that may require sagacious solution leveraging on the advantageous attributes of hardware. Hardware-based security solutions for accelerating cryptographic primitives like hash function and block cipher using hardware fabrics on FPGA and ASIC has been studied comprehensively in the literature. As an essential part, the storage element for preserving secret keys is alway the target of adversarial attacks. Unfortunately, conventional methods for key preservation such as applying a “One-Time-Programmable” Non-Volatile Memory (OTP NVM) storage where the key is restricted for read only by authorized identities, has been experimentally demonstrated vulnerable to varieties of physical attacks. The technology of Physical Unclonable Function (PUF) emerged at the right moment, when traditional approaches failed to circumvent this issue. Compared to the OTP NVM, PUF is superior in the security strength against physical attacks owing to its inherently tamper-evident property and physical randomness that renders predicting unknown secret patterns extracted from it a difficult job. The incentive of research in this dissertation is to improve the security and reliability of existing PUF implementations supported by applying emerging Non-Volatile-Memory (eNVM) technologies. Even though PUF is recognized as an efficient primitive for key preservation/generation and cryptographic protocols, it has been criticized for low reliability under certain environmental conditions and limited strength of security against intelligent attacks. The research in this dissertation will review these problems firstly, and propose several PUF designs using the eNVM media to achieve the best performance in security and reliability with minimum overhead. The first PUF design is featured by physically reconfiguration property, that is, the key pool of the PUF can be dynamically refreshed as required. Compared to an existing instance called “logically reconfigurable PUF”, the proposed design does not need any auxiliary components for algorithmically refreshing challenges and responses of a PUF. An illustrative design based on Phase Change Memory (PCM) by exploiting process variation and programming uncertainties of PCM cell devices have been used for demonstration. Statistics of measurement results on an experimental PCM chip proved the expected effectiveness of the proposed scheme. The second design utilizes the non-volatility of eNVM technologies for enhancing reliability of memory-based PUFs. The core idea of this approach is the Automatic Write-Back (AWB) technique which latches the initially generated response bits by comparing the mismatch…