Design and analysis of an FPGA-based, multi-processor HW-SW system for SCC applications

The last 30 years have seen an increase in the complexity of embedded systems from a collection of simple circuits to systems consisting of multiple processors managing a wide variety of devices. This ever increasing complexity frequently requires that high assurance, fail-safe and secure design techniques be applied to protect against possible failures and breaches. To facilitate the implementation of these embedded systems in an efficient way, the FPGA industry recently created new families of devices. New features added to these devices include anti-tamper monitoring, bit stream encryption, and optimized routing architectures for physical and functional logic partition isolation. These devices have high capacities and are capable of implementing processors using their reprogrammable logic structures. This allows for an unprecedented level of hardware and software interaction within a single FPGA chip. High assurance and fail-safe systems can now be implemented within the reconfigurable hardware fabric of an FPGA, enabling these systems to maintain flexibility and achieve high performance while providing a high level of data security. The objective of this thesis was to design and analyze an FPGA-based system containing two isolated, softcore Nios processors that share data through two crypto-engines. FPGA-based single-chip cryptographic (SCC) techniques were employed to ensure proper component isolation when the design is placed on a device supporting the appropriate security primitives. Each crypto-engine is an implementation of the Advanced Encryption Standard (AES), operating in Galois/Counter Mode (GCM) for both encryption and authentication. The features of the microprocessors and architectures of the AES crypto-engines were varied with the goal of determining combinations which best target high performance, minimal hardware usage, or a combination of the two

Teaching FPGA Security

International audienceTeaching FPGA security to electrical engineering students is new at graduate level. It requires a wide field of knowledge and a lot of time. This paper describes a compact course on FPGA security that is available to electrical engineering master's students at the Saint-Etienne Institute of Telecom, University of Lyon, France. It is intended for instructors who wish to design a new course on this topic. The paper reviews the motivation for the course, the pedagogical issues involved, the curriculum, the lab materials and tools used, and the results. Details are provided on two original lab sessions, in particular, a compact lab that requires students to perform differential power analysis of FPGA implementation of the AES symmetric cipher. The paper gives numerous relevant references to allow the reader to prepare a similar curriculum

Barrel Shifter Physical Unclonable Function Based Encryption

Physical Unclonable Functions (PUFs) are circuits designed to extract physical randomness from the underlying circuit. This randomness depends on the manufacturing process. It differs for each device enabling chip-level authentication and key generation applications. We present a protocol utilizing a PUF for secure data transmission. Parties each have a PUF used for encryption and decryption; this is facilitated by constraining the PUF to be commutative. This framework is evaluated with a primitive permutation network - a barrel shifter. Physical randomness is derived from the delay of different shift paths. Barrel shifter (BS) PUF captures the delay of different shift paths. This delay is entangled with message bits before they are sent across an insecure channel. BS-PUF is implemented using transmission gates; their characteristics ensure same-chip reproducibility, a necessary property of PUFs. Post-layout simulations of a common centroid layout 8-level barrel shifter in 0.13 {\mu}m technology assess uniqueness, stability and randomness properties. BS-PUFs pass all selected NIST statistical randomness tests. Stability similar to Ring Oscillator (RO) PUFs under environment variation is shown. Logistic regression of 100,000 plaintext-ciphertext pairs (PCPs) failed to successfully model BS- PUF behavior

Variation Aware Placement for Efficient Key Generation using Physically Unclonable Functions in Reconfigurable Systems

With the importance of data security at its peak today, many reconfigurable systems are used to provide security. This protection is often provided by FPGA-based encrypt/decrypt cores secured with secret keys. Physical unclonable functions (PUFs) use random manufacturing variations to generate outputs that can be used in keys. These outputs are specific to a chip and can be used to create device-tied secret keys. Due to reliability issues with PUFs, key generation with PUFs typically requires error correction techniques. This can result in substantial hardware costs. Thus, the total cost of a $n$-bit key far exceeds just the cost of producing $n$ bits of PUF output. To tackle this problem, we propose the use of variation aware intra-FPGA PUF placement to reduce the area cost of PUF-based keys on FPGAs. We show that placing PUF instances according to the random variations of each chip instance reduces the bit error rate of the PUFs and the overall resources required to generate the key. Our approach has been demonstrated on a Xilinx Zynq-7000 programmable SoC using FPGA specific PUFs with code-offset error correction based on BCH codes. The approach is applicable to any PUF-based system implemented in reconfigurable logic. To evaluate our approach, we first analyze the key metrics of a PUF - reliability and uniqueness. Reliability is related to bit error rate, an important parameter with respect to error correction. In order to generate reliable results from the PUFs, a total of four ZedBoards containing FPGAs are used in our approach. We quantify the effectiveness of our approach by implementing the same key generation scheme using variation-aware and default placement, and show the resources saved by our approach

Remote Attacks on FPGA Hardware

Immer mehr Computersysteme sind weltweit miteinander verbunden und über das Internet zugänglich, was auch die Sicherheitsanforderungen an diese erhöht. Eine neuere Technologie, die zunehmend als Rechenbeschleuniger sowohl für eingebettete Systeme als auch in der Cloud verwendet wird, sind Field-Programmable Gate Arrays (FPGAs). Sie sind sehr flexible Mikrochips, die per Software konfiguriert und programmiert werden können, um beliebige digitale Schaltungen zu implementieren. Wie auch andere integrierte Schaltkreise basieren FPGAs auf modernen Halbleitertechnologien, die von Fertigungstoleranzen und verschiedenen Laufzeitschwankungen betroffen sind. Es ist bereits bekannt, dass diese Variationen die Zuverlässigkeit eines Systems beeinflussen, aber ihre Auswirkungen auf die Sicherheit wurden nicht umfassend untersucht. Diese Doktorarbeit befasst sich mit einem Querschnitt dieser Themen: Sicherheitsprobleme die dadurch entstehen wenn FPGAs von mehreren Benutzern benutzt werden, oder über das Internet zugänglich sind, in Kombination mit physikalischen Schwankungen in modernen Halbleitertechnologien. Der erste Beitrag in dieser Arbeit identifiziert transiente Spannungsschwankungen als eine der stärksten Auswirkungen auf die FPGA-Leistung und analysiert experimentell wie sich verschiedene Arbeitslasten des FPGAs darauf auswirken. In der restlichen Arbeit werden dann die Auswirkungen dieser Spannungsschwankungen auf die Sicherheit untersucht. Die Arbeit zeigt, dass verschiedene Angriffe möglich sind, von denen früher angenommen wurde, dass sie physischen Zugriff auf den Chip und die Verwendung spezieller und teurer Test- und Messgeräte erfordern. Dies zeigt, dass bekannte Isolationsmaßnahmen innerhalb FPGAs von böswilligen Benutzern umgangen werden können, um andere Benutzer im selben FPGA oder sogar das gesamte System anzugreifen. Unter Verwendung von Schaltkreisen zur Beeinflussung der Spannung innerhalb eines FPGAs zeigt diese Arbeit aktive Angriffe, die Fehler (Faults) in anderen Teilen des Systems verursachen können. Auf diese Weise sind Denial-of-Service Angriffe möglich, als auch Fault-Angriffe um geheime Schlüsselinformationen aus dem System zu extrahieren. Darüber hinaus werden passive Angriffe gezeigt, die indirekt die Spannungsschwankungen auf dem Chip messen. Diese Messungen reichen aus, um geheime Schlüsselinformationen durch Power Analysis Seitenkanalangriffe zu extrahieren. In einer weiteren Eskalationsstufe können sich diese Angriffe auch auf andere Chips auswirken die an dasselbe Netzteil angeschlossen sind wie der FPGA. Um zu beweisen, dass vergleichbare Angriffe nicht nur innerhalb FPGAs möglich sind, wird gezeigt, dass auch kleine IoT-Geräte anfällig für Angriffe sind welche die gemeinsame Spannungsversorgung innerhalb eines Chips ausnutzen. Insgesamt zeigt diese Arbeit, dass grundlegende physikalische Variationen in integrierten Schaltkreisen die Sicherheit eines gesamten Systems untergraben können, selbst wenn der Angreifer keinen direkten Zugriff auf das Gerät hat. Für FPGAs in ihrer aktuellen Form müssen diese Probleme zuerst gelöst werden, bevor man sie mit mehreren Benutzern oder mit Zugriff von Drittanbietern sicher verwenden kann. In Veröffentlichungen die nicht Teil dieser Arbeit sind wurden bereits einige erste Gegenmaßnahmen untersucht

Compound Effects of Clock and Voltage Based Power Side-Channel Countermeasures

The power side-channel attack, which allows an attacker to derive secret information from power traces, continues to be a major vulnerability in many critical systems. Numerous countermeasures have been proposed since its discovery as a serious vulnerability, including both hardware and software implementations. Each countermeasure has its own drawback, with some of the highly effective countermeasures incurring large overhead in area and power. In addition, many countermeasures are quite invasive to the design process, requiring modification of the design and therefore additional validation and testing to ensure its accuracy. Less invasive countermeasures that do not require directly modifying the system do exist but often offer less protection. This thesis analyzes two non-invasive countermeasures and examines ways to maximize the protection offered by them while incurring the least amount of overhead. These two countermeasures are called clock phase noise (CPN) and voltage noise (VN), and are placed on the same FPGA as an AES encryption module that we are trying to protect. We test these designs against a highly effective algorithm called correlation power analysis (CPA) and a preprocessing technique called the sliding window attack (SW). We found that the combined effects of the two countermeasures was greater than the impact of either countermeasure when used independently, and published a paper in the 2019 IEEE 30th International Conference on Application-specific Systems, Architectures and Processors (ASAP) on our findings. We found that our best combined countermeasure protected about 76% of the maximum amount of traces that a well-known but invasive competitor, wave dynamic differential logic (WDDL), could with only about 41% of the area and 78% of the power. However, the sliding window attack significantly reduced the amount of protection our combined countermeasure could offer to only 11% of that offered by WDDL. Since then, we updated our methodology and made some adjustments to VN and CPN. Our CPN countermeasure greatly improved, and therefore so did our combined countermeasure, which on average protected up to about 90% of the maximum amount of traces that WDDL could with only about 43% of the area and about 60% of the power. This is remarkable because these results are after the sliding window attack, meaning that our post-proposal countermeasures protect almost as well as WDDL while requiring only about half of the resources