Physically unclonable functions based on a controlled ring oscillator

Решается задача построения нового класса физически неклонируемых функций (ФНФ) на базе управляемого кольцевого осциллятора (УКО). Актуальность создания УКОФНФ связана с активным развитием физической криптографии, применяемой для целей идентификации электронных изделий и формирования криптографических ключей. Показано, что классические физически неклонируемые функции на основе кольцевых осцилляторов (КОФНФ) характеризуются большой аппаратурной избыточностью из-за необходимости реализовывать большое число КО, в силу того что, каждый бит ответа требует наличия независимой пары реальных КО. В тоже время КОФНФ характеризуются лучшими статистическими свойствами по сравнению с ФНФ типа арбитр и не требуют обеспечения идеальной симметричности и идентичности реализуемых КО. В качестве альтернативы КОФНФ предлагается новый класс физически неклонируемых функций, а именноУКОФНФ, использующий управляемые кольцевые осцилляторы, основанные на управлении частотой формируемых импульсов без изменения функциональности и структуры осциллятора. Важным достоинством УКО является возможность реализации на его основе множества КО,количество которых достигает 2m, где m есть количество разрядов осциллятора, и каждый из них определяется подаваемым запросом. В статье рассматриваются три альтернативных структуры предлагаемых ФНФ, а именно УКОФНФ1, УКОФНФ2 и УКОФНФ3. Показываются их основные достоинства и недостатки, в том числе, в случае двух вариантов реализации, а именно на программированной логике (FPGA) и произвольной логике (ASIC). В качестве базового варианта для реализации на FPGA рассматривается УКОФНФ2 менее подверженный межкристальной и, что более важно, внутрикристальной зависимости, вызванной технологическими особенностями производственного процесса. Практические исследования проводились путем реализации на современных FPGA УКОФНФ2, оценки ее работоспособности и основных ее характеристик. Экспериментально подтверждена работоспособность нового класса ФНФ при их реализации на программируемой логике, а также высокие показатели их основных статистических характеристик

MeLPUF: Memory in Logic PUF

Physical Unclonable Functions (PUFs) are used for securing electronic designs across the implementation spectrum ranging from lightweight FPGA to server-class ASIC designs. However, current PUF implementations are vulnerable to model-building attacks; they often incur significant design overheads and are challenging to configure based on application-specific requirements. These factors limit their application, primarily in the case of the system on chip (SoC) designs used in diverse applications. In this work, we propose MeL-PUF - Memory-in-Logic PUF, a low-overhead, distributed, and synthesizable PUF that takes advantage of existing logic gates in a design and transforms them to create cross-coupled inverters (i.e. memory cells) controlled by a PUF control signal. The power-up states of these memory cells are used as the source of entropy in the proposed PUF architecture. These on-demand memory cells can be distributed across the combinational logic of various intellectual property (IP) blocks in a system on chip (SoC) design. They can also be synthesized with a standard logic synthesis tool to meet the area,power, or performance constraints of a design. By aggregating the power-up states from multiple such memory cells, we can create a PUF signature or digital fingerprint of varying size. We evaluate the MeL-PUF signature quality with both circuit-level simulations as well as with measurements in FPGA devices. We show that MeL-PUF provides high-quality signatures in terms of uniqueness, randomness, and robustness, without incurring large overheads. We also suggest additional optimizations that can be leveraged to improve the performance of MeL-PUF.Comment: 5 pages, 16 figure

Assessing Security Risks with the Internet of Things

For my honors thesis I have decided to study the security risks associated with the Internet of Things (IoT) and possible ways to secure them. I will focus on how corporate, and individuals use IoT devices and the security risks that come with their implementation. In my research, I found out that IoT gadgets tend to go unnoticed as a checkpoint for vulnerability. For example, often personal IoT devices tend to have the default username and password issued from the factory that a hacker could easily find through Google. IoT devices need security just as much as computers or servers to keep the security, confidentiality, and availability of data in the right hands

Practical Lightweight Security: Physical Unclonable Functions and the Internet of Things

In this work, we examine whether Physical Unclonable Functions (PUFs) can act as lightweight security mechanisms for practical applications in the context of the Internet of Things (IoT). In order to do so, we first discuss what PUFs are, and note that memory-based PUFs seem to fit the best to the framework of the IoT. Then, we consider a number of relevant memory-based PUF designs and their properties, and evaluate their ability to provide security in nominal and adverse conditions. Finally, we present and assess a number of practical PUF-based security protocols for IoT devices and networks, in order to confirm that memory-based PUFs can indeed constitute adequate security mechanisms for the IoT, in a practical and lightweight fashion. More specifically, we first consider what may constitute a PUF, and we redefine PUFs as inanimate physical objects whose characteristics can be exploited in order to obtain a behaviour similar to a highly distinguishable (i.e., “(quite) unique”) mathematical function. We note that PUFs share many characteristics with biometrics, with the main difference being that PUFs are based on the characteristics of inanimate objects, while biometrics are based on the characteristics of humans and other living creatures. We also note that it cannot really be proven that PUFs are unique per instance, but they should be considered to be so, insofar as (human) biometrics are also considered to be unique per instance. We, then, proceed to discuss the role of PUFs as security mechanisms for the IoT, and we determine that memory-based PUFs are particularly suited for this function. We observe that the IoT nowadays consists of heterogeneous devices connected over diverse networks, which include both high-end and resource-constrained devices. Therefore, it is essential that a security solution for the IoT is not only effective, but also highly scalable, flexible, lightweight, and cost-efficient, in order to be considered as practical. To this end, we note that PUFs have been proposed as security mechanisms for the IoT in the related work, but the practicality of the relevant security mechanisms has not been sufficiently studied. We, therefore, examine a number of memory-based PUFs that are implemented using Commercial Off-The-Shelf (COTS) components, and assess their potential to serve as acceptable security mechanisms in the context of the IoT, not only in terms of effectiveness and cost, but also under both nominal and adverse conditions, such as ambient temperature and supply voltage variations, as well as in the presence of (ionising) radiation. In this way, we can determine whether memory-based PUFs are truly suitable to be used in the various application areas of the IoT, which may even involve particularly adverse environments, e.g., in IoT applications involving space modules and operations. Finally, we also explore the potential of memory-based PUFs to serve as adequate security mechanisms for the IoT in practice, by presenting and analysing a number of cryptographic protocols based on these PUFs. In particular, we study how memory-based PUFs can be used for key generation, as well as device identification, and authentication, their role as security mechanisms for current and next-generation IoT devices and networks, and their potential for applications in the space segment of the IoT and in other adverse environments. Additionally, this work also discusses how memory-based PUFs can be utilised for the implementation of lightweight reconfigurable PUFs that allow for advanced security applications. In this way, we are able to confirm that memory-based PUFs can indeed provide flexible, scalable, and efficient security solutions for the IoT, in a practical, lightweight, and inexpensive manner