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

On Metrics to Quantify the Inter-Device Uniqueness of PUFs

Physically Unclonable Functions (PUFs) have been an emerging topic in hardware security and trust in recent years, and many different kinds of PUFs have been presented in the literature. An important criterion is always the diversity of PUF responses for different devices, called inter-device uniqueness. A very popular uniqueness metric consists of calculating the pairwise hamming distance between the response bit-strings of all devices, assuming that all response bits are uncorrelated. Such correlations, however, should be regarded when a statement about inter-device uniqueness is made. We therefore propose a novel correlation metric to fulfil this requirement. Furthermore, we show that the hamming distance metric is actually redundant when at the same time the also popular bit-aliasing metric is applied

Physical Unclonable Functions based on Temperature Compensated Ring Oscillators

Physical unclonable functions (PUFs) are promising hardware security primitives suitable for low-cost cryptographic applications.Ring oscillator (RO) PUF is a well-received silicon PUF solution due to its ease of implementation and entropy evaluation. However, the responses of RO-PUFs are susceptible to environmental changes, in particular, to temperature variations. Additionally, a conventional RO-PUF implementation is usually more power-hungry than other PUF alternatives. This paper explores circuit-level techniques to design low-power RO-PUFs with enhanced thermal stability. We introduce a power-efficient approach based on a phase/frequency detector (PFD) to perform pairwise comparisons of ROs. We also propose a temperature compensated bulk-controlled oscillator and investigate its feasibility and usage in PFD-based RO-PUFs. Evaluation results demonstrate that the proposed techniques can effectively reduce the thermally induced errors in PUF responses while imposing a very low power overhead

ФИЗИЧЕСКИ НЕКЛОНИРУЕМЫЕ ФУНКЦИИ

Анализируются методы построения физически неклонируемых функций, являющихся основойфизической криптографии. Показываются ограничения при реализации подобных функций для цифровых устройств, в особенности с программируемой архитектурой. Предлагаются комбинированные физически неклонируемые функции. Экспериментально подтверждается их эффективность для случая программируемых логических матриц

Reliability Enhancement Of Ring Oscillator Based Physically Unclonable Functions

Tez (Yüksek Lisans) -- İstanbul Teknik Üniversitesi, Fen Bilimleri Enstitüsü, 2012Thesis (M.Sc.) -- İstanbul Technical University, Institute of Science and Technology, 2012Bu çalışmada, halka osilatör tabanlı fiziksel klonlanamayan fonksiyon devrelerinin, çeşitli çevresel etkiler karşısında güvenilirliklerin artırılması amaçlanmıştır. Öncelikle, osilatör çiftlerinin ürettiği frekans farklılıklarını ve dinamik etkileri gözlemleyip modelleyebilmek için çeşitli sahada programlanabilir kapı dizilerinin (FPGA) farklı bölgelerinde osilatör çiftleri gerçeklenmiş ve frekans farklılıkları ölçülmüştür. Bu ölçümler sonucunda halka osilatör çiftlerinine ilişkin statik ve dinamik dağılımlar elde edilmiştir. Güvenilirliği artırmak amacıyla halka osilatörleri etiketleyen bir yöntem önerilmiştir. Bu çalışmada ayrıca, bir osilatör çiftinden birden fazla bit elde etme işlemi de incelenmiş ve dinamik etkilere karşı test edilmiştir. Etiketleme yönteminin etkinliğini ve bir osilatör çiftinden birden fazla bit elde etme işlemini gerçek devre üzerinde incelemek amacıyla, fiziksel klonlanamayan fonksiyon devresi FPGA üzerinde gerçeklenmiştir. Sıcaklık odası ile ortamın sıcaklığı 10 – 65 °C arasında değiştirilmiştir. Sonuç olarak, ortam sıcaklığının artmasıyla birlikte güvenilmez bit sayısının arttığı gözlenmiştir. Etiketleme yöntemi kullanıldığında güvenilmez bite rastlanmamıştır. Bir halka osilatör çiftinden birden fazla bit (iki ve üç bit bilgi) elde edilmesi de test edilmiştir. Elde edilen iki ve üç bitlik verilerin küçük bir farklılıkla birlikte eşit dağılımlı olduğu gözlenmiştir. Bir osilatör çiftinden elde edilen bit sayısı arttıkça, güvenilir olmayan bitlerin sayısı da artmıştır. Fakat bir osilatörden iki ve üç bit elde etmede tüm hataların komşu bölgede olduğu gözlenmiştir.In this thesis, it is aimed to enhance the reliability of ring oscillator based Physically Unclonable Functions (PUFs) under different environmental variations. In order to observe and model the frequency difference of ring oscillator pairs and dynamic effects, ring oscillators are realized and measured at different locations of different Field Programmable Gate Arrays (FPGAs). After the measurements, static and dynamic distributions of ring oscillator pairs are obtained. In order to increase the reliability, a new technique that is labeling ring oscillators, is proposed. Also, in this study, the process of obtaining multiple bits from a ring oscillator pair is observed and tested with respect to dynamic effects. In order to analyze the enhancement of labeling technique and multiple bit extraction at the circuit, the PUF circuit is implemented on an FPGA. The ambient temperature is changed between 10 – 65 °C with a temperature chamber. As a result, it is observed that with increasing ambient temperature, the number of unreliable bits are increased. When labeling technique is used, no unreliable bits are observed. Multiple bits extraction (two and three bits extraction) is also tested. It is observed that the distribution of two and three bit wide data are almost equally distributed. The number of unreliable bits are increased with the extracted bit numbers. However, it is seen that all erronous bits are caused by jumping to adjacent region.Yüksek LisansM.Sc

MAG-PUFs:Authenticating IoT devices via electromagnetic physical unclonable functions and deep learning

The challenge of authenticating Internet of Things (IoT) devices, particularly in low-cost deployments with constrained nodes that struggle with dynamic re-keying solutions, renders these devices susceptible to various attacks. This paper introduces a robust alternative mitigation strategy based on Physical-Layer Authentication (PLA), which leverages the intrinsic physical layer characteristics of IoT devices. These unique imperfections, stemming from the manufacturing process of IoT electronic integrated circuits (ICs), are difficult to replicate or falsify and vary with each function executed by the IoT device. We propose a novel lightweight authentication scheme, MAG-PUFs, that uses the unintentional Electromagnetic (EM) emissions from IoT devices as Physical Unclonable Functions (PUFs). MAG-PUFs operate by collecting these unintentional EM emissions during the execution of pre-defined reference functions by the IoT devices. The authentication is achieved by matching these emissions with profiles recorded at the time of enrollment, using state-of-the-art Deep Learning (DL) approaches such as Neural Networks (NN) and Autoencoders. Notably, MAG-PUFs offer compelling advantages: (i) it preserves privacy, as it does not require direct access to the IoT devices; and, (ii) it provides unique flexibility, permitting the selection of numerous and varied reference functions. We rigorously evaluated MAG-PUFs using 25 Arduino devices and a diverse set of 325 reference function classes. Employing a DL framework, we achieved a minimum authentication F1-Score of 0.99. Furthermore, the scheme's efficacy in detecting impostor EM emissions was also affirmed, achieving a minimum F1-Score of 0.99. We also compared our solution to other solutions in the literature, showing its remarkable performance. Finally, we discussed code obfuscation techniques and the impact of Radio Frequency (RF) interference on the IoT authentication process.</p

MAG-PUFs:Authenticating IoT devices via electromagnetic physical unclonable functions and deep learning

The challenge of authenticating Internet of Things (IoT) devices, particularly in low-cost deployments with constrained nodes that struggle with dynamic re-keying solutions, renders these devices susceptible to various attacks. This paper introduces a robust alternative mitigation strategy based on Physical-Layer Authentication (PLA), which leverages the intrinsic physical layer characteristics of IoT devices. These unique imperfections, stemming from the manufacturing process of IoT electronic integrated circuits (ICs), are difficult to replicate or falsify and vary with each function executed by the IoT device. We propose a novel lightweight authentication scheme, MAG-PUFs, that uses the unintentional Electromagnetic (EM) emissions from IoT devices as Physical Unclonable Functions (PUFs). MAG-PUFs operate by collecting these unintentional EM emissions during the execution of pre-defined reference functions by the IoT devices. The authentication is achieved by matching these emissions with profiles recorded at the time of enrollment, using state-of-the-art Deep Learning (DL) approaches such as Neural Networks (NN) and Autoencoders. Notably, MAG-PUFs offer compelling advantages: (i) it preserves privacy, as it does not require direct access to the IoT devices; and, (ii) it provides unique flexibility, permitting the selection of numerous and varied reference functions. We rigorously evaluated MAG-PUFs using 25 Arduino devices and a diverse set of 325 reference function classes. Employing a DL framework, we achieved a minimum authentication F1-Score of 0.99. Furthermore, the scheme's efficacy in detecting impostor EM emissions was also affirmed, achieving a minimum F1-Score of 0.99. We also compared our solution to other solutions in the literature, showing its remarkable performance. Finally, we discussed code obfuscation techniques and the impact of Radio Frequency (RF) interference on the IoT authentication process.</p