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Environmental monitoring is essential for safeguarding the health of our planet and protecting human health and well-being. Without trust, the effectiveness of environmental monitoring and the ability to address environmental challenges are significantly compromised. In this paper, we present a sensor platform capable of performing authenticated and trustworthy measurements, together with a lightweight security protocol for sending the data from the sensor to a central server anonymously. Besides presenting a new and very efficient symmetric-key-based protocol, we also demonstrate on real hardware how existing embedded security modules can be utilized for this purpose. We provide an in-depth evaluation of the performance and a detailed security analysis. [ABSTRACT FROM AUTHOR]

Environmental monitoring is essential for safeguarding the health of our planet and protecting human health and well-being. Without trust, the effectiveness of environmental monitoring and the ability to address environmental challenges are significantly compromised. In this paper, we present a sensor platform capable of performing authenticated and trustworthy measurements, together with a lightweight security protocol for sending the data from the sensor to a central server anonymously. Besides presenting a new and very efficient symmetric-key-based protocol, we also demonstrate on real hardware how existing embedded security modules can be utilized for this purpose. We provide an in-depth evaluation of the performance and a detailed security analysis.

To ensure the security of network data transmission, a network data encryption method based on TrustZone was analyzed. The hardware layer was used to provide hardware support for network data encryption. The framework layer was provided with a trusted operating kernel and a common kernel with a rich execution environment through the kernel layer. The framework layer used the key security management unit on the client-application-side to create, write, read, and delete the security key file. The network data encryption and decryption unit on the client-application-side constructed a session connection between the client application side and the trusted application side under the kernel provided by the kernel layer by calling the hardware of the hardware layer. Moreover, the network data encryption and decryption instructions were transmitted to the trusted-application-side network data encryption and decryption unit. The encryption of the memristor neural network and the cubic chaotic map were employed. The network data encryption and decryption results were presented to the user through the application layer. Experiments results prove that, the interval of the optimal key chaotic sequence must be controlled between [-1,1]. The ASCII code value of the network data character sequence before encryption has an obvious distribution pattern to encrypt the network data to be transmitted under the wireless sensor network scenario. The value of the 0-1 balance index of the encrypted network data of this study's method is the closest to 0, and the highest values are approximately 0.0088, 0.0079, and 0.0067. The method in this study can effectively encrypt and decrypt network data. Under different attack types, this method has high integrity of encrypted network data and a high value of avalanche effect. Thus, it has effective anti-attack performance. [ABSTRACT FROM AUTHOR]

The growing use of deep neural networks (DNNs) in various applications has raised concerns about the security and privacy of model parameters and runtime execution. To address these concerns, researchers have proposed using trusted execution environments (TEEs) to build trustworthy neural network execution. This paper comprehensively surveys the literature on trusted neural networks, viz., answering how to efficiently execute neural models inside trusted enclaves. We review the various TEE architectures and techniques employed to achieve secure neural network execution and provide a classification of existing work. Additionally, we discuss the challenges and present a few open issues. We intend that this review will assist researchers and practitioners in understanding the state-of-the-art and identifying research problems.

Hyperledger Fabric is a distributed ledger solution platform based on a modular architecture. The cryptographic algorithm is the core of the platform to ensure the security and tamper-resistant of the data on the chain. However, the original Fabric platform lacks the protection of user's keys and cryptographic operations. To this end, this paper proposes a data privacy protection method for Hyperledger Fabric based on Trustzone technology, which places the user's key and the cryptographic operation process of private data in the trusted execution environment for protection. The experimental results based on the existing blockchain network show that the scheme can effectively ensure the security of data encryption process and key static storage, greatly reduce the trusted computing base and the attack surface. The performance loss is within an acceptable range. [ABSTRACT FROM AUTHOR]

The past decade has seen the rapid development of data in many areas. Data has enormous commercial potential as a new strategic resource that may efficiently boost technical growth and service innovation. However, individuals are becoming increasingly concerned about data misuse and leaks. To address these issues, in this paper, we propose TrustControl, a trusted data usage control system to control, process, and protect data usage without revealing privacy. A trusted execution environment (TEE) is exploited to process confidential user data. First of all, we design a secure and reliable remote attestation mechanism for ARM TrustZone, which can verify the security of the TEE platform and function code, thus guaranteeing data processing security. Secondly, to address the security problem that the raw data may be misused, we design a remote dynamic code injection method to regulate that data can only be processed for the expected purpose. Our solution focuses on protecting the sensitive data of the data owner and the function code of the data user to prevent data misuse and leakage. Furthermore, we implement the prototype system of TrustControl on TrustZone-enabled hardware. Real-world experiment results demonstrate that the proposed Trust-Control is secure and the performance overhead of introducing our prototype system is very low. [ABSTRACT FROM AUTHOR]

Combating the OS-level malware is a very challenging problem as this type of malware can compromise the operating system, obtaining the kernel privilege and subverting almost all the existing anti-malware tools. This work aims to address this problem in the context of mobile devices. As real-world malware is very heterogeneous, we narrow down the scope of our work by especially focusing on a special type of OS-level malware that always corrupts user data. We have designed mobiDOM, the first framework that can combat the OS-level data corruption malware for mobile computing devices. Our mobiDOM contains two components, a malware detector and a data repairer. The malware detector can securely and timely detect the presence of OS-level malware by fully utilizing the existing hardware features of a mobile device, namely, flash memory and Arm TrustZone. Specifically, we integrate the malware detection into the flash translation layer (FTL), a firmware layer embedded into the flash storage hardware, which is inaccessible to the OS; in addition, we run a trusted application in the Arm TrustZone secure world, which acts as a user-level manager of the malware detector. The FTL-based malware detection and the TrustZone-based manager can communicate with each other stealthily via steganography. The data repairer can allow restoring the external storage to a healthy historical state by taking advantage of the out-of-place-update feature of flash memory and our malware-aware garbage collection in the FTL. Security analysis and experimental evaluation on a real-world testbed confirm the effectiveness of mobiDOM.

Security is one of the main challenges of the Internet of Things (IoT). IoT devices are mainly powered by low-cost microcontrollers (MCUs) that typically lack basic hardware security mechanisms to separate security-critical applications from less critical components. Recently, Arm has started to release Cortex-M MCUs enhanced with TrustZone technology (i.e., TrustZone-M), a system-wide security solution aiming at providing robust protection for IoT devices. Trusted Execution Environments (TEEs) relying on TrustZone hardware have been perceived as safe havens for securing mobile devices. However, for the past few years, considerable effort has gone into unveiling hundreds of vulnerabilities and proposing a collection of relevant defense techniques to address several issues. While new TEE solutions built on TrustZone-M start flourishing, the lessons gathered from the research community appear to be falling short, as these new systems are trapping into the same pitfalls of the past. In this paper, we present uTango, the first multi-world TEE for modern IoT devices. uTango proposes a novel architecture aiming at tackling the major architectural deficiencies currently affecting TrustZone(-M)-assisted TEEs. In particular, we leverage the very same TrustZone hardware primitives used by dual-world implementations to create multiple and equally secure execution environments within the normal world. We demonstrate the benefits of uTango by conducting an extensive evaluation on a real TrustZone-M hardware platform, i.e., Arm Musca-B1. uTango will be open-sourced and freely available on GitHub in hopes of engaging academia and industry on securing the foreseeable trillion IoT devices.

The TrustZone technology is incorporated in a majority of recent ARM Cortex A and Cortex M processors widely deployed in the IoT world. Security critical code execution inside a so-called secure world is isolated from the rest of the application execution within a normal world. It provides hardware-isolated area called a trusted execution environment (TEE) in the processor for sensitive data and code. This paper demonstrates a vulnerability in the secure world in the form of a cross-world, secure world to normal world, covert channel. Performance counters or Performance Monitoring Unit (PMU) events are used to convey the information from the secure world to the normal world. An encoding program generates appropriate PMU event footprint given a secret S. A corresponding decoding program reads the PMU footprint and infers S using machine learning (ML). The machine learning model can be trained entirely from the data collected from the PMU in user space. Lack of synchronization between PMU start and PMU read adds noise to the encoding/decoding ML models. In order to account for this noise, this study proposes three different synchronization capabilities between the client and trusted applications in the covert channel. These are synchronous, semi-synchronous, and asynchronous. Previously proposed PMU based covert channels deploy L1 and LLC cache PMU events. The latency of these events tends to be 100–1000 cycles limiting the bandwidth of these covert channels. We propose to use microarchitecture level events with latency of 10–100 cycles captured through PMU for covert channel encoding leading to a potential 100× higher bandwidth. This study conducts a series of experiments to evaluate the proposed covert channels under various synchronization models on a TrustZone supported Cortex-A processor using OP-TEE framework. As stated earlier, switch from signaling based on PMU cache events to PMU microarchitectural events leads to approximately 15× higher covert channel bandwidth. This proposed finer-grained microarchitecture event encoding covert channel can achieve throughput of the order of 11 Kbits/s as opposed to previous work's throughput of the order of 760 bits/s. [ABSTRACT FROM AUTHOR]

Combating the OS-level malware is a very challenging problem as this type of malware can compromise the operating system, obtaining the kernel privilege and subverting almost all the existing anti-malware tools. This work aims to address this problem in the context of mobile devices. As real-world malware is very heterogeneous, we narrow down the scope of our work by especially focusing on a special type of OS-level malware that always corrupts user data. We have designed mobiDOM, the first framework that can combat the OS-level data corruption malware for mobile computing devices. Our mobiDOM contains two components, a malware detector and a data repairer. The malware detector can securely and timely detect the presence of OS-level malware by fully utilizing the existing hardware features of a mobile device, namely, flash memory and Arm TrustZone. Specifically, we integrate the malware detection into the flash translation layer (FTL), a firmware layer embedded into the flash storage hardware, which is inaccessible to the OS; in addition, we run a trusted application in the Arm TrustZone secure world, which acts as a user-level manager of the malware detector. The FTL-based malware detection and the TrustZone-based manager can communicate with each other stealthily via steganography. The data repairer can allow restoring the external storage to a healthy historical state by taking advantage of the out-of-place-update feature of flash memory and our malware-aware garbage collection in the FTL. Security analysis and experimental evaluation on a real-world testbed confirm the effectiveness of mobiDOM. [ABSTRACT FROM AUTHOR]

Hyperledger Fabric is a distributed ledger solution platform based on a modular architecture. The cryptographic algorithm is the core of the platform to ensure the security and tamper-resistant of the data on the chain. However, the original Fabric platform lacks the protection of user’s keys and cryptographic operations. To this end, this paper proposes a data privacy protection method for Hyperledger Fabric based on Trustzone technology, which places the user‘s key and the cryptographic operation process of private data in the trusted execution environment for protection. The experimental results based on the existing blockchain network show that the scheme can effectively ensure the security of data encryption process and key static storage, greatly reduce the trusted computing base and the attack surface. The performance loss is within an acceptable range.

Many mobile applications deliver and show sensitive and private textual content to users including messages, social network posts, account information, and verification codes. All such textual content must be displayed to users but must be strongly protected from unauthorized access in mobile devices. Unfortunately, this is not the case in mobile devices today: malware that can compromise the OS can easily access textual content of other applications. We present SchrodinText, a system solution for strongly protecting the confidentiality of an application's selected UI textual content from a fully compromised OS. SchrodinText leverages a novel security monitor based on two hardware features on ARM processors: virtualization hardware and TrustZone. Our key contribution is a set of novel techniques that allow the OS to perform text rendering without needing access to the text itself, hence minimizing the trusted computing base (TCB). These techniques, collectively called oblivious rendering, enable the OS to rasterize and lay out all the characters without access to the text; the monitor resolves the right character glyphs onto the framebuffer observed by the user and protects them from the OS. Using our prototypes, we show that SchrodinText incurs noticeable overhead but that its performance is usable. [ABSTRACT FROM AUTHOR]

Due to the development of Internet of Things technology, the security protection of embedded systems has become a systemic problem that needs to be considered and tried to be solved urgently. A variety of embedded computer system security protection methods are compared, and ARM TrustZone security protection scheme is analyzed. The main differences between the two technologies (TrustZone-A and TrustZone-M) are analyzed, and the applicable scenarios and implementation characteristics of the two solutions are given. The implementation principle of the trusted startup process based on TrustZone technology is described, and the feasibility of the implementation of abnormal program detection based on the TrustZone-A monitoring mode code is discussed. Finally, combined with typical application scenarios, a security protection scheme based on TrustZone-M technology and an implementation example of a security communication protocol are designed and proposed. [ABSTRACT FROM AUTHOR]

This paper presents an improvement of control flow attestation (C-FLAT) for Linux. C-FLAT is a control attestation system for embedded devices. It was implemented as a software executing in ARM's TrustZone on bare-metal devices. We extend the design and implementation of C-FLAT through the use of a type 2 Nanovisor in the Linux operating system. We call our improved system "C-FLAT Linux". Compared to the original C-FLAT, C-FLAT Linux reduces processing overheads and is able to detect the SlowLoris attack. We describe the architecture of C-FLAT Linux and provide extensive measurements of its performance in benchmarks and real-world scenarios. In addition, we demonstrate the detection of the SlowLoris attack on the Apache web server. [ABSTRACT FROM AUTHOR]

Hardware support for isolated execution (e.g., ARM TrustZone) enables the development of a trusted execution environment (TEE) that ensures the security of the code and data while communicating with a compromised rich execution environment (REE). The ability to satisfy various security services is complicated and usually consists of trusted applications, a trusted kernel and a secure monitor. However, formally verifying the security of an entire TEE security remains challenging. We present a methodology for designing a TEE in a way that enables verification of its security properties. Our methodology consists of forcing a trusted application and kernel to communicate with an REE via a narrow interface and compile and link them with a small secure monitor that implements the interface and runs at the highest privilege level. We provide functional verification of the secure monitor to ensure that it correctly switches the TEE/REE, communicates with the REE at a pre-defined memory space and has no integer overflow vulnerability. We also perform a verification of the secure monitor's scheduler to ensure that it satisfies information flow noninterference. We present a modular verification framework that can prove an end-to-end security property for cross-language programmes (e.g., C and assembly languages). Our evaluation suggests that the methodology scales to real-world TEE applications.

The TrustZone technology is incorporated in a majority of recent ARM Cortex A and Cortex M processors widely deployed in the IoT world. Security critical code execution inside a so-called secure world is isolated from the rest of the application execution within a normal world. It provides hardware-isolated area called a trusted execution environment (TEE) in the processor for sensitive data and code. This paper demonstrates a vulnerability in the secure world in the form of a cross-world, secure world to normal world, covert channel. Performance counters or Performance Monitoring Unit (PMU) events are used to convey the information from the secure world to the normal world. An encoding program generates appropriate PMU event footprint given a secret S. A corresponding decoding program reads the PMU footprint and infers S using machine learning (ML). The machine learning model can be trained entirely from the data collected from the PMU in user space. Lack of synchronization between PMU start and PMU read adds noise to the encoding/decoding ML models. In order to account for this noise, this study proposes three different synchronization capabilities between the client and trusted applications in the covert channel. These are synchronous, semi-synchronous, and asynchronous. Previously proposed PMU based covert channels deploy L1 and LLC cache PMU events. The latency of these events tends to be 100–1000 cycles limiting the bandwidth of these covert channels. We propose to use microarchitecture level events with latency of 10–100 cycles captured through PMU for covert channel encoding leading to a potential 100× higher bandwidth. This study conducts a series of experiments to evaluate the proposed covert channels under various synchronization models on a TrustZone supported Cortex-A processor using OP-TEE framework. As stated earlier, switch from signaling based on PMU cache events to PMU microarchitectural events leads to approximately 15× higher covert channel bandwidth. This proposed finer-grained microarchitecture event encoding covert channel can achieve throughput of the order of 11 Kbits/s as opposed to previous work’s throughput of the order of 760 bits/s.

This paper presents a comprehensive survey on the development of Intel SGX (software guard extensions) processors and its applications. With the advent of SGX in 2013 and its subsequent development, the corresponding research works are also increasing rapidly. In order to get a more comprehensive literature review related to SGX, we have made a systematic analysis of the related papers in this area. We first search through five large-scale paper retrieval libraries by keywords (i.e., ACM Digital Library, IEEE/IET Electronic Library, SpringerLink, Web of Science, and Elsevier Science Direct). We read and analyze a total of 128 SGX-related papers. The first round of extensive study is conducted to classify them. The second round of intensive study is carried out to complete a comprehensive analysis of the paper from various aspects. We start with the working environment of SGX and make a conclusive summary of trusted execution environment (TEE). We then focus on the applications of SGX. We also review and study multifarious attack methods to SGX framework and some recent security improvements made on SGX. Finally, we summarize the advantages and disadvantages of SGX with some future research opportunities. We hope this review could help the existing and future research works on SGX and its application for both developers and users. [ABSTRACT FROM AUTHOR]

Control-Flow Integrity (CFI) is a class of defensive techniques against control-flow attacks such as Return-Oriented Programming. We propose a light-weight CFI scheme for RTOS-based applications, TZmCFI, which utilizes TrustZone for Armv8-M, a hardware-assisted security feature for embedded systems with tight resource constraints. TZmCFI embodies several existing CFI techniques to provide a comprehensive protection. The traditional shadow stack technique is used to ensure stack integrity and validate function returns. To protect exception handlers, TZmCFI extends shadow exception stacks, which are a variant of the traditional shadow stack technique we proposed in our previous work, for RTOS integration and performance improvement. We conducted an experiment on Arm Versatile Express Cortex-M Prototyping System (V2M-MPS2+) to evaluate the run-time overhead of the proposed system. [ABSTRACT FROM AUTHOR]

Security is one of the major challenges that devices connected to the Internet of Things (IoT) face today. Remote attestation is used to measure these devices’ trustworthiness on the network by measuring the device platform’s integrity. Several software-based attestation mechanisms have been proposed, but none of them can detect runtime attacks. Although some researchers have attempted to tackle these attacks, the proposed techniques require additional secured hardware parts to be integrated with the attested devices to achieve their aim. These solutions are expensive and not suitable in many cases. This paper proposes a dual attestation process, SAPEM, with two phases: static and dynamic. The static attestation phase examines the program memory of the attested device. The dynamic program flow attestation examines the execution correctness of the application code. It can detect code injection and runtime attacks that hijack the control-flow, including data attacks that affect the program control-flow. The main aim is to minimize attestation overhead while maintaining our ability to detect the specified attacks. We validated SAPEM by implementing it on Raspberry Pi using its TrustZone extension. We attested it against the specified attacks and compared its performance with the related work in the literature. The results show that SAPEM significantly minimizes performance overhead while reliably detecting runtime attacks at the binary level. [ABSTRACT FROM AUTHOR]

With the development of blockchain-based digital currencies, the security of digital wallets becomes more and more important. As far as we know, there is no safe lightweight wallet in hyperledger fabric. To solve the problem, we proposed a T rustzone-based S ecure L ightweight W allet for H yperledger F abric (hereafter referred to as TSLWHF). Firstly, we designed an Unspent Transaction Output (UTXO) set of transactions under blockchain and a signature verification mechanism for transactions, which made it possible to implement the lightweight wallet in hyperledger fabric. Then, we implemented a reliable protection mechanism for private keys and wallet's address, which solved the problem that users' information might be stolen or replaced. Meanwhile, the transaction verification results are guaranteed not to be tampered by hackers through verifying transactions in Trusted Execution Environment (TEE) and encrypting local block headers. Finally, to demonstrate utility, we deployed the system in hyperledger fabric and trustzone. Experiments showed that the wallet reduces the size of locally stored data while protecting the security of user's assets. The time spent on TSLWHF to execute a transaction is 0.589s, which improves transaction's performance compared to Bitcoin wallet. • In hyperledger fabric, we implemented a digital currency system based on the UTXO model, which supports the Simple Payment Verification (SPV). • We designed a secure trustzone-based lightweight wallet for hyperledger fabric, which can protect users' digital assets. • We conducted abundant evaluations, and our proposed system is secure and brings less overheads. [ABSTRACT FROM AUTHOR]

This paper presents an improvement of control flow attestation (C-FLAT) for Linux. C-FLAT is a control attestation system for embedded devices. It was implemented as a software executing in ARM’s TrustZone on bare-metal devices. We extend the design and implementation of C-FLAT through the use of a type 2 Nanovisor in the Linux operating system. We call our improved system “C-FLAT Linux”. Compared to the original C-FLAT, C-FLAT Linux reduces processing overheads and is able to detect the SlowLoris attack. We describe the architecture of C-FLAT Linux and provide extensive measurements of its performance in benchmarks and real-world scenarios. In addition, we demonstrate the detection of the SlowLoris attack on the Apache web server.

TrustZone technology has been widely used in the security protection of various smart systems, such as data encryption, fingerprint login, DRM protection, electronic payment and so on. TrustZone technology provides programs with a trusted execution environment (TEE) that is isolated from the host environment to provide the runtime protection for important code and data. Therefore, the calling process of the security application based on TrustZone has changed, then the application adds processes such as data sharing and messaging between the secure and non-secure worlds, which causes additional performance overhead. This paper locates four key elements that affect the performance of the security application: world switch, interrupt, shared memory management, and data copy. On this base, four corresponding performance optimization methods are proposed. Through the AES encryption service based on TrustZone technology, the proposed performance optimization methods were compared and tested to verify their effectiveness. Experimental results show that: 1. Setting parameters reasonably can improve the performance by 31% at most. 2. Masking external interrupts can improve the performance by 4.5% at most. 3. Memory reusing can improve the performance by 37% at most. 4. Reducing memory copy can improve the performance by 39% at most. [ABSTRACT FROM AUTHOR]

Abstract Third-party IME (Input Method Editor) apps are often the preference means of interaction for Android users’ input. In this paper, we first discuss the insecurity of IME apps, including the Potentially Harmful Apps (PHAs) and malicious IME apps, which may leak users’ sensitive keystrokes. The current defense system, such as I-BOX, is vulnerable to the prefix substitution attack and the colluding attack due to the post-IME nature. We provide a deeper understanding that all the designs with the post-IME nature are subject to the prefix-substitution and colluding attacks. To remedy the above post-IME system’s flaws, we propose a new idea, pre-IME, which guarantees that “Is this touch event a sensitive keystroke?” analysis will always access user touch events prior to the execution of any IME app code. We design an innovative TrustZone-based framework named IM-Visor which has the pre-IME nature. Specifically, IM-Visor creates the isolation environment named STIE as soon as a user intends to type on a soft keyboard, then the STIE intercepts,Android event sub translates and analyzes the user’s touch input. If the input is sensitive, the translation of keystrokes will be delivered to user apps through a trusted path. Otherwise, IM-Visor replays non-sensitive keystroke touch events for IME apps or replays non-keystroke touch events for other apps. A prototype of IM-Visor has been implemented and tested with several most popular IMEs. The experimental results show that IM-Visor has small runtime overheads.

Due to the increasing total value of the digital currency, the security of encryption wallet is becoming more and more important. The hardware-based wallet is safe, but it is inconvenient because users need to carry an additional physical device, the software-based wallet is convenient, but the safety cannot be guaranteed. All these wallets need to synchronize the blockchain, while most current mobile devices do not have the capability to store all blocks. To solve these problems, mobile devices can use simplified payment verification (SPV). Nevertheless, in existing methods, there is no good way to protect the verification process of the transaction. In this paper, we design a secure blockchain lightweight wallet based on Trustzone to protect SPV. It is more portable compared with the hardware wallet, and safer than the software wallet. Through the isolation, it can also protect the private key and the wallet's address from being stolen by the attackers no matter whether the Rich OS is malicious or not. Meanwhile, it can protect the verification process by verifying transactions in the secure execution environment (SEE), and keep the local block headers unreadable directly from the Rich OS through encryption. We deploy it on the RASPBERRY PI 3 MODEL B development board. The result of the experiment shows that it has little impact on the system.

Summary: Smartwatches are becoming increasingly ubiquitous as they offer new capabilities to develop sophisticated applications that make daily life easier and more convenient for consumers. The services provided include applications for mobile payment, ticketing, identification, access control, etc. While this makes modern smartwatches very powerful devices, it also makes them very attractive targets for attackers. Indeed, PINs and Pattern Lock have been widely used in smartwatches for user authentication. However, such authentication methods are not robust against various forms of cybersecurity attacks, such as side channel, phishing, smudge, shoulder surfing, and video‐recording attacks. Moreover, the recent adoption of hardware‐based solutions, like the Trusted Execution Environment (TEE), can mitigate only partially such problems. Thus, the user's security and privacy are at risk without a strong authentication scheme in place. In this work, we propose 2GesturePIN, a new authentication framework that allows users to authenticate securely to their smartwatches and related sensitive services through solely two gestures. 2GesturePIN leverages the rotating bezel or crown, which are the most intuitive ways to interact with a smartwatch, as a dedicated hardware. 2GesturePIN improves the resilience of the regular PIN authentication method against state‐of‐the‐art cybersecurity attacks while maintaining a high level of usability. [ABSTRACT FROM AUTHOR]

Physical health records belong to healthcare providers, but the information contained within belongs to each patient. In an increasing manner, more health-related data is being acquired by wearables and other IoT devices following the ever-increasing trend of the Quantified Self. Even though data protection regulations (e.g., GDPR) encourage the usage of privacy-preserving processing techniques, most of the current IoT infrastructure was not originally conceived for such purposes. One of the most used communication protocols, MQTT, is a lightweight publish-subscribe protocol commonly used in the Edge and IoT applications. In MQTT, the broker must process data on clear text, hence exposing a large attack surface for a malicious agent to steal/tamper with this health-related data. In this paper, we introduce MQT-TZ, a secure MQTT broker leveraging Arm TRUSTZONE, a popular Trusted Execution Environment (TEE). We define a mutual TLS-based handshake and a two-layer encryption for end-to-end security using the TEE as a trusted proxy. We provide quantitative evaluation of our open-source PoC on streaming ECGs in real time and highlight the trade-offs. [ABSTRACT FROM AUTHOR]

TrustZone is a hardware security technique in ARM mobile devices. Using TrustZone, software components running within the secure world can be completely isolated from the normal world, which ensures hardware-enforced security access control over the underlying computing resources. In order to support multiple trusted applications, TrustZone runs its own operating system, called the secure OS, within the secure world. Unfortunately, attackers have been exploiting privilege escalation vulnerabilities in a secure OS, as reported in most of major secure OSes from product vendors including Samsung, Huawei, and Qualcomm. More critically, as all trusted applications are running on the same secure OS instance, compromising the secure OS leads to compromising all trusted applications, rendering the secure OS as a single point of failure endangering the entire TrustZone's security. This paper presents PrOS, our mechanism to privatize secure OSes through direct virtualization of TrustZone. PrOS allows each trusted application to run with its own secure OS such that the secure OS is no longer a single point of security failure. One particular challenge for PrOS lies in how efficiently to implement software-only virtualization for TrustZone for a practical deployment in real systems despite the condition that the current ARM architectures do not support hardware-assisted virtualization for TrustZone. As opposed to the common belief that software-only virtualization is inefficient and sluggish, we have found several common design features inherent in the secure OS to leverage for optimally tailoring the TrustZone virtualization scheme. We implemented PrOS on a 64-bit ARM development board. According to our evaluation, PrOS incurs 0.02 and 1.18 percent performance overheads on average in the normal and secure worlds, respectively, demonstrating its effectiveness in the field. [ABSTRACT FROM AUTHOR]

Side-channel power analysis is a powerful method of breaking secure cryptographic algorithms, but typically power analysis is considered to require specialized measurement equipment on or near the device. Assuming an attacker first gained the ability to run code on the unsecure side of a device, they could trigger encryptions and use the on-board ADC to capture power traces of that hardware encryption engine. This is demonstrated on a SAML11 which contains a M23 core with a TrustZone-M implementation as the hardware security barrier. This attack requires 160 × 106 traces, or approximately 5 GByte of data. This attack does not use any external measurement equipment, entirely performing the power analysis using the ADC on-board the microcontroller under attack. The attack is demonstrated to work both from the non-secure and secure environment on the chip, being a demonstration of a cross-domain power analysis attack. To understand the effect of noise and sample rate reduction, an attack is mounted on the SAML11 hardware AES peripheral using classic external equipment, and results are compared for various sample rates and hardware setups. A discussion on how users of this device can help prevent such remote attacks is also presented, along with metrics that can be used in evaluating other devices. Complete copies of all recorded power traces and scripts used by the authors are publicly presented.