Search

The energy levels of hydrogen-like atomic systems can be calculated with great precision. Starting from their quantum mechanical solution, they have been refined over the years to include the electron spin, the relativistic and quantum field effects, and tiny energy shifts related to the complex structure of the nucleus. These energy shifts caused by the nuclear structure are vastly magnified in hydrogen-like systems formed by a negative muon and a nucleus, so spectroscopy of these muonic ions can be used to investigate the nuclear structure with high precision. Here we present the measurement of two 2S–2P transitions in the muonic helium-4 ion that yields a precise determination of the root-mean-square charge radius of the α particle of 1.67824(83) femtometres. This determination from atomic spectroscopy is in excellent agreement with the value from electron scattering1, but a factor of 4.8 more precise, providing a benchmark for few-nucleon theories, lattice quantum chromodynamics and electron scattering. This agreement also constrains several beyond-standard-model theories proposed to explain the proton-radius puzzle2,3,4,5, in line with recent determinations of the proton charge radius6,7,8,9, and establishes spectroscopy of light muonic atoms and ions as a precise tool for studies of nuclear properties., Nature, 589 (7843), ISSN:0028-0836, ISSN:1476-4687

The energy levels of hydrogen-like atomic systems can be calculated with great precision. Starting from their quantum mechanical solution, they have been refined over the years to include the electron spin, the relativistic and quantum field effects, and tiny energy shifts related to the complex structure of the nucleus. These energy shifts caused by the nuclear structure are vastly magnified in hydrogen-like systems formed by a negative muon and a nucleus, so spectroscopy of these muonic ions can be used to investigate the nuclear structure with high precision. Here we present the measurement of two 2S-2P transitions in the muonic helium-4 ion that yields a precise determination of the root-mean-square charge radius of the α particle of 1.67824(83) femtometres. This determination from atomic spectroscopy is in excellent agreement with the value from electron scattering

The invasive computing paradigm offers applications the possibility to dynamically spread their computation in a multicore/multiprocessor system in a resource-aware way. If applications are assumed to act maliciously, many security problems arise. In this acticle, we discuss different ways to deal with security problems in a resource-aware way. We first formalize the attacker model and the different security requirements that applications may have in multi-core systems. We then survey different hardware and software security mechanisms that can be dynamically configured to guarantee security on demand for invasive applications.

With SDN/NFV, the telecom industry embraces operational flexibility and cost optimization, while facing new risks from off-premise cloud computing, known as introspection by malicious operators. Introspection is identified as a serious risk only by the IT industry in general when considering cloud operation. To mitigate it, processor vendors have invested in the last decade to design Trusted Execution Environments (TEEs) plugged into their processor architectures. TEEs bring a quantum hardware-level security higher than any software-based security. They are all essentially aimed at protecting data and code when executed and processed in the cloud or in untrusted environment. In this paper, we emphasize on the blocking factors for the use of TEEs today: processor market fragmentation, major architectural and design deviations between TEEs from various CPU vendors and finally, a relatively complex enablement of these TEE technologies for non-security experts. We describe a code interpretation solution to break those blocking factors by providing a universal abstraction layer for TEEs. The paper gives a conceptual blueprint of a solution that enables Intel's SGX and AMD's SEV, defined as the most contemplated candidates in this paper for SDN/NFV or 5G deployment. Our study presents the key challenges and advanced functionalities we view as essential for meeting key SDN/NFV requirements and which are deploy ability, software performance and easy setup. Innovative directions are given to deal efficiently with these upcoming requirements.

We present TEEshift, a tool suite that protects the confiden- tiality and integrity of code by shifting selected functions into TEEs. Our approach works entirely on binary-level and does not require the adaption of source code projects or build environments, nor does it require compiler-level patches. Programmers provide a list of ELF symbols pointing to the functions that should be protected. After post-processing an ELF binary with TEEshift, the selected functions are not present in cleartext anymore. Only after attesting to a re- mote party that the loading enclave behaves with integrity, the functions are decrypted, but remain inside the enclave protected against reverse engineering. An online connection is only required when a program starts for the first time on a PC. Afterwards, sealing is used to securely store the decryption key and bind it to the PC. By allowing program- mers to move selected function into TEEs, without patching their source code, we provide a convenient way to enable TEEs in existing projects while preserving the flexibility for a finegrained security and performance tradeoff. We evaluated our tool using a real world gaming application, confirming the practicability of our approach for existing projects. We overcome the limitation of the fragmented TEE landscape by building on top of Asylo, an open framework by Google for apps which aim to support different TEEs such as Intel SGX and AMD SEV using a unified API.

© 2016 IEEE. Attackers target many different types of computer systems in use today, exploiting software vulnerabilities to take over the device and make it act maliciously. Reports of numerous attacks have been published, against the constrained embedded devices of the Internet of Things, mobile devices like smartphones and tablets, high-performance desktop and server environments, as well as complex industrial control systems. Trusted computing architectures give users and remote parties like software vendors guarantees about the behaviour of the software they run, protecting them against software-level attackers. This paper defines the security properties offered by them, and presents detailed descriptions of twelve hardware-based attestation and isolation architectures from academia and industry. We compare all twelve designs with respect to the security properties and architectural features they offer. The presented architectures have been designed for a wide range of devices, supporting different security properties. ispartof: IEEE Transactions on Computers vol:67 issue:3 pages:361-374 status: published

We study the problem of data exposure in main memory caused by insecure deallocation, which is still the default in all common memory management schemes. We propose declarative approaches to handle unreasonably long data lifetime at the programming language level, and present several directions on how current platforms can be improved to minimize the lifetime of confidential data. For the particularly difficult case of Java with its automated garbage collection approach, we present a specific implementation of our approach for the Dalvik VM runtime environment. We give the application level programmer of Android more control over memory by making garbage collection predictable, and by providing the ability to explicitly override and free memory. While the performance impact arising from our approach is negligible in most scenarios, we prove its effectiveness by validating that no freed Java objects can be traced in RAM at runtime anymore.

The Sancus security architecture for networked embedded devices was proposed in 2013 at the USENIX Security conference. It supports remote (even third-party) software installation on devices while maintaining strong security guarantees. More specifically, Sancus can remotely attest to a software provider that a specific software module is running uncompromised, and can provide a secure communication channel between software modules and software providers. Software modules can securely maintain local state, and can securely interact with other software modules that they choose to trust. Over the past three years, significant experience has been gained with applications of Sancus, and several extensions of the architecture have been investigated – both by the original designers as well as by independent researchers. Informed by these additional research results, this journal version of the Sancus paper describes an improved design and implementation, supporting additional security guarantees (such as confidential deployment) and a more efficient cryptographic core. We describe the design of Sancus 2.0 (without relying on any prior knowledge of Sancus), and develop and evaluate a prototype FPGA implementation. The prototype extends an MSP430 processor with hardware support for the memory access control and cryptographic functionality required to run Sancus. We report on our experience with using Sancus in a variety of application scenarios, and discuss some important avenues of ongoing and future work. ispartof: ACM Transactions on Privacy and Security vol:20 issue:3 pages:7- status: published

For the first time, we practically demonstrate that Intel SGX enclaves are vulnerable against cache-timing attacks. As a case study, we present an access-driven cache-timing attack on AES when running inside an Intel SGX enclave. Using Neve and Seifert's elimination method, as well as a cache probing mechanism relying on Intel PMC, we are able to extract the AES secret key in less than 10 seconds by investigating 480 encrypted blocks on average. The AES implementation we attack is based on a Gladman AES implementation taken from an older version of OpenSSL, which is known to be vulnerable to cache-timing attacks. In contrast to previous works on cache-timing attacks, our attack is executed with root privileges running on the same host as the vulnerable enclave. Intel SGX, however, was designed to precisely protect applications against such root-level attacks. As a consequence, we show that SGX cannot withstand its designated attacker model when it comes to side-channel vulnerabilities. To the contrary, the attack surface for side-channels increases dramatically in the scenario of SGX due to the power of root-level attackers, for example, by exploiting the accuracy of PMC, which is restricted to kernel code.

The weakest link in software-based full disk encryption is the authentication procedure. Since the master boot record must be present unencrypted in order to launch the decryption of remaining system parts, it can easily be manipulated and infiltrated by bootkits that perform keystroke logging; consequently, password-based authentication schemes become attackable. The current technological response, as enforced by BitLocker, verifies the integrity of the boot process by use of the trusted platform module. But, as we show, this countermeasure is insufficient in practice. We present STARK, the first tamperproof authentication scheme that mutually authenticates the computer and the user in order to resist keylogging during boot. To achieve this, STARK implements trust bootstrapping from a secure token to the whole PC. The secure token is an active USB drive that verifies the integrity of the PC and indicates the verification status by an LED to the user. This way, users can ensure the authenticity of the PC before entering their passwords.

In this paper, we present a novel approach on isolating operating system components with Intel SGX. Although SGX has not been designed to work in kernel mode, we found a way of wrapping Linux kernel functionality within SGX enclaves by moving parts of it to user space. Kernel components are strictly isolated from each other such that a vulnerability in one kernel module cannot escalate into compromising the entire kernel. We provide a proof-of-concept implementation which protects an exemplary kernel function, namely full disk encryption, using an Intel SGX enclave. Besides integrity of the disk encryption, our implementation ensures that the confidentiality of the disk encryption key is protected against all software level attacks as well as physical attacks. In addition to the user password, we use a second authentication factor for deriving the encryption key which is stored sealed and bound to the platform. Thus, stealing the hard drive and sniffing the user password is insufficient for an attacker to break disk encryption. Instead, the two factor authentication scheme requires an attacker to additionally obtain the actual machine to be able to break encryption.

We present HyperCrypt, a hypervisor-based solution that encrypts the entire kernel and user space to protect against physical attacks on main memory, such as cold boot attacks. HyperCrypt is fully transparent for the guest operating system and all applications running on top of it. At any time, only a small working set of memory pages remains in clear while the vast majority of pages are constantly kept encrypted. By utilizing CPU-bound encryption, the symmetric encryption key is never exposed to RAM. We evaluated our prototype running a standard Linux system with an nginx web sever. With the default configuration of 1024 cleartext pages, successful cold boot attacks are rendered highly unlikely due to large caches of at least 4 MB in modern CPUs. The performance overhead of nginx is raised by factor 1.37 compared to a non-virtualized system.

We present RamCrypt, a solution that allows unmodified Linux processes to transparently work on encrypted data. RamCrypt can be deployed and enabled on a per-process basis without recompiling user-mode applications. In every enabled process, data is only stored in cleartext for the moment it is processed, and otherwise stays encrypted in RAM. In particular, the required encryption keys do not reside in RAM, but are stored in CPU registers only. Hence, RamCrypt effectively thwarts memory disclosure attacks, which grant unauthorized access to process memory, as well as physical attacks such as cold boot and DMA attacks. In its default configuration, RamCrypt exposes only up to 4 memory pages in cleartext at the same time. For the nginx web server serving encrypted HTTPS pages under heavy load, the necessary TLS secret key is hidden for 97% of its time.

Different applications concurrently running on modern MPSoCs can interfere with each other when they use shared resources. This interference can cause side channels, i.e., sources of unintended information flow between applications. To prevent such side channels, we propose a hybrid mapping methodology that attempts to ensure spatial isolation, i.e., a mutually-exclusive allocation of resources to applications in the MPSoC. At design time and as a first step, we compute compact and connected application mappings (called shapes). In a second step, run-time management uses this information to map multiple spatially segregated shapes to the architecture. We present and evaluate a (fast) heuristic and an (exact) SAT-based mapper, demonstrating the viability of the approach.

We review the status of the proton charge radius puzzle. Emphasis is given to the various experiments initiated to resolve the conflict between the muonic hydrogen results and the results from scattering and regular hydrogen spectroscopy., EPJ Web of Conferences, 113, ISSN:2100-014X, ISSN:2101-6275

Laser spectroscopy of the Lamb shift (2S-2P energy difference) in light muonic atoms or ions, in which one negative muon $\mu^-$ is bound to a nucleus, has been performed. The measurements yield significantly improved values of the root-mean-square charge radii of the nuclei, owing to the large muon mass, which results in a vastly increased muon wave function overlap with the nucleus. The values of the proton and deuteron radii are 10 and 3 times more accurate than the respective CODATA values, but 7 standard deviations smaller. Data on muonic helium-3 and -4 ions is being analyzed and will give new insights. In future, the (magnetic) Zemach radii of the proton and the helium-3 nuclei will be determined from laser spectroscopy of the 1S hyperfine splittings, and the Lamb shifts of muonic Li, Be and B can be used to improve the respective charge radii., Comment: Contribution to LEAP 2016 in Kanazawa, Japan

The main memory of today's computers contains lots of sensitive data, in particular from applications that have been used recently. As data within RAM is stored in cleartext, it is exposed to attackers with physical access to a system. In this paper we introduce Exzess, a hardware-based mitigation against physical memory disclosure attacks such as, for example, cold boot and DMA attacks. Our FPGA-based prototype with accompanying software components demonstrates the viability, security and performance of our novel approach for partial main memory encryption via memory proxies. The memory proxy approach will be compared to other existing mitigation techniques and possible further uses beyond encryption will be discussed, as well. Exzess effectively protects against physical attacks on main memory while being transparent to applications and the operating system after initialization.

Protecting the intellectual property of software that is distributed to third-party devices which are not under full control of the software author is difficult to achieve on commodity hardware today. Modern techniques of reverse engineering such as static and dynamic program analysis with system privileges are increasingly powerful, and despite possibilities of encryption, software eventually needs to be processed in clear by the CPU. To anyhow be able to protect software on these devices, a small part of the hardware must be considered trusted. In the past, general purpose trusted computing bases added to desktop computers resulted in costly and rather heavyweight solutions. In contrast, we present Soteria, a lightweight solution for low-cost embedded systems. At its heart, Soteria is a program-counter based memory access control extension for the TI MSP430 microprocessor. Based on our open implementation of Soteria as an openMSP430 extension, and our FPGA-based evaluation, we show that the proposed solution has a minimal performance, size and cost overhead while effectively protecting the confidentiality and integrity of an application's code against all kinds of software attacks including attacks from the system level.

A multipass laser cavity is presented which can be used to illuminate an elongated volume from a transverse direction. The illuminated volume can also have a very large transverse cross section. Convenient access to the illuminated volume is granted. The multipass cavity is very robust against misalignment, and no active stabilization is needed. The scheme is suitable for example in beam experiments, where the beam path must not be blocked by a laser mirror, or if the illuminated volume must be very large. This cavity was used for the muonic-hydrogen experiment in which 6 $\mu$m laser light illuminated a volume of 7 x 25 x 176 mm^3, using mirrors that are only 12 mm in height. We present our measurement of the intensity distribution inside the multipass cavity and show that this is in good agreement with our simulation., Comment: 13 pages, 8 figures. Delayed submission. Original open access article at https://www.osapublishing.org/oe/fulltext.cfm?uri=oe-22-11-13050

Avalanche photodiodes are commonly used as detectors for low energy x-rays. In this work we report on a fitting technique used to account for different detector responses resulting from photo absorption in the various APD layers. The use of this technique results in an improvement of the energy resolution at 8.2 keV by up to a factor of 2, and corrects the timing information by up to 25 ns to account for space dependent electron drift time. In addition, this waveform analysis is used for particle identification, e.g. to distinguish between x-rays and MeV electrons in our experiment., 6 pages, 6 figures

© 2004-2012 IEEE. Due to the requirements of the Internet-of-Things, modern embedded systems have become increasingly complex, running different applications. In order to protect their intellectual property as well as the confidentiality of sensitive data they process, these applications have to be isolated from each other. Traditional memory protection and memory management units provide such isolation, but rely on operating system support for their configuration. However, modern operating systems tend to be vulnerable and cannot guarantee confidentiality when compromised. We present Atlas, a hardware-based security architecture, complementary to traditional memory protection mechanisms, ensuring code and data confidentiality through transparent encryption, even when the system software has been exploited. Atlas relies on its zero-software trusted computing base to protect against system-level attackers and also supports secure shared memory. We implemented Atlas based on the LEON3 softcore processor, including toolchain extensions for developers. Our FPGA-based evaluation shows minimal cycle overhead at the cost of a reduced maximum frequency. ispartof: IEEE TRANSACTIONS ON DEPENDABLE AND SECURE COMPUTING vol:16 issue:3 pages:415-423 status: published