587 research outputs found
Relaxed freshness in component authentication
We suggests a relaxed freshness paradigm for challenge-response authentication for each field of application where challenger and responder are tightly coupled and authentication takes place in a friendly environment. Replay attacks are not feasible under this premise, and freshness can be relaxed to relative freshness: no refresh is required as long as all previously tested responders were authentic. One field of application is anti-counterfeiting of electronic device components. The main contribution is a formal security proof of an authentication scheme with choked refresh. A practical implication is the lifetime increase of stored challenge-response-pairs. This is a considerable advantage for solutions based on hardware intrinsic security. For solutions based on symmetric keys, it opens the possibility to use challenge-response-pairs instead of secret keys by the challenger – a cheap way to reduce the risk of key disclosure
Chip and Skim: cloning EMV cards with the pre-play attack
EMV, also known as "Chip and PIN", is the leading system for card payments
worldwide. It is used throughout Europe and much of Asia, and is starting to be
introduced in North America too. Payment cards contain a chip so they can
execute an authentication protocol. This protocol requires point-of-sale (POS)
terminals or ATMs to generate a nonce, called the unpredictable number, for
each transaction to ensure it is fresh. We have discovered that some EMV
implementers have merely used counters, timestamps or home-grown algorithms to
supply this number. This exposes them to a "pre-play" attack which is
indistinguishable from card cloning from the standpoint of the logs available
to the card-issuing bank, and can be carried out even if it is impossible to
clone a card physically (in the sense of extracting the key material and
loading it into another card). Card cloning is the very type of fraud that EMV
was supposed to prevent. We describe how we detected the vulnerability, a
survey methodology we developed to chart the scope of the weakness, evidence
from ATM and terminal experiments in the field, and our implementation of
proof-of-concept attacks. We found flaws in widely-used ATMs from the largest
manufacturers. We can now explain at least some of the increasing number of
frauds in which victims are refused refunds by banks which claim that EMV cards
cannot be cloned and that a customer involved in a dispute must therefore be
mistaken or complicit. Pre-play attacks may also be carried out by malware in
an ATM or POS terminal, or by a man-in-the-middle between the terminal and the
acquirer. We explore the design and implementation mistakes that enabled the
flaw to evade detection until now: shortcomings of the EMV specification, of
the EMV kernel certification process, of implementation testing, formal
analysis, or monitoring customer complaints. Finally we discuss
countermeasures
Multiparty key agreement protocols
A class of multiparty key agreement protocols based on secret sharing is presented. The trust infrastructure necessary to achieve the intended security goals is discussed
Tunable Security for Deployable Data Outsourcing
Security mechanisms like encryption negatively affect other software quality characteristics like efficiency. To cope with such trade-offs, it is preferable to build approaches that allow to tune the trade-offs after the implementation and design phase. This book introduces a methodology that can be used to build such tunable approaches. The book shows how the proposed methodology can be applied in the domains of database outsourcing, identity management, and credential management
Implementation and Analysis of Practical Algorithm for Data Security
In this paper, we present a complete implementation of the Practical Algorithm for Data Security (PADS) proposed by Albath et al., an end-to-end security scheme employing symmetric key encryption. The implementation takes full advantage of the modular design of the TinyOS environment. The simplicity of the algorithm allows for efficient implementation in hardware, a requirement for resource constrained devices. The protocol adds only four bytes of data per packet, on par with industry standards. Simulation and empirical results of the scheme are also provided. The analysis shows that the Practical Algorithm for Data Security is superior to standard security schemes
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Secure Remote Attestation for Safety-Critical Embedded and IoT Devices
In recent years, embedded and cyber-physical systems (CPS), under the guise of Internet-of-Things (IoT), have entered many aspects of daily life. Despite many benefits, this develop-ment also greatly expands the so-called attack surface and turns these newly computerizedgadgets into attractive attack targets. One key component in securing IoT devices is malwaredetection, which is typically attained with (secure) remote attestation. Remote attestationis a distinct security service that allows a trusted verifier to verify the internal state of aremote untrusted device. Remote attestation is especially relevant for low/medium-end em-bedded devices that are incapable of protecting themselves against malware infection. Assafety-critical IoT devices become commonplace, it is crucial for remote attestation not tointerfere with the device’s normal operations. In this dissertation, we identify major issues inreconciling remote attestation and safety-critical application needs. We show that existingattestation techniques require devices to perform uninterruptible (atomic) operations duringattestation. Such operations can be time-consuming and thus may be harmful to the device’ssafety-critical functionality. On the other hand, simply relaxing security requirements of re-mote attestation can lead to other vulnerabilities. To resolve this conflict, this dissertationpresents the design, implementation, and evaluation of several mitigation techniques. In par-ticular, we propose two light-weight techniques capable of providing interruptible attestationmodality. In contrast to traditional techniques, our proposed techniques allow interrupts tooccur during attestation while ensuring malware detection via shuffled memory traversals ormemory locking mechanisms. Another type of techniques pursued in this dissertation aimsto minimize the real-time computation overhead during attestation. We propose using peri-odic self-measurements to measure and record the device’s state, resulting in more flexiblescheduling of the attestation process and also in no real-time burden as part of its interactionwith verifier. This technique is particularly suitable for swarm settings with a potentiallylarge number of safety-critical devices. Finally, we develop a remote attestation HYDRAarchitecture, based on a formally verified component, and use it as a building block in ourproposed mitigation techniques. We believe that this architecture may be of independentinterest
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