Clavier d'ordinateur

Résumé

Un clavier d’ordinateur est une interface homme-machine munie de touches permettant à l'utilisateur d'entrer dans l'ordinateur une séquence de données, notamment textuelle. Les touches sont généralement des boutons en plastique reliés chacun à un interrupteur électronique. D'un point de vue électronique, elles sont similaires aux boutons d’une souris, d’une télécommande ou d’une manette de console de jeu, mais d'un point de vue pratique, elles ont des qualités propres à leur fonction : un symbole, une lettre, un chiffre, un mot ou une sont habituellement imprimées ou gravées sur la touche, autrement appelée Keycap, afin de permettre à l'utilisateur de saisir les caractères, pour écrire du texte ou pour exécuter une fonction particulière. Les claviers peuvent aussi être virtuels ou tactiles. Afin d'assurer une certaine familiarité des usagers avec les différents modèles de clavier, ceux-ci sont l’objet de plusieurs normes. La technique de frappe au clavier se nomme dactylographie

Source officielle

https://fr.wikipedia.org/wiki/Clavier_d'ordinateur

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Computer keyboards are often used to transmit confidential data such as passwords. Since they contain electronic components, keyboards eventually emit electromagnetic waves. These emanations could reveal sensitive information such as keystrokes. The technique generally used to detect compromising emanations is based on a wide-band receiver, tuned on a specific frequency. However, this method may not be optimal since a significant amount of information is lost during the signal acquisition. Our approach is to acquire the raw signal directly from the antenna and to process the entire captured electromagnetic spectrum. Thanks to this method, we detected four different kinds of compromising electromagnetic emanations generated by wired and wireless keyboards. These emissions lead to a full or a partial recovery of the keystrokes. We implemented these side-channel attacks and our best practical attack fully recovered 95% of the keystrokes of a PS/2 keyboard at a distance up to 20 meters, even through walls. We tested 12 different keyboard models bought between 2001 and 2008 (PS/2, USB, wireless and laptop). They are all vulnerable to at least one of the four attacks. We conclude that most of modern computer keyboards generate compromising emanations (mainly because of the manufacturer cost pressures in the design). Hence, they are not safe to transmit confidential information.

USENIX Association2009

Chargement

Computer Aided Cryptanalysis from Ciphers to Side Channels

Martin Vuagnoux

In this dissertation, we study the security of cryptographic protocols and cryptosystems from the mathematical definition of the primitives, up to their physical implementations in the real world. We propose a representation of the chronological design using six layers (cryptographic primitives, cryptographic protocols, implementation, computer insecurity, side channel cryptanalysis and computer human interactions). We do the assumption that these layers should not be studied independently. Indeed, many negligible security weaknesses coming from different layers can be correlated to provide devastating practical attacks on cryptosystems. However, the complexity of a complete security analysis becomes huge and interdisciplinary knowledge is needed. These limitations are probably the reasons of the lack of complete security analysis in practice. We define a novel approach, to combine and study the six layers simultaneously. We propose to follow the data flow of a system and to perform security analysis across the six layers. This technique is applied in practice to the security analysis of computer keyboards, RC4, IEEE 802.11, and e-passports. Thanks to this method, we found 34 additional exploitable correlations in RC4 and we defined the best key recovery attacks on WEP and WPA. We also identified weaknesses in the design and the implementation of e-passports. Therefore, we show that the security risk of every layer seems to be related to its level of complexity. Thus, the implementation layer, the computer insecurity layer, the side channel layer and the computer human interfaces layer are subject to cost-effective attacks in practice. Interestingly, these layers are not intensively studied in cryptography, where research stays usually focused on the two first layers (and some side channel attacks). In this dissertation, we also propose frameworks for computer aided cryptanalysis. Indeed, when the complexity of a system is too important to perform manual analysis, some tools may automatically find weaknesses. Increasing complexity in systems adds new vulnerabilities. Straightforward but automated analysis becomes relevant. Two frameworks have been developed. The first one automatically highlights linear correlation in RC4. The second framework, called Autodafé automatically detects buffer overflows in modern software, using a technique called Fuzzing by Weighting Attacks with Markers.

EPFL2010

Chargement

HRI usability evaluation of interaction modes for a teleoperated agricultural robotic sprayer

Thanasis Hadzilacos

Teleoperation of an agricultural robotic system requires effective and efficient human-robot interaction. This paper investigates the usability of different interaction modes for agricultural robot teleoperation. Specifically, we examined the overall influence of two types of output devices (PC screen, head mounted display), two types of peripheral vision support mechanisms (single view, multiple views), and two types of control input devices (PC keyboard, PS3 gamepad) on observed and perceived usability of a teleoperated agricultural sprayer. A modular user interface for teleoperating an agricultural robot sprayer was constructed and field-tested. Evaluation included eight interaction modes: the different combinations of the 3 factors. Thirty representative participants used each interaction mode to navigate the robot along a vineyard and spray grape clusters based on a 2 x 2 x 2 repeated measures experimental design. Objective metrics of the effectiveness and efficiency of the human-robot collaboration were collected. Participants also completed questionnaires related to their user experience with the system in each interaction mode. Results show that the most important factor for human-robot interface usability is the number and placement of views. The type of robot control input device was also a significant factor in certain dependents, whereas the effect of the screen output type was only significant on the participants' perceived workload index. Specific recommendations for mobile field robot teleoperation to improve HRI awareness for the agricultural spraying task are presented. (C) 2017 Elsevier Ltd. All rights reserved.

Elsevier Sci Ltd2017

Chargement

Computer Aided Cryptanalysis from Ciphers to Side Channels

Martin Vuagnoux

EPFL2010