We address the problem of shoulder-surfing attacks on authentication schemes by proposing IllusionPIN (IPIN), a PIN-based authentication method that operates on touchscreen devices. IPIN uses the technique of hybrid images to blend two keypads with different digit orderings in such a way, that the user who is close to the device is seeing one keypad to enter her PIN, while the attacker who is looking at the device from a bigger distance is seeing only the other keypad. The user’s keypad is shuffled in every authentication attempt, since the attacker may memorize the spatial arrangement of the pressed digits. To reason about the security of IPIN, we developed an algorithm which is based on human visual perception and estimates the minimum distance from which an observer is unable to interpret the keypad of the user. We tested our estimations with 84 simulated shoulder-surfing attacks from 21 different people. None of the attacks was successful against our estimations. In addition, we estimated the minimum distance from which a camera is unable to capture the visual information from the keypad of the user. Based on our analysis, it seems practically almost impossible for a surveillance camera to capture the PIN of a smartphone user when IPIN is in use.
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@cite_14: Secure login methods based on human cognitive skills can be classified into two categories based on information available to a passive attacker: (i) the attacker fully observes the entire input and output of a login procedure, (ii) the attacker only partially observes the input and output. Login methods secure in the fully observable model imply very long secrets and or complex calculations. In this paper, we study three simple PIN-entry methods designed for the partially observable attacker model. A notable feature of the first method is that the user needs to perform a very simple mathematical operation, whereas, in the other two methods, the user performs a simple table lookup. Our usability study shows that all the methods have reasonably low login times and minimal error rates. These results, coupled with low-cost hardware requirements (only earphones), are a significant improvement over existing approaches for this model [9,10]. We also show that side-channel timing attacks present a real threat to the security of login schemes based on human cognitive skills.
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@cite_41: Secure user identification is important for the increasing number of eyewear computers but limited input capabilities pose significant usability challenges for established knowledge-based schemes, such as passwords or PINs. We present SkullConduct, a biometric system that uses bone conduction of sound through the user's skull as well as a microphone readily integrated into many of these devices, such as Google Glass. At the core of SkullConduct is a method to analyze the characteristic frequency response created by the user's skull using a combination of Mel Frequency Cepstral Coefficient (MFCC) features as well as a computationally light-weight 1NN classifier. We report on a controlled experiment with 10 participants that shows that this frequency response is person-specific and stable -- even when taking off and putting on the device multiple times -- and thus serves as a robust biometric. We show that our method can identify users with 97.0 accuracy and authenticate them with an equal error rate of 6.9 , thereby bringing biometric user identification to eyewear computers equipped with bone conduction technology.
@cite_10: With the embedding of EEG (electro-encephalography) sensors in wireless headsets and other consumer electronics, authenticating users based on their brainwave signals has become a realistic possibility. We undertake an experimental study of the usability and performance of user authentication using consumer-grade EEG sensor technology. By choosing custom tasks and custom acceptance thresholds for each subject, we can achieve 99 authentication accuracy using single-channel EEG signals, which is on par with previous research employing multi-channel EEG signals using clinical-grade devices. In addition to the usability improvement offered by the single-channel dry-contact EEG sensor, we also study the usability of different classes of mental tasks. We find that subjects have little difficulty recalling chosen “pass-thoughts” (e.g., their previously selected song to sing in their mind). They also have different preferences for tasks based on the perceived difficulty and enjoyability of the tasks. These results can inform the design of authentication systems that guide users in choosing tasks that are both usable and secure.
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@cite_40: Recent years have seen an exponential growth in the use of various biometric technologies for trusted automatic recognition of humans. With the rapid adaptation of biometric systems, there is a growing concern that biometric technologies may compromise the privacy and anonymity of individuals. Unlike credit cards and passwords, which can be revoked and reissued when compromised, biometrics are permanently associated with a user and cannot be replaced. To prevent the theft of biometric patterns, it is desirable to modify them through revocable and noninvertible transformations to produce cancelable biometric templates. In this article, we provide an overview of various cancelable biometric schemes for biometric template protection. We discuss the merits and drawbacks of available cancelable biometric systems and identify promising avenues of research in this rapidly evolving field.
@cite_23: Because biometrics-based authentication offers several advantages over other authentication methods, there has been a significant surge in the use of biometrics for user authentication in recent years. It is important that such biometrics-based authentication systems be designed to withstand attacks when employed in security-critical applications, especially in unattended remote applications such as e-commerce. In this paper we outline the inherent strengths of biometrics-based authentication, identify the weak links in systems employing biometrics-based authentication, and present new solutions for eliminating some of these weak links. Although, for illustration purposes, fingerprint authentication is used throughout, our analysis extends to other biometrics-based methods.
@cite_5: Shoulder-surfing -- using direct observation techniques, such as looking over someone's shoulder, to get passwords, PINs and other sensitive personal information -- is a problem that has been difficult to overcome. When a user enters information using a keyboard, mouse, touch screen or any traditional input device, a malicious observer may be able to acquire the user's password credentials. We present EyePassword, a system that mitigates the issues of shoulder surfing via a novel approach to user input. With EyePassword, a user enters sensitive input (password, PIN, etc.) by selecting from an on-screen keyboard using only the orientation of their pupils (i.e. the position of their gaze on screen), making eavesdropping by a malicious observer largely impractical. We present a number of design choices and discuss their effect on usability and security. We conducted user studies to evaluate the speed, accuracy and user acceptance of our approach. Our results demonstrate that gaze-based password entry requires marginal additional time over using a keyboard, error rates are similar to those of using a keyboard and subjects preferred the gaze-based password entry approach over traditional methods.
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@cite_13: 
@cite_12: Tangible user interfaces are portals to digital information. In the future, securing access to such material will be an important concern. This paper describes the design, implementation and evaluation of a PIN entry system based on audio or haptic cues that is suitable for integration into such physical systems. The current implementation links movements on a mobile phone touch screen with the display of non-visual cues; selection of a sequence of these cues composes a password. Studies reveal the validity of this approach in terms of task times and error rates that improve over prior art. In sum, this paper demonstrates the potential of non-visual PINs as a mechanism for securing access to a range of systems, ultimately incorporating mobile, ubiquitous or tangible interfaces.
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The principle states that at least part of the information of interest has to be transmitted through channels that are not observable. This way, an observer is always missing a piece of information and shoulder-surfing is mitigated even in cases that multiple observations or recordings are possible. However, the performance of such schemes in usability and deployability varies. For example, schemes which use audio and haptic information @cite_12 @cite_33 suffer from high authentication time and their requirements for additional hardware heavily affect their deployability. However, the emergence of touchscreen devices which are pressure-sensitive may favor schemes which use this kind of haptic information @cite_14 @cite_13 @cite_18 @cite_6 @cite_31 @cite_17 , if they are combined with satisfying usability. Gaze-based authentication @cite_5 corresponds to high authentication time, and authentication based on brainwaves @cite_10 or bone conduction @cite_41 requires special equipment. Fingerprint authentication @cite_23 is a scheme that gains popularity nowadays by offering excellent usability. A usual problem with biometrics like fingerprints is that they cannot be revoked. In addition, biometrics can be used to uniquely identify a person and they raise privacy concerns. However, the concept of cancelable biometrics @cite_40 could alleviate both problems.