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A pattern lock system is a widely used graphical password mechanism in today’s mobile computing environment. To unlock a smartphone, a user draws a memorized graphical pattern with a finger on a flat touchscreen whereas the finger actually leaves its oily residues, also called smudges, on the surface of the touchscreen. The smudges can be exploited by(More)
When a user interacts with a computing system to enter a secret password, shoulder surfing attacks are of great concern. To cope with this problem, previous methods presumed limited cognitive capabilities of a human adversary as a deterrent, but there was a pitfall with the assumption. In this paper, we show that human adversaries, even without a recording(More)
Small touchscreens are widely used in consumer electronics, such as smartphones and mobile electronic devices. However, typing on the small touchscreen is still worth studying. In fact, smartphone users are experiencing difficulties and also many errors in typing alphanumeric keys with their thumbs because a small virtual keyboard even with the reduced set(More)
Users typically reuse the same personalized identification number (PIN) for multiple systems and in numerous sessions. Direct PIN entries are highly susceptible to shoulder-surfing attacks as attackers can effectively observe PIN entry with concealed cameras. Indirect PIN entry methods proposed as countermeasures are rarely deployed because they demand a(More)
The increasing video resolution of handheld devices such as smartphones makes it harder for users to accurately touch a tiny item on a small touchscreen without conducting pinch-to-zoom and correction actions. To deal with this problem, an offset-free point-and-click mechanism is proposed in this paper. The touch pointer implemented in dual layers allows(More)
Users typically reuse the same personalized identification number (PIN) for multiple systems and in numerous sessions. Direct PIN entries are highly susceptible to shoulder-surfing attacks as attackers can effectively observe PIN entry with concealed cameras. Indirect PIN entry methods proposed as countermeasures are rarely deployed because they demand a(More)
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