The hat-guessing number is a graph invariant defined by Butler, Hajiaghayi, Kleinberg, and Leighton. We determine the exactly for book graphs with sufficiently many pages, improving previously known lower bounds of He Li matching an upper bound Gadouleau. prove that $K_{3,3}$ $3$, making this first complete bipartite $K_{n,n}$ which to be smaller than $n+1$ Gadouleau Georgiou. Finally, we windm...

While much has changed in Internet security over the past decades, textual passwords remain as the dominant method to secure user web accounts and they are proliferating in nearly every new web services. Nearly every web services, no matter new or aged, now enforce some form of password creation policy. In this work, we conduct an extensive empirical study of 50 password creation policies that ...

The dynamical properties of finite dynamical systems (FDSs) have been investigated in the context of coding theoretic problems, such as network coding and index coding, and in the context of hat games, such as the guessing game and Winkler’s hat game. In this paper, we relate the problems mentioned above to properties of FDSs, including the number of fixed points, their stability, and their ins...

Mobile devices, such as smartphones and tablets, frequently store confidential data, yet implementing a secure device unlock functionality is non-trivial due to restricted input methods. Graphical knowledge-based schemes have been widely used on smartphones and are generally well adapted to the touchscreen interface on small screens. Recently, graphical password schemes based on emoji have been...

We introduce the Binary Matrix Guessing Problem and provide two algorithms to solve this problem. The first algorithm we introduce is Elementwise Probing Algorithm (EPA) which is very fast under a score which utilizes Frobenius Distance. The second algorithm is Additive Reinforcement Learning Algorithm which combines ideas from perceptron algorithm and reinforcement learning algorithm. This alg...

Equivocation rate has been widely used as an information-theoretic measure of security after Shannon[12]. It simplifies problems by removing the effect of atypical behavior from the system. In [11], however, Merhav and Arikan considered the alternative of using guessing exponent to analyze the Shannon’s cipher system. Because guessing exponent captures the atypical behavior, the strongest expre...

Various factors could conceivably promote the accuracy of guesses during a recognition test. Two that we identified in previous studies are forced-choice testing format and high perceptual similarity between the repeat target and novel foil. In restricted circumstances, the relative perceptual fluency of the target can be compared with that of the foil and used as a reliable cue to guide accura...