Computational puzzles are mildly difficult computational problems that require resources (processor cycles, memory, or both) to solve. Puzzles have found a variety of uses in security. In this paper we are concerned with client puzzles: a type of puzzle used as a defense against Denial of Service (DoS) attacks. Before engaging in a resource consuming protocol with a client, a server demands tha...

Sudoku puzzles enjoy world-wide popularity, and a large community of puzzlers is hoping for ever more difficult puzzles. A crucial step for generating difficult Sudoku puzzles is the fast assessment of the difficulty of a puzzle. In a study in 2006, it has been shown that SAT solving provides a way to efficiently differentiate between Sudoku puzzles according to their difficulty, by analyzing w...

In this paper we introduce new types of square-piece jigsaw puzzles, where in addition to the unknown location and orientation of each piece, a piece might also need to be flipped. These puzzles, which are associated with a number of real world problems, are considerably harder, from a computational standpoint. Specifically, we present a novel generalized genetic algorithm (GA)based solver that...

Various cryptographic puzzle schemes have been proposed as defenses against Denial of Service (DoS) attacks. However, these schemes have two common shortcomings that diminish their effectiveness as a DoS mitigation solution. First, the DoS-resilience that these schemes provide is minimized when there is a large disparity between the computational power of malicious and legitimate clients. Secon...

Particle swarm optimization (PSO) has shown to be a robust and efficient optimization algorithm therefore PSO has received increased attention in many research fields. This paper demonstrates the feasibility of applying the Dynamic Inertia Weight Particle Swarm Optimization to solve a Non-Polynomial (NP) Complete puzzle. This paper presents a new approach to solve the Nonograms Puzzle using Dyn...

In this paper we propose a modification to Genetic Algorithm which we call as Retrievable Genetic Algorithm (Ret-GA) and use it to solve a given Sudoku puzzle. Although a number of approaches exist for solving a given Sudoku puzzle, very few papers with heuristic approaches are available for obtaining its solution. In this work, the fitness function is modeled in a new way considering puzzle-ch...