Natural Strategic Abilities in Voting Protocols

Security properties are often focused on the technological side of the system. One implicitly assumes that the users will behave in the right way to preserve the property at hand. In real life, this cannot be taken for granted. In particular, security mechanisms that are difficult and costly to use are often ignored by the users, and do not really defend the system against possible attacks. Here, we propose a graded notion of security based on the complexity of the user's strategic behavior. More precisely, we suggest that the level to which a security property $\varphi$ is satisfied can be defined in terms of (a) the complexity of the strategy that the voter needs to execute to make $\varphi$ true, and (b) the resources that the user must employ on the way. The simpler and cheaper to obtain $\varphi$, the higher the degree of security. We demonstrate how the idea works in a case study based on an electronic voting scenario. To this end, we model the vVote implementation of the \Pret voting protocol for coercion-resistant and voter-verifiable elections. Then, we identify "natural" strategies for the voter to obtain receipt-freeness, and measure the voter's effort that they require. We also look at how hard it is for the coercer to compromise the election through a randomization attack

Natural strategic ability under imperfect information

Strategies in game theory and multi-agent logics are mathematical objects of remarkable combinatorial complexity Recently, the concept of natural strategies has been proposed to model more human-like reasoning about simple plans and their outcomes So far, the theory of such simple strategic play was only considered in scenarios where all the agents have perfect information about the state of the game In this paper, we extend the notion of natural strategies to games with imperfect information We also show that almost all the complexity results for model checking carry over from the perfect to imperfect information setting That is, verification of natural strategies is usually no more complex for agents with uncertainty This tells games of natural strategic ability clearly apart from most results in game theory and multi-agent logics. © 2019 International Foundation for Autonomous Agents and Multiagent Systems (www.ifaamas.org) Ail rights reserved

Natural strategic ability under imperfect information

International audienceStrategies in game theory and multi-agent logics are mathematical objects of remarkable combinatorial complexity Recently, the concept of natural strategies has been proposed to model more human-like reasoning about simple plans and their outcomes So far, the theory of such simple strategic play was only considered in scenarios where all the agents have perfect information about the state of the game In this paper, we extend the notion of natural strategies to games with imperfect information We also show that almost all the complexity results for model checking carry over from the perfect to imperfect information setting That is, verification of natural strategies is usually no more complex for agents with uncertainty This tells games of natural strategic ability clearly apart from most results in game theory and multi-agent logics

Natural strategic ability under imperfect information

International audienceStrategies in game theory and multi-agent logics are mathematical objects of remarkable combinatorial complexity Recently, the concept of natural strategies has been proposed to model more human-like reasoning about simple plans and their outcomes So far, the theory of such simple strategic play was only considered in scenarios where all the agents have perfect information about the state of the game In this paper, we extend the notion of natural strategies to games with imperfect information We also show that almost all the complexity results for model checking carry over from the perfect to imperfect information setting That is, verification of natural strategies is usually no more complex for agents with uncertainty This tells games of natural strategic ability clearly apart from most results in game theory and multi-agent logics