Building Regular Registers with Rational Malicious Servers and Anonymous Clients

• Published in: Cyber Security Cryptography and Machine Learning Vol. 10332; pp. 50 - 67
• Main Authors: Del Pozzo, Antonella, Bonomi, Silvia, Lazzeretti, Riccardo, Baldoni, Roberto
• Format: Book Chapter
• Language: English
• Published: Switzerland Springer International Publishing AG 2017; Springer International Publishing
• Series: Lecture Notes in Computer Science
• Subjects: Anonymity; Bayesian game; Rational malicious processes; Regular register
• ISBN: 3319600796; 9783319600796
• ISSN: 0302-9743; 1611-3349
• DOI: 10.1007/978-3-319-60080-2_4

The paper addresses the problem of emulating a regular register in a synchronous distributed system where clients invoking \documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$$\mathsf{read}()$$\end{document} and \documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$$\mathsf{write}()$$\end{document} operations are anonymous while server processes maintaining the state of the register may be compromised by rational adversaries (i.e., a server might behave as rational malicious Byzantine process). We first model our problem as a Bayesian game between a client and a rational malicious server where the equilibrium depends on the decisions of the malicious server (behave correctly and not be detected by clients vs returning a wrong register value to clients with the risk of being detected and then excluded by the computation). We prove such equilibrium exists and finally we design a protocol implementing the regular register that forces the rational malicious server to behave correctly.