Mixnet optimization methods

Authors: Iness Ben Guirat (imec-COSIC KU Leuven), Claudia Diaz (imec-COSIC KU Leuven and Nym Technologies SA)

Volume: 2022
Issue: 3
Pages: 456–477
DOI: https://doi.org/10.56553/popets-2022-0081

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Abstract: We propose a method to optimally select mix network parameters for a given deployment context and adversarial model. Our method considers both worstcase and average-case anonymity and selects configurations that meet worst-case constraints while maximizing average anonymity. We apply our methods to mixnet size optimization to determine the number and width of mixnet layers, and provide results for various deployment and adversarial scenarios. For cases where the deployment context suddenly changes (drop in user traffic) we evaluate countermeasures based on mix-generated dummy traffic and show that inexpensive link dummies can significantly boost protection in some of these cases.

Keywords: mixnet, anonymity, parameter optimization

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