International Association
for Cryptologic Research

We present cryptographic personas, an approach for facilitating access to pseudonymous speech within communities without enabling abuse. In systems equipped with cryptographic personas, users are able to authenticate to the service provider under new, unlinkable personas at will and post messages under those personas. When users violate community norms, their ability to post anonymously can be revoked. We develop two significant improvements to existing work on anonymous banning systems that make it possible to integrate cryptographic personas into real-time applications like group messaging: we show how to push expensive proof generation into an offline phase and find a way to optimize server-side overhead using recent proof folding techniques. We implement cryptographic personas, integrating them into a variety of settings, and show that they are concretely efficient enough for deployment.