Paper 2025/1969 Original: eprint.iacr.org/2025/1969 ↗

Cryptographic Personas: Responsible Pseudonyms Without De-Anonymization

Abstract

We present cryptographic personas, an approach for facilitating access to pseudonymous speech within a community 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. Cryptographic personas draws on techniques from recent work, zk-promises. We develop two significant improvements over existing work 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 Signal and Slack, and show that they are concretely efficient enough for deployment.