Nameless and Safe Messaging in Mesh Networks Utilizing Stronger, Nameless Double Ratchet

Paper 2023/1053

ASMesh: Nameless and Safe Messaging in Mesh Networks Utilizing Stronger, Nameless Double Ratchet

Alexander Bienstock, New York College

Paul Rösler, FAU Erlangen-Nürnberg

Yi Tang, College of Michigan

Summary

The vast majority of safe messengers have single, centralized service suppliers that relay ciphertexts between customers to allow asynchronous communication. Nonetheless, in some eventualities resembling mass protests in censored networks, counting on a centralized supplier is deadly. Mesh messengers try to resolve this drawback by constructing advert hoc networks through which consumer shoppers carry out the ciphertext-relaying process. But, current analyses of extensively deployed mesh messengers uncover extreme safety weaknesses (Albrecht et al. CT-RSA’21 & USENIX Safety’22).

To help the design of safe mesh messengers, we offer a brand new, extra full safety mannequin for mesh messaging. Our mannequin captures ahead and post-compromise safety, in addition to ahead and post-compromise anonymity, each of that are particularly necessary on this setting. We additionally establish novel, stronger confidentiality objectives that may be achieved as a result of particular traits of mesh networks (e.g., delayed communication, distributed community and adversary).

Lastly, we develop a brand new protocol, referred to as ASMesh, that provably satisfies these safety objectives. For this, we revisit Sign’s Double Ratchet and suggest non-trivial enhancements. On high of that, we add a mechanism that gives ahead and post-compromise anonymity. Thus, our protocol effectively supplies sturdy confidentiality and anonymity below previous and future consumer corruptions. Most of our outcomes are additionally relevant to conventional messaging.

We show safety of our protocols and consider their efficiency in simulated mesh networks. Lastly, we develop a proof of idea implementation.