FoSAM: Forward Secret Messaging in Ad-Hoc Networks

Fuente: arXiv
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Hauptverfasser: Schadt, Daniel, Coijanovic, Christoph, Strufe, Thorsten
Format: Preprint
Veröffentlicht: 2026
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author Schadt, Daniel
Coijanovic, Christoph
Strufe, Thorsten
author_facet Schadt, Daniel
Coijanovic, Christoph
Strufe, Thorsten
contents Apps such as Firechat and Bridgefy have been used during recent protests in Hong Kong and Iran, as they allow communication over ad-hoc wireless networks even when internet access is restricted. However, these apps do not provide sufficient protection as they do not achieve forward secrecy in unreliable networks. Without forward secrecy, caught protesters' devices will disclose all previous messages to the authorities, putting them and others at great risk. In this paper, we introduce FoSAM, the first protocol to provide proven anonymous and forward secret messaging in unreliable ad-hoc networks. Communication in FoSAM requires only the receiver's public key, rather than an interactive handshake. We evaluate the performance of FoSAM using a large-scale simulation with different user movement patterns, showing that it achieves between 92% and 99% successful message delivery. We additionally implement a FoSAM prototype for Android.
format Preprint
id arxiv_https___arxiv_org_abs_2603_12871
institution arXiv
publishDate 2026
record_format arxiv
spellingShingle FoSAM: Forward Secret Messaging in Ad-Hoc Networks
Schadt, Daniel
Coijanovic, Christoph
Strufe, Thorsten
Cryptography and Security
Apps such as Firechat and Bridgefy have been used during recent protests in Hong Kong and Iran, as they allow communication over ad-hoc wireless networks even when internet access is restricted. However, these apps do not provide sufficient protection as they do not achieve forward secrecy in unreliable networks. Without forward secrecy, caught protesters' devices will disclose all previous messages to the authorities, putting them and others at great risk. In this paper, we introduce FoSAM, the first protocol to provide proven anonymous and forward secret messaging in unreliable ad-hoc networks. Communication in FoSAM requires only the receiver's public key, rather than an interactive handshake. We evaluate the performance of FoSAM using a large-scale simulation with different user movement patterns, showing that it achieves between 92% and 99% successful message delivery. We additionally implement a FoSAM prototype for Android.
title FoSAM: Forward Secret Messaging in Ad-Hoc Networks
topic Cryptography and Security
url https://arxiv.org/abs/2603.12871