Multi-Device for Signal

Sébastien Campion; Julien Devigne; Céline Duguey; Pierre-Alain Fouque

Paper 2019/1363

Multi-Device for Signal

Sébastien Campion, Julien Devigne, Céline Duguey, and Pierre-Alain Fouque

Abstract

Nowadays, we spend our life juggling with many devices such as smartphones, tablets or laptops, and we expect to easily and efficiently switch between them without losing time or security. However, most applications have been designed for single device usage. This is the case for secure instant messaging (SIM) services based on the Signal protocol, that implements the Double Ratchet key exchange algorithm. While some adaptations, like the Sesame protocol released by the developers of Signal, have been proposed to fix this usability issue, they have not been designed as specific multi-device solutions and no security model has been formally defined either. In addition, even though the group key exchange problematic appears related to the multi-device case, group solutions are too generic and do not take into account some properties of the multi-device setting.Indeed, the fact that all devices belong to a single user can be exploited to build more efficient solutions. In this paper, we propose a Multi-Device Instant Messaging protocol based on Signal, ensuring all the security properties of the original Signal.

Metadata

Available format(s): PDF
Category: Cryptographic protocols
Publication info: Published elsewhere. Major revision. ACNS2020
Keywords: Secure Instant Messaging Ratcheting Multi-Device
Contact author(s): celine duguey @ irisa fr
History: 2019-11-27: received
Short URL: https://ia.cr/2019/1363
License: CC BY

BibTeX

@misc{cryptoeprint:2019/1363,
      author = {Sébastien Campion and Julien Devigne and Céline Duguey and Pierre-Alain Fouque},
      title = {Multi-Device for Signal},
      howpublished = {Cryptology {ePrint} Archive, Paper 2019/1363},
      year = {2019},
      url = {https://eprint.iacr.org/2019/1363}
}