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Communication Dans Un Congrès Année : 2021

MLS: how Zero-Knowledge can secure Updates

Résumé

The Messaging Layer Security (MLS) protocol currently developed by the IETF aims at providing a group secure messaging solution. The goal is to provide end-to-end security, including Forward Secrecy and Post Compromise Secrecy, properties well studied for one-toone protocols. MLS proposes a tree-based regular asynchronous update of the group secrets, where a single user can alone perform a complete update. A main drawback is that a malicious user can create a denial of service attack by sending invalid update information. In this work, we propose a solution to prevent this kind of attacks, giving a checkpoint role to the server that transmits the messages. In our solution, the user sends to the server a proof that the update has been computed correctly, without revealing any information about this update. We use a Zero-Knowledge (ZK) protocol together with verifiable encryption as building blocks. As a main contribution, we provide two different ZK protocols to prove knowledge of the input of a pseudo random function implemented as a circuit, given an algebraic commitment of the output and the input.
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Dates et versions

hal-03558760 , version 1 (04-02-2022)

Identifiants

  • HAL Id : hal-03558760 , version 1

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Julien Devigne, Céline Duguey, Pierre-Alain Fouque. MLS: how Zero-Knowledge can secure Updates. ESORICS 2021, Oct 2021, Darmstadt / Virtual, Germany. ⟨hal-03558760⟩
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