Continuous Authentication in Secure Messaging


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Date

2022

Publication Type

Conference Paper

ETH Bibliography

yes

Citations

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Abstract

Secure messaging schemes such as the Signal protocol rely on out-of-band channels to verify the authenticity of long-running communication. Such out-of-band checks however are only rarely actually performed by users in practice. In this paper, we propose a new method for performing continuous authentication during a secure messaging session, without the need for an out-of-band channel. Leveraging the users’ long-term secrets, our Authentication Steps extension guarantees authenticity as long as long-term secrets are not compromised, strengthening Signal’s post-compromise security. Our mechanism further allows to detect a potential compromise of long-term secrets after the fact via an out-of-band channel. Our protocol comes with a novel, formal security definition capturing continuous authentication, a general construction for Signal-like protocols, and a security proof for the proposed instantiation. We further provide a prototype implementation which seamlessly integrates on top of the official Signal Java library, together with bandwidth and storage overhead benchmarks.

Publication status

published

Book title

Computer Security – ESORICS 2022

Volume

13555

Pages / Article No.

361 - 381

Publisher

Springer

Event

27th European Symposium on Research in Computer Security (ESORICS 2022)

Edition / version

Methods

Software

Geographic location

Date collected

Date created

Subject

Secure messaging; Authentication; Compromise detection; Post-compromise security

Organisational unit

09653 - Paterson, Kenneth / Paterson, Kenneth check_circle

Notes

Funding

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