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MLS architecture
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Unidirectional transport #222

Closed ekr closed 10 months ago

ekr commented 1 year ago

While it is difficult or impossible to prevent a network adversary from suppressing payloads in transit, in certain infrastructures such as banks or governments settings, unidirectional transports can be used and be enforced via electronic or physical devices such as diodes. This can lead to payload corruption which does not affect the security or privacy properties of the MLS protocol but does affect the reliability of the service. In that case specific measures can be taken to ensure the appropriate level of redundancy and quality of service for MLS.

RECOMMENDATION: If unidirectional transport is used for the secure transport channel, prefer using a transport protocol which provides Forward Error Correction.

This seems like a pretty niche use case. Given that we want MLS nodes to routinely update keys, it's hard to see how a unidirectional transport is going to work well. Moreover, none of our major transports provide FEC, so...

beurdouche commented 10 months ago

I agree this is niche but knowing of some of these use cases I think it is fine to keep this text and discard the recommendation. See https://github.com/mlswg/mls-architecture/pull/238