Block resumption PSK from being used

xmtp / libxmtp

LibXMTP is a shared library encapsulating the core functionality of the XMTP messaging protocol, such as cryptography, networking, and language bindings.

MIT License

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Block resumption PSK from being used #678

Closed richardhuaaa closed 2 months ago

richardhuaaa commented 4 months ago

Here is the relevant section of the MLS spec: https://www.rfc-editor.org/rfc/rfc9420.html#name-reinitialization

We don't have the resources to support this feature properly, therefore we should block it from happening

franziskuskiefer commented 3 months ago

The reinit PSKs need to be stored because OpenMLS needs them as part of the group state right now. Two checks are needed to prevent reinit PSKs from being used

Block any ReInit proposal
Block any Welcome with a PreSharedKeyID of type resumption with usage reinit