this post was submitted on 20 Aug 2023
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Lemmy Support

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Support / questions about Lemmy.

Matrix Space: #lemmy-space

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Authentify users from other instances (lemmy.mindoki.com)
submitted 1 year ago by [email protected] to c/[email protected]
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Hello !

When someone connects to my instances communities, but from another instance, how do I know it's no spoofing involved?

Cheers

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[–] [email protected] 3 points 1 year ago

It should be a signature that is sent together with the ActivityPub Object. Yes, if the signature doesn't match, the content, whether a post, comment, favorite, upvote, etc... should be dropped.

Here is the source code of the library that lemmy uses to handle incoming objects and you can see that it does a call to verify the signature of the actor:

https://docs.rs/activitypub_federation/latest/src/activitypub_federation/actix_web/inbox.rs.html#18-54