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1. Embed this notice
   silverpill (silverpill@mitra.social)'s status on Wednesday, 26-Feb-2025 06:59:32 JST silverpill

   in reply to

   • Julien Genestoux
   • Raphael Lullis
   • Ryan Barrett

   @raphael @snarfed.org @Julien51 Key ownership can be verified out of band, for example via personal website or by meeting IRL. When this is not possible, we have to Trust On First Use.

   • Embed this notice
     Raphael Lullis (raphael@mastodon.communick.com)'s status on Wednesday, 26-Feb-2025 06:59:33 JST Raphael Lullis

     in reply to

     • Julien Genestoux
     • Ryan Barrett

     @snarfed.org @Julien51

     But assume that your server receives a random message. It is properly signed and you can verify the actor. How can you guarantee that the message was sent by the user and not the admin?

   • Embed this notice
     Ryan Barrett (snarfed.org@fed.brid.gy)'s status on Wednesday, 26-Feb-2025 06:59:34 JST Ryan Barrett

     in reply to

     • Julien Genestoux

     In practice on the fediverse today, as @raphael says, most fediverse servers do custodial keys. Client-managed keys and signing are still possible though! See @silverpill's FEP-ae97 on client signing. LD Signatures are also relevant; they're not ubiquitous like HTTP Sigs, but still somewhat common, eg Mastodon does them. Also see the SWICG HTTP Sigs report.

     cc @Julien51

   • Embed this notice
     Raphael Lullis (raphael@mastodon.communick.com)'s status on Wednesday, 26-Feb-2025 06:59:35 JST Raphael Lullis

     in reply to

     • Julien Genestoux

     @Julien51

     Do you mean that it hasn't been tempered by the server admin? No. The keys are managed by the server. So a malicious admin could generate messages on behalf of the user.

   • Embed this notice
     Julien Genestoux (julien51@mastodon.cloud)'s status on Wednesday, 26-Feb-2025 06:59:36 JST Julien Genestoux

     In the activitypub world is there any way to know *for sure* (cryptographically) that a specific use posted a toot?