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A comment on Facebook crawls links in PDFs you send in Messenger. Parent comment

Re:Facebook crawls links in PDFs you send in Messenger by kerng on Saturday October 26, 2019 @03:06PM (#21365543)
Same can be done if e2e is enabled. Nothing prevents Facebook from sending links from client to a "validation" service.

They do this already in WhatsApp for instance.

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Re:Facebook crawls links in PDFs you send in Messenger by JadeNB on Saturday October 26, 2019 @03:32PM (#21365687)
Maybe I'm being foolish, but isn't the point of e2e that Facebook wouldn't even know what you were sending (a link or otherwise), it being encrypted in flight?
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Re:Facebook crawls links in PDFs you send in Messenger by roywiggins on Saturday October 26, 2019 @05:26PM (#21366329)
The WhatsApp client knows, since that's the "end." Nothing technical stops Facebook from bundling some code in the client to pass data about the messages back to a central server.
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Re:Facebook crawls links in PDFs you send in Messenger by progval on Saturday October 26, 2019 @04:30PM (#21365991)
Yes, but it's hard to trust e2e when keys go through a blackbox (Facebook's API), and clients are controlled by Facebook (closed source applications and JS).

It's better than no encryption, but not what technical people usually mean by e2e encryption

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Re:Facebook crawls links in PDFs you send in Messenger by kerng on Saturday October 26, 2019 @08:54PM (#21367268)
Facebook can send the URLs from client to their service, that just bypasses the e2e channel and opens up a nice side channel for Facebook to peek into messages.
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