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> WhatsApp can now read your recent messages when you report a user This feature is just an extension of manually making a screenshot and attaching it to the m

• varispeed 6y ago
  Does it mean messages can be read without agreement? Let's imagine "a glitch" where operator sees that user has opt in, but they didn't - can they see messages?
  • bzb6 6y ago
    If you are asking whether a back door can allow them to read your messages, the answer is “obviously, that’s why it’s a back door”
  • est31 6y ago
    I don't know the implementation on the client, but in theory it can be implemented locally on the client only, and I made the above statements under the assumption that it's how it's implemented. The user issues the report command in the UI and the client takes its local copy and uploads it to the server as part of the report. So it's mainly a convenience feature. The only case where the current E2EE security model is changed is when the protocol gains a feature to enable the client to attach a cryptographic proof about the message's content. That would violate the non-repudiation properties of the Signal protocol, but it would make reports more believable as you can't fake them any more with a modified client. As I've said I don't know the implementation, but it's entirely possible that they didn't include any cryptographic proof and keep it equivalent to screenshotting.
    • upofadown 6y ago
      >That would violate the non-repudiation properties of the Signal protocol,... Signal achieves non-repudiation by allowing forgery of messages after they have been transferred and verified by the receiver. It is not possible to undo that. You would have to make a special exception at the time the message was transferred which wouldn't be practical in this case. This all assumes that you believe that establishing forgeability actually achieves non-repudiation in the first place. Facebook might want to pass along the signature information anyway.
    • varispeed 6y ago
      So is there a way to capture user's screen without user knowing and essentially bypassing the end to end encryption altogether? (the images would be sent to a different endpoint for example)
      • est31 6y ago
        The report feature is initiated by the user. Only the copy of the user's correspondence who sends the report is sent. If there is a risk that the user doesn't know that the correspondence is sent if they hit the report button, then fb should add a warning, but the feature itself is fine IMO.
  • personjerry 6y ago
    It tells you clearly on the report screen, before you submit, as I recall.
    • _vmyf 6y ago
      ~~Suppose law enforcement reports a user to build a case against them, then the user's message could be subpoenaed right?~~ ~~Even worse, 3 letter agencies~~ Forget I said anything
      • multjoy 6y ago
        Yes. Same as any organisation who is sent a copy of the screenshots by the user.
        • _vmyf 6y ago
          oof i'm stupid
      • spoondan 6y ago
        No. If Alice reports Bob, the report only includes the most recent messages from Bob to Alice as forwarded from Alice's local copy of their chat. No other messages are made available to WhatsApp. None of Bob's other messages to other people are included, nor could they be since Alice wouldn't have them. In your scenario, if Alice was law enforcement or cooperating with law enforcement, her reporting Bob and then them subpoenaing WhatsApp would only grant them circuitous access to messages from Bob they already had on Alice's device.
        • _vmyf 6y ago
          ah, i'm stupid
  • spoondan 6y ago
    No. WhatsApp does not keep delivered messages, and, by default, messages are end-to-end encrypted and cannot be read by WhatsApp.[1] As shown in the screenshots of the reporting feature in the article, reporting causes your phone to send (forward) the relevant messages from your phone to WhatsApp as part of the report. For reporting a user or business, the relevant messages are "most recent messages" from the user/business. For reporting a group, the relevant messages are "most recent messages" in the group. This feature does not change the privacy story for WhatsApp in any way. You already trust users you are chatting with to not copy or screenshot private messages and share them. You already trust the app to not forward or store your messages without your consent. [1] See bullet point "Your Messages" under section "Information We Collect" on https://www.whatsapp.com/legal/privacy-policy https://www.whatsapp.com/legal/privacy-policy.
• rodorgas 6y ago
  The difference is that a screenshot may be fake. If the intermediary is revealing user private messages, it’s a stronger evidence than just making up a photoshopped screenshot.
  • sneak 6y ago
    I imagine that the API-based uploads of the recent decrypts from the user being reported can also be faked, so I'm not sure that this is a very important distinction.
    • Asraelite 6y ago
      There is some difference in the skill level required to convincingly craft a fake screenshot versus to spoof an API request, but yeah, it's not a huge difference.
      • est31 6y ago
        The fact that it's an API request will make it easier to create checks. For example, they could check if the length of the messages match with the length of the encrypted ciphertext the server sent. In theory you can do with this a screenshot already, by redigitizing the content, but it's harder. Or they could check whether the received/sent/etc dates match with what the servers recorded, etc.
      • kenniskrag 6y ago
        do not underestimate the script kiddy tools, which are created to proof a vulnerability. For example rooting a phone by hand is pretty hard. Many tools exist to do it automatically.
        • tasinn 6y ago
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• sneak 6y ago
  > As much as I like E2EE, I don't see where the problem lies? It's a step along a continuum where the end-to-end encrypted messenger wasn't uploading plaintext before, and now it is. Apple's similar previously end-to-end encrypted iMessage went through a similar evolution: now iOS uploads the complete iMessage plaintext history to Apple (with Apple keys) via iCloud Backup. We now know that Facebook deems it okay to exfiltrate plaintext, post-decryption, from the device in certain circumstances. This means we need to be cognizant and vigilant around the precise nature and boundaries of those circumstances, because "plaintext doesn't leave the device and get transmitted to Facebook" is no longer true. A tap or two by one of the people you're talking to could upload your decrypted plaintext directly to the person-in-the-middle; this is a relatively significant footgun that we should remain aware of.
  • est31 6y ago
    Facebook should definitely make it explicit that by reporting, you share the last N messages with that account with Facebook and make them accessible to Facebook employees/contractors. Regarding the iMessage backup thing, I fully agree with you that it's a major problem. But it's a different thing. Also, again, the feature already exists. You can already make screenshots and share them with facebook, with the world, etc. There are entire subreddits that publicly share IM histories with people. This is nothing that facebook can initiate. If the feature gets changed to something that they can initiate, I would agree that it's bad. But this isn't.
    • sneak 6y ago
      > Regarding the iMessage backup thing, I fully agree with you that it's a major problem. But it's a different thing. It's certainly a different product thing, yes. But from an Alice-Mallory-Bob end-to-end encryption block diagram it's the exact same thing: Bob's device is sending Alice's plaintext, post-decryption, to Mallory (using Mallory's TLS keys). > If the feature gets changed to something that they can initiate, I would agree that it's bad. But this isn't. Considering that many (most?) users have app auto-update turned on, it's not entirely certain that Facebook can't initiate it.
  • 6y ago
• ffpip 6y ago
  > I don't see where the problem lies? There is no problem. I'm just informing people reading HN of this change. Your messages will now be sent when you report a person/group.
  • dang 6y ago
    The problem is that you submitted the post with a misleading title. "WhatsApp can now read your recent messages when you report a user" implies that they've acquired some new power to read user data when in reality it's you who are forwarding them a copy, for the obvious reason that reporting a user would be meaningless without that.
    • hannasanarion 6y ago
      They didn't get a copy of your messages with a report until today. This is a meaningful change.
      • deleted 6y ago
        [deleted]
    • ffpip 6y ago
      > implies that they've acquired some new power to read user data when in reality They have added this power to read user data when you report it. All of which I have included in the title. >for the obvious reason that reporting a user would be meaningless without that. This is a change from past behavior. WhatsApp didn't forward a copy of messages when you reported people previously. Now they do. Which is what I clearly mentioned in the title. This meaningless way of reporting people was what users were used to. None of the comments commenting about click-bait are mentioning what is factually wrong with the title. They are just saying they understood it different, which is okay.
      • pvg 6y ago
        It's not ok on HN where clickbait titles and editorialized titles are not ok, 'factually correct' or not. You can't just say we should agree to disagree on whether to have clickbait or editorialized titles.
• gentleman11 6y ago
  The problem isn’t the feature per-se, it’s facebooks track record with user data and a lack of trust. This is explicitly something you would not want Facebook in specific doing because you want to keep them at a further distance
• croes 6y ago
  But the sending of the recent messages seems to mandatory for reporting a user. That's more than sending a screenshot.
• threesmegiste 6y ago
  Facebook blaming is regular and got good rating