4 ms·

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.

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.