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There was another article claiming there's no backdoor. https://news.ycombinator.com/item?id=13394900 https://news.ycombinator.com/item?id=13394900. Anybody wi

There was another article claiming there's no backdoor. https://news.ycombinator.com/item?id=13394900 https://news.ycombinator.com/item?id=13394900. Anybody with any ideas what is happening exactly?

tonfa 10y ago
It's what the other article says, for in flight message (single tick), if the key changes it might be reencrypted with a new key if the recipient key changes. If there's a double-tick it's too late, and it won't reencrypt. In practice, unless you have a very long monologue, only one message would "leak", not the full discussion. (after the key changes you'll get a warning if you have the settings to show cryptographic details enabled).
- FabHK 10y ago
  Nice term, btw, "in flight message" :-)
- mentat 10y ago
  People have "monologues" on IM all the time. I'm sure FB has the data from Messenger and WhatsApp, what the aggregate exposure in message volume is at any time. I do not have that data but I suspect it's "a lot".
cryptozeus 10y ago
Update (May 31, 2016) Facebook responded to my white-hat report "[...] We were previously aware of the issue and might change it in the future, but for now it's not something we're actively working on changing.[...]"
kasey_junk 10y ago
Backdoor and vulnerability are not the same thing. Your link is to an article explaining the design decisions that lead to the weakness that is being taken advantage of. A purpiseful & public design trade off is not a backdoor.
- PunchTornado 10y ago
  It IS a backdoor. 1) Signal protocol doesn't have this issue, it was introduced by Whatsup. 2) It wasn't public until now. 3) The security notification is turned off by default in android and ios apps. Huge issue especially since Whatsup is recommended for activists and whistle-blowers. https://www.youtube.com/watch?v=we-pJE5JjAs https://www.youtube.com/watch?v=we-pJE5JjAs
  - FabHK 10y ago
    It was made public in April last year. Most knowledgeable advice only recommends Signal, and possibly Threema or Wire, for communication that needs to be secure, see e.g. https://www.securemessagingapps.com https://www.securemessagingapps.com
    - tptacek 10y ago
      Can you point me to the cryptographic engineer who has ever recommended Threema or Wire over Signal?
y7 10y ago
Basically, disagreement over the term "backdoor", which sounds like it was put there intentionally. WhatsApp/Moxie: we made a security/usability trade-off. The video's author/The Guardian: this trade-off allows an attacker to intercept messages (undetected, as long as he permanently cuts off the recipient's phone), which is bad.
- Certhas 10y ago
  Isn't undetected, as long as he permanently cuts off the recipient's phone a bit of a contradiction?
- FabHK 10y ago
  > undetected No, a) not if user has enabled security notifications (disabled by default) b) not across a back-and-forth conversation, provided user checks for blue double ticks
detaro 10y ago
and here is the discussion about a guardian article this is in response to: https://news.ycombinator.com/item?id=13389935 https://news.ycombinator.com/item?id=13389935
whyoh 10y ago
It's an "intentional vulnerability". It's there to prevent users from being annoyed. Which is a bit of a lame excuse, because users would only be "annoyed" in very rare cases and special circumstances, namely: A sends a message to B while B is offline AND then B gets a new phone before coming back online. Even if you disagree with me that it's a very rare case, WhatsApp could still give us an option to show a confirmation before automatically re-sending messages to a new device.
- FabHK 10y ago
  It's not that rare. It happens anytime the other user gets a new phone, or re-installs WhatsApp. > WhatsApp could still give us an option to show a confirmation before automatically re-sending messages to a new device. Just to clarify: they do optionally notify you (off by default), but after having re-sent the re-keyed messages. It would be nice if they (optionally) offered you a choice to re-send the message, or discard it. (You could then verify key fingerprints out of band before making that choice.) Doing that (making it "blocking") would leak information, OpenWhisperSystems argues, correctly.
  - whyoh 10y ago
    >It's not that rare. It happens anytime the other user gets a new phone, or re-installs WhatsApp. That, and the messages also have to be sent while the user is offline, otherwise there is no vulnerability--assuming you enabled the currently available notifications. So I still believe it's a very rare circumstance and very few people would get "annoyed" by a notification/confirmation for that specific circumstance. >It would be nice if they (optionally) offered you a choice to re-send the message, or discard it. That's exactly what I had in mind.
    - FabHK 10y ago
      > and the messages also have to be sent while the user is offline, otherwise there is no vulnerability a) the notification and concomitant irritation to non-technical users is there when the other user switches phone, whether they were online or not b) the vulnerability is there when the server is compromised, whether the other user is online or not (can just filter out "delivery receipts")
geocar 10y ago
That is a very loaded question. It may be easier to understand "what is going on" broadly if you try to frame it in terms of actions: What can you do about this? What do you want to do about this? The "backdoor" (insecurity) is that Facebook can read and spoof your WhatsApp messages, and can be compelled to by any government of a country in which they operate, or by any determined attacker. This surprises people because they believe WhatsApp is secure, since Facebook said so, and because it ostensibly obtains that security from someone who is endorsed by someone else who is considered knowledgable about security. https://news.ycombinator.com/item?id=11431728 https://news.ycombinator.com/item?id=11431728 However it is (in this case) insecure because of a "user-interface issue" (whatever Moxie means by that). Basically, the key and software can be changed at any time, and if it is changed (because of a cloned phone, or with FaceBook's help, or with Google/Apple's help, or because someone hacks some FaceBook/Apple/Google servers, or for other reasons). Moxie intimates that this shouldn't be called a "backdoor" because it wasn't put in with malice, even if it was put in intentionally. Do you agree with that? https://news.ycombinator.com/item?id=13396129 https://news.ycombinator.com/item?id=13396129 Now what do you want to do? Do you want to get some pitchforks and find someone to stab? Do you want to stop using WhatsApp and convince other people to do so as well? Do you want to learn more about security and how cryptography works? Right now, we are looking some kind of campaign- perhaps it is organised and malicious, or perhaps we are seeing multiple actors who have multiple ways of benefitting so they only appear coordinated. That is, are you making this decision yourself? Or are you being encouraged down a path that supports someone elses' goals? Do these actors want to impeach FaceBook/Whatsapp/Signal because they like chaos and carnage and hope that by being doomsayers they will get you to watch their video/read their blog and earn money from advertising? Do these actors want to impeach FaceBook/Whatsapp/Signal because they think we (society) need to actually demand real security and privacy? Should we ask a private company to respect our security and privacy wishes? Or should we ask our government (which is us)? Do these actors want to impeach FaceBook/Whatsapp/Signal because they have a competitors' product? Is there another popular "secure messaging" product for mobile devices that does not have these problems? Do these actors want to impeach FaceBook/Whatsapp/Signal because these tools are actually quite secure and problematic, and it would be more convenient if people who wanted privacy and security could be more easily investigated covertly? Is this a "false flag" on privacy launched perhaps by a state actor? Are there other reasons actors would want to impeach FaceBook/Whatsapp/Signal? What is going on "exactly" has questions and answers on so many levels it is difficult to know where to begin, but I have popcorn.

There was another article claiming there's no backdoor. https://news.ycombinator.com/item?id=13394900 https://news.ycombinator.com/item?id=13394900. Anybody with any ideas what is happening exactly?

tonfa 10y ago

It's what the other article says, for in flight message (single tick), if the key changes it might be reencrypted with a new key if the recipient key changes. If there's a double-tick it's too late, and it won't reencrypt. In practice, unless you have a very long monologue, only one message would "leak", not the full discussion. (after the key changes you'll get a warning if you have the settings to show cryptographic details enabled).

FabHK 10y ago
Nice term, btw, "in flight message" :-)
mentat 10y ago
People have "monologues" on IM all the time. I'm sure FB has the data from Messenger and WhatsApp, what the aggregate exposure in message volume is at any time. I do not have that data but I suspect it's "a lot".

cryptozeus 10y ago

Update (May 31, 2016) Facebook responded to my white-hat report "[...] We were previously aware of the issue and might change it in the future, but for now it's not something we're actively working on changing.[...]"

kasey_junk 10y ago

Backdoor and vulnerability are not the same thing. Your link is to an article explaining the design decisions that lead to the weakness that is being taken advantage of. A purpiseful & public design trade off is not a backdoor.

PunchTornado 10y ago
It IS a backdoor. 1) Signal protocol doesn't have this issue, it was introduced by Whatsup. 2) It wasn't public until now. 3) The security notification is turned off by default in android and ios apps. Huge issue especially since Whatsup is recommended for activists and whistle-blowers. https://www.youtube.com/watch?v=we-pJE5JjAs https://www.youtube.com/watch?v=we-pJE5JjAs
- FabHK 10y ago
  It was made public in April last year. Most knowledgeable advice only recommends Signal, and possibly Threema or Wire, for communication that needs to be secure, see e.g. https://www.securemessagingapps.com https://www.securemessagingapps.com
  - tptacek 10y ago
    Can you point me to the cryptographic engineer who has ever recommended Threema or Wire over Signal?

y7 10y ago

Basically, disagreement over the term "backdoor", which sounds like it was put there intentionally. WhatsApp/Moxie: we made a security/usability trade-off. The video's author/The Guardian: this trade-off allows an attacker to intercept messages (undetected, as long as he permanently cuts off the recipient's phone), which is bad.

Certhas 10y ago
Isn't undetected, as long as he permanently cuts off the recipient's phone a bit of a contradiction?
FabHK 10y ago
> undetected No, a) not if user has enabled security notifications (disabled by default) b) not across a back-and-forth conversation, provided user checks for blue double ticks

detaro 10y ago

and here is the discussion about a guardian article this is in response to: https://news.ycombinator.com/item?id=13389935 https://news.ycombinator.com/item?id=13389935

whyoh 10y ago

It's an "intentional vulnerability". It's there to prevent users from being annoyed. Which is a bit of a lame excuse, because users would only be "annoyed" in very rare cases and special circumstances, namely: A sends a message to B while B is offline AND then B gets a new phone before coming back online. Even if you disagree with me that it's a very rare case, WhatsApp could still give us an option to show a confirmation before automatically re-sending messages to a new device.

FabHK 10y ago
It's not that rare. It happens anytime the other user gets a new phone, or re-installs WhatsApp. > WhatsApp could still give us an option to show a confirmation before automatically re-sending messages to a new device. Just to clarify: they do optionally notify you (off by default), but after having re-sent the re-keyed messages. It would be nice if they (optionally) offered you a choice to re-send the message, or discard it. (You could then verify key fingerprints out of band before making that choice.) Doing that (making it "blocking") would leak information, OpenWhisperSystems argues, correctly.
- whyoh 10y ago
  >It's not that rare. It happens anytime the other user gets a new phone, or re-installs WhatsApp. That, and the messages also have to be sent while the user is offline, otherwise there is no vulnerability--assuming you enabled the currently available notifications. So I still believe it's a very rare circumstance and very few people would get "annoyed" by a notification/confirmation for that specific circumstance. >It would be nice if they (optionally) offered you a choice to re-send the message, or discard it. That's exactly what I had in mind.
  - FabHK 10y ago
    > and the messages also have to be sent while the user is offline, otherwise there is no vulnerability a) the notification and concomitant irritation to non-technical users is there when the other user switches phone, whether they were online or not b) the vulnerability is there when the server is compromised, whether the other user is online or not (can just filter out "delivery receipts")

geocar 10y ago

That is a very loaded question. It may be easier to understand "what is going on" broadly if you try to frame it in terms of actions: What can you do about this? What do you want to do about this? The "backdoor" (insecurity) is that Facebook can read and spoof your WhatsApp messages, and can be compelled to by any government of a country in which they operate, or by any determined attacker. This surprises people because they believe WhatsApp is secure, since Facebook said so, and because it ostensibly obtains that security from someone who is endorsed by someone else who is considered knowledgable about security. https://news.ycombinator.com/item?id=11431728 https://news.ycombinator.com/item?id=11431728 However it is (in this case) insecure because of a "user-interface issue" (whatever Moxie means by that). Basically, the key and software can be changed at any time, and if it is changed (because of a cloned phone, or with FaceBook's help, or with Google/Apple's help, or because someone hacks some FaceBook/Apple/Google servers, or for other reasons). Moxie intimates that this shouldn't be called a "backdoor" because it wasn't put in with malice, even if it was put in intentionally. Do you agree with that? https://news.ycombinator.com/item?id=13396129 https://news.ycombinator.com/item?id=13396129 Now what do you want to do? Do you want to get some pitchforks and find someone to stab? Do you want to stop using WhatsApp and convince other people to do so as well? Do you want to learn more about security and how cryptography works? Right now, we are looking some kind of campaign- perhaps it is organised and malicious, or perhaps we are seeing multiple actors who have multiple ways of benefitting so they only appear coordinated. That is, are you making this decision yourself? Or are you being encouraged down a path that supports someone elses' goals? Do these actors want to impeach FaceBook/Whatsapp/Signal because they like chaos and carnage and hope that by being doomsayers they will get you to watch their video/read their blog and earn money from advertising? Do these actors want to impeach FaceBook/Whatsapp/Signal because they think we (society) need to actually demand real security and privacy? Should we ask a private company to respect our security and privacy wishes? Or should we ask our government (which is us)? Do these actors want to impeach FaceBook/Whatsapp/Signal because they have a competitors' product? Is there another popular "secure messaging" product for mobile devices that does not have these problems? Do these actors want to impeach FaceBook/Whatsapp/Signal because these tools are actually quite secure and problematic, and it would be more convenient if people who wanted privacy and security could be more easily investigated covertly? Is this a "false flag" on privacy launched perhaps by a state actor? Are there other reasons actors would want to impeach FaceBook/Whatsapp/Signal? What is going on "exactly" has questions and answers on so many levels it is difficult to know where to begin, but I have popcorn.