4 ms·

Google gets the metadata? That's news to me. I thought the metadata was encrypted by the TextSecure server?

phaer 13y ago
I don't know, but I would have guessed that Google needs to know when it should deliver a message and where it should go, no? That is metadata in my definition.
- jlund 13y ago
  GCM payloads are fully encrypted. Google would be able to tell that you are a TextSecure user who is receiving a message, but they cannot tell who the message is coming from nor can they look at its contents (obviously).
  - avn2109 13y ago
    But crucially, this will still be vulnerable to timing attacks, if I'm not mistaken.
    - tptacek 13y ago
      What's the specific timing attack you're considering here?
      - nialo 13y ago
        There may not be the traditional byte at a time comparison type timing attack, but maybe this is still vulnerable to timing correlation attacks in the same sense that tor is. That is, Google or someone monitoring Google's network can look at all the messages and see who is talking to whom by matching up timing and encrypted message bodies.
      - e12e 13y ago
        I'm guessing: I send a message, you receive a message -> possible to infer (with some confidence) that I messaged you? (I don't know if that would be feasible, but I suppose that's what avn2109 meant). [ie: not a timing attack, but traffic analysis]
        avn2109 12y ago
        Good point. I did indeed mean traffic analysis, not "timing attack."
droopyEyelids 13y ago
Every network that carries your communication gets the metadata. In this case, it seems like that metadata would 'just' be the time you sent and received messages from the server. Depending on how Google's push protocol works. So for the average person that would be fine, but if you were seriously annoying a government that was in bed with your phone company, they could probably figure out who was a part of your cell by the timing of your sent and received messages.

phaer 13y ago

I don't know, but I would have guessed that Google needs to know when it should deliver a message and where it should go, no? That is metadata in my definition.

jlund 13y ago
GCM payloads are fully encrypted. Google would be able to tell that you are a TextSecure user who is receiving a message, but they cannot tell who the message is coming from nor can they look at its contents (obviously).
- avn2109 13y ago
  But crucially, this will still be vulnerable to timing attacks, if I'm not mistaken.
  - tptacek 13y ago
    What's the specific timing attack you're considering here?
    - nialo 13y ago
      There may not be the traditional byte at a time comparison type timing attack, but maybe this is still vulnerable to timing correlation attacks in the same sense that tor is. That is, Google or someone monitoring Google's network can look at all the messages and see who is talking to whom by matching up timing and encrypted message bodies.
    - e12e 13y ago
      I'm guessing: I send a message, you receive a message -> possible to infer (with some confidence) that I messaged you? (I don't know if that would be feasible, but I suppose that's what avn2109 meant). [ie: not a timing attack, but traffic analysis]
      - avn2109 12y ago
        Good point. I did indeed mean traffic analysis, not "timing attack."

droopyEyelids 13y ago

Every network that carries your communication gets the metadata. In this case, it seems like that metadata would 'just' be the time you sent and received messages from the server. Depending on how Google's push protocol works. So for the average person that would be fine, but if you were seriously annoying a government that was in bed with your phone company, they could probably figure out who was a part of your cell by the timing of your sent and received messages.