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> end-to-end encryption Well, they do collect and use metadata, e.g. chat history: https://www.forbes.com/sites/thomasbrewster/2017/01/22/whatsapp-facebook-ba

> end-to-end encryption Well, they do collect and use metadata, e.g. chat history: https://www.forbes.com/sites/thomasbrewster/2017/01/22/whatsapp-facebook-backdoor-government-data-request/#79424ada1030 https://www.forbes.com/sites/thomasbrewster/2017/01/22/whats... There's better options regarding privacy, e.g. Signal, which does not collect metadata.

tinus_hn 8y ago
According to that article WhatsApp provided almost no data except who was in the group and who was sending messages. There is no way Signal can function without having the same data available.
- majewsky 8y ago
  Signal was once subpoenaed by the FBI to give up all stored data/metadata relating to a certain account. They responded with the account creation timestamp and the last-connected timestamp, suggesting that they do not store information about group ownerships or contacts. Source: https://www.aclu.org/blog/national-security/secrecy/new-documents-reveal-government-effort-impose-secrecy-encryption https://www.aclu.org/blog/national-security/secrecy/new-docu...
  - tinus_hn 8y ago
    Once they become big they will be forced to keep that data. It is really difficult to force them to change the client or the protocol but not to force them to keep data they have access to on the server.
  - baby 8y ago
    This is because Signal works differently for group chat. In WhatsApp, the server delivers your encrypted message to each member of the group. It's an optimization called "server-side fan-out". Check the whitepaper for more deatils: https://www.whatsapp.com/security/WhatsApp-Security-Whitepaper.pdf https://www.whatsapp.com/security/WhatsApp-Security-Whitepap... Interestingly this is also what the Signal libraries implement. So applications making use of them will generally make use of this optimization. For some reason, the Signal application itself was not making use of this optimization. My guess is that it had not updated its code yet when I looked. This might have changed since then. BUT, and that's a big but, as a passive observer (and if Signal kept logs of things) you can still figure out group chat membership by looking at who sent the same kind of message (same length) to who, and at what time. Basic relationship graph stuff.
- move-on-by 8y ago
  Yes, there is a way and it’s already in beta. It’s called sealed-sender and you can read about it in this signal blog post: https://signal.org/blog/sealed-sender/ https://signal.org/blog/sealed-sender/
- tialaramex 8y ago
  The Signal clients have this data, Signal's servers do not. Didn't you see recently on HN they announced they now have a mechanism so that their servers aren't even aware of who sent a message? The recipient can tell who it's from but the server just sees like a stamp on the outside "This is one of the messages Bob agreed to receive from people" and it says to itself "OK, Bob said he wants these, don't care who it's from".
  - baby 8y ago
    Do you know how they prevent people from spamming messages then? If you can't identify someone how can you rate limit them?
    - tialaramex 8y ago
      Users have to volunteer the tokens to friends (co-conspirators, lovers, whatever) or assert that they just love receiving garbage from strangers, so conventional "spam" is impossible. AIUI The system can count usages of Bob's tokens and rate-limit those. If Bob's Ex Gina is sending him fifty "Fuck you, Bob" messages per day, that might mean Bob's friend Harry has to admit his identity to the server to cut through the noise. Eventually Bob blocks Gina and she's no longer able to use his token and annoy his friends. Blocking someone invalidates your old tokens.

tinus_hn 8y ago

According to that article WhatsApp provided almost no data except who was in the group and who was sending messages. There is no way Signal can function without having the same data available.

majewsky 8y ago
Signal was once subpoenaed by the FBI to give up all stored data/metadata relating to a certain account. They responded with the account creation timestamp and the last-connected timestamp, suggesting that they do not store information about group ownerships or contacts. Source: https://www.aclu.org/blog/national-security/secrecy/new-documents-reveal-government-effort-impose-secrecy-encryption https://www.aclu.org/blog/national-security/secrecy/new-docu...
- tinus_hn 8y ago
  Once they become big they will be forced to keep that data. It is really difficult to force them to change the client or the protocol but not to force them to keep data they have access to on the server.
- baby 8y ago
  This is because Signal works differently for group chat. In WhatsApp, the server delivers your encrypted message to each member of the group. It's an optimization called "server-side fan-out". Check the whitepaper for more deatils: https://www.whatsapp.com/security/WhatsApp-Security-Whitepaper.pdf https://www.whatsapp.com/security/WhatsApp-Security-Whitepap... Interestingly this is also what the Signal libraries implement. So applications making use of them will generally make use of this optimization. For some reason, the Signal application itself was not making use of this optimization. My guess is that it had not updated its code yet when I looked. This might have changed since then. BUT, and that's a big but, as a passive observer (and if Signal kept logs of things) you can still figure out group chat membership by looking at who sent the same kind of message (same length) to who, and at what time. Basic relationship graph stuff.
move-on-by 8y ago
Yes, there is a way and it’s already in beta. It’s called sealed-sender and you can read about it in this signal blog post: https://signal.org/blog/sealed-sender/ https://signal.org/blog/sealed-sender/
tialaramex 8y ago
The Signal clients have this data, Signal's servers do not. Didn't you see recently on HN they announced they now have a mechanism so that their servers aren't even aware of who sent a message? The recipient can tell who it's from but the server just sees like a stamp on the outside "This is one of the messages Bob agreed to receive from people" and it says to itself "OK, Bob said he wants these, don't care who it's from".
- baby 8y ago
  Do you know how they prevent people from spamming messages then? If you can't identify someone how can you rate limit them?
  - tialaramex 8y ago
    Users have to volunteer the tokens to friends (co-conspirators, lovers, whatever) or assert that they just love receiving garbage from strangers, so conventional "spam" is impossible. AIUI The system can count usages of Bob's tokens and rate-limit those. If Bob's Ex Gina is sending him fifty "Fuck you, Bob" messages per day, that might mean Bob's friend Harry has to admit his identity to the server to cut through the noise. Eventually Bob blocks Gina and she's no longer able to use his token and annoy his friends. Blocking someone invalidates your old tokens.