3 ms·

Perhaps this would be another way to obfuscate the collection of metadata with techniques similar to anti-fingerprinting in Tor. An app like Signal could sync t

Perhaps this would be another way to obfuscate the collection of metadata with techniques similar to anti-fingerprinting in Tor. An app like Signal could sync the time across all parties and send/receive all data in predetermined packet sizes and at predetermined delivery times across vast enough segments of their network. This would in theory make it a lot harder to infer who are the partners in a specific conversation based on timestamps and traffic volume. The mechanism for picking the interval and packet size is debatable as long as the entropy of these values is low enough (does not allow for uniquely identifiable values). Maybe randomly from a list of predetermined values, taking into account some priority you set in advance, the size of the message, or the network conditions. If every client/server on the network sent and received the data in synced identically looking bursts it might raise the bar for successful metadata analysis. Any chance Signal or any other app already do this?

gruez 7y ago
Is approach is going to kill battery life because the phone has to be always online to receive those times transmission.
- ghostpepper 7y ago
  Most modern CPUs/SoCs spend most of their time (ideally) asleep or trying to go to sleep, and then waking at predefined intervals to transmit data. As long as this interval could be synchronized to some multiple of the transmission interval I don't think this would negatively impact battery life.
pmoriarty 7y ago
The techniques you're talking about, and others, have also been used in anonymous remailers[1] to resist traffic analysis[2]. The mixminion[3] remailer design document[4] goes in to details on those mitigations. Of course, real time conversations require certain constraints that email messages don't have, so some of the mitigations techniques used in remailers might not be practical here. Signal's designers must have been well aware of Tor and anonymous remailers, so if traffic analysis mitigation techniques were not used by Signal it was a deliberate design decision on their part. [1] - https://en.wikipedia.org/wiki/Anonymous_remailer https://en.wikipedia.org/wiki/Anonymous_remailer [2] - https://en.wikipedia.org/wiki/Traffic_analysis https://en.wikipedia.org/wiki/Traffic_analysis [3] - https://en.wikipedia.org/wiki/Mixminion https://en.wikipedia.org/wiki/Mixminion [4] - https://www.mixminion.net/minion-design.pdf https://www.mixminion.net/minion-design.pdf

gruez 7y ago

Is approach is going to kill battery life because the phone has to be always online to receive those times transmission.

ghostpepper 7y ago
Most modern CPUs/SoCs spend most of their time (ideally) asleep or trying to go to sleep, and then waking at predefined intervals to transmit data. As long as this interval could be synchronized to some multiple of the transmission interval I don't think this would negatively impact battery life.

pmoriarty 7y ago

The techniques you're talking about, and others, have also been used in anonymous remailers[1] to resist traffic analysis[2]. The mixminion[3] remailer design document[4] goes in to details on those mitigations. Of course, real time conversations require certain constraints that email messages don't have, so some of the mitigations techniques used in remailers might not be practical here. Signal's designers must have been well aware of Tor and anonymous remailers, so if traffic analysis mitigation techniques were not used by Signal it was a deliberate design decision on their part. [1] - https://en.wikipedia.org/wiki/Anonymous_remailer https://en.wikipedia.org/wiki/Anonymous_remailer [2] - https://en.wikipedia.org/wiki/Traffic_analysis https://en.wikipedia.org/wiki/Traffic_analysis [3] - https://en.wikipedia.org/wiki/Mixminion https://en.wikipedia.org/wiki/Mixminion [4] - https://www.mixminion.net/minion-design.pdf https://www.mixminion.net/minion-design.pdf