4 ms·

> If your communication is encrypted it shouldn't matter if it passes AT&T networks. IIRC, the signals intelligence agencies like the NSA learn almost as much

by 394549 8y ago

> If your communication is encrypted it shouldn't matter if it passes AT&T networks. IIRC, the signals intelligence agencies like the NSA learn almost as much from traffic analysis (e.g. who's talking to who and when) and metadata than from actual message content. Mere encryption itself often doesn't protect much from that.

imglorp 8y ago
I'd argue that metadata is more important than content. It enables suspicion-by-association lines of inquiry. Once you know whos' involved in a conversation, it's much easier to target them for closer attention, such as hacking their machine or rubber-hose cryptography, both of which nullify any crypto you might have used.
- JumpCrisscross 8y ago
  > I'd argue that metadata is more important than content Isn't metadata, practically speaking, a subset of content? (If you have the latter, you almost certainly also have the former?) Metadata is more useful than content if you're capacity constrained, technologically or legally, in collection and/or analysis.
  - AndrewKemendo 8y ago
    Isn't metadata, practically speaking, a subset of content? Importantly to how we think about communication, no. Metadata is the signature that accompanies or encapsulates content, viewable to the world. You can completely conceal content, through encryption for example, but you can't completely conceal metadata. In other words there must be a physical exchange of energy somewhere (communication), and metadata tells you something about how the exchange happened, irrespective and ignorant of what the content is.
    - schoen 8y ago
      > you can't completely conceal metadata You can do it with a very high cost (in overhead, latency, and availability) by having a large number of people all send and receive messages, on a fixed or randomized schedule, exceeding their maximum possible amount of communication with one another. Then someone monitoring the network knows that each of the participants in this system could have communicated with any other participant, but not whether or not the communication took place.
      - AndrewKemendo 8y ago
        Even ignoring the practicality part, it becomes a timing game, because "empty" messages - even if they were filled with unintelligible "random" hex - would traverse the network differently than ones with variable length/size content and would be able to be filtered out pretty quickly. The bottom line is that you are going to leave a signature of some sort through communications - the question is, can you properly build a comms system system that is functional within the limits of your risk/reward criteria.
        schoen 8y ago
        > Even ignoring the practicality part, it becomes a timing game, because "empty" messages - even if they were filled with unintelligible "random" hex - would traverse the network differently than ones with variable length/size content and would be able to be filtered out pretty quickly. To eliminate the statistical observability of metadata, the padding needs to reach or exceed the maximum capacity of the channel. So you can't have people sending more messages than the padded channel permits per time period. In your example, packets "with variable length/size content" would need to be absolutely prohibited, or else all packets' length would need to be randomized, and message data would need to be sent following strictly the same distribution as padding messages. For example, you and I could have a rule of exchanging exactly 1 MB of data per day, at a specified time, every day. Then an observer wouldn't be able to tell whether, on a particular day, we had actually communicated something to each other or just allowed the padding data to go out. Clearly in this system we're not ever allowed to use it to transmit more than 1 MB per day, without destroying the metadata unobservability property. An attacker still knows that you and I are part of a system that offers us an otherwise unobservable channel, but not when we do or don't make use of that channel. There are lots of variants that also allow many-to-many messaging, again at a high cost in overhead, latency, and availability.
lern_too_spel 8y ago
There is no evidence of this. If you have a system outside the US sending encrypted data to a system inside the US, all anybody can see is that these two systems are talking to each other. They can't see whose communication is inside that encrypted data to tell who is talking to whom and when.

by 394549 8y ago

imglorp 8y ago

I'd argue that metadata is more important than content. It enables suspicion-by-association lines of inquiry. Once you know whos' involved in a conversation, it's much easier to target them for closer attention, such as hacking their machine or rubber-hose cryptography, both of which nullify any crypto you might have used.

JumpCrisscross 8y ago
> I'd argue that metadata is more important than content Isn't metadata, practically speaking, a subset of content? (If you have the latter, you almost certainly also have the former?) Metadata is more useful than content if you're capacity constrained, technologically or legally, in collection and/or analysis.
- AndrewKemendo 8y ago
  Isn't metadata, practically speaking, a subset of content? Importantly to how we think about communication, no. Metadata is the signature that accompanies or encapsulates content, viewable to the world. You can completely conceal content, through encryption for example, but you can't completely conceal metadata. In other words there must be a physical exchange of energy somewhere (communication), and metadata tells you something about how the exchange happened, irrespective and ignorant of what the content is.
  - schoen 8y ago
    > you can't completely conceal metadata You can do it with a very high cost (in overhead, latency, and availability) by having a large number of people all send and receive messages, on a fixed or randomized schedule, exceeding their maximum possible amount of communication with one another. Then someone monitoring the network knows that each of the participants in this system could have communicated with any other participant, but not whether or not the communication took place.
    - AndrewKemendo 8y ago
      Even ignoring the practicality part, it becomes a timing game, because "empty" messages - even if they were filled with unintelligible "random" hex - would traverse the network differently than ones with variable length/size content and would be able to be filtered out pretty quickly. The bottom line is that you are going to leave a signature of some sort through communications - the question is, can you properly build a comms system system that is functional within the limits of your risk/reward criteria.
      - schoen 8y ago
        > Even ignoring the practicality part, it becomes a timing game, because "empty" messages - even if they were filled with unintelligible "random" hex - would traverse the network differently than ones with variable length/size content and would be able to be filtered out pretty quickly. To eliminate the statistical observability of metadata, the padding needs to reach or exceed the maximum capacity of the channel. So you can't have people sending more messages than the padded channel permits per time period. In your example, packets "with variable length/size content" would need to be absolutely prohibited, or else all packets' length would need to be randomized, and message data would need to be sent following strictly the same distribution as padding messages. For example, you and I could have a rule of exchanging exactly 1 MB of data per day, at a specified time, every day. Then an observer wouldn't be able to tell whether, on a particular day, we had actually communicated something to each other or just allowed the padding data to go out. Clearly in this system we're not ever allowed to use it to transmit more than 1 MB per day, without destroying the metadata unobservability property. An attacker still knows that you and I are part of a system that offers us an otherwise unobservable channel, but not when we do or don't make use of that channel. There are lots of variants that also allow many-to-many messaging, again at a high cost in overhead, latency, and availability.

lern_too_spel 8y ago

There is no evidence of this. If you have a system outside the US sending encrypted data to a system inside the US, all anybody can see is that these two systems are talking to each other. They can't see whose communication is inside that encrypted data to tell who is talking to whom and when.