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Firstly, I completely agree with you regarding why this is bad news. However, I don't understand one thing: let's say our hypothetical user has been posting in a private subreddit for carrot fetishists, which Trump will make illegal in 2018. If, today, a NSL was received by Reddit, isn't it potentially already too late for our carrot fetishist, even if they immediately stop visiting the subreddit or delete their account? Now, the carrot lover knows there was a NSL, but there isn't anything they can do except wait and see what happens when the new legislation rolls around in 2018. Emigrate, maybe? Serious question; I don't know how these things work. Asking for a friend.

They can at least stop posting about carrots. If they haven't posted anything personally identifiable that could link their 'carrotlover314' account to their real identity, then they can discard that account. At worst, if it is indeed a case of past lewd carrot-related acts being punishable by death, they'd have a head start to get out of the country before the Carrotstasi get there.

It's not much but it's something.

It wouldn't matter. The US constitution prohibits laws that criminalize earlier actions that were legal when committed.

[1] https://en.wikipedia.org/wiki/Ex_post_facto_law

Perhaps they won't get you for stuff you did today that is legal today.

But if you are still a carrot fetishist in the future, they can use the knowledge that you used to be a carrot fetishist to set up a sting operation. A little parallel reconstruction, they seize your phone and laptop, and next thing you know you're in prison in the future, thanks to the data they hoovered up today and will be in their database forever.

Recall the Communist witch-hunt in the cold war. That was done without retroactive policing and parallel construction. Just because they cannot imprison you for actions taken before the action was illegal doesn't mean they can't fuck you over in other ways. It's the thought police all over again.

That doesn't protect you from targeted enforcement of other laws.

The US constitution prohibits unreasonable search and seizure on its face.

You are right, the only benefit to the carrot lover is that they know, within a reasonable level of certainty, that their carrot loving activities may be called into question in the future.

Which, in my mind, is preferable to the alternative.

> Germany and Russia would like to have a chat with you.

So would J Edgar Hoover.

I apologize in advance if this sounds pedantic or like I am just trying to be difficult to be difficult. I am genuinely interested in this subject and appreciate your response. You never really stated what I am doing differently in the canary-removed universe (C0) than I would be doing in the universe where the canary is still present(C1). Respectfully it seems you gave reasons why surveillance is bad, but its not clear what utility I derive from the canary and what I would do differently in C0 vs C1.

I probably should have been more explicit about two of my big problems/uncertainties with warrant canaries in my initial comment. The biggest issue is that they only really seem to matter in circumstances where I assumed the service provided was a secure and private communication platform. My personal threat model does not treat the reddit platform as a secure and private communication platform and Reddit Inc. is just slightly less of an adversary than Eve's Agency. (sidenote: You are Threat Model Shostack correct?)

My other issue is that the canaries seem to be backward looking and do not do much for my future outlook. It seems that the knowledge that an NSL was served just tells me about the past, but very little about the future. Should I assume that since an NSL was served once that I should expect that they will continue to be served repeatedly and regularly going forward? I am having trouble expressing the latter adequately and clearly, hopefully it is teased out below.

For the sake of argument I am assuming/ignoring that Eve does not do global surveillance and cannot easily associate requests from my IP to reddit with submissions/comment timestamps, vote changes, etc.

  > If the NSA hoovered up this data, suddenly they might learn a lot
  > about you that they didn't know before

In C0, I am screwed, Eve's organization knows I frequent /r/BDSM, /r/guns, /r/earthliberationfront, etc. Am I to assume that further NSLs will be served in the future and therefore I stop visiting my favorite subreddits? If I was concerned about the privacy of my actions what was I doing using a public insecure communication platform?

In C1, I continue to visit /r/BDSM, /r/guns, /r/earthliberationfront, etc and the record of my sensitive activities on reddit is even larger if they are served an NSL in the future.

  > suddenly things that may have been frowned upon before by
  > the general public are suddenly made illegal by Executive order
  > or some other horrible twisting of our laws? This provides the
  > government with a great way to narrow down the list and identify
  > targets that have become "inconvenient" for them.

In C0 I have a greater reason to believe that I am on the "inconvenient list". In C1 I am still doing all the things its just I have less certainty if I am on the list.

  > Think it can't happen or that this is an off-the-wall conspiracy
  > theory? Germany and Russia would like to have a chat with you.

I don't think this sounds crazy. I just do not understand what the difference is between C0 and C1. As far as I am concerned the only difference between C0 and C1 is that I know my activities may have been reviewed by Eve in C0.

  > Case in point from a couple days ago:
  > https://news.ycombinator.com/item?id=11374839

As far as that study is concerned the difference between C0 and C1 is that in C0 I am more aware or "subtly reminded" of the existence of mass surveilance and therefore self-censor. There are fewer subtler reminders of mass surveillance in C1 therefore I self-censor less in C1 than in C0. That makes canaries seem bad?

I agree. The safe bet is that everyone will give you up, and will lie about it. So you plan from there ;)

Edit: spelling

If I'm understanding you, you're wondering what to do with the information, and comparing it to an identical situation where you don't have the information.

You're right that an early-warning system hasn't been developed. We have no way of knowing what the NSA will decide to analyse after the fact. Indeed, we do not know if an asteroid will hit the earth tomorrow. At one level, there is a limit to our ability to predict the future.

So it's up to the individual. We self-censor, or don't. The chilling effect of the knowledge of surveillance is well documented. Are you making a point that thinking you're being spied upon is more damaging than any fallout of the actual spying?

> Right now that data is ONLY available internally at Reddit

Or anybody monitoring their traffic. coughNSAcough

Anybody monitoring their traffic who is also capable of breaking TLS.

So, the NSA.

Or somebody who has access to their servers, which are AWS.

I would be shocked if NSA didn't get a secret court order to get AWS access.

Traffic flow analysis would probably work quite well on reddit. They could confirm/deny with high confidence whether certain subreddits/posts are accessed without any need to decrypt, just by how big the responses are.

Since all the posts on Reddit are timestamped, someone sniffing traffic could probably do a decent job tying HTTPS requests (and the IP addresses they came from) to new posts that show up, and the users who posted them.

I was initially sceptical that traffic analysis would be enough, but it appears that mainstream TLS does indeed leak a lot of metadata, especially with the typical structure of splitting resources across distinct servers (eg: static.example.com for images). I wonder if the security of something the size of Reddit might not be improved by simply having a large fleet of dns round-robin app servers that all deliver all content from one domain.

I found:

"Identifying Website Users by TLS Traffic Analysis: New Attacks and Effective Countermeasures"

https://hal.inria.fr/hal-00732449/

Does anyone know of other, recent research in this area? It's been a long time since I last looked at opaque data captures of TLS/SSL traffic.

I also found: https://tools.ietf.org/html/draft-ietf-tls-chacha20-poly1305... which states in part:

"It should be noted that AEADs, such as ChaCha20-Poly1305, are not intended to hide the lengths of plaintexts. When this document speaks of side-channel attacks, it is not considering traffic analysis, but rather timing and cache side-channels. Traffic analysis, while a valid concern, is outside the scope of the AEAD and is being addressed elsewhere in future versions of TLS."

On a skim of https://tools.ietf.org/html/draft-ietf-tls-tls13-11 I couldn't find anything new wrt. recommendations on padding with the goal of thwarting traffic analysis?

Anyone have any pointers on this?

Who needs to break encryption when you can break 99% of deployed OS kernels across all platforms?