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Comment by upofadown | Hacker News Reader

>Because everything in Signal is end-to-end encrypted by default, the broad set of personal information that is typically easy to retrieve in other apps simply doesn’t exist on Signal’s servers.

The E2EE in Signal only protects the actual content of messages. In the case where Signal takes an assertive action, and the users are not paying any attention to their "safety numbers" (probably the most common case) they could in theory get message content with a MITM attack.

With an less assertive action (simply saving the data) Signal could get access to things like contacts and phone numbers.

Tutanota and Protonmail have both been forced in the past to take assertive actions to retain data as a result of legal warrants. Does American law even allow such warrants? If not then perhaps the USA is underrated as a place to base privacy oriented services.

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A judge can sign an order commanding a witness or party to preserve documentation and evidence, under penalty of contempt of court. However, there is still a great deal of uncertainty as to what actions the subject of the subpoena must take in order to preserve that evidence. It's pretty clear that you have to disable automated destruction mechanisms, you can't disable any recording functions you may already have, and you can't go and shred relevant papers in your possession; but whether a court can order you to write code or take other burdensome steps in order to record certain electronic records that you didn't record before to assist an ongoing investigation is still a very open question.

Sadly, not an open question in the UK.

What's the law in the UK, out of curiosity?

Even assuming we're just talking about traffic data rather than content of communications:

https://www.legislation.gov.uk/ukpga/2016/25/section/87/enac...

Ctrl+f for "generation"

Out of curiosity do you if you're within your rights to say "this will cost 'x' amount, we cannot afford it" or say if this is requested we would prefer to dissolve the company?

Basically can the UK government compel you under the threat of criminal prosecution?

I don't know of any instance when someone has threatened to close the company, in the UK (but then again, these notices aren't public knowledge, so just because you don't hear something doesn't mean it doesn't happen).

Noncompliance with a data retention notice lands you in court, but it's a civil matter, not criminal - though if you then ignore an order of the court, you could be facing some jail time and/or a fine for contempt of court. https://www.legislation.gov.uk/ukpga/2016/25/section/95/

Regarding compliance costs, there's a vague provision in the IPA for contribution to your expenditure: https://www.legislation.gov.uk/ukpga/2016/25/section/249 A little more detail, although not much, can be found in the accompanying Communications Data Code of Practice

I am a lawyer, but I am not YOUR lawyer.

As far as I understand Signal can't just save all the data because of how the app/server are architected:

They use sealed sender: https://signal.org/blog/sealed-sender/

Private contact discovery: https://signal.org/blog/private-contact-discovery/

And a "Private Group System" which is supposed to keep group membership information from the server: https://signal.org/blog/signal-private-group-system/

Though of course they could still push malicious updates.

Sealed sender only means Signal doesn't know who sent a particular message. They have to know who the recipient is so they can deliver it. Like forging the "From:" address on an email. Except in the Signal case the IP address/port of the sender is unique to the user and if the recipient responds then the link between the users is made.

The private contact discovery depends on an Intel SGX hardware enclave on their server. Which is good in this case as it implies more work to bypass it but where is the ultimate trust here? Intel? Did Signal ever get this working?

In general Signal can just see what IP address/port picks up a particular user's pre-keys if they want to know who is talking to who.

You said

> The E2EE in Signal only protects the actual content of messages.

> [By] (simply saving the data) Signal could get access to things like contacts and phone numbers.

And the linked blog posts show that for a few years now they've been working on limiting their own access to this kind of data --- i.e. it's not as simple as just saving it (like e.g. WhatsApp is able to and most likely doing 100% of the time to build social graphs).

Now of course all of those things are likely vulnerable to some attacks, but that's another discussion and it doesn't change the fact that Signal doesn't have immediate easy access in the way you claimed in your original comment. The fact is that there are some barriers and they'd have to put some effort into either disabling these protections or exploit flaws in them to get to the data.

>...it doesn't change the fact that Signal doesn't have immediate easy access in the way you claimed in your original comment.

I did not at all mean to imply that. The assertive action that Signal would have to take might involve actual work. The question is if they could be forced to do that work by the authorities of the country they operate from. I doubt that the amount of work would really factor into the legal stuff.

Signal of course might of already done the work as part of some cooperation with a national signals organization or simply because someone felt bored and contrary, but they could not admit that if they want to preserve the value of the information gathered.

The E2EE encryption part is in the end the only provable aspect of Signal Messenger. The leakage of meta information is inherent when one entity controls all the infrastructure.

> Does American law even allow such warrants?

Even worse - American laws allow the US government agencies to actually access the servers directly (or even add other servers or routers) in the data centre of the service provider, and the service provider is legally obliged to not tell anyone about it!

Out of interest, is there a place where this practice doesn't exist (genuinely don't know), where service providers are allowed to tell targets they are being subject to a warrant?

To not really answer your question, this kinda thing AFAIK can also happen in Australia.

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