[personal profile] mjg59
Moxie, the lead developer of the Signal secure communication application, recently blogged on the tradeoffs between providing a supportable federated service and providing a compelling application that gains significant adoption. There's a set of perfectly reasonable arguments around that that I don't want to rehash - regardless of feelings on the benefits of federation in general, there's certainly an increase in engineering cost in providing a stable intra-server protocol that still allows for addition of new features, and the person leading a project gets to make the decision about whether that's a valid tradeoff.

One voiced complaint about Signal on Android is the fact that it depends on the Google Play Services. These are a collection of proprietary functions for integrating with Google-provided services, and Signal depends on them to provide a good out of band notification protocol to allow Signal to be notified when new messages arrive, even if the phone is otherwise in a power saving state. At the time this decision was made, there were no terribly good alternatives for Android. Even now, nobody's really demonstrated a free implementation that supports several million clients and has no negative impact on battery life, so if your aim is to write a secure messaging client that will be adopted by as many people is possible, keeping this dependency is entirely rational.

On the other hand, there are users for whom the decision not to install a Google root of trust on their phone is also entirely rational. I have no especially good reason to believe that Google will ever want to do something inappropriate with my phone or data, but it's certainly possible that they'll be compelled to do so against their will. The set of people who will ever actually face this problem is probably small, but it's probably also the set of people who benefit most from Signal in the first place.

(Even ignoring the dependency on Play Services, people may not find the official client sufficient - it's very difficult to write a single piece of software that satisfies all users, whether that be down to accessibility requirements, OS support or whatever. Slack may be great, but there's still people who choose to use Hipchat)

This shouldn't be a problem. Signal is free software and anybody is free to modify it in any way they want to fit their needs, and as long as they don't break the protocol code in the process it'll carry on working with the existing Signal servers and allow communication with people who run the official client. Unfortunately, Moxie has indicated that he is not happy with forked versions of Signal using the official servers. Since Signal doesn't support federation, that means that users of forked versions will be unable to communicate with users of the official client.

This is awkward. Signal is deservedly popular. It provides strong security without being significantly more complicated than a traditional SMS client. In my social circle there's massively more users of Signal than any other security app. If I transition to a fork of Signal, I'm no longer able to securely communicate with them unless they also install the fork. If the aim is to make secure communication ubiquitous, that's kind of a problem.

Right now the choices I have for communicating with people I know are either convenient and secure but require non-free code (Signal), convenient and free but insecure (SMS) or secure and free but horribly inconvenient (gpg). Is there really no way for us to work as a community to develop something that's all three?

Date: 2016-05-15 09:47 pm (UTC)
vlion: cut of the flammarion woodcut, colored (Default)
From: [personal profile] vlion
One of the big takeaways here is that opsec is hard, and most people don't have a pressing need to operate in an opsec mode, so they opt for convenience.

Inasmuch as Moxie is looking for adoption, he's opting to shift out of an opsec mode in proportion to this. For people who have a *significant* need to operate out of the snooping ability of Google, then Signal is not an option: it relies on a friendly Google. This permeates everything in the ecosystem - friendly services such as Google or Apple (not neutral) are taken to be mandatory for user friendliness. It's important to understand that if you're concerned about Big Siblings, then you have to control the software; and most / all of the hardware.

This is of course in separate context from the Libre Software requirements, of course!

I'm not sure who Moxie is serving at this point in the game. Not people who have reasonable concern for a Big Sibling. Unsure who is paying his bills: Twitter, I think. My analysis would be that Signal is adequate for purpose when dealing with ordinary snooping concerns - family concerns, coffeeshop snooping, etc. For people dealing with Significant Security Concerns... not sure there are reliable options; all paths are fraught with risk.

Date: 2016-05-16 12:49 am (UTC)
From: (Anonymous)
"For people who have a *significant* need to operate out of the snooping ability of Google, then Signal is not an option: it relies on a friendly Google."

I don't think that it does. Signal has never been touted to thwart a adversary that's dedicated to the task of performing traffic analysis. I mean, it used to use _SMS_ to transport the cyphertext of encrypted messages. SMS! You know, that data transport mechanism that the NSA is reported to regard as "just metadata" that falls under the "business records" section of the third-party doctrine, can be retained forever, and can be sent off to Law Enforcement just because they ask nicely.

The only _official_ claim I've seen made about Signal that it protects the _contents_ of your messages from adversaries that don't have root on either or both of the conversing party's computers. This means that Signal protects you just as well from Google as it does from the NSA.

Really, if you don't trust Google enough to send securely encrypted messages through their data routing service, then why do you trust them enough to use an OS that they authored? The author of your OS has root on the computer that runs it. This is a fact. Therefore, if you don't trust the author of your OS you cannot trust the machine it runs on.

"Unsure who is paying his bills: Twitter, I think."

Twitter acquired Whisper Systems and made Marlinspike its head of cybersecurity in 2011. Marlinspike left Twitter in 2013 to found Open Whisper Systems. While it's _entirely_ possible that his small fortune made from the Twitter acquisition and paycheck from the Twitter job are still paying the bills, it's more likely that the Wikipedia article is correct and that OWS is funded by grants and donations: https://en.wikipedia.org/wiki/Open_Whisper_Systems#Funding


Matthew Garrett

About Matthew

Power management, mobile and firmware developer on Linux. Security developer at Google. Ex-biologist. @mjg59 on Twitter. Content here should not be interpreted as the opinion of my employer.

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