RedPhone Removed from Google Play Store

Cathal Garvey cathalgarvey at cathalgarvey.me
Thu Nov 13 11:41:58 PST 2014


Oh, for sure Moxie has a threat model that makes sense to him, but I 
dispute that it makes any sense in the real world. Google's certificate 
system is TOFU, so whatever certificate Google pushes to a users' device 
is what that device trusts updates from thenceforth. And, there's no 
obvious way for an Android user to verify a certificate *even if they 
were so inclined*. For my part, as an Android user with a knowledge of 
and interest in crypto, I have *never* checked a signed APK. Ever.

So, if even the more technical end of Moxie's customer base don't check 
APK signatures, and if most people simply take what Google Play offers 
them, what's to stop Google pushing a malicious TextSecure? Nothing. 
Nothing, at all, ever. And all the machinations and air-gaps Moxie and 
co implement are meaningless, because the TOFU scheme makes Google the 
root of all trust on the Google Play market.

If it were merely about certificates, Moxie would offer up-to-date APKs 
through his own website and F-Droid repository, allowing him to have 
utter control over timely updates without an intermediate trusted agent. 
But he doesn't, and when I asked I finally got an answer: It's because 
F-Droid doesn't offer metrics, debugging, and analytics. Essentially, he 
wants Google play so he can get silent feedback on what the Apps are 
doing in the wild.

I don't object to this as long as it's opt-in for users, but I do object 
that it's being presented as something (threat model) rather than 
developer convenience. I love TextSecure, and I'm grateful to Moxie and 
co for creating it. It lets me layer security on a legacy platform that 
everyone uses in a way that's transparent and extremely user-friendly, 
while offering security granularity for those so inclined (cert checks). 
But the delivery is through an intermediary that are essentially a 
public-facing wing of the NSA, and they have total control over the 
trust/threat model for 95% of the user-base. So..I don't even.

On 13/11/14 17:51, Eric Mill wrote:
> Moxie's laid out very clear reasons for why he uses Google Play and
> discourages other people from building it. You may not agree with him,
> but he at least has what I think is a coherent security model that he's
> sticking to.
>
> Really great discussion on it here:
>
> https://github.com/whispersystems/textsecure/issues/53
> https://github.com/whispersystems/textsecure/issues/127
>
> Namely, he trusts apps signed with his signature (a process he manages
> using his own airgapped system) and that's it. *You* may not hinge your
> trust of the application on his signature, but he does, and he wants
> ideally every TextSecure install to have it.
>
> Both threads above are from before the CyanogenMod deal. To make that
> happen, Moxie's team built a secure self-update path for the app, which
> removed most of the barriers to requiring Google Play.
>
> The other main barrier is push delivery, which right now uses Google
> Cloud Messaging. High quality push delivery to a kabillion devices is
> very hard, and not easy to replace. However, Moxie has encouraged people
> to take advantage of the server's WebSockets support, and to build an
> option for that into the client if they want to remove the last barrier
> to Google support -- while warning that WebSockets delivery will not be
> nearly as good as GCM-based delivery.
>
> I was talking with a friend about this over the weekend, and I think
> that the push that's happening for fully reproducible builds -- where
> every build produces an identical binary with an identical hash -- would
> resolve some of the issues Moxie has.
>
> Then, Moxie can sign the hash of the binary, and others who build the
> source code or get binaries from other places can verify that hash. That
> still requires some tooling or verification UX, and for builds to be
> reproducible by other people than Moxie, but it could make a difference.
>
> -- Eric
>
> On Thu, Nov 13, 2014 at 6:12 AM, Cathal Garvey
> <cathalgarvey at cathalgarvey.me <mailto:cathalgarvey at cathalgarvey.me>> wrote:
>
>     Nope, I haven't had to install Play for Textsecure at all, and I
>     don't use or have a personal Google account. When it offers to set
>     up data channel, just skip it, and TS reverts to encrypting over SMS
>     instead.
>
>     Redphone also has a "no google" mode where it announces incoming
>     calls to other RP users with a simultaneous SMS, but I've found it
>     to be very buggy in my builds; calls connect but no sound
>     transmitted, etc.
>
>     As far as "where to get it", here's a copy:
>     https://ngrok.com:61924/__owncloud/public.php?service=__files&t=__264659e23e8733b528386eaa6f52d5__ef
>     <https://ngrok.com:61924/owncloud/public.php?service=files&t=264659e23e8733b528386eaa6f52d5ef>
>
>     Cert is self-signed:
>     SHA1: 63:9B:E2:FA:D8:A9:66:DE:46:B7:__E4:C2:18:47:73:04:C0:12:FE:1F
>     SHA256:
>     CF:D2:82:0D:C8:65:CE:EB:2E:3F:__36:EC:DA:9E:82:4E:2E:BD:51:19:__6A:7E:11:65:50:40:57:9E:B8:79:__8D:A2
>
>     This is an older build by now. Frankly I'm holding out for a JS
>     build of Textsecure and I'll probably try FFOS, then. FDroid and
>     Textsecure are my "killer apps" tying me to Android. I just wish
>     Moxie would let them play nice together.
>
>
>     On 12/11/14 23:13, Seth wrote:
>
>         On Wed, 12 Nov 2014 14:29:04 -0800, <bluelotus at openmailbox.org
>         <mailto:bluelotus at openmailbox.org>> wrote:
>
>             Where can TextSecure be downloaded?
>
>
>         Best workaround I've found so far if you want to download Google
>         Play
>         APKs on your computer and then transfer them to your phone
>         manually is
>         Raccoon:
>
>         http://www.onyxbits.de/raccoon
>
>         Requires java along with a 'dummy' Google account, but gets the
>         job done
>         with the least amount of hassle.
>
>         Unfortunately, it appears that TextSecure still requires the Google
>         Services framework to be installed and running on the Android
>         device.
>         Haven't figured out yet how to do this manually this without
>         installing
>         Google Play.
>
>         Also, FWIW, you can (or at least you used to be able to)
>         manually remove
>         a Google account from an Android phone without having to factory
>         reset
>         the device.
>
>         http://www.sleetherz.com/__android-news/how-to-change-__gmail-account-on-android-__market-without-factory-reset/__2511/
>         <http://www.sleetherz.com/android-news/how-to-change-gmail-account-on-android-market-without-factory-reset/2511/>
>
>
>
>
> --
> konklone.com <https://konklone.com> | @konklone
> <https://twitter.com/konklone>



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