[dublinben]

GCM is merely one minor component. The existence of the microg project proves that you can implement one without the other.

[Sir_Cmpwn]

MicroG does not implement GCM.

[floatboth]

MicroG does implement the GCM client! I've been getting push notifications through that thing for several months.

[kuschku]

No, it implements one half of it.

Signal still has to be linked with a proprietary binary, which contains lots of tracking code.

[Sir_Cmpwn]

Through Google, yes, but you can't bring along your own push notification delivery service.

[tptacek]

Your argument has become circular, because the what Signal uses push notifications for isn't security-relevant: the messages are empty and used only as a wakeup.

[Sir_Cmpwn]

They still contain information, though. They say when you're talking on Signal. Matched with someone else's messages at about the right frequency to indicate a conversation, they give a pretty decent idea of who you're talking to.

[tptacek]

They give the same information that TCP/IP traffic analysis does.