https://github.com/whispersystems?page=1

here there are libraries and all source code of the project.

It is a starting point, since there is also a C library.

Well, all of a sudden there's two Signal clients for Sailfish:

https://github.com/aebruno/whisperfish

https://openrepos.net/content/schorsch/sailsecure

Unfortunately they're separate clients and not integrated into the Messages application (and of course a bunch of stuff is still missing from both clients), but at least it's something.

integration to system means writing signal protocol as telepathy module, which requires a lot of extra efforts and knowledge. and i know only some persons who can really do that. so please go ahead and do system integration yourself

I do appreciate it. Telepathy itself even needs a lot of work before Signal could work with it.

I think that the best chance for working Signal system integration is waiting for some Pidgin (libpurple) plugin to appear and try getting it to work through telepathy-haze.

Given its limitations on SailfishOS (only Messages chat), I am afraid that the resources put into a Telepathy plugin might be better used in a full 3rd party client. It'd be nice to have, though.

Then telepathy-haze would have to see an enormous upgrade as well, because it doesn't really work all that well.

native version is available on openrepos. sailsecure. not system inzegrated but anyway. one android app less

There is now a binary RPM file available for Whisperfish at https://github.com/aebruno/whisperfish/releases

Really cool!

Just tried to install it to Oneplus One with CM12.1 + Sailfish 2.0.0.10 but it did not appear in the applications. Any ideas?

I see an app on my Jolla.

It's pretty official looking interface, very fluid. Wish I had people to contact to actually test it on -- but really glad we're already at this stage!