You can find the sources of the latest release on Alioth.
The archives are signed by one of these gpg keys:
There are binary packages of the shadow tool suite in many OpenSource distributions (Debian, Ubuntu, Gentoo, Fedora, Mandriva, and probably others).
Alioth Git Repository
The latest Debian sources are available from our GIT repository.
You can browse the source on the web.
Upstream Git Repository
Ongoing development work is done on github.