LibrebIobit is correct. You can install via the 'try trisquel' option, then
selecting the 'install Trisquel' option. You can perform an encrypted install
via the installer. This will be an encrypted install like any other GNU/Linux
install.
What you can't do is encrypt the /boot too.
I'm currently running Debian with full encryption install and it's a nice
set-up. As much as I really want to support Trisquel I can't wait or do some
temporary install. I have lots of work to do and need a working system. It
also made me worried about the potential speed a future broken system might
be sorted. So I'm sticking with my long-term, familiar Debian. That's not to
take anything away from Trisquel - it's a superb distro and I support it.
It's just not ideal for me right now.
