I mean this tomb. My web browser throws a warning for their security certificate (unknown issuer) and judging by their github page, it's not developed too actively.
Are there any alternatives that work exactly the same way: by storing a whole LUKS encrypted filesystem inside a single file? The filesystem inside the container file should be able to be mounted transparently, just like a regular LUKS filesystem on a real partition (tomb can do this).
This rules out ecryptfs as option, because it encrypts every file on its own.
I also want to avoid truecrypt/veracrypt due to past controversies related to this project (they were the reason why I looked for an alternative to them when I found tomb).
Also, since LUKS is Linux specific and only works on just 1-2 BSD flavors as I know, any solution that works for both Linux and BSD flavors (at least OpenBSD, NetBSD and FreeBSD) is very welcome. I just emphasize again that the main requirement is to be able to store a whole encrypted filesystem inside a single file.