GPG is being used in this application to verify the integrity of the downloads.
It uses public key cryptography to check the signature of the files to ensure
that they have not been tampered with or become corrupted.

Once you have a legitimate copy of this package, you can be assured that it
will not extract any files that do not pass the signature check. Even if the
the webserver gets hacked in the future, the hypothetical miscreants cannot
replace the downloads without failing the signature checks because they do
not have access to the private key used to sign the files. Even if they were
to replace the public key included in this package, they cannot replace the
good copy that you already have. (New users would not be protected in such
a scenario, however.) The private key is kept on my development PC, which is
not reachable from the Internet. So undetected tampering would require some
pretty serious hacking in order to succeed.

If the signature checks start consistently failing at some point in the future,
it could indicate that the webserver has been compromised, or that someone is
attempting a man-in-the-middle attack against you.

The idea behind this level of security is to make the webserver a less appealing
target for hackers, since they cannot simply replace the files with malware and
have them mass distributed to the end users. Hopefully this also makes the users
more confident about utilizing this package for easy updates.

The scripts are all effectively "open source", and the tools themselves are
well-known open source programs that have not been modified or even recompiled.
