Securely adding new users to content server? [on hold]

Securely adding new users to content server? [on hold]

1) I'm currently making a small time storage server for personal use a
maybe a few friends. If you already have an account and can work UNIX
command line, then you can use programs such as puTTY to access it. I'm
currently making a program that lets you visually transfer files back and
forth, with a layout similar to dropbox. However, I'd like to add a
"Create new user" feature and I'm not sure how to securely do it.
Sure, I can have the program execute something like "sudo adduser jim" and
supply the sudo password, but this would require me to include an
administrative password within the jar file. I know there are obfuscation
programs out there, but it doesn't necessarily make it more secure. I'd
prefer to create users with ssh, but I'm open to whatever works and is
secure.
2) I just thought of something. What if I created an administrative user
with a their sudo ability limited to only creating new users? Does this
sound like a reasonably secure solution? If not, what are the cons of this
method?