[X4U] encrypted disk images question

[John Baltutis]

On 10/4/09, Michael Elliott <michaelelliott at me.com> wrote:
>
> Can anyone point me to a primer on how to make a disk image that I can
>
> 1) encrypt so that it's password protected
> AND
> 2) has a variable size (increases on-the-fly as the needs increase)
>
> BUT
> 3) is accessible to more than one user account when mounted
> BUT
> 4) is inaccessible to other accounts that I don't want it accessible to?

First two detailed in Disk Utilities help under sparse image and encryption.
AFAIK, the other two aren't doable, since logging out or using FUS unmounts all
mounted disk images. I don't use the latter, but that would be my take based on
other built-in security measures. The real question is why? It really can't be
that difficult to mount the image and provide the password after logging in.