barber pole progress bar?

[Kee Nethery]

How do I do a barber pole progress bar? 

I know that I should not use the "set cursor to busy" command in a Mac OS X app because that now signifies that the system is hung (thanks everyone for teaching me the proper way). I know instead I should use a progress bar. All well and good but ... I have an encryption process that is going to take some unknowable amount of time to complete and I know when it starts (0%) and when it ends (100%) but have no way to know how far along it is in between. What I think I want is a barber pole kind of progress bar that shows activity so that the user knows something is happening.

Any ideas on the proper way to show that something invisible is happening and the user should relax, the system has not hung?

Kee Nethery