Hardware key [possible reposting]

[Michael Herman]

You probably want to avoid using the ls* commands to read a unique
hardware identifier/serial number.  It is my understanding that most of
the information returned from these commands comes from Object Data
Manager (hard disk) files and hence is potentially alterable by someone
with the appropriate permissions and know-how.

Austin recommended we use the uname (2) library call.  The last field 
of the structure contains the hardware processor id.

The command "uname -a" will give you a quick peek at what uname returns.