Greetings.

I'm seeking wisdom from the monastery on handling creation of an array of bytes. I've done some research and it appears that I can use the pack command, but I am at a loss on how to obtain the results I seek.

I need to construct a "token" formatted as:

bytes 0 - 3: unsigned 32 bit representation of seconds since the epoch
bytes 4 - 7: unsigned 32 bit number (this represents an employee id)
byte 8: A check byte computed from the exclusive-or ("xor") of all the
+ previous bytes
[download]

I understand I can get the seconds since the epoch using time(), and I have the employee id as a 9 digit number - how do I format these into the above token and how do I create the xor check byte?

Any and all assistance is greatly appreciated.