Write a pair of programs, in C or as shell scripts, to send and receive a message by a covert channel on a MINIX 3 system. A permission bit can be seen even when a file is otherwise inaccessible, and the sleep command or system call is guaranteed to delay for a fixed time, set by its argument. Measure the data rate on an idle system. Then create an artificially heavy load by starting up numerous different background processes and measure the data rate again.