cell protection based on a formula

I would like to ensure cells in a sheet become unprotected once a particular
month has started and protected once a month has ended.

I have a sheet for each calendar month and want the cells to automatically
unprotect themselves when the month starts and then protect themselves once
the month ends. I know I could have a cell showing the current date and I
could easily have a formula to produce a Yes if this date falls within the
month in question.

Is it possible to then apply the cell protection based on this result - or
is there an easier way to do it!

Thanks

Andrew