Hardtack is a very long term storage food source.
It doesn't taste particularly good, but not bad either.
DO NOTE that the key is to NOT use fats or oils and to NOT ALLOW moisture to reach the dried hardtack blocks.
http://www.survivalsullivan.com/how-to-make-hardtack/I point out the long baking cycle, TWO double baking cycles with a cooling period between. TWO hours ON EACH SIDE, in each cycle. 2hr - flip - 2hr - cool - 2hr - flip - 2hr
You want all the moisture out of the bricks. That means a minimum of FIVE hours for each batch.