Its possible to produce keys and contacts without or with very little chance of bouncing - the price however a factor as well, hence must other methods be used to make Debouching.

•  How to remove bouncing (prel) from a signal

If your lucky to have switches with two outputs and one input will the best way to avoid bouncing be a SR-latch.

If your working on/off switches and buttons will some kind of RC-filtering be a solution - eventually together with a buffer with some hysteresis (smith-trigger input)

Finally can bouncing be removed with a relative simple filter - involving a shift register with n-bits, a SR-latch and some logic.

Its your task to Implement this as a VHDL code
(Please note that this circuit not the "ideal" solution and is bound to be modified)