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.

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 lo

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)