Let's take a contactless card for example (one for public transport lets say (i.e. MiCard)), the data is encrypted on the card and encrypted on the reader as far as I know.
So how come somebody who could read those cards couldn't just clone the card, copying all the encrypted data onto another card and go around using that? It's all encrypted on the card anyway, isn't it?
If this is the case, why don't people do it and wouldn't contactless credit/debit cards and many other pieces of encrypted data be the same?
** Not sure if this was the right area to ask, apologies if it's not.