Hi,
Is it possible to copy/clone info from a card, say an travelcard (oystercard) or pass to a building? Basically copy the card/nfc info to the phone allowing you to use your phone instead of the original card? So you can use your phone as a pass/travel pass.

This would be awesome.

you can copy and send info, but you can't copy MAC

There are basically two types of wireless identification cards - the simple ones that just send a long number once they get near the reader and more sophisticated ones with two way communication that work on the challenge-response principle, where the secret key never leaves the card.

Unsurprisingly, it is very hard to impossible to clone cards of the second sort.