Hard digital money

I talk about my digital cash idea a lot.  My digital cash card requires no external network and is perfectly counterfeit proof.  The idea behind hard digital cash is a chip manufactured with a secret code that know human being knows, and the code is destroyed after being embedded in the chip.  The chip is manufactured by a machine that embeds two codes, one common code for communications and one that is unique per chip.  The code is destroyed if the chip is dismembered, and the code is Xray shielded. When this chip is put in a digital money card, the this chip can exchange moeny data with other chips, and have secure exchange with secret codes and the entire system is within the digital realm, no human interaction.

So, the banker issuing cash can have a million chips ordered up, one chip containing the secret codes for the others, which the banker keeps.  The cards come with buttons such that the one card touches the buttons of the other card, direct comm at the button causes an exchange between the cards.  At any point the card holder can take the digital card and exchange it at the bank for external money, using the bankers master card.