A system and method to improve on the security of credit cards when money needs to be charged or transferred by assigning a different charge number to every transaction. A charge number is a combination of the card number and a random number that is generated through a user initiated preauthorization...http://www.google.com.hk/patents/US7100821?utm_source=gb-gplus-share專利 US7100821 - Charge card and debit transactions using a variable charge number
