Abstract: A coding and deciphering system is used to prevent fraudulent credit card transactions. The traditional plastic credit card is replaced by an electronic credit card that may look like a credit card sized calculator. The electronic credit card is password protected. After activated by entering the correct password, it turns the data of a transaction into an enciphered code uniquely associated to that transaction. Such an enciphered code must accompany the un-coded transaction data for each transaction. The computer of the credit company deciphers this code by using the information stored in the authorized user's account. The deciphered code is used to compare with the un-coded transaction data. The transaction is authorized if a match is found, otherwise the transaction is denied. The extremely high level of security this method provides will make most credit card fraud impossible.