Abstract: Multiple secure transactions are provided through use of a method that uses customer one-time unique purchase order numbers (“Coupons”) generated by an algorithm that uses a permutated user key and a user insertion key as input variables. A user key (such as a Personal Identification Number, or “PIN”) is combined with a permutation variable that is correlated with a customer sequence number to create the permutated user key. A random number generator is used to generate the user insertion key correlated with the customer sequence number. The algorithm can insert the permutated user key into a user account number through use of the user insertion key. A Coupon is validated by confirming that it is contained in a set of money source Coupons generated by a money source using the user key and a random number generator that is synchronized with the random number used to generate Coupons.