Space efficient method of redeeming electronic payments

A method of using a machine to redeem for a seller electronic payments generated by and received from a customer using a master key unknown to the seller, the machine including a memory storing instruction of the method in machine readable form, the method comprising:

• a) storing in the memory the master key;
• b) receiving from the seller a redemption request including a seller identifier, a first value of a payment index, a first unverified electronic payment associated with the first value of the payment index, a second value of the payment index, a second verified electronic payment associated with the second value of the payment index;
• c) authenticating the first unverified electronic payment by comparing the first unverified electronic payment to a first hash of a first string including the master key, the seller identifier, and the first value of the payment index;
• d) if the first unverified electronic payment is authenticated:
• 1) determining a first amount due to the seller, the first amount including the first unverified electronic payment;
• and
• 2) crediting the seller for the first amount due,
• e) if the first electronic payment is not authenticated:
• 1) authenticating the second verified electronic payment by comparing the second verified electronic payment to a second hash of a second string including the master key, the seller identifier, and the second value of the payment index;
• 2) if the second verified electronic payment is authenticated:
• A) determining a second amount due to the seller, the second amount not including the first unverified electronic payment;
• and
• B) crediting the seller for the second amount due.

An article of manufacture comprising:

• a) a memory;
• and
• b) instructions stored in the memory in machine readable form for a method of redeeming for a seller electronic payments generated by and received from a customer using a master key unknown to the seller, the method comprising:
• 1) storing in memory the master key;
• 2) receiving from the seller a redemption request including a seller identifier, a first value of a payment index, and an electronic payment associated with the first value of the payment index;
• 3) authenticating the electronic payment by comparing the electronic payment to a first hash of a first string including the master key, the seller identifier, and the first value of the payment index;
• 4) if the electronic payment is authenticated:
• A) determining an amount due to the seller;
• and
• B) crediting the seller for the amount due.

An article of manufacture comprising:

• a) a memory;
• and
• b) instructions stored in the memory in machine readable form for a method of redeeming for a seller electronic payments generated by and received from a customer using a master key unknown to the seller, the method comprising:
• 1) storing the master key in the memory;
• 2) receiving from the seller a redemption request including a seller identifier, a first value of a payment index, a first unverified electronic payment associated with the first value of the payment index, a second value of the payment index, a second verified electronic payment associated with the second value of the payment index;
• 3) authenticating the first unverified electronic payment by comparing the first unverified electronic payment to a first hash of a first string including the master key, the seller identifier, and the first value of the payment index;
• 4) if the first unverified electronic payment is authenticated:
• A) determining a first amount due to the seller, the first amount including the first unverified electronic payment;
• and
• B) crediting the seller for the first amount due;
• 5) if the first electronic payment is not authenticated:
• A) authenticating the second verified electronic payment by comparing the second verified electronic payment to a second hash of a second string including the master key, the seller identifier, and the second value of the payment index;
• B) if the second verified electronic payment is authenticated:
• i) determining a second amount due to the seller, the second amount not including the first unverified electronic payment;
• and
• ii) crediting the seller for the second amount due.