System and method for authorizing a financial transaction

A method of altering an authorization amount comprising:

• a payment terminal receiving a preliminary authorization amount;
• the payment terminal receiving application data from a payment card interfaced with the payment terminal, the application data comprising an account number uniquely associated with the payment card;
• the payment terminal generating an adjusted authorization amount from the account number and the preliminary authorization amount, the adjusted authorization amount being different from the preliminary authorization amount;
• the payment terminal determining whether the adjusted authorization amount can be authorized offline, and transmitting a cryptogram request to the payment card, the cryptogram request including the adjusted authorization amount;
• the payment card generating a cryptogram and transmitting the cryptogram to the payment terminal;
• the payment terminal receiving the cryptogram and receiving an authorization response message confirming authorization of the adjusted authorization amount;
• and
• the payment terminal confirming that the cryptogram was generated from the adjusted authorization amount and from a cryptographic key uniquely associated with the payment card.

A non-transitory computer-readable medium storing computer processing instructions thereon for execution by a payment terminal, the computer processing instructions, when executed by the payment terminal, causing the payment terminal to:

• receive a preliminary authorization amount;
• receive application data from a payment card interfaced with the payment terminal, the application data comprising an account number uniquely associated with the payment card;
• generate an adjusted authorization amount from the account number and the preliminary authorization amount, the adjusted authorization amount being different from the preliminary authorization amount;
• determine whether the adjusted authorization amount can be authorized offline, and transmit a cryptogram request to the payment card, the cryptogram request including the adjusted authorization amount;
• receive a cryptogram from the payment card and receive an authorization response message confirming authorization of the adjusted authorization amount;
• and
• confirm that the cryptogram was generated from the adjusted authorization amount and from a cryptographic key uniquely associated with the payment card.