System and method for authorizing financial transactions with online merchants

A system for authorizing a financial transaction of a financial presentation device such as a credit or debit card being presented from a customer to an online merchant. The system includes a peripheral device having a processor configured to generate a dynamic verification value for the card which changes for each financial transaction, and to transmit the dynamic verification value to a user computer via an I/O interface during an online transaction. The system also includes an authentication computer having a memory for storing information used to generate a comparison verification value, a communication device for receiving the dynamic verification value originating from the peripheral device, a processor and an authentication module executable by the processor adapted to generate the comparison verification value using information stored in memory. The authentication computer determines whether to authorize the financial transaction based on whether the comparison verification value matches the received dynamic verification value.