A method comprising: generating on a payment device comprising a payment service, a first verification value unique to a transaction wherein said first verification value is derived by encrypting data comprising an account number and data based upon transaction data for the transaction using a unique derived key derived from the account number and a master derivation key, the unique derived key being unique to the payment service, generating a payment record comprising the first verification value, payment data comprising the account number, the data based upon transaction data for the transaction, and an indicator that indicates that the transaction being conducted is a contactless transaction and that the payment record includes the first verification value; and communicating the payment record to a service provider computer, wherein if the payment device generates the first verification value, the payment device transmits the payment record to the point of sale terminal, which transmits the payment record to the service provider computer, wherein the service provider computer receives the payment record, determines from the indicator in the payment record that the payment record includes the first verification value and that the transaction being conducted is a contactless transaction, and independently generates a second verification value on the service provider computer, wherein the second verification value is generated from the account number in the payment data and the data based upon transaction data for the transaction using a same process as used to generate the first verification value, compares , based on a determination that the payment record includes the first verification value, the first verification value to the second verification value, approves the transaction if the first verification value matches the second verification value; and disapproves the transaction if the first verification value does not match the second verification value. generating on a payment device comprising a payment service, a first verification value unique to a transaction wherein said first verification value is derived by encrypting data comprising an account number and data based upon transaction data for the transaction using a unique derived key derived from the account number and a master derivation key, the unique derived key being unique to the payment service, generating a payment record comprising the first verification value, payment data comprising the account number, the data based upon transaction data for the transaction, and an indicator that indicates that the transaction being conducted is a contactless transaction and that the payment record includes the first verification value; and communicating the payment record to a service provider computer, wherein if the payment device generates the first verification value, the payment device transmits the payment record to the point of sale terminal, which transmits the payment record to the service provider computer, wherein the service provider computer receives the payment record, determines from the indicator in the payment record that the payment record includes the first verification value and that the transaction being conducted is a contactless transaction, and independently generates a second verification value on the service provider computer, wherein the second verification value is generated from the account number in the payment data and the data based upon transaction data for the transaction using a same process as used to generate the first verification value, compares , based on a determination that the payment record includes the first verification value, the first verification value to the second verification value, approves the transaction if the first verification value matches the second verification value; and disapproves the transaction if the first verification value does not match the second verification value. <EOS>