Fecha de publicación: 05/01/2023 Fuente: Wipo Milk or dairy products Disclosed are methods for exchanging transaction data, including transmitting a first public encryption key and transaction data associated with a transaction to a computing device via a near field communication (NFC) connection, receiving a second public encryption key and a transaction message associated with the transaction via the NFC connection, and appending the second public encryption key and the transaction message associated with the transaction to a database stored in a memory in communication with at least one integrated circuit, wherein the at least one integrated circuit is powered by an electromagnetic field generated by the computing device. Systems and computer program products are also provided.