Abstract: Described are a system, method, and computer program product for secure client device and consumer authentication. The method includes receiving a primary account number (PAN) of an account of a consumer from a merchant system and determining whether the PAN has been registered with a public key of a public-private key pair of a client device of the consumer. The method also includes, in response to determining that the PAN has been registered, transmitting a login request to a transaction processing system including a device identifier of the client device based on the PAN. The method further includes receiving a login response from the transaction processing system associated with successful authentication of the client device and, in response to receiving the login response, processing a transaction by generating a transaction authorization request message including the PAN to the transaction processing system.