A method of processing an online transaction request involves a network gateway generating a revised transaction request from an incoming transaction request that is received from a client terminal. The revised transaction request includes a revised transaction message that is derived from the incoming transaction request and a revised transaction request cryptogram that is generated from the revised transaction message. The revised transaction request cryptogram is uniquely associated with an identity token that is interfaced with the client terminal. The network gateway receives a transaction authorization from an issuer server for the revised transaction request, and provides a revised transaction authorization message to the client terminal in accordance with the received transaction authorization. The revised transaction authorization message provides an indication of authorization of the revised transaction request.