Abstract: The present invention relates to systems, devices, and methods for conducting financial transactions, digital asset exchanges, and multi-currency interoperability on a private network of member subscribers in communication with other commercial banking and finance networks and services, where the system includes a specially adapted currency storage and conversion card apparatus, the card further comprising means for executing said transactions and exchanges using one or two or more currencies, where at least one of said currencies in preferred embodiments is a virtual digital currency hosted on said private network and combining features of both decentralized and centrally-regulated cryptocurrency systems; as well as a host of hardware and software means for integrating all of the above advantageously in various contingencies and circumstances.