Our design has been implemented in C++. The core of the system can be viewed as a distributed cryptographic application framework. The issuer and merchant sides have been implemented to run on AIX, whereas the client (buyer) runs on Windows 95. A buyer can access web-sites of merchants through a browser. If the web-site is e-money-enabled, on a purchase it returns a document with a special mime-type, which the browser has been configured to recognize. The browser then invokes an external e-money daemon. The daemon launches (if not already running) a graphical user interface for the client, and rest of the communication between the three parties takes place via the daemon. The transaction databases have been implemented persistently, so that malfunctions such as network breakdowns do not hamper the protocol.