A secure cashless gaming system comprises a plurality of gaming devices which may or may not be connected to a central host network. Each gaming device includes an intelligent data device reader which is uniquely associated with a security module interposed between the intelligent data device reader and the gaming device processor. A portable data device bearing credits is used to allow players to play the various gaming devices. When a portable data device is presented to the gaming device, it is authenticated before a gaming session is allowed to begin. The intelligent data device reader in each gaming device monitors gaming transactions and stores the results for later readout in a secure format by a portable data extraction unit, or else for transfer to a central host network. Gaming transaction data may be aggregated by the portable data extraction unit from a number of different gaming devices, and may be transferred to a central accounting and processing system for tracking the number of remaining gaming credits for each portable data unit and/or player. Individual player habits can be monitored and tracked using the aggregated data. The intelligent data device reader may be programmed to automatically transfer gaming credits from a portable data device the gaming device, and continually refresh the credits each time they drop below a certain minimum level, thus alleviating the need for the player to manually enter an amount of gaming credits to transfer to the gaming device.