Abstract: A gaming machine (100) and a method of operating a gaming machine are provided. Encrypted information, including player credit information and identification information, is received at the gaming machine from a cash device (190) using a non-contact reader (160). The received information is decrypted using one of a preset number of stored time-stamped keys, the stored time-stamped keys being stored in a first in first out buffer (SAM2) and having been updated sequentially from a remote central server (110). The gaming machine is enabled for play by the player if the information has been successfully decrypted and the received player credit information meets predetermined criteria to allow play on the gaming machine. Updated information, including updated player credit information, is encrypted with one of the stored time-stamped keys on enablement of the gaming machine for play. The encrypted updated information is written to the cash device.