A computer device and method for encoding a message corresponding to an outcome of a computer game, and a computer device and method for decoding the message to detect a fraudulent outcome. The computer device used to generate the encoded message includes (1) a memory device containing encoding control code and (2) a processor configured to process the encoding control code in conjunction with a computer game outcome to generate an encoded message containing the computer game outcome and to transmit the encoded message to a human-readable output device, such as a display device. The computer device includes various tamper resistant or tamper evidence features. A secure module containing the processor and memory is used to plug into an existing personal computer or dedicated game device. The device also includes a system for metering use of a computer game. The method for encoding the message includes the steps of executing a computer game program to generate a computer game outcome, encoding the computer game outcome to generate an encoded message, and providing the encoded message to a user, who may then transmit the encoded message to a device configured for decoding the encoded message to reveal the computer game outcome. A second central or host computer device is used to decode the encoded message. The second computer device has (a) a memory device containing decoding control code and an encoded message corresponding to a computer game outcome and (b) a processor configured to process the code to decode the encoded message to reveal the computer game outcome.