Device and method to render multimedia data stream tamper-proof based on block chain recording

A method for rendering a multimedia data stream tamper-proof and of evidential value when recorded in a block chain system reads and decodes the multimedia data stream to obtain multiple frames of data arranged in sequence, and calculates a hash value of each frame of data of the multimedia data stream. One or more items of data are selected from the multiple frames of data based on a predetermined rule and information as to properties of the one or more items of data is uploaded to the block chain system for recording purposes. A device for applying the method to a multimedia data stream is also disclosed.