Abstract: The present disclosure relates to data transmission methods and apparatuses. In one example method, a source device performs identity authentication on and negotiate a key with a transmission device that needs to output audio-video data or perform transformation processing on a transmission path to a sink device, and generates a key distribution packet used to encrypt or decrypt an audio-video stream only for the transmission device that needs to output audio-video data or perform transformation processing.

Abstract: A data transmission method and apparatus are provided, to improve security of audio-video data transmission. In this application, the source device performs identity authentication on and negotiate a key with a transmission device that needs to output audio-video data or perform transformation processing on a transmission path to the sink device, and generates a key distribution packet used to encrypt or decrypt an audio-video stream only for the transmission device that needs to output audio-video data or perform transformation processing. Another device on the transmission path cannot know the key and cannot perform decryption, so that transmission security of the audio-video stream can be improved. In addition, the source device centrally performs identity authentication and authorization control on other transmission devices that need to output the audio-video data or perform transformation processing.