Abstract: A method includes, when a first card in a secure element (SE) system of a terminal is in an inactive state after the terminal is powered off, subsequent to receiving, using a near-field communication (NFC) system, an instruction for selecting the first card that is received from a card reading device, the terminal determines, based on the instruction, that the first card allows automatic card switching, and activates the first card using the SE system, and after the terminal receives again, using the NFC system, the instruction for selecting the first card from the card reading device, the first card of the terminal executes a transaction service with the card reading device.

Abstract: The technology of this application relates to a content transmission protection method and a related device, to avoid leakage of an audio/video stream when a transmit end and a receive end perform authentication. The method includes, in a process of establishing a transmission link between a transmit end and a receive end, the transmit end performs authentication key exchange with the receive end to obtain an authentication key. The transmit end performs session key agreement with the receive end based on the authentication key to obtain a session key. The transmit end performs authorization control on the receive end after establishment of the transmission link between the transmit end and the receive end is completed. The transmit end sends an encrypted audio/video stream to the receive end after the transmit end completes authorization control on the receive end. The encrypted audio/video stream is encrypted based on the session key.