This application provides a data encryption method, a data decryption method, a secure data backup method, a secure data restoration method, and an electronic device. Different types of data packets in the card data are separately encrypted by using a secure element SE and a trusted execution environment TEE. In the encryption process, a user and a third-party card data provider are introduced, and are separately responsible for generation, storage, and delivery of one of key factors. Then, a real backup key is generated with reference to a key factor provided by a mobile phone party. After being encrypted in the SE and the TEE by using the backup key, the card data is uploaded to a cloud server for backup. The application can ensures data backup security in the SE and the TEE.