Abstract: A data encryption and decryption method is provided. The method is used in a data encryption and decryption system and includes: establishing, by a data encryption and decryption device, a first secure sockets layer (SSL) connection with a mobile device; receiving a data transmitted from the mobile device; generating a first symmetric key, encrypting the data using the first symmetric key, and generating first encrypted data; encrypting the first symmetric key using a first public key, and generating a first encrypted key; and transmitting the first encrypted data and the first encrypted key to the mobile device.