Short message encryption and decryption communication system and communication method thereof

The invention discloses a short message encryption and decryption communication system which comprises a private key generator, a sending terminal and a receiving terminal, wherein the private key generator is used for generating system parameters and a primary key; the sending terminal is connected with the private key generator and communicated with the receiving terminal; the receiving terminal is connected with the private key generator and communicated with the sending terminal; the private key generator is used for generating private keys of the sending terminal and the receiving terminal; the private keys are obtained by the sending terminal and the receiving terminal from the private key generator; a symmetric key is shared by the sending terminal and the receiving terminal; a short message is encrypted or decrypted by the sending terminal and the receiving terminal in accordance with the symmetric key; and additionally, the symmetric key is updated. According to the short message encryption and decryption communication system, while encryption short messages are sent, the key is updated, and all of the short messages are encrypted by using different keys, so that the effect of one-time encryption is achieved, and the safety of short message interaction is guaranteed. The invention further discloses a communication method of the short message encryption and decryption communication system.