Methods and devices for data encrypting and decrypting and communication system

The invention discloses methods and devices for data encrypting and decrypting and a communication system. The method for data encrypting comprises the following steps: segmenting data into segment data comprising at least two segments; encrypting the segment data in parallel to obtain the ciphertext of the segment data; adopting a linear algorithm to calculate all the segment data in parallel toobtain a message authentication code; and obtaining encrypted data according to the ciphertext and the message authentication code. The method for data decrypting comprises the following steps: segmenting data to be verified to obtain ciphertext segments and a message authentication code; decrypting all segment ciphertext to obtain decipher text and decipher text segments; adopting the linear algorithm to calculate all the decipher text in parallel to obtain a check code; and judging whether the data to be verified is right or not according to the check code and the message authentication code.