Data transmission method and system

The invention discloses a data transmission method and system, and the method comprises the steps: a data sender sends an identity authentication request comprising a digital signature and an identity identifier to a data receiver, so that the data receiver carries out the identity authentication of the data sender based on the identity authentication request; the data sender receives the token information and the public key information sent by the data receiver after determining that the identity authentication is passed; the data sender segments the plaintext data to be transmitted and determines a segmented data sequence; the data sender determines first ciphertext data and second ciphertext data based on the segmented data sequence, and sends the token information, the first ciphertext data and the second ciphertext data to the data receiver; and the data receiver determines the segmented data sequence based on the token information, the first ciphertext data, the second ciphertext data and private key in