Digital signature scheme has three components. A complete digital signature scheme consists of three parts: key generation algorithm, signature algorithm and verification algorithm. Key generation algorithm: according to the system parameters, a public key and a private key are generated for the signer for encryption and decryption. Signature algorithm: an algorithm for generating a digital signature. Generally, the private key of the signature subject is used to calculate the data digest and generate a digital signature. The verification algorithm is an algorithm that checks whether the digital signature is valid (that is, whether it was generated by a designated entity), and verifies the digital signature based on the public key.