Digital signature technology is a combination of public key encryption technology and message decomposition function Different from encryption, the purpose of digital signature is to ensure the integrity and authenticity of information.

Digital signature must guarantee the following three points:

(1) The receiver can verify the sender's signature on the message.

(2) The sender cannot deny the signature of the message afterwards.

(3) The receiver cannot forge the signature of the message.

Now widely used digital signature technologies based on public key cryptosystem mainly include:

(1)RSA system, which is based on the difficulty of solving the problem of decomposing a large integer into two large prime numbers.

(2) For E1Gamal system, it is difficult to solve the discrete logarithm problem based on multiplication groups over finite fields.