Focus on analysis: In e-commerce transactions, SET protocol is mainly to solve the problem of secure network payment of bank cards. In the payment request stage, dual digital signature technology can ensure that merchants can see the buyer's shopping information, but can't see the buyer's account information. Buyers generate ordering information and payment information after purchasing items on e-commerce websites. The buyer uses the hash algorithm to generate the digital digest of the order information and the digital digest of the payment information, and then connects the digital digest of the order information and the digital digest of the payment information, and then uses the hash algorithm to generate the double digital digest. The buyer encrypts the double digital digest with his own private key to generate a double digital signature, which is then sent to the merchant together with the order information digest and the payment information digest. After receiving the information, the merchant decrypts the received double-digit signature with the public key of the buyer, generates a new order information digest with the same hash algorithm, and generates a new double-digit digest from the new order information digest and payment information digest, which is compared with the double-digit digest sent by the buyer to ensure the integrity and authenticity of the information.