Using a combination of public key encryption and private key encryption to ensure data confidentiality. In the SET protocol, the confidentiality of payment environment information is encrypted through an algorithm that combines public key encryption and private key encryption. Obtained from payment information. The public key encryption algorithm it uses is the RSA public key cryptography system, and the private key encryption algorithm uses the DES data encryption standard. The combination of these two different encryption technologies is visualized as a digital envelope in SET. RSA encryption is equivalent to sealing it with an envelope. The message is first encrypted with a 56-bit DES key and then loaded with a number encrypted using a 1024-bit RSA public key. Envelopes are transmitted between the parties to the transaction. The combination of these two keys ensures the confidentiality of data information in transactions.

1. Use information digest technology to ensure the integrity of information

The SET protocol uses a digital signature scheme to ensure the integrity of the message and authenticate the message source. The digital signature scheme uses The same encryption principles are used for message encryption. That is, the digital signature is combined with the RSA encryption algorithm to generate an information digest. The information digest is the only value corresponding to the message obtained after the message is processed by the HASH function. Every change of one data bit in the message will cause about half of the data bits in the information digest to change. . The possibility that two different messages have the same information digest is extremely small, so the one-way nature of the HASH function makes it infeasible to calculate the summary of the information from the information summary. These characteristics of information summaries ensure the integrity of the information.

2. Use dual signature technology to ensure the identity authentication of both parties to the transaction

The SET protocol applies dual signatures (Dual Signatures) technology. In a secure e-commerce transaction, the cardholder's order information and payment instructions correspond to each other. The merchant can only deliver goods according to the order information after confirming the order information corresponding to the cardholder's payment instruction; and the bank can only deliver goods according to the merchant's requirements after confirming that the order information corresponding to the cardholder's payment instruction is true and reliable. Make payment. In order to achieve the goal of merchants legally verifying the cardholder's payment instructions and banks legally verifying the cardholder's ordering information without infringing on the customer's privacy, the SET protocol uses double signature technology to ensure that the customer's privacy is not violated.