Encryption technology is an active information security precautionary measure, the principle of which is to utilize certain encryption algorithms to convert plaintext into meaningless ciphertext, preventing illegal users from understanding the original data, thus ensuring the confidentiality of the data. The process of changing plaintext into ciphertext is called encryption, and the process of restoring ciphertext to plaintext is called decryption, and the rules of encryption and decryption are called cryptographic algorithms. In the process of encryption and decryption, the variable parameters of encryption and decryption used by the encryptor and decryptor are called keys.

Currently, the two types of encryption techniques that have gained widespread use are the symmetric key encryption regime and the asymmetric key encryption regime. The main difference between them is whether the cipher used for encryption and decryption is the same.

1. Symmetric key encryption system

Symmetric key encryption, also known as private key encryption, that is, the sender and receiver of the message with a key to encrypt and decrypt data. Its biggest advantage is that it is fast in encryption/decryption and suitable for encrypting large amounts of data, but key management is difficult.

Using symmetric encryption will simplify the processing of encryption; instead of having to research and exchange encryption algorithms for specialized devices with each other, each participant will use the same encryption algorithms and exchange only ****-enjoyed specialized keys. If the communicating parties can ensure that the private key has not been compromised during the key exchange phase, confidentiality and message integrity can be achieved by encrypting the confidential information using symmetric encryption and by sending a message digest or message hash along with the message.

2. Asymmetric key encryption system

Asymmetric key encryption system, also known as public key encryption. It requires the use of a pair of keys to complete the encryption and decryption operations respectively, one publicly released, i.e., the public key, and the other secretly kept by the user himself, i.e., the private key. The sender of the message uses the public key to encrypt and the receiver of the message uses the private key to decrypt. The public key mechanism is flexible, but encryption and decryption are much slower than symmetric key encryption.

In an asymmetric encryption system, the key is broken into a pair. Either of these keys can be disclosed to others in an unclassified manner as a public key (encryption key), while the other is kept as a private key (decryption key). The private key can only be held by the trading party that generated the key pair, and the public key can be widely distributed.

The program realizes the process of information exchange: trade party A generates a pair of keys and discloses one of them as a public key to other trade parties; trade party B, who gets the public key, encrypts the information with the key and sends it to trade party A; trade party A decrypts the encrypted information with the other private key that it keeps.