The most basic symmetric encryption: key encryption

Encryption by key and decryption by key.

Asymmetric encryption

If another person in the middle pretends to be A and sends files to B through B’s public key encryption, how will B know that he has been cheated?

A digital signature

The CA certificate

CA is short for Certificate Authority, also known as Certificate Authority. It is a third-party organization responsible for managing and issuing certificates. Its role is to check the validity of the identity of the certificate holder and issue certificates to prevent the certificates from being forged or tampered with.

Symmetric Encryption Algorithm Data Encryption Standard (DES) : the symmetric algorithm is a Data Encryption Standard with high speed and is suitable for encrypting a large amount of Data. Triple DES (3DES) is a symmetric algorithm based on DES. RC2 and RC4 are symmetric algorithms. They encrypt a large amount of data with variable length keys and are faster than DES. Advanced Encryption Standard (AES) Asymmetric algorithm RSA: invented by RSA, it is a public key algorithm that supports variable length keys. The length of the file block to be encrypted is also variable