Encrypt / decrypt public / private key

One ： encryption / Decrypt

encryption ： The process of converting plaintext into ciphertext
Decrypt ： The process of converting ciphertext into plaintext

Two ： Secret key

The essence of a secret key is a string , Its unit of measurement is bit( position ), According to the way the secret key is used , Encryption can be divided into two categories , Symmetric and asymmetric encryption , Symmetric encryption means that both encryption and decryption use the same secret key , At present, the most popular symmetric encryption algorithm is AES encryption algorithm , The length of the secret key is 128、192 or 256, High security , Good performance .

• Encrypted packet mode ： Encrypt plaintext groups , Used in wechat payment AEAD_AES_256_GCM Group encryption .

Asymmetric encryption means that only the private key can be used for decryption after public key encryption , In turn, , After the private key is encrypted, it can only be decrypted with the public key , among RSA Encryption algorithm is the most famous asymmetric encryption algorithm .
for instance ： If Tom、Jerry To a friend zhangsan Send a message ,zhangsan You can distribute your public key to Tom and Jerry, such Tom and Jerry You can use this public key to encrypt , At this time, only those who have the private key zhangsan Can decrypt the message , Ensure the confidentiality of the message . Conversely, suppose zhangsan Encrypt with the private key ,Tom And Jerry After receiving the message, use zhangsan Decrypt the distributed public key , Successful decryption indicates that the message is zhangsan Sent .

3、 ... and ： Symmetric encryption VS Asymmetric encryption

Symmetric encryption ：
advantage ; It's fast
shortcoming ： The secret key needs to be shared by both sides of the information exchange , Once stolen , The message will be cracked

Asymmetric encryption ：
advantage ： Private key is strictly confidential , Public key arbitrary distribution , Hackers can't crack the ciphertext after obtaining the public key
shortcoming ： It's very slow

Four ：HTTPS Encrypted transmission process

stay HTTPS In transit , Both transmission speed and transmission security shall be ensured , At this time, the server public key can be transmitted asymmetrically , After the server obtains the encrypted session master secret key , Then decrypt the server private key to obtain the session master key , Then use symmetric encryption for data transmission to ensure transmission efficiency .