Take you a minute to learn about symmetric encryption and asymmetric encryption

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1、 Symmetric encryption

Use the same key for encryption and decryption

There is a key key, Encrypted data name=user password=123456. Use key Yes name and password Encrypt the other party's use key Yes name and password To decrypt Get the decrypted real data .

Features of symmetric encryption ： Symmetric encryption has high encryption strength , Hard to crack .

But in practical application, it faces a very thorny problem ： How to save the key safely ？

2、 Asymmetric encryption

It refers to having a pair of keys ( Public and private keys )： Use the public key to encrypt the data , After encryption, only the private key can be decrypted .

1. long-range Server received Client End user TopGun Login request for ,Server Send your public key to the user .
2.Client Use this public key , Encrypt password .
3.Client Send the encrypted password to Server End .
4. long-range Server Use your own private key , Decrypt login password , Then verify its legitimacy .
5. If the verification result , to Client Corresponding response .
The private key is Server Unique end , That's the guarantee Client Even if the login information of is stolen in the process of network transmission , There is no private key to decrypt , Ensure the security of data , This makes full use of the characteristics of asymmetric encryption .

ssh When connecting, you will use : encryption algorithm , Key exchange algorithm , Integrity check

ssh How to apply the encryption method in ：ssh Both symmetric and asymmetric encryption are used .

Asymmetric encryption is used when authenticating user connections , Symmetric encryption encrypts data when the user starts transmitting data after connecting

What are the encryption algorithms of symmetric encryption ,

AES,DES,3DES
DES yes ⼀ A packet data encryption technology （ First, divide the data into fixed length ⼩ Data blocks , After entering ⾏ encryption ）, Faster , optimum ⽤ On ⼤ Quantity data encryption ,⽽3DES yes ⼀ Species based on DES Encryption algorithm , send ⽤3 Different keys are the same ⼀ Grouped data blocks into ⾏3 Secondary encryption , So as to make the secret ⽂ Stronger ⾼.
Compare with DES and 3DES Algorithm ⽽⾔,AES The algorithm has more ⾼ The speed and resources make ⽤ efficiency , The security level is also higher ⾼ 了 , It is called the next ⼀ Generation encryption standard .

What encryption algorithms are needed for asymmetric encryption

RSA,DSA,ECC
RSA and DSA Safety and other ⽅⾯ The performance is almost the same ,⽽ECC It has a lot of superior performance , Including processing speed , Bandwidth requirements , Storage space and so on .