Symmetric encryption and asymmetric encryption

Asymmetric encryption

In 1976, US scholars dime and Henman proposed a new key exchange protocol to solve the problems of public information transfer and key management, allowing communication Parties to exchange information on insecure media, securely reach an agreement on the key, which is the "public key system ". Symmetric encryptionAlgorithmThis method is also called an asymmetric encryption algorithm ".

Unlike symmetric encryption algorithms, asymmetric encryption algorithms require two keys: public key and private key ). A public key is a pair of private keys. If a public key is used to encrypt data, only the corresponding private key can be used for decryption. If a private key is used to encrypt data, only the corresponding public key can be decrypted. Because encryption and decryption use two different keys, this algorithm is called asymmetric encryption algorithm.

The basic process for asymmetric encryption algorithms to exchange confidential information is: Party A generates a pair of keys and discloses one of them as a public key to other Parties; if Party B obtains the public key, it encrypts the confidential information and sends it to Party A. Party A decrypts the encrypted information with another private key. Party A can only use its private key to decrypt any Information encrypted by its public key.

Asymmetric encryption algorithms have good confidentiality and eliminate the need for end users to exchange keys. However, encryption and decryption take a long time and are slow, it is not suitable for encrypting files, but only for encrypting a small amount of data.

The security of classic asymmetric encryption algorithms, such as RSA, is quite high.

Public Key and Private Key

The private key is half the secret of the key pair used together with the public key algorithm, while the Public Key is half of the non-secret.
1. The public key and private key appear in pairs.

2. Public Keys are called public keys. Only private keys that you know are called public keys.

3. Only the corresponding private key can decrypt the data encrypted with the public key.

4. Only the corresponding public key can decrypt the data encrypted with the private key.

5. If the public key can be used for decryption, it must be the secret of the corresponding private key.

6. If you can use the private key for decryption, it must be the secret of the corresponding public key.

 

Symmetric encryption

You need to use the same key encryption algorithm for encryption and decryption.Due to its speed, symmetric encryption is usually used when the message sender needs to encrypt a large amount of data.. Symmetric encryption is also called key encryption.