Basic principle of public key

Basic principle of public key encryption technology

The encryption algorithms in modern encryption technology are all public, while the key is private. First of all, we need to encrypt the data with encryption algorithm, and let the receiver decrypt it with the key, so as to realize the safe transmission of the data.

Both encryption and decryption use keys. Without the key, the encrypted file cannot be decrypted, which means that anyone can decrypt it as long as there is a key, so it is meaningless if the key is encrypted by an attacker.

* * * shared key encryption method: The method of encryption and decryption using the same key is called * * * shared key encryption system, also known as symmetric key encryption.

Using symmetric key encryption, the key must also be sent to the other party, otherwise the other party cannot decrypt it. But how can we safely hand over the key to the other party? When spreading on the internet, if the communication is intercepted and the key falls into the hands of the attacker, then encryption will lose its meaning. In addition, there must be a way to safely save the received key. ?

Sending the key risks being eavesdropped, but without sending the key, the other party cannot decrypt it. If the key can be transmitted reliably, why can't the data be transmitted reliably?

Public key encryption: Public key encryption uses two asymmetric keys, one is called private key and the other is called public key.

In the public key encryption method, the sender uses the public key issued by the receiver to encrypt and then sends it to the receiver. After receiving the encrypted information, the receiver uses its own private key to decrypt it. This method does not need to send the key to decrypt, so there is no need to worry about the situation that the key is stolen by the attacker.

In addition, it is extremely difficult to restore information to the original text according to the secret and public keys. With the present technology, it is not realistic.