Simply put, encryption is a method of sending information by password. Only the person with the correct key can unlock the password of this information. To others, this information looks like a series of random letters, numbers and symbols. Encryption is especially important if you want to send sensitive information that should not be seen by others. Because e-mail is sent on the Internet, it may be intercepted by attackers, so it is very important to add an extra layer of protection for sensitive information. Like digital signature, public key encryption uses PGP and other software, uses mathematical algorithms to transform information, and relies on public keys and private keys. However, there are differences between encryption and digital signature. The purpose of encryption is to secretly hide content by converting information into passwords. The purpose of digital signature is completeness and identification, verifying the sender of the message and indicating that the content has not been modified. Although encryption and digital signature can be used separately, you can also use digital signature for encrypted information. When you sign a message, you use your private key, and anyone can verify that the signature is legal with your public key. When you encrypt a message, you use this public key for the person who receives your message and use his or her private key to decode the message. In order to keep people's private keys secret and protect them with passwords, the recipient of this information should be the only one who can view it. 1. Get the public key of the person you want him to read this information. If you get this key from an open key ring, you can contact that person directly and use this key to verify that a series of related letters and numbers are correct fingerprints. Encrypt this email with their public key. Most e-mail client software has the function of easily completing this task. When this person receives this message, he or she will be able to decrypt it.