PGP works based on numerical encryption using public and private keys. For example, when User A wants to send an encrypted email to User B, the later generates a pair of public and private keys. The private key is kept secret and the public key should be shared with User A.

User A encrypts the email using the public key of User B and digitally signs the email using the former's private key and sends the email. To decrypt the email, User B needs to use the private key associated with the public key used to encrypt the email. Learn more