PGP allows you to encrypt and decrypt messages, digitally sign them, verify the identity of the sender (if also uses PGP) and manage keys.

PGP works by cipher does not use one, but two different keys. The first is used to encrypt and its output is the encrypted message. You can read (decrypted) message only with the second key. This process is called asymmetric cipher. Asymmetric cipher, has over traditional ciphers (symmetric) using the same key for encryption and decryption, one big advantage. Your encryption (public) key can be placed on the public, but trusted site (eg personal web site or key server) where everyone can copy it and encrypt it the classified message. Message can then feel free to send and will be sure that it can be read only recipient, respectively holder of the private (decrypting) key.

In addition to encrypt messages, PGP solves the problems of their authenticity. The principle is similar to that of the encryption. The sender attached to the message special addendum, which generates the one-way text messages using any of hash functions. This addendum called "message digest", encrypted with your private key to form an electronic signature. The recipient obtains the sender's public key, decrypts the attached signature and compares it to how it should look in its calculation. If both results agree, the message can be regarded as proven.