In 1991 the American Phil Zimmerman decided to set up this system for enhancing the safety of digital communication, especially emails. He could this system Pretty Good Privacy (PGP). In 1991 besloot de Amerikaan Phil Zimmerman om dit systeem in te zetten voor de beveiliging van digitale communicatie, met name e-mails. Hij noemde zijn systeem Pretty Good Privacy (PGP).

PGP combines traditional encryption with asymmetrical cryptography, in order to make messages unreadable. With a password-or rather a passphrase- a larger code which you can keep a secret and which is impossible to decipher, you create a public and private key which is linked to your email-address.

You spread this public key, so that people know how to encrypt messages for you specifically. The private key should be stored as safely as possible. If you want to be thorough, you could encrypt it again, put it on a USB-stick and keep it in a safe.

When someone sends you a PGP email, you should re-enter the passphrase which guards your private key. This private key ensures your message becomes readable. You can also use PGP to encrypt messages and to send them to others, but usually this system is employed to protect emails.

PGP can also work the other way around: you can supply a digital signature to a message. You use the private key to add encrypted text to a message. With your public key the recipient can read your message and check that it was indeed you who sent it.