Encryption is a method of protecting data by translating it into a secret code. Encrypted data is sometimes referred to as cypher text as opposed to unencrypted plaint text. To read an encrypted document, one must have either a key or password to decrypt it. There are two general categories of encrypted data: symmetrical and asymmetrical.

Asymmetrical Encryption is also called public-key encryption. This system uses a public key and a private key to encrypt data. The intended recipient of an encrypted message can provide his or her public key to the individual sending the message. The sender then uses the public key to encrypt the message. The private key is held only by the intended recipient. In essence, the public key is used to lock the data and the private key is used to unlock the data. It is impossible to decrypt the data without the private key. Pretty Good Privacy (PGP) is a widely used encryption tool in the United States.

Like asymmetrical encryption, Symmetrical Encryption uses keys to encrypt and decrypt messages. However, rather than using two separate keys, the same key is used to encrypt and decypher the message.