Another type of cryptosystem uses different keys for encryption and decryption, and is referred to as asymmetric encryption. One example is public key cryptosystems, which use two keys, one of which is public and the other private. The encryption algorithm may also be public, so that anyone wishing to send a user a message can use the user’s publicly known key in conjunction with the algorithm to encrypt it. Only the owner of the private key can then decipher the message. Public key cryptosystems can also be used to send a ‘digital signature’ with a message and prove that the message came from the person who claimed to have sent it. The most well known asymmetric encryption is RSA (the name is derived from the initials of the three designers of the algorithm).