Using this method, a message originator uses a private key to encrypt a message. Anyone who has the sender's public key, which is widely distributed, can decrypt the message. The receiver knows that the message really did originate from the sender because the public key only decrypts messages that were encrypted by the private key held by the sender. Thus, private key encryption solves the authentication problem because a recipient can be assured that a message is really from the person it says it's from. Public-key systems can also solve the privacy problem.
Someone sending a message can use the recipient's known public key to encode the message.
Since the private key is the only way to decrypt a message encoded with the public key, the sender is assured that nobody but the intended recipient can read the message. Finally, public-key systems solve the problem of reliability because a message sender can include information inside the encrypted message that allows the recipient to determine whether or not the message has been tampered with. Therefore, public-key cryptography allows messages that are authenticated, private, and reliable. RSA is also the name of the company founded by the RSA inventors, a company which provides cryptographic solutions to industry. Netscape Communications, for instance, uses RSA public-key cryptography in the Netsite Commerce Server to provide authentication, privacy, and message integrity.