The intended receiver of the message would hold a second key called the PRIVATE KEY, with which the message could be decrypted. Thus, the receiver could freely transmit the public key to the sender without worrying about it being intercepted by anyone else. The sender could then use the public key to encrypt a message and transmit it to the receiver, who would be the only person holding the private key and thus, it is hoped, the only person able to decrypt the message.