Abstract: A subscribing user generates a private key and a corresponding public key stored locally in a “key-ring.” The public key is uploaded to a key repository on a communications server, where public keys of subscribers are maintained. When sending a secure message, the sender's key-ring is checked to determine whether the public key for the recipient is present. If yes, then the public key is used to encrypt the message. If no, then a lookup request is sent to the server to determine whether a public key is available for the recipient. If there is, then the public key is downloaded from the repository to the sender. When the recipient receives the secure message, the recipient's private key is used to decrypt the message. The sender's most recent public key also is transmitted with the message and stored in the recipient's key-ring for future messages sent back to the key owner. Automated key management features are included.