Abstract: A network device for maintaining data security generates different keys corresponding to data received from a sender. The different keys comprise a secret key, a client key, and a server key. The client and server keys form the secret key when combined. The network device encrypts the data with the secret key and discards the secret key in response. The network device generates a Uniform Resource Locator (URL) for requesting the data from the network device. The URL comprises the client key and a randomly-generated data identifier associated with the data. The network device sends the URL to an electronic address of a recipient and discards the client key in response.

Abstract: A system and method for traversing a firewall for a voice-over-IP session or other communication session uses four main components: a relay agent, and NAT 30Agent, a SIP proxy and a application server. The SIP proxy is located in the public network and SIP signaling messages are routed through the SIP proxy. The sever opens ports in the firewall for signaling between the SIP proxy and the relay agent behind the firewall. The application server also opens ports in the firewall for media traffic. The NAT 30Agent disposed in the path from the firewall to the Internet filters media packets and changes the public source address of the media packets to a predetermined address associated with the open media port.