A method for implementing a simple protocol, referred to as the universal transport interface (UTI), that can be used to create high speed Internet Protocol (IP) tunnels for transmitting a variety of different payloads across a network. Payload packets may comprise any currently known packet protocol, including but not limited to time division multiplex data, IP packets, asynchronous transfer mode (ATM) cells, Packet-over-SONET/SDH (POS) packets, and Frame Relay frames. The universal transport interface protocol consists of a predefined set of mappings whereby any known protocol can be packaged into a single, conceptually simple packet format. This format is referred to as the universal transport encapsulation (UTE) format. UTE format packets are, by design, amenable to transport over an IP network without further modification beyond standard IP encapsulation. The disclosed method further implements a security key system to prevent unauthorized use or interception of UTE packets on the network.