HIP
also: Host Identity Protocol, HIT (Host Identity Tag)
HIP (Host Identity Protocol) is a network protocol that separates a host's identity from its network location, allowing secure communication that persists even when IP addresses change.
HIP decouples a computer's identity (who it is) from its locator (where it is on the network). Traditional networking ties identity directly to IP addresses, but HIP uses cryptographic host identifiers instead, enabling seamless mobility and improved security.
In HIP, each host has a Host Identity Tag (HIT)—a 128-bit identifier derived from a public key—and uses the traditional IP address purely as a locator. When a host moves networks and gets a new IP, its HIT remains constant, so established connections can survive the address change without disruption.
Example: A laptop with HIP can move from WiFi to mobile data; the HIT stays the same while IP addresses change, and applications using HIP maintain their sessions without reconnecting. HIP also adds authentication and encryption at the network layer by default.
HIP is standardized in RFC 7401 and related RFCs, though it remains less common than traditional IPv4/IPv6, being primarily used in research, military, and specialized mobile environments.