Host Identity Protocol Architecture

This memo describes the Host Identity (HI) namespace, that provides a cryptographic namespace to applications, and the associated protocol layer, the Host Identity Protocol, located between the internetworking and transport layers, that supports end-host mobility, multihoming and NAT traversal. Herein are presented the basics of the current namespaces, their strengths and weaknesses, and how a HI namespace will add completeness to them. The roles of the HI namespace in the protocols are defined. This document obsoletes RFC 4423 and addresses the concerns raised by the IESG, particularly that of crypto agility. The section on security considerations describe also measures against flooding attacks, usage of identities in access control lists, weaker types of identifiers and trust on first use. This document incorporates lessons learned from the implementations of RFC 5201 and goes further to explain how HIP works as a secure signaling channel.