• HIP user's manual: wiki.
• HIP APIs: Doxygen
• shim6 user's manual: pdf html

The below RFC explains the architectural thinking behind HIP, circa 2003.

• Host Identity Protocol Architecture

Currently, the main drafts to implement HIP are the following:

• Host Identity Protocol
• Using the ESP Transport Format with HIP
• End-Host Mobility and Multihoming with HIP

Follow this link to see the current HIP WG drafts.