draft-hip-base states today as follows:
Responder's HIT Hash Algorithm (RHASH): hash algorithm used for
various hash calculations in this document. The algorithm is the
same as is used to generate the Responder's HIT. RHASH can be
determined by inspecting the Prefix of the ORCHID (HIT). The
Prefix value has a one-to-one mapping to a hash function.
RFC 4843 states, on the other hand, as follows:
Hash_function : The one-way hash function (i.e., hash function with
pre-image resistance and second pre-image
resistance) to be used according to the document
defining the context usage identified by the
Context ID. For example, the current version of
the HIP specification defines SHA1 [RFC 3174] as
the hash function to be used to generate ORCHIDs
used in the HIP protocol [HIP-BASE].
That is, in RFC 4843 RHASH is identified by the Context ID, which is,
in turn, defined in hip-base.
So, the definition of RHASH needs to be updated as follows:
Responder's HIT Hash Algorithm (RHASH): hash algorithm used for
various hash calculations in this document. The algorithm is the
same as is used to generate the Responder's HIT. RHASH is
defined by the Orchid Context ID. For HIP, the present RHASH
algorithm is defined in Section 3.2. A future version of HIP
may define a new RHASH algorithm by defining a new Context ID.
I don't know what is the right process for this, now that the doc is
past IESG.
--Pekka Nikander