Re: [Hipsec] clarification on HIT Suite IDs

[Francis Dupont <[e-mail]>]

Tom Henderson writes:
>        For the time being, the HIT Suite uses only four bits because
>        these bits have to be carried in the HIT.  Using more bits for the
>        HIT Suite ID reduces the cryptographic strength of the HIT.

=> yes, there is a long discussion in RFC 7343 about this tradeoff.

> which implied to me that the HIT suite ID may in the future consume more 
> bits presently allocated to hash.

=> the fact the problem could exist doesn't mean it will exist...

> > So there is nothing very clear about what will happen if one will need
> > more than 15 HIT Suite-IDs... BTW according to appendix E I should add
> > "at the same time" (appendix E proposes to reuse values, making unlikely
> > to really need more than 15 values).
> 
> I'm not sure where you are proposing to add the clause; can you point 
> out the sentence?

=> one will need more than 15 HIT Suite-IDs ->
one will need more than 15 HIT Suite-IDs at the same time

> > => no, the current choice makes more sense with the HIT Suite-IDs
> > from OGAs. But it is a matter of taste for sure...
> 
> Perhaps we could start by trying to resolve whether the plan should be 
> to reuse four-bit values if the space is eventually exceeded, or whether 
> the HIT suite ID may grow in the future (and how that affects the 
> ORCHID).

=> clearly the current plan is the first (reuse 4 bit values).
The second is just a provision in the case the first fails.

> Maybe we do not need to specify the plan in this draft; maybe 
> we could just avoid the problem for now and just keep value 0 reserved 
> and state that what to do when the HIT_SUITE_ID space is exhausted is 
> for further study, with deprecated value reuse and expansion of the HIT 
> Suite ID being two possibilities.

=> perhaps it was considered as too optimistic? BTW I have no idea
about the future need in new values in the HIT_SUITE_ID / OGA space
(but does somebody already have one?)

> Another basic question I have is whether the table 11 in Appendix E 
> should be merged with the unlabeled table at the end of 5.2.10 (and 
> located in 5.2.10), and whether Appendix E text in general ought to be 
> brought forward in the draft to section 3.2 and/or 5.2.10.

=> it is a question for the hipsec mailing list (I subscribed to it
but from my personal e-mail).

Regards

Francis Dupont <[e-mail]>