iSCSI: IKE groups and DH-CHAP

[Black_David@emc.com]

> I proposed earlier that the ability to specify N and g should be
> deleted and replaced by an enumerated list of specific standardized
> groups, exactly as IKE does it.  There has been no feedback on that
> except for Tom Wu's comment that g=2 is not an appropriate choice for
> SRP (unlike IKE).  So that means the IKE groups are not directly
> useable because we would have to replace g=2 by g=<a generator> for
> SRP.

I also like the enumerated list of groups approach, for many of
the reasons Paul and Jim have pointed out. 

> I don't know if the objection to g=2 is applicable to DH-CHAP;
> unfortunately, that question goes well beyond my crypto skills but
> there are others on this list who do have the ability to answer that
> question.

I don't believe so, because DH-CHAP is only doing an unadorned
unauthenticated DH exchange.  I'm also not a crypto expert, but
one possible cause for SRP's stronger requirement is that
it's using significantly larger exponents than a DH exchange would.
Perhaps Tom Wu can explain ...

Thanks,
--David