Re: length of IV in ESP_NULL cipher

[Paul Koning <pkoning@equallogic.com>]

>>>>> "Scott" == Scott Fluhrer <sfluhrer@cisco.com> writes:

 Scott> On Thu, 8 Jan 2004, Tarun Ahuja wrote:

 >> Which essentially means the length of the IV should be 0 but
 >> FreeSWAN uses a length of 4bytes IV (equal to blocksize) for NULL
 >> cipher.

 Scott> Well, either FreeSWAN is broke (at least in this respect) or
 Scott> you are mistaken about the operation of the FreeSWAN code.

Agreed.  I'm pretty sure I had our (Xedia) implementation talking to
FreeSWAN some years ago, so my suspicion is that the implementation is
actually correct.

Are you looking at the packet length when you made this observation?
Remember that ESP_NULL DOES require padding (to multiples of four)
because that's the minimum requirement in ESP independent of cipher.
I think I have seen implementations (at least back in 1999 or so) that
got this wrong.

    paul