Re: [perpass] NULL Cipher RFC 2410 to HISTORIC ???

["Moriarty, Kathleen" <[e-mail]>]

AH was intended to preserve integrity, so Michael's argument makes perfect sense.  If you are going to use AH, you want to ensure integrity from end-to-end.

Use cases for this are valid, but I just don't think there was much interest for actual deployment.  I only came across it once and agreed with the usage, but people (operators) in general were not interested.  Data corruption was the motivator in the one use case I worked on, but you could check a hash on the received data to accomplish that anyway.  I think the views were different from research/protocol design to operators in this case.

NAT may be part of it, but if no one is interested to use it...

Best regards,
Kathleen

-----Original Message-----
From: perpass [mailto:[e-mail]] On Behalf Of Michael Richardson
Sent: Monday, December 09, 2013 10:47 AM
To: Phillip Hallam-Baker
Cc: perpass; Yoav Nir; Merike Kaeo
Subject: Re: [perpass] NULL Cipher RFC 2410 to HISTORIC ???


Phillip Hallam-Baker <[e-mail]> wrote:
    >     Phil,

    >     The issue is not that ESP needs a NULL cipher. It's that AH
    > wouldn't traverse NAT, and so they needed ESP to do the work that AH
    > was designed to do.


    > I understand that, though the fact that ESP with authentication would
    > work through NAT but not AH seems remarkably odd to me. It suggests
    > that the design is wrong.

    > That flags a design error in the protocol AFIAK. 

No, it's because NAT is an attack by a middle box on end to end flow, and back in 1994, we didn't think anyone would be so stupid as to do that kind of thing.



--
Michael Richardson <[e-mail]>, Sandelman Software Works