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

[Stephen Kent <[e-mail]>]

Merike,
> And so I reply to myself but got curious and wanted evidence.  I found 
> first references of AH/ESP and NULL in 1996 June IPsec archives. 
> http://www.sandelman.ottawa.on.ca/ipsec/1996/06/msg00030.html
>
> And while  some interesting tidbits, the joggle for my memory banks 
> was that there was a bunch of discussion on where AH would be used 
> with ESP and whether ESP only would also be relevant.  And while I 
> couldn't find exact reference to the March 1998 interop testing in 
> North Carolina that showed issues with AH not traversing NATs I am 
> fairly certain that was the case and why in practice people starting 
> using ESP-Null.  (it wasn't in the notes for the follow-up IETF IPsec 
> meeting).
>
> Someone else from that time may also be able to chime in.
>
The very first IPsec designs called for use of AH plus ESP to offer 
authentication, integrity and confidentiality. That dual protocol use 
was a significant burden, so
ESP was extended to offer all three services, and AH remained as an 
auth/integ but no confid alternative, for various reasons.  (One reason, 
as you noted, was export controls on encryption.) Later we revised ESP 
to incorporate NULL encryption for the reasons I cited earlier; I forgot 
about the NAT problem.

Steve