Subject: Re: Security & draft-deering-ipv6-encap-addr-deletion-00.txt

From: Steve Deering <[email-masked]>
Date: Tue, 11 Dec 2001 21:24:04 -0800

At 9:44 AM -0800 12/11/01, Christian Huitema wrote:
>Now, with the compression, we would in many cases be able to "compress"
>the source address, resulting in:
>
><-- outer IPv6 header ->            <-- inner IPv6 packet, encrypted -> 
>+----+--------+--------+------------+----+--------+ +------------ 
>|    |        |        |            |    |        | | 
>|oNAF|  oSRC  |  oDEST | ESP header |iNAF|  iDEST | |  iPAYLOAD 
>|    |        |        |            |    |        | | 
>+----+--------+--------+------------+----+--------+ +------------
>
>The big difference between the two is the iSRC is not protected by the
>encryption, but recomposed after decryption by copying oSRC -- which is
>not protected. This would open an attack avenue for a hacker or, heavens
>forbids, a NAT...

OK, I think I get it.  If you used AH in the outer header to assure
the authenticity of oSRC, you could then safely put it back into the
reconstructed inner header.  But that would add the overhead of an AH
header, which would reduce or eliminate any benefit from the compression.

There may be other zero-extra-overhead solutions, but I need to think
about it some more...

Steve

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From: Francis Dupont <[email-masked]>
Date: Wed, 12 Dec 2001 17:07:29 +0100

In your previous mail you wrote:

=> use AH *and* ESP: the overhead of AH is near the same than the
authentication function in ESP.

[email-masked]