Re: combining SA proposals in IKE [was: Some questions]

[Stephen Kent <kent@bbn.com>]

Lewis,

Well, we do try to provide IP layer data origin authentication, as this
info is important to higher layer protocols.  The inbound SAD checks
against the selectors used for the SA are part of this, to prevent an
authorized sender from relabeling traffic as being from a different sender.
So, I think we do need to prevent looping attacks even for transport mode
ESP.  Using different keys for each direction does this pretty well.
Perhaps we ought to tighten the KEYMAT specs to fix this potential problem.

>Transport-mode ESP-with-auth is only designed to protect upper protocol layer
>info, not IP layer info (uh, with the possible exception of some IPv6
>destination options). So it's not trying to provide IP-layer data origin
>authentication.
>
>Just using ESP without an auth algorithm is asking for this type of trouble,
>as noted in the ESP document.

Steve

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References:

• Re: combining SA proposals in IKE [was: Some questions]
• From: FUKUMOTO Atsushi <fukumoto@isl.rdc.toshiba.co.jp>
• Re: combining SA proposals in IKE [was: Some questions]
• From: Lewis McCarthy <lmccarth@cs.umass.edu>

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