Re: Bruce Schneier on IPsec

[Stephen Kent <kent@xxxxxxx>]

Paul,

Yes, ESP w/o authentication is susceptible to certain forms of active 
attacks that can result in a breach of confidentiality, under certain 
circumstances. I think the easiest way to characterize such 
circumstances is that muxing multiple user data streams over a single 
SA provides the opportunity for such attacks.  Since IPsec allows for 
fine grained SAs, it is possible to avoid such attacks and thus there 
are safe ways of using this option as well.  The text of 2401 alludes 
to such concerns already.  A stronger and more precise set of 
warnings could be added if necessary.

Steve