Re: draft-ietf-ipsec-ciph-aes-ctr-00.txt

[Michael Richardson <mcr@sandelman.ottawa.on.ca>]

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>>>>> "Waterhouse" == Waterhouse, Richard <Richard.Waterhouse@GDC4S.Com> writes:
    Waterhouse> There is another application area that can benefit from CTR
    Waterhouse> mode. CTR doesn't do error extension. If you are working in a
    Waterhouse> noisy environment, have an application that can tolerate
    Waterhouse> errors (but still don't want a bit error to multiply), need
    Waterhouse> confidentiality but can do without authentication (e.g., you

  I understand what you are saying, and it would apply to things like link
encryption, where one uses a continuous CTR mode. I do not believe that it
applies to packet oriented networks. Packets are either accepted in their
entirety, or discarded (and retransmitted). 

  While it might be that some media applications are such that a corrupted,
un-authenticatable packet is better than no packet at all, such applications
would also, by extension, be vulnerable to introduction of bogus packets,
and general denial of service on them. 
  I would suggest that such a security model is outside the scope of the
current ESP transform - i.e. we are talking about more than just swapping 
3DES for AES-CTR in the cipher table.

]       ON HUMILITY: to err is human. To moo, bovine.           |  firewalls  [
]   Michael Richardson, Sandelman Software Works, Ottawa, ON    |net architect[
] mcr@sandelman.ottawa.on.ca http://www.sandelman.ottawa.on.ca/ |device driver[
] panic("Just another Debian GNU/Linux using, kernel hacking, security guy"); [

  
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