Re: speaking of keys

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

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>>>>> "Stephen" == Stephen Kent <kent@bbn.com> writes:
    Stephen> Also, let's remember that the key size is not the only factor in 
    Stephen> determining the security of these systems.  It's tempting to raise 

  Absolutely.

    Stephen> software implementation on a user WS/laptop where there are lots more 
    Stephen> likely ways that the security of the traffic will be compromised 
    Stephen> (other than solving the discrete log problem for a 1024-bit group) 
    Stephen> and where the performance hit will be most visible and thus may 
    Stephen> eventually motivate an individual to NOT use IPsec at all.

  I think that we can write a MAY for a smaller size (i.e. 1024). 
  The reason to pick something for the MUST is interoperability. That is the
only reason.

    Stephen> I don't have a problem with a MAY for bigger groups, but I really 
    Stephen> think it is most appropriate to focus on the management facility to 
    Stephen> allow user communities to select their own, of whatever size they 
    Stephen> feel is appropriate.

  It has been a long time since anyone has talked about APIs. 

  Bill Sommerfeld has promised to take us (IPSP specifically) down that path
again, and it is high time that we do this. I do not think that applications
writers should have to deal with DH modulus size. I think that we should have
a direct mapping that gives minimum modulus sizes for particular levels of
security.

  I don't have a problem with having a notch in the slider set for "80-bits",
which really implies a 1024-bit modulus with 3DES or 128-bit AES, with
another notch at 128.

  It would be nice if there was another unit we could use other than bits
to expose to the user, but I don't see another one that is CPU-speed
independant (not local CPU speed, but CPU speed size of attacker). 
Herman style:
  "You must be at least $$$-well funded to bother brute forcing this castle".

]       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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