Hi Marcelo and Sean,
Comments inline.
On Thu, 18 Dec 2008, marcelo bagnulo braun wrote:
Sean Shen escribió:
[...]
I don't think the it's proper to impose all nodes must be able to validate
RSA signature. Especially when we are looking for general agility
solutions,
we should not consider one particular algorithm different from others.
but the fact is that rsa is different cause it is alreadys pecified, and the
cga have by default an rsa key and so on
I agree with Sean. RSA as already been specified, but at least, if we want
to include a support for RSA, it must be a "SHOULD" rather than a
"MUST".
Besides, to impose rsa validation is too strong, for the nodes which only
want ECC for key size and speed reasons, this requirement is not proper.
but you mentioned that RSA validation is cheaper than rsa signing, so maybe
these light weigth nodes can do rsa valdiation...
My point is unless we properly scope the types of nodes we want to support
and what are the requirements, we are arguing in the abstract. I guess
niether you nor me can have an auhtoritative voice on this... maybe we should
ask some people more involved on these light weight devices to figure out
what are reasonable assumptions to make.
Concerning this point, an intern in our lab wrote a report on CGA/SEND
performances using ECC/ECDSA (not only that, but this is was is
concerning us here).
You can download it at:
http://www-lor.int-evry.fr/%7Emaknavic/Rapports_Recherche/RR-Boudguiga-CGA-Performance.zip
Interesting part are in Chapter 5, especially when comparing CGA
signature generation/verification time between RSA and ECDSA and also in
lightweight nodes (a Nokia Tablet PC).
It may help have a more realistic comparison between RSA and ECDSA.
right, i am not arguing with that
I am just saying that there are 3 levels of power and CPU and memory
consuption
The lowest level if ECC only
The intermediate level is ECC and RSA validation
The highest level is ECC and RSA validation plus RSA signing (wihc requires
having a RSA key pair)
I guess the point is whehter the intermediate level is good enough or we need
to aim for the lowest level
Maybe it sounds stupid, but maybe we should allow the 3 levels at once
in the spec. Each administrator will then choose the more suited
solution. To me (from a practical standpoint), we can have the 3 levels
without increasing complexity.
Regards,
Tony_______________________________________________
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