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bluesky - Re: The Grapevine Project

bluesky AT lists.ibiblio.org

Subject: Global-Scale Distributed Storage Systems

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  • From: steve jenson <stevej AT sieve.net>
  • To: Global-Scale Distributed Storage Systems <bluesky AT franklin.oit.unc.edu>
  • Subject: Re: The Grapevine Project
  • Date: Wed, 05 Dec 2001 17:43:56 -0800


Stephen Blackheath wrote:
>

On Thu, 06 Dec 2001 13:00, you wrote:

Stephen Blackheath wrote:

We use a 'hash cash' technique
(which we call "Solve A Hard Problem") for defence against
denial-of-service attacks - the assumption being that legitimate nodes
have more CPU power than attackers.

that seems like a silly assumption. What about DDoS?


Firstly, understand that when I say "legitimate nodes have more CPU power", I am referring to the sum of all legitimate nodes vs. the sum of all attackers.


So it's not so much an assumption as a constraint? I'm not trying to be nitpicky but to clear up ambiguity. Speaking of constraints, I'm unable
to find a clear, concise Threat Model established in your literature.


Ultimately, if an attacker has more of something than you do, then the attacker will win. The only thing you have control over as designer is what that something is. We chose CPU time rather than network bandwidth or access to IP addresses, because none of the strategies relating to the latter things seemed to work. I am certainly open to better ideas.


This isn't necessarily true, have you read Ross Anderson's excellent
work 'Security Engineering' (ISBN 0471389226)? He outlays possible
strategies to protect agains *DoS, one of which is late binding of
names.


DDoS - if you're talking about it as an attack from nodes outside the network - - is difficult against the Grapevine due to the high cost of 'harvesting' IP addresses.


No, I'm talking about malicious nodes from within your network working in tandem.

cheers,

steve





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