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Re: resistance to swamping attacks.

Bill Sommerfeld <sommerfeld@apollo.hp.com> Fri, 20 September 1996 02:47 UTC

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To: Kim Toms <kim@morningstar.com>
Cc: ipsec@TIS.COM
Subject: Re: resistance to swamping attacks.
In-Reply-To: kim's message of Fri, 20 Sep 1996 01:50:35 +0000. <199609200150.BAA18018@picu.morningstar.com>
Date: Thu, 19 Sep 1996 22:52:10 -0400
From: Bill Sommerfeld <sommerfeld@apollo.hp.com>
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> I'm no expert in cryptography, but it seems to me that what is needed is
> a function which is expensive for the originator of a packet to
> calculate, but cheap for the receiver to verify.  This will make sure
> that the source of a swamping attack must have a much larger CPU than
> the receiver.  I don't know if there are any such functions, but perhaps
> the cryptographically sophisticated among us could enlighten?

A simple imbalance in "expense" isn't enough -- what if the attacker
does a lot of precomputation before launching the attack?

					- Bill

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