Subject: Re: OpenSSH key size
To: Michael Richardson <>
From: Ted Unangst <>
List: tech-security
Date: 09/15/2005 22:01:21
On Thu, 15 Sep 2005, Michael Richardson wrote:

> John Gilmore suggested that 2048 is the wrong number. One should add
> ~100 to that number.  
> The concept being, if someone builds a machine that can crack 2048-bit
> numbers, it won't be able to do 2049-ones. A machine that can do 2049
> may well be able to 4096. So, you get the brute-force resistance of 4096
> (in terms of $$$ to build) without the cost. 
> This is not a technical argument -- it is an economic one.

hopefully there is some sort of technical argument to support this 
"factoring machines only come in powers of two" idea?  without any more 
detail, it kinda sounds like "256 bit keys are twice as hard to crack as 
128 bit keys".

And that's why I won't have sex with you.