From: Cedric Tefft <CedricT@datastorm.com>
Date: Fri, 5 Jan 1996 06:36:31 +0800
To: Scott Brickner <sjb@universe.digex.net>
Subject: Re: 2047 bit keys in PGP
Message-ID: <30EC6B75@ms-mail.datastorm.com>
MIME-Version: 1.0
Content-Type: text/plain



> From: Scott Brickner
> To: Cedric Tefft
> Subject: Re: 2047 bit keys in PGP
> Date: Thursday, January 04, 1996 3:41PM
>
> Return-Path: <sjb@universe.digex.net>
> Message-Id: <199601042141.QAA15905@universe.digex.net>
> X-Authentication-Warning: universe.digex.net: Host localhost didn't use 
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>     protocol
> To: Cedric Tefft <CedricT@bart.datastorm.com>
> Subject: Re: 2047 bit keys in PGP
> In-Reply-To: (Your message of Thu, 04 Jan 1996 14:12:00 PST.)
>     <30EC5109@ms-mail.datastorm.com>
> Date: Thu, 04 Jan 1996 15:41:51 -0600
> From: Scott Brickner <sjb@universe.digex.net>
> 
 ----------------------------------------------------------------------------  
 --
> Cedric Tefft writes:
> > If his algorithm effectively cuts my keyspace in half, I need to make it 

> >twice as large as I would need if my attacker's best algorithm were brute 

> >force.
>
> Um.  No.  If his algorithm cuts the keyspace in half, you only need to
> make it one bit larger.
>
You are correct.  I'm afraid I was thinking one thing and typing another.

What I meant to say is that the attacker has an algorithm that effectively 
cuts my keySIZE (instead of keyspace) in half,  i.e. his algorithm requires 
him to try on average only 2^1023 keys (instead of 2^2047 for a brute force 
attack) to crack my key of 2048 bits.

Thanks for pointing this out.

"Who needs encryption when their thoughts are unclear in plaintext?"

 - Cedric