From: frantz@netcom.com (Bill Frantz)
Date: Wed, 21 Aug 1996 09:23:38 +0800
To: cypherpunks@toad.com>
Subject: Re: Key Length Correlation
Message-ID: <199608202153.OAA21170@netcom8.netcom.com>
MIME-Version: 1.0
Content-Type: text/plain


At  1:02 PM 8/20/96 -0700, Jeff Davis wrote:
>I've read Blaze and diffie's paper on Semetric Key Length.  I'm currious
>how semetric key length correlates to public key cryptography length.  Does
>public key length have to be much longer, (assuming the algorithms are strong),
>to provide the same level of security as a shorter semetric key?  TIA   

According to Applied Cryptography V2, 

     Symmetric and Public-key Key Lengths 
with Similar Resistances to Brute-Force Attacks

      Symmetric                Public-key
      Key Length               Key Length
       56 bits                  348 bits
       64 bits                  512 bits
       80 bits                  768 bits
       112 bits                 1792 bits
       128 bits                 2304 bits

Regards - Bill


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