From: Hilarie Orman <ho@cs.arizona.edu>
Date: Sun, 5 Nov 1995 10:35:39 +0800
To: bsimpson@morningstar.com
Subject: Re: Photuris Primality verification needed
In-Reply-To: <1973.bsimpson@morningstar.com>
Message-ID: <9511050229.AA00198@uncial.CS.Arizona.EDU>
MIME-Version: 1.0
Content-Type: text/plain


>  Recently, someone asked for a smaller prime of only 512-bits for speed.
>  This is more than enough for the strength of keys needed for DES, 3DES,
>  MD5 and SHA.  Perhaps this would be easier to have more complete and
>  robust verification as well.

Depending on what you think of the strength of those algorithms, the 512-bit
mod p system may not be strong enough.

The *strength* of 512-bit mod p DH systems is only about 56 bits.  You need
1024-bit primes for a *strength* of 80 bits.

In contrast, the 155-bit elliptic curve in the Photuris draft has a
strength of about 76 bits.