From: Bill Stewart <stewarts@ix.netcom.com>
Date: Sat, 11 Nov 1995 05:50:02 +0800
To: Phil Karn <karn@qualcomm.com>
Subject: Re: Photuris Primality verification needed
Message-ID: <199511090913.BAA08368@ix.ix.netcom.com>
MIME-Version: 1.0
Content-Type: text/plain


At 07:47 PM 11/8/95 -0800, you wrote:
>>Including the provision for the 512 bit prime is *HARMFUL* and
>>*DANGEROUS*.  Export control is not really an issue here, because if
>>companies in the United States cannot provide secure networking,
>>there are other companies in the world that can.
>
>You've convinced me. I remove my proposal to include a recommended 512-bit
>modulus. The smallest standard modulus will remain 1024-bits.

If speed is really a concern, you could do a 640 or 768 bit modulus
("Hey, back when we wrote that, everybody assumed 640 would be enough for
everybody!"), or alternatively, let people use 512-bit private modulus values -
they're still short, but they're not a target if everybody's got their own
(which also means that popular applications shouldn't ship with a
built-in 512-bit prime; if Windows 97 did that, it'd be about the same
as putting it in the spec, so really short primes should probably require
user-generation, which may contradict the desire to use short numbers
to save time.)

One question is how to conveniently let the standard offer negotiation for
the modulus length and value without adding a lot of handshake steps
        -> WILL MODLENGTH 512PRIV 768 1024 1024ALT 2048
        <- DO MODLENGTH 512PRIV
        -> WILL MODULUS
8758432798573409875098347509834750983745098348584395984357908347509843750984
3750983
        <- 404 HEY, THAT'S NOT A STRONG PRIME!



#--
#				Thanks;  Bill
# Bill Stewart, Freelance Information Architect, stewarts@ix.netcom.com
# Phone +1-510-247-0663 Pager/Voicemail 1-408-787-1281