From: Peter Monta <pmonta@qualcomm.com>
Date: Thu, 1 Feb 1996 14:07:59 +0800
To: cypherpunks@toad.com
Subject: Re: Crypto-smart-card startup Inside Technologies
In-Reply-To: <m0thqvv-00092XC@pacifier.com>
Message-ID: <199602010541.VAA21657@mage.qualcomm.com>
MIME-Version: 1.0
Content-Type: text/plain


jim bell <jimbell@pacifier.com> writes:

> >  [ Inside Technologies ]
> >  ..."In public-key cryptography, 512-bit keys are typical and
> >  already vulnerable.  So we are looking at 640-bit-long keys
> >  supported by a scalable design."
> 
> This kind of thing disgusts me.  We already know 512-bit keys are weak.  As
> I recall, I was told that 512 bit keys could be cracked in 20,000
> MIPS-years.  If the ballpark formula holds that adding 10 bits doubles the
> security, that merely means that 640 bits is 2**(128/10) or 8000 times
> strong.  While obviously better than 512, it is not ENOUGH better to make me
> confident that this is a long-term secure length.  768 or 1024 bits should
> be considered the minimum.  A deliberate design of 640 bits makes it look
> like it's intended to be crackable in 5-10 years, much as DES was suspected
> of a similar design decision in limiting its keylength to 56 bits.

But the "scalable design" presumably means the hardware can deal
with a variety of modulus lengths.  As you say, they would be
short-sighted to make a fixed choice.

Peter Monta   pmonta@qualcomm.com
Qualcomm, Inc./Globalstar