[48874] in Cypherpunks
Re: Crypto-smart-card startup Inside Technologies
daemon@ATHENA.MIT.EDU (jim bell)
Thu Feb 1 00:24:18 1996
Date: Wed, 31 Jan 1996 20:47:07 -0800
To: Peter Monta <pmonta@qualcomm.com>, cypherpunks@toad.com
From: jim bell <jimbell@pacifier.com>
At 12:30 AM 1/31/96 -0800, Peter Monta wrote:
>There's an article in the January 29 _EE Times_ about a French
>cryptographic-smart-card startup called Inside Technologies.
>Tidbits:
>
> ..."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.
