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RE: 3DES with 40-bit key?
How do I get off this list?
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> Sent: Sunday, March 28, 1999 11:03 PM
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> Subject: Re: 3DES with 40-bit key?
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> Ari Huttunen wrote:
> > Many of you will think this issue is braindead.
> > I agree. However, as I understand that from now
> > on the only MUST IMPLEMENT algorithm for ISAKMP
> > and IPSEC is 3DES, the issue of what to do with
> > export control rises. So, assume that export
> > control limits the key length to 40 bits. How
> > would I specify and negotiate this with IKE?
> I wouldn't say it's a braindead idea -- just that it's wrong. 3DES is
> defined in RFC 2451 as having a 192-bit key; 168 bits participate in
> the key schedule. The key length is not negotiable for this cipher.
> If you were to do the equivalent of the CDMF transform to create a
> DES-like cipher with 40 bits of strength, it wouldn't be DES;
> similarly, a 40-bit version of 3DES would not be 3DES, and you would
> not have implemented this cipher, so you would not have satisfied any
> MUST IMPLEMENT clause.
> If you did something like this and tried to pass it off as a conforming
> IPSec implementation, it would be fraudulent. If you can't get export
> licenses for the algorithms you want, then you can't export them.
> Simple as that.
> By the way, the "weak ciphers for US export" limit has been raised to
> 56 bits with a BXA review.
> Jim Gillogly