On 02/23/2006 12:16, Douglas Otis wrote:
On Feb 22, 2006, at 7:52 PM, Douglas Otis wrote:
On Feb 22, 2006, at 6:47 PM, Hallam-Baker, Phillip wrote:
In rebuttal to Doug's point about not depending on the DNS
supporting longer key sizes, an ECDSA key that gives equivalent
strength to a 128 bit symmetric cipher is 256 bits with point
compression and 512 bits without. An equivalent ECDSA signature is
512 bits in either case. The comparable key size for RSA is 3072
bits for key and signature.
This looks great, but at what price? From what other companies
beyond Certicom Inc. would licenses need to be obtained in order to
support the EC algorithm? Is there any information with respect to
existing terms?
As a follow-on:
Certicom may grant royalty free licenses in some cases.
http://www.certicom.com/download/aid-545/IETF.pdf
http://www1.ietf.org/ietf/IPR/IETF-2006Jan26-Certicom-IPR.pdf
http://www.ietf.org/ietf/IPR/certicom-ipr-rfc3526-rfc2409-ikev2.txt
http://www.ietf.org/ietf/IPR/CERTICOM-SMIME
http://www.ietf.org/ietf/IPR/certicom_smime_license.pdf
http://www.ietf.org/ietf/IPR/CERTICOM-IPSEC-ECC
http://www.ietf.org/ietf/IPR/CERTICOM-ECDSA
One of the points that DKIM currently has in its favor is that it can be
implemented in all major MTAs without conflicting with the existing licensing
of those programs (both proprietary and open, including GPL).
I think that if DKIM were to be dependent on crypto technology with more
restrictive licensing terms, it would represent a substantial impediment to
adoption. IANAL, so I have no idea if the representations above would
present a problem or not, but I do think that we should understand the
impacts of these patents on the ability of DKIM to be implemented everywhere
before we proceed to far towards a solution with additional licensing
considerations.
Scott K
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