Re: [Cfrg] Point format endian
Watson Ladd <watsonbladd@gmail.com> Tue, 27 January 2015 16:35 UTC
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Date: Tue, 27 Jan 2015 08:35:35 -0800
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From: Watson Ladd <watsonbladd@gmail.com>
To: Derek Atkins <derek@ihtfp.com>
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Cc: "cfrg@irtf.org" <cfrg@irtf.org>, Paul Hoffman <paul.hoffman@vpnc.org>
Subject: Re: [Cfrg] Point format endian
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On Tue, Jan 27, 2015 at 8:25 AM, Derek Atkins <derek@ihtfp.com> wrote: > Paul, > > On Tue, January 27, 2015 11:07 am, Paul Hoffman wrote: >> We do not need "consensus" in this RG, just assurance that what we >> recommend does not have security holes. No one has suggested any security >> holes based on the endianness. The argument that "using different math >> would add code" is true, but pretty much irrelevant relative the to the >> size of the code needed to add a new curve. There is no interoperability >> issue: if someone messes up the math in either endian direction, they will >> know the first time they test their code, and there is approximately >> 2^-128 chance that if they got it wrong and only tested one vector, that >> they will accidentally get a good result. >> >> The longer we argue about our preferences (instead of actual security >> issues), the worse off the IETF is. > > It is important for interoperability. If I tell you that my ECC Public > Key is 0102030405060708090a but you interpret that as 0a090807060504030201 > -- we will get different results even if both of us implement the math > correctly. So I would argue that transmission encoding of keys and > results *is* a matter of security. When I wrote the relevant section of the Turner draft, I was careful to specify the keys as sequences of bytes. The concern you mention doesn't exist: everything is a sequence of 32 bytes, with a defined way to turn that into a number and process that number. If you don't actually read the spec, of course you'll get it wrong. > > Then of course there's the matter of using the shared secret in another > algorithm, like AES. Again, byte-order differences would result in > different AES keys. Yet another matter of security. > > Yes, it just mean we just need to "choose one". But for the last 20+ > years we've already chosen: network-byte-order. I think Emerson had something to say about this argument. > >> --Paul Hoffman > > -derek > > -- > Derek Atkins 617-623-3745 > derek@ihtfp.com www.ihtfp.com > Computer and Internet Security Consultant > > _______________________________________________ > Cfrg mailing list > Cfrg@irtf.org > http://www.irtf.org/mailman/listinfo/cfrg -- "Those who would give up Essential Liberty to purchase a little Temporary Safety deserve neither Liberty nor Safety." -- Benjamin Franklin
- Re: [Cfrg] Point format endian (was: Adoption of … Dan Brown
- Re: [Cfrg] Point format endian (was: Adoption of … Peter Gutmann
- Re: [Cfrg] Point format endian (was: Adoption of … Alyssa Rowan
- Re: [Cfrg] Point format endian (was: Adoption of … Alyssa Rowan
- Re: [Cfrg] Point format endian (was: Adoption of … Michael Clark
- Re: [Cfrg] Point format endian (was: Adoption of … Michael Clark
- Re: [Cfrg] Point format endian (was: Adoption of … Watson Ladd
- Re: [Cfrg] Point format endian (was: Adoption of … Michael Clark
- Re: [Cfrg] Point format endian (was: Adoption of … Peter Gutmann
- Re: [Cfrg] Point format endian (was: Adoption of … Stephen Farrell
- Re: [Cfrg] Point format endian (was: Adoption of … Peter Gutmann
- Re: [Cfrg] Point format endian (was: Adoption of … Alyssa Rowan
- Re: [Cfrg] Point format endian (was: Adoption of … Stephen Farrell
- Re: [Cfrg] Point format endian (was: Adoption of … Peter Gutmann
- Re: [Cfrg] Point format endian (was: Adoption of … Stephen Farrell
- Re: [Cfrg] Point format endian (was: Adoption of … Salz, Rich
- Re: [Cfrg] Point format endian Derek Atkins
- Re: [Cfrg] Point format endian Salz, Rich
- Re: [Cfrg] Point format endian Stephen Farrell
- Re: [Cfrg] Point format endian Paul Hoffman
- Re: [Cfrg] Point format endian Derek Atkins
- Re: [Cfrg] Point format endian Derek Atkins
- Re: [Cfrg] Point format endian Blumenthal, Uri - 0558 - MITLL
- Re: [Cfrg] Point format endian Paul Hoffman
- Re: [Cfrg] Point format endian Watson Ladd
- Re: [Cfrg] Point format endian (was: Adoption of … Dan Harkins
- Re: [Cfrg] Point format endian (was: Adoption of … Watson Ladd
- Re: [Cfrg] Point format endian (was: Adoption of … Andy Lutomirski
- Re: [Cfrg] Point format endian (was: Adoption of … Dan Harkins
- Re: [Cfrg] Point format endian (was: Adoption of … Stephen Farrell
- Re: [Cfrg] Point format endian Tony Arcieri
- Re: [Cfrg] Point format endian (was: Adoption of … Michael Clark
- Re: [Cfrg] Point format endian Damien Miller
- Re: [Cfrg] Point format endian Phillip Hallam-Baker
- Re: [Cfrg] Point format endian Phillip Hallam-Baker
- Re: [Cfrg] Point format endian (was: Adoption of … Watson Ladd
- Re: [Cfrg] Point format endian (was: Adoption of … D. J. Bernstein
- Re: [Cfrg] Point format endian (was: Adoption of … Dan Harkins
- Re: [Cfrg] Point format endian (was: Adoption of … Watson Ladd