Re: [secdir] secdir review of draft-cakulev-mikey-ibake-02

"Dan Harkins" <> Wed, 22 September 2010 22:51 UTC

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Date: Wed, 22 Sep 2010 15:51:38 -0700
From: Dan Harkins <>
To: Glen Zorn <>
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Cc:, 'Tim Polk' <>,,,
Subject: Re: [secdir] secdir review of draft-cakulev-mikey-ibake-02
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On Wed, September 22, 2010 2:27 am, Glen Zorn wrote:
> Section 4.1
> .         The first sentence of paragraph 4 contains rather confusing
> notation.  It says "The Initiator next chooses a random x and computes xP
> (i.e. adds P to itself x times), where P is a point on elliptic curve E
> known to all users."  The notation "xP" is a conventional one for
> expressing
> the multiplication of P by x, which is not the same as the addition of P
> to
> itself x times.  If the latter interpretation is actually, I think that a
> better notation should be chosen.

  Actually multiplication of P by x is "the addition of P to itself x-1
times" since adding P to itself 1 time would be P + P = 2P.

  Regarding the notation, it would be nice if there was some convention
on how to should show ECC operations in an I-D or RFC. Should it be
multiplicative notation or additive notation? Should points on the curve
be upper-case and scalars are lower-case, or vice versa? How do you
represent the elliptic curve identity element? RFC 5931 uses additive
notation, uses upper-case for points and lower-case for scalars and calls
it the "point at infinity", respectively, while David McGrew's fundamental
ECC draft uses multiplicative notation, uses lower-case for points and
upper-case for scalars and defines it as "e", respectively.

  This draft is proposing "xP" while the additive notation used in
RFC 5931 is "x*P". So this is yet another notation for the same old thing.

  A diktat from the IESG or the Security Area ADs would be helpful.