David,
My first "gut-level" reaction to the maximum values you
propose is (at least) a mild disquiet. But what the actual
values should be is beyond my knowledge in this area and - if
you think they'll work, then that's fine with me.
Otherwise, the changes you propose are fine with me...
--
Eric Gray
Principal Engineer
Ericsson
> -----Original Message-----
> From: mcgrew [mailto:[EMAIL PROTECTED]
> Sent: Thursday, October 11, 2007 2:25 PM
> To: Eric Gray
> Cc: General Area Review Team; Tim Polk
> Subject: Re: Gen-ART review of draft-mcgrew-auth-enc-03.txt
> Importance: High
>
> Hi Eric,
>
> On 9/21/07 12:10 PM, "Eric Gray" <[EMAIL PROTECTED]> wrote:
>
> > I have been selected as the General Area Review Team (Gen-ART)
> > reviewer for this draft (for background on Gen-ART, please see
> > http://www.alvestrand.no/ietf/gen/art/gen-art-FAQ.html).
> >
>
> Thanks for the review and the good comments! I have put
> together a new
> version of the document based on your comments plus some that
> came in from
> Phil Rogaway and Jari Arkko, which is attached.
>
> > Please resolve these comments along with any other comments you
> > may receive.
> >
> >
> > Document: An Interface and Algorithms for Authenticated Encryption
> > draft-mcgrew-auth-enc-03.txt
> > Reviewer: Eric Gray
> > Review Date: 9/21/2007
> >
> > Summary:
> > =======
> > This draft is nearly ready for publishing as a Proposed Standard.
> >
> > Comments/Questions:
> > ==================
> > At several places, the acronym "AAD" is used when it appears as if
> > "AEAD" was intended.
>
> Actually, the acronyms are distinct, but apparently the
> document neglected
> to formally define what AAD is. I've added a definition to
> Section 1. I
> have also changed "Additional Authenticated Data" to
> "Associated Data" based
> on Phil's comments.
>
> > This occurs in the following places:
> >
> > o First sentence, next-to-last paragraph, on page 6
> > o Throughout section 3.3 (both paragraphs, bottom Pp 10, top Pp 11)
> > o First sentence, last paragraph, on page 14
> >
> > One reason why this appears to be the case, is that section 3.3
> > is entitled "Construction of AEAD Inputs" - but the very first
> > sentence starts "If the AAD input ..."
> >
> > If AAD is a distinct term, what does it mean? If it is not a
> > distinct term, well...
> >
> ______________________________________________________________
> _________
> >
> > In section 4, second paragraph, is it possible to assign a P_MAX
> > value of zero in a particular algorithm, and - if so - what does
> > it mean to say:
> >
> > "Each AEAD algorithm MUST accept any plaintext with a
> length between
> > zero and P_MAX octets, inclusive, where the value P_MAX
> is specific
> > to that algorithm"
> >
> > ?
>
> I suggest the following addition: "The value of P_MAX MUST
> be larger than
> zero, and SHOULD be at least 65,536 (2^16) octets; if
> possible, it SHOULD be
> at least 4,294,967,296 (2^32) octets. These sizes are
> typical upper limits
> for network data packets. Other applications may use even
> larger values of
> P_MAX, so it is desirable for general-purpose algorithms to
> support higher
> values."
>
> >
> > Similar questions also apply to A_MAX and N_MAX in the third and
> > fourth paragraphs (respectively) of the same section.
>
> Some clarifications:
>
> "The value of A_MAX MUST be larger than zero, and SHOULD be
> at least 65,536
> (2^16) octets; if possible, it SHOULD be at least 4,294,967,296 (2^32)
> octets. Other applications may use even larger values of
> A_MAX, so it is
> desirable for general-purpose algorithms to support higher values."
>
> "The values of N_MAX and N_MIN MAY be equal."
>
> >
> ______________________________________________________________
> _________
> >
> > In the last sentence of section 5.3.1, "he" should probably be
> > "an attacker" (it is not clear who "he" is) and "ensues" should
> > probably be "may ensue" (a vulnerability does not guarantee an
> > attack).
> >
>
> Good catch; I'll make that substitution.
>
> Best regards,
>
> David
>
>
>
>
>
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