Re: [secdir] SECDIR review of draft-kyzivat-case-sensitive-abnf

Paul Kyzivat <pkyzivat@alum.mit.edu> Sat, 06 September 2014 16:12 UTC

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Date: Sat, 06 Sep 2014 12:12:33 -0400
From: Paul Kyzivat <pkyzivat@alum.mit.edu>
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To: Chris Lonvick <lonvick.ietf@gmail.com>, iesg@ietf.org, secdir@ietf.org, draft-kyzivat-case-sensitive-abnf.all@tools.ietf.org
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Subject: Re: [secdir] SECDIR review of draft-kyzivat-case-sensitive-abnf
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Chris,

Thanks for the comments.

On 9/5/14 6:02 PM, Chris Lonvick wrote:
> Hi,
>
> I have reviewed this document as part of the security directorate's
> ongoing effort to review all IETF documents being processed by the IESG.
> These comments were written primarily for the benefit of the security
> area directors. Document editors and WG chairs should treat these
> comments just like any other last call comments.
>
> The abstract is:
>
>     This document extends the base definition of ABNF (Augmented Mackus-
>     Naur Form) to include a way to specify ASCII string literals that are
>     matched in a case-sensitive manner.
>
>
> Overall, I don't like the statement in the Security Considerations
> section, but it is consistent with all other documents related to
> defining ABNF, and I can't find any noteworthy security issues anyway.
>  From that, I have no objection to moving this document forward.

As you can see, I just followed precedent since I wasn't doing anything 
that would alter the security implications in any way.

But I am open to suggestions for something better to say.

> I did find some nits and have some suggestions for improving readability.
>
> 1 - "Mackus-Naur" is used in two places rather than "Backus-Naur".

Yes. I don't know how that happened.

> 2 - The last sentence of section 2.1 is:
>
>     This mechanism has a clear readability
>     disadvantage, with respect to using a literal text string with a
>     prefix, and new the prefix mechanism is preferred.
>
>
> Perhaps you meant:
>     This mechanism of using a literal text string with a prefix has a clear
>     readability disadvantage.  The prefix mechanism described in this
>     specification can be much more easily read.

No. "This mechanism" refers to "the way that has been used in the past" 
(specify the individual characters numerically). How about:

"The new way (using a literal text string with a prefix) has a clear 
readability advantage over the old way."

> 3 - This part of Section 2.1 may be cleared up some:
>   ---vvv---
>
> If no prefix is present then the string is case-insensitive.
>
>     Hence:
>
>           rulename = %i"aBc"
>
>     and:
>
>           rulename = "abc"
>
>     will both match "abc", "Abc", "aBc", "abC", "ABc", "aBC", "AbC", and
>     "ABC".
>
>
>   ---^^^---
>
>   Suggested:
>    ---vvv---
>       To be consistent with current implementations of ABNF, having no
>       prefix means that the string is case-insensitive, and is equivalent
>       to having the "%i" prefix.

This seems good, except for the use of "current". That doesn't age well. 
I suggest replacing "current" with "prior".

	Thanks,
	Paul

>     Hence:
>
>           rulename = %i"aBc"
>
>     and:
>
>           rulename = "abc"
>
>     are equivalent and both will match "abc", "Abc", "aBc", "abC", "ABc",
>     "aBC", "AbC", and "ABC".
> ---^^^---
>
> Best regards,
> Chris
>