Re: [TLS] New Cached info draft

Marsh Ray <marsh@extendedsubset.com> Fri, 26 March 2010 18:38 UTC

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Date: Fri, 26 Mar 2010 13:38:29 -0500
From: Marsh Ray <marsh@extendedsubset.com>
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To: Stefan Santesson <stefan@aaa-sec.com>
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Cc: Adam Langley <agl@imperialviolet.org>, "tls@ietf.org" <tls@ietf.org>
Subject: Re: [TLS] New Cached info draft
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On 3/26/2010 9:36 AM, Stefan Santesson wrote:
> I have submitted a 05 version of cached info draft that fixes the recorded
> errors and problems.
> 
> http://tools.ietf.org/rfcdiff?url2=draft-ietf-tls-cached-info-05.txt

Cool.

As a check, I implemented the FNV-1 64 algorithm directly from the
pseudocode in the draft, and without reference to any other docs.

Then I tried a few test vectors from
http://isthe.com/chongo/src/fnv/test_fnv.c

The results look good:

For input data:
0 bytes
Digest is: CB F2 9C E4 84 22 23 25

For input data:
0000  61                                                a
1 bytes
Digest is: AF 63 BD 4C 86 01 B7 BE

For input data:
0000  FF 00 00 01                                       ....
4 bytes
Digest is: D6 B2 B1 7B F4 B7 12 61

For input data:
0000  68 74 74 70 3A 2F 2F 65 6E 2E 77 69 6B 69 70 65   http://en.wikipe
0010  64 69 61 2E 6F 72 67 2F 77 69 6B 69 2F 46 6F 77   dia.org/wiki/Fow
0020  6C 65 72 5F 4E 6F 6C 6C 5F 56 6F 5F 68 61 73 68   ler_Noll_Vo_hash
48 bytes
Digest is: 26 CA F8 8B CB EF 2D 19


Minor suggestions:

It might help to mention that this is FNV-1 and not the FNV-1a variant.

The pseudocode relies on indentation for correct interpretation.
Whitespace seems to sometimes get whacked around a bit in these docs. A
pair of curlys might prevent a (trivial) ambiguity.

Including a few of these test vectors might in the document could be
useful, especially because there's not a solid normative ref for FNV-1.
Feel free to use my text. I printed the digest as individual bytes to
emphasize that they are a network sequence rather than a host integer.

- Marsh