Re: Question about verifying signatures

Stephen Paul Weber <singpolyma@singpolyma.net> Wed, 31 March 2010 01:46 UTC

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Date: Tue, 30 Mar 2010 20:46:52 -0500
From: Stephen Paul Weber <singpolyma@singpolyma.net>
To: Wim Lewis <wiml@hhhh.org>
Cc: ietf-openpgp@imc.org
Subject: Re: Question about verifying signatures
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References: <20100330202049.GA21672@mediacentre> <Pine.NEB.4.64.1003301503480.14845@photomat-new.hhhh.org>
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Somebody claiming to be Wim Lewis wrote:
> I agree that paragraph isn't completely unambiguous. IIRC, the data
> passed to the SHA1/MD5/whatever algorithm is the bare document
> contents (possibly with EOL canonicalization as described above),
> concatenated with some "trailer" bytes which depend on the version
> number of the signature, but are a copy of part of the signature
> subpacket itself plus perhaps a length field and so on (see the last
> three paragraphs of [5.2.4]).

So, I'm concatenating:

* The literal contents of any literal data packet(s).
* The literal bytes of the signature packet up to and including the "hashed"
  subpackets
* 0x04
* 0xFF
* The length of the second thing in this list

As the "message" to hash?  I'm going to try that.

- -- 
Stephen Paul Weber, @singpolyma
Please see <http://singpolyma.net> for how I prefer to be contacted.
edition right joseph
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