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Re: Outstanding question - rule on cleartext signing last line

Ian G <iang@systemics.com> Mon, 26 December 2005 16:32 UTC

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Date: Mon, 26 Dec 2005 16:20:28 +0000
From: Ian G <iang@systemics.com>
Organization: http://financialcryptography.com/
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To: David Shaw <dshaw@jabberwocky.com>
Cc: OpenPGP <ietf-openpgp@imc.org>
Subject: Re: Outstanding question - rule on cleartext signing last line
References: <43980274.2080404@iang.org> <20051208104150.GA14918@epointsystem.org> <43981C74.1070403@systemics.com> <87bqzrhj6i.fsf@wheatstone.g10code.de> <20051208145205.GA5943@jabberwocky.com> <43AFE21B.1000102@algroup.co.uk> <20051226153615.GB7066@jabberwocky.com>
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David Shaw wrote:

> Can you give an example of why you feel this is a bug?

I think it is a bug if we decide that the
process of cleartext signing is reversable.

So, if the process of verification creates
a file that is the pre-signed version, then
it has to decide whether the final CRLF has
to be preserved or stripped in the unsigned
output.

So, does this output as a line terminated
string or as an unterminated string? :

-----BEGIN PGP SIGNED MESSAGE-----

my signed text
-----BEGIN PGP SIGNATURE-----
xxxxx
-----END PGP SIGNATURE-----

Now, if we decide that the process of signing
is not one that is deterministically reversable,
it is not an issue.  In practice, verification
is possibly all we need - and we have that.

(I have been unable to convince myself that we
need reversibility - I can't think of a case
where I would want it... but that's just me!)

iang

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