Re: including the entire fingerprint of the issuer in an OpenPGP certification

Daniel Kahn Gillmor <dkg@fifthhorseman.net> Tue, 18 January 2011 22:18 UTC

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Date: Tue, 18 Jan 2011 17:18:41 -0500
From: Daniel Kahn Gillmor <dkg@fifthhorseman.net>
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Subject: Re: including the entire fingerprint of the issuer in an OpenPGP certification
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On 01/18/2011 05:05 PM, David Shaw wrote:
> I don't think we want people using other than the consensus fingerprint algorithms and methods.  I suggest we make the first byte a version field, which can be 
> set to '4' today for the current fingerprint, '5' for v5 keys, etc.

Are we talking about versioning the fingerprint scheme, or versioning
the key?  It sounds like a versioned fingerprint scheme, not a versioned
key scheme to me.

If we say '4' means the fingerprinting standard in RFC 4880 (OpenPGPv4)
and '5' means some other fingerprint scheme then we're effectively
creating a new registry to be managed by IANA, right?

I have no objection to that (and presumably it would be an exceptionally
slow-growing registry) but it'd be good to be clear about what we're doing.

I'd just as soon name the notation issuer-fpr4@whatever.example for the
current fingerprint and then name a new notation
issuer-fpr5@whatever.example when that happens, reusing the existing
notation registry.

(or, if this works and we want iana to allocate a "global" notation
title, just ask for "issuer-fpr4" now, an "issuer-fpr5" later)

This is all fiddly syntax choices, of course, without much importance,
other than avoiding (current and future) bureaucratic overhead.

> I suppose we could skip that field and detect version based on size,
> but why use heuristics when we can know for sure with a version byte?

We could also be sure if the name of the notation is precise enough.

	--dkg