Re: Signature types

[David Shaw <dshaw@xxxxxxxxxxxxxxx>]

On Sat, Aug 27, 2005 at 09:50:18AM +0200, Daniel A. Nagy wrote:
> 
> I am wondering if I understand the following correctly:
> 
> 0x40 Timestamp signature.
> 
> It is calculated directly on any document like a 0x00 signature (BTW, it
> would probably makes sense to introduce a 0x41 timestamp for textual
> documents), but the issuer of the signature does not claim authorship or
> endorse the document, just states the fact that the document existed at the
> time when the signature was issued.

Signature over a signature, just like 0x50.  It's not exactly made
clear in section 5.2.1, but note that it gets a signature target
subpacket.  That only makes sense if it is a signature over a
signature.  Note that 0x40 actually existed in rfc-1991 as well (also
a signature over a signature).

> This one I do not understand at all:
> 
> 0x50 Third-Party Confirmation signature.
> 
> What is the signature calculated on? The document? The certified signature?
> Both?

The signature.  I thought this one was pretty clear (from 5.2.1):

        This signature is a signature over some other OpenPGP
	signature packet(s). It is analogous to a notary seal on the
	signed data.

David