Subject: V5 signatures

From: Jon Callas <[email-masked]>
Date: Thu, 27 May 1999 16:35:37 -0700

At 11:19 AM -0700 4/23/1999, Anonymous said:

Sorry for dropping this on the floor..

   > (4) A V5 signature packet that allows 4-byte lengths.

   Yet another signature packet version! Is this a scheme to increase
   S/MIME support?

No, it's there for things like PGP ticket. If someone is building a
lightweight authorization scheme, it's conceivable that a signature would
need to be bigger than 8383 bytes. V4 signatures don't allow that.

	Jon

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From: Werner Koch <[email-masked]>
Date: Fri, 28 May 1999 10:10:29 +0200

> need to be bigger than 8383 bytes. V4 signatures don't allow that.

How did you calculate this?

5.2.3.1 says somewhere:

       if the 1st octet = 255, then
           lengthOfLength = 5
           subpacket length = [four-octet scalar starting at 2nd_octet]

However, the octet count for the [un]hashed subpackets is limited to
65535.

Because this is a conflict we really should address it with a new v5
signature paket.  Changes to an implementaion are minimal.  And while
we are at it, we should consider to apply some rules to the name part
of notation data - so that we can have unique names.  Thomas Roessler
already mentioned this and proposed a SSH like scheme for this.

-- 
Werner Koch at guug.de           www.gnupg.org           keyid 621CC013

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From: Thomas Roessler <[email-masked]>
Date: Fri, 28 May 1999 11:27:10 +0200

On 1999-05-28 10:10:29 +0200, Werner Koch wrote:

> Because this is a conflict we really should address it with a new
> v5 signature paket.  Changes to an implementaion are minimal.  And
> while we are at it, we should consider to apply some rules to the
> name part of notation data - so that we can have unique names.
> Thomas Roessler already mentioned this and proposed a SSH like
> scheme for this.

I wouldn't confine this to V5 signatures. ;)

As for notation data naming, the suggestion is as follows.  It's
derived from what the secsh internet drafts do for "registering"
new algorithms.

------------------------------

Notation data naming

   OpenPGP "notation data" signature sub-packets traditionally consist
   of a name and a value, both of which are arbitrary, UTF-8 encoded
   strings.

   The OpenPGP standard does not define any registry for defined
   notation data names, nor does it describe safe extension mechanisms.

   The present document defines two name spaces for notation data names:
   The IETF name space and the user name space.

   Notation data names in the IETF name space consist of an arbitrary
   string of UTF-8 encoded characters, with the exception that the
   character "@" ("at") MUST NOT occur in such a name.

   XXX - describe IANA registration procedures.

   Notation data names in the user name space consist of a tag, followed
   by the "@" character, followed by a DNS domain name.  The tag may be
   an arbitrary string of UTF-8 encoded characters, with the exception
   that the character "@" MUST NOT occur in such a name.  The DNS domain
   name must be under the exclusive control of the person or entity
   which introduces the notation data name in question.

   For example, if The Example Corporation wishes to introduce sample
   notation data, the appropriate notation data name could be
   "[email-masked]".

------------------------------

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From: Werner Koch <[email-masked]>
Date: Fri, 28 May 1999 12:37:01 +0200

> However, the octet count for the [un]hashed subpackets is limited to

It just came to my mind, that large signature packets (currently they
have a limit of about 128k) do impose a problem:

It will then not be possible to keep the complete signature packet in
memory.  Signatures may be (theoretical) very large - up to 4 Gigs and
due to this they have to be handled like plaintext.

Doess it really make sense to build a protocol - based on OpenPGP - 
which puts all it's dat into a signature packet?  Such data should go
into a literal text packet or some new packet type.