Subject: Re: partial packet lengths in PGP 8

From: "Hal Finney" <[email-masked]>
Date: Thu, 10 Apr 2003 16:27:10 -0700

Brian Smith writes:
> What's the reason for requiring that the first partial length be so long?
>  512 octets is considerably more than the headers, IV, etc of any data
> packet would be.

A literal data packet could have up to a 256 byte long filename plus a
few more bytes for the other data, so you need it to be bigger than that.
And 512 is the next size up.

Hal

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From: Werner Koch <[email-masked]>
Date: Fri, 11 Apr 2003 10:29:07 +0200

> And 512 is the next size up.

and signature packets can be of any size ...

-- 
  Nonviolence is the greatest force at the disposal of
  mankind. It is mightier than the mightiest weapon of
  destruction devised by the ingenuity of man. -Gandhi

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From: Derek Atkins <[email-masked]>
Date: 11 Apr 2003 11:39:19 -0400

> and signature packets can be of any size ...

IIRC signature packets MUST use a determinate length and are limited
to about 8192 bytes (unless this was changed somewhere along the
line).

-derek

-- 
       Derek Atkins, SB '93 MIT EE, SM '95 MIT Media Laboratory
       Member, MIT Student Information Processing Board  (SIPB)
       URL: http://web.mit.edu/warlord/    PP-ASEL-IA     N1NWH
       [email-masked]                        PGP key available

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From: "Michael Young" <[email-masked]>
Date: Fri, 11 Apr 2003 13:46:36 -0400

From: "Derek Atkins" <[email-masked]>
> to about 8192 bytes (unless this was changed somewhere along the

The current draft does require that they be determinate, but I don't
see a numeric limit.  There are hard limits to the hashed and unhashed
subpackets (2^16-1 each) and (arguably) practical limits to the size of
the MPIs that form the signature, but that comes to well more than 8192.

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From: Derek Atkins <[email-masked]>
Date: 11 Apr 2003 15:10:06 -0400

Perhaps it's my flakey memory, but I recall that when Colin and
I were working on PGP3/5, when we were designing what eventually
turned into 2440, we had some packets that required a 2-bit LoL
implementation due to compatibility reasons with PGP 2.x...  I
could be totally off my rocker, here -- this work was done 8 years
ago so it's been a while and I've tried to forget that part of my
life ;)

-derek

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From: Werner Koch <[email-masked]>
Date: Fri, 11 Apr 2003 21:55:07 +0200

> to about 8192 bytes (unless this was changed somewhere along the

Right.  I had only the length headers of the subpackets in mind which
indeed would allow up to 2^32 bytes for a subpacket.  However, the
total length of all subpackets is limited to 2 * 2^16 bytes.

Sorry for the confusion,

Salam-Shalom,

   Werner