Subject: Chained Encrypted Data Packets?

From: Jon Callas <[email-masked]>
Date: Mon, 8 Nov 1999 11:42:54 -0800

Is this a good idea? Should I allow this? Anyone, anyone, Implementers?

Note -- after this was suggested, I argued that nothing in 2440 forbids
someone from doing this. Should I specifically encourage it?

	Jon

Date: Thu, 26 Nov 1998 15:14:38 +0100
From: Andrea Halter <[email-masked]>
Organization: Kuesnachter Schwimm-Verein
To: [email-masked]
CC: Marcel Waldvogel <[email-masked]>
Subject: Semantics of having multiple encrypted data packets

To provide for random read/write semantics, we would like to chain
multiple Symmetrically Encrypted Data Packets, each of constant length.
In RFC 2440, this is not listed as one of the message formats.

Therefore, we suppose that our approach is not standards compliant. But
does any of you see a better way to support random access without
re-encrypting the whole message each time? Will other implementations be
able to understand this? Could we even tweak the standard into this
direction (ignoring that we're a few weeks late)?

cu
Andi, Marcel

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From: "William H. Geiger III" <[email-masked]>
Date: Mon, 08 Nov 1999 14:59:46 -0600

In <v04210100b44cd72f63dc@[204.254.20.189]>, on 11/08/99 

>	Jon

I don't have a problem with it so long as it is clearly documented.

I am assuming what they are doing is generating a symetric key and then
encrypting the file in individual 512 byte sectors on the disk (assuming
the file system uses 512 byte sectors). I don't see a problem with this
other than the packet overhead from having multiple packets used to
encrypt a message.

How are they going to handle the padding if the data for the last packet
is smaller than their fixed length requirments (ie 10 bytes of data for a
512 byte packet)?

-- 
---------------------------------------------------------------
William H. Geiger III                    http://www.openpgp.net  
Geiger Consulting    

Data Security & Cryptology Consulting
Programming, Networking, Analysis
 
PGP for OS/2:                   http://www.openpgp.net/pgp.html
---------------------------------------------------------------

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From: Werner Koch <[email-masked]>
Date: Tue, 9 Nov 1999 10:09:19 +0100

> someone from doing this. Should I specifically encourage it?

I argued the same when someone asked me about this.  I don't think
that we should mention this in the Standard.  I do not think
that this is a good way for sending messages between remote device and
that is for what OpenPGP is used in the first place.

However, a sentence in the implemenation notes won't do any harm.
Better not get into trouble by adding a new feature and start to
discuss this for weeks. 

  Werner

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

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From: "William H. Geiger III" <[email-masked]>
Date: Tue, 09 Nov 1999 16:48:22 -0600

In <[email-masked]>, on 11/09/99 

>I argued the same when someone asked me about this.  I don't think that
>we should mention this in the Standard.  I do not think that this is a
>good way for sending messages between remote device and that is for what
>OpenPGP is used in the first place.

>However, a sentence in the implemenation notes won't do any harm. Better
>not get into trouble by adding a new feature and start to discuss this
>for weeks. 

If those who are using this format wish to document it I will be glad to
put it up on my website along with the RFC 2440 docs.

Otherwise I am indifferent on the issue.