Subject: Re: V3 secret keys

From: <[email-masked]>
Date: Mon, 6 Feb 2006 19:00:41 -0500

On Mon, 06 Feb 2006 17:38:01 -0500 Hal Finney <[email-masked]> 
wrote:

>Note that V3 keys only support ciphers with a block size of 8 
>bytes, so
>I think it is OK to explicitly say "8 octets" here.

are v4 keys different in this respect ?

(i.e., is there any cipher currently within the open pgp standard 
that v4 keys support that v3 keys could not?

classically, v3 keys were started when all that was available was 
IDEA,
but Disastry extended 2.6x for v3 keys to accept 'any' open-pgp 
cipher, 
even for symmetric protection of the secret key

(i have occasionally found it useful to prepare v3 non-IDEA test 
keys,
for gnupg testers who prefer not to use patented algorithms, even 
for testing, if there is a convenient way around it)

[am not trying to awaken a v3 / v4 controversy ;-)
am just trying to 'understand' what i might have 'missed' ]

tia,
vedaal

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---

From: [email-masked] (Daniel A. Nagy)
Date: Tue, 7 Feb 2006 01:27:31 +0100

> that v4 keys support that v3 keys could not?

The difference is that in the case of v4 keys, the secret part is encrypted
like a regular byte stream, with no regard to the contents. In the case of
V3, there were resynchronization steps introduced between the MPIs.

I sincerely hope that this whole mess will be cleaned up with V5, where
there seems to be a consensus not to implement encrypted private key packets
at all, but put unencrypted private key packets into integrity protected
symmetrically encrypted packets instead.

Personally, I would suggest removing encrypted packet formats from the
standard altogether; there is no reason to stay interoperable with those. If
one wants to export old keys, they should remove the encryption first. New
implementations should enclose unencrypted private keys (of eiter version)
in symmetrically encrypted packets with MDC.

-- 
Daniel