Subject: Re: [openpgp] New S2K specifiers?
From: Jon Callas <[email-masked]>
To: [email-masked]
Cc: Jon Callas <[email-masked]>, Daniel Kahn Gillmor <[email-masked]>, openpgp <[email-masked]>
Date: Mon, 1 Apr 2019 20:34:44 -0700
List-Id: "Ongoing discussion of OpenPGP issues." <openpgp.ietf.org>

> On Apr 1, 2019, at 6:46 PM, [email-masked] wrote:
> 
> Will the new S2K be only for the V5 key format?
> Or will it also be used for Conventionally Encrypted messages?

It would be for any key, or for conventionally encrypted messages.

> 
> If it will be used for Conventionally Encrypted messages too, then there can be backward incompatibility issues, 
> as well as intercompatibility issues with different implementations.
> 
> (I still think it's a good idea, but may be a really lot of extra work, so maybe only for V5 keys now).

Remember, definition is not implementation. You’re right that from an implementation standpoint, it might be best to make messages default to the old S2K for a while, but do it for V4 and V5 keys as well.

	Jon