Re: [openpgp] SHA-2 support should be mandatory – change defaults

Robert J. Hansen rjh at
Mon Aug 11 08:49:32 CEST 2014

(Since this has taken a turn for the GnuPG-specific, I have migrated
this thread to GnuPG-Users.  It was originally found on the IETF OpenPGP
working group page.)

>> even though it's not default, you can change your gpg.conf(5) to
>> use a specific hashing algorithm
> In particular, set the following preferences in GnuPG:
> digest-algo SHA512 cipher-algo AES256
> The man page incorrectly warns against using them, and advises that
> you use the 'personal-' variants instead. These effectively do
> nothing.

The man page is correct.  Please don't use these options.  Please don't
encourage people to use these options.  It's very easy to misuse these
options in ways that will destroy interoperability with other OpenPGP

> If any downstream package maintainers are reading this, email me,
> and I'll be delighted to open an issue to include a modern gpg.conf 
> skeleton in your package.

I would be happy to look at your suggestions for inclusion in the FAQ;
however, I'll tell you in advance the FAQ will not recommend using
digest-algo or cipher-algo.

> Does *anyone* on this list use an OpenPGP implementation that does
> not support SHA-2 and AES? (And, if so, can you estimate how many
> users are in a similar position?)

Given the OpenPGP mailing list is comprised mostly of people who
implement OpenPGP for a living, it is unlikely there will be many people
there who use old versions of software.

Try looking here on GnuPG-Users.  You'll have to hunt a little bit, but
it's pretty easy to find people seeking help with GnuPG 1.2, which is
well over a decade old.  On Enigmail, I recently had a frustrating
experience helping a user who was trying to use GnuPG to exchange
traffic with a PGP *2.6* user... a codebase which is about 20 years old now.

So, short answer: yes, there are implementations that do not support
SHA-2 and/or AES.  Yes, they are still in use.  Yes, we really wish
they'd all just vanish or else upgrade to the latest, but no, they have
no plans of doing that.

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