The keyring is a property of GnuPG and you should not mess around with it. Use
--export and --import to add keys. Extending the bad behaviour of using
multiple keyrings would be Bad Thing.

Besides the WKD scenario Andre describes, there are already many existing uses
of a separate keyring where having other keyrings configured via
~/.gnupg/gpg.conf already conflicts with the intended use, except when using
--no-options:

1. /etc/apt/trusted.gpg
2. /usr/share/keyrings/debian-keyring.gpg
3. our company's keyring with acceptable keys for encryption of certain

sensitive information

Basically everywhere where multiple users use a single keyring, often with
"--trust-model always", where you do not want additionally configured keyrings
to disturb the result and give a false sense of security.

Please explain why this a Bad Thing[tm] and what the correct workflow would be.

I have explained this several times over the last decade. The primary reason is
that it is not possible to keep a consistent vewi on the localally availabale
keys when a user is allowed to remove and add storage at will without gpg having
any control over it. You may end up with duplicated keys and gpg will only
update one of them. The next time the keyrings are "mounted" in a different
order and key is used for update. This leads to all kinds of problems. This is
not a distributed database with a 3 -phase commit system.

I have proposed a solution gor 2.3 based a on central key managing daemon, which
then has the chance to track changes. Interesting fact is that aheinecke has
strongly opposed that idea.

Ah, I understand. I currently have two keyrings (the default keyrings and
debian-keyring.gpg) in my user account. So I will export the keys from
debian-keyring.gpg and import them into my regular keyring.

But this is a different topic from the one described here:
This issue is about allowing gpgme to use exactly one different keyring (not an
additional keyring) that is different from the default keyring or other keyrings
configured in the user's gpg.conf.

So it is just about allowing in gpgme what is already possible via the command
line. Or maybe you would prefer to allow passing command line options to gpg via
gpgme to avoid the wrapper script mentioned below?

We try to deprecate the use of the --keyring option because that is too
troublesome for many reasons. We can't remove that option from gpg proper for
compatibilty reasons. But not adding a new feature to GPGME won't raise any
compatibility problem and thus we can fortunately reject this request.

Please tell me how I should model my workflows in this case:

• There is a a centrally managed set of public keys (currently in a keyring

file, but I'm open to suggestions)

• Different users should be able to use this set of keys (and no others) for

certain tasks:

1. Encrypt a file to any of those key (but no others!), but also decrypt the

file with their secret key (which is not centrally managed)

2. Iterate over all keys and do something with them (here: publish them in the

WKD after having made changes to the set of keys)

Sign the keys and set the signing key to fully trusted.

Sign the keys and set the signing key to fully trusted.

does not solve 1.:

Encrypt a file to any of those key (but no others!),

(because people may trust other keys)

and it does not solve 2. without keeping a separate list of keys/fingerprints:

Iterate over all keys

additionally _all_ users have to regularly update _all_ these keys, otherwise
things like expired subkeys will lead to failing encryption. (This is no theory:
We've been there and don't want to have this again)

@thomas: You may want to look at gpg sync, which I think makes at least some of
what you want to do easier.
https://firstlook.org/code/2016/10/12/introducing-gpg-sync-an-open-source-tool-for-organizations-that-encrypt-email/

(repost, I just noticed that neal is not in the nosy list. I'll unlink the old
entry afterwards)

neal: Interesting idea, this (or for a non-gui version: a signed list of
fingerprints available from a central source and retrieving those keys) would
solve 2 (iterating over all keys) and 3 (regularly update).

For the non-gui variant I wondered about how to use --verify and check that the
file was signed by the authority key (--verify only prints the keyid,
"--keyid-format none" does not allow --verify to print fingerprints in 2.1.15,
I'll file a separate issue). I was a bit disappointed when I saw that gpg sync
just calls the command line with --keyid-format 0xlong and does screen scraping
to verify the verification.

But still, how to solve 1 with gpg itself? Of course I could "manually" verify
in the application that only the intended keys have been used, but as shown with
gpg sync's code above: This is not always easily possible.

Reported the problem mentioned here in T2835
("keyid-format none" ignored for --verify and other commands)

Regarding the original issue discussed here:
What about an option in gpg/gpgme to limit all operations to keys contained in a
"whitelist" file?

(accept --recipient keys only if they are contained in the file, --list-keys
shows only keys listed in this file, --refresh-keys only refreshes keys listed
here, etc.)

FWIW I strongly disagree with the sentiment that GPGME should be a "dumbed down" "Easy" GnuPG API. It should be GnuPG made stable -> A stable and reliable C API for the Free Software OpenPGP implementation GnuPG. But this is off topic. SCNR. It's much easier just to use process calls in many cases but I understand why this should not be done and leads to maintenance problems / bugs.

I think we are talking "aneinander vorbei". AFAIK we agreed (on the Osnabrück meeting) that we will cater to this usecase: Multiple different keyrings for some operations. Or "curated" keyring. Through GPGK and so we will have some API (key probably not a keyring for a context) like this in GPGME at some point in the next years. This is why I think this issue might be kept open to say: Yes we see the usecase but we will not solve it by exposing, what you call a hack, through GPGME. But we will solve it at some point with a better solution.

Well, this will be a different thing and more related to the to-be-implemented key origin feature.
I would thus suggest to open a new task for this.

Did anything get implemented to handle this? We have a central network file share where we store our public and secret key rings. We have several different applications that access these key rings. I'm trying to convert one of them from using gpg.exe via the command line with the --keyring and --secret-keyring paramters to using gpgme, but I don't see a way to specify the keyrings. Any help would be appreciated.

This is not really what the issue here is talking about. This issue was about "merging" multiple keyrings into a single view. If I understand you correctly you want to have matching pubrings and secret key directories for different applications. That is fully covered and what many users do by setting GNUPGHOME through the environment, the --homedir option or the windows registry.

So if I have \MyDirectory\pubring.pgp and MyDirectory\secring.pgp files, how do I use the --homedir option to access those?

secring.gpg is only used by unsupported legacy versions of GnuPG. Since 2.1 it is not anymore used.

Please don't replace single files from the GnuPG home directory. Use

--export --export-options backup
--import  --import-options restore

To copy public keys to a different installation. The easiest way to specify the home direcory is by using

GNUPGHOME=/home/foo/.my-other-gnupg-keys
export GNUPGHOME

or

GNUPGHOME=/home/foo/.my-other-gnupg-keys  kleopatra