We have received a bug report from a user, which I am going to post, since it accurately describes the problem:
> My hardware token (YubiKey NEO) has several applets, including PIV and OpenPGP. Needless to say, I need and use both of them.
> On Mac OS X, tokend connects to the token immediately upon its insertion, which is necessary to present the token as a (PIV) keychain in the Keychain Access, and make its keys/certificates otherwise available to the Mac OS X applications.
> However, when I try to use gpg, or any component of GPGTools that needs access to this token (to its OpenPGP applet), this tool detects that the token is already being used - and refuses to connect to it, with the following messages in the /tmp/scdaemon.log:
> 016-09-06 21:09:24 scdaemon[67807] PC/SC OPEN failed: sharing violation (0x8010000b)
> 2016-09-06 21:09:24 scdaemon[67807] PC/SC OPEN failed: sharing violation (0x8010000b)
> 2016-09-06 21:09:33 scdaemon[67807] PC/SC OPEN failed: sharing violation (0x8010000b)
> Expected
> I would expect and like sharing - especially since they share the “token” but not the “applet”: PIV applications cannot use OpenPGP interface, and vs. versa (I think).
> I know about the design ideology (security concerns), but this kills usability, particularly with Apple Mail, where I need to process both PGP-protected and S/MIME-protected emails (obviously from different crowds, but that is not relevant).
> Same applies to Thunderbird, except there is no tokend involved - just inability of GPG Suite to share the token with PIV suite. I’d like it remedied.
> Additional info
> There is a workaround - but it is ugly: insert the token, start Apple Mail, process all the S/MIME emails. Quit Mail, kill OpenSC.tokend. Run “gpg2 —card-status” (assuming it connects and provides expected result). Start Mail, process PGP/MIME emails. Quit Mail, remove the token, re-insert it - now PIV and S/MIME are functioning again.
> Ugly as a mule. Can you please either remove this restriction, or better yet - add a configuration parameter that would allow token sharing?
Seems in 2005 the same bug has been filed for Windows OS: https://dev.gnupg.org/T412
A workaround is documented here: https://www.nitrokey.com/documentation/frequently-asked-questions#how-to-make-gnupg-release-exclusive-smartcard-access
Seems Jan (nitrokey) has requested this in 2015: https://lists.gnupg.org/pipermail/gnupg-devel/2015-August/030245.html
Also discussed in the OpenSC tracker 2017: https://github.com/OpenSC/OpenSC/issues/953