[Nix-dev] Using a smartcard with GPG

[Nikita Karetnikov]

Since NixOS is an unusual system, I’ve decided to ask here before
talking to the GnuPG people.

How can I access a smart card?  'pccardctl'
(see https://github.com/NixOS/nixpkgs/pull/6172) detects it:

$ /nix/store/dwibbrcls43c0bxkcj52qj6mi8xipd6a-pcmciautils-017/bin/pccardctl ls
Socket 0 Bridge:   	[yenta_cardbus] 	(bus ID: 0000:05:00.0)
Socket 0 Device 0:	[cm4040_cs]		(bus ID: 0.0)

$ /nix/store/dwibbrcls43c0bxkcj52qj6mi8xipd6a-pcmciautils-017/bin/pccardctl status
Socket 0:
  5.0V 16-bit PC Card
  Subdevice 0 (function 0) bound to driver "cm4040_cs"

$ /nix/store/dwibbrcls43c0bxkcj52qj6mi8xipd6a-pcmciautils-017/bin/pccardctl ident
Socket 0:
  product info: "OMNIKEY", "CardMan 4040", "", ""
  manfid: 0x0223, 0x0200

I've tried adding the following lines to 'configuration.nix' as
suggested in
https://bugs.launchpad.net/ubuntu/+source/gnupg/+bug/107337, but it
doesn't make a difference:

  services.udev.extraRules =
    ''
	SUBSYSTEM=="cardman_4040", GROUP="scard", MODE="0660"
	'';

  users.extraGroups = { sdcard = { }; };
  users.extraGroups.sdcard.members = [ "nikita" ];

After switching to the new config and rebooting:

$ ls -l /dev/cmx0
crw-rw---- 1 root root 248, 0 Feb  5 16:45 /dev/cmx0

$ gpg2 --card-edit

scdaemon[2242]: error sending PC/SC OPEN request: Broken pipe
scdaemon[2242]: error sending PC/SC OPEN request: Broken pipe
gpg: selecting openpgp failed: Card error
gpg: OpenPGP card not available: Card error

With ‘sudo’:

$ sudo gpg2 --card-status
gpg: selecting openpgp failed: Card not present
gpg: OpenPGP card not available: Card not present
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