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Revision as of 11:38, 19 November 2011


Prepare your Smartcard

Install the ccid package and start the pcscd daemon. Insert your smartcard reader and check the output of gpg --card-status

Creating the master key

Run gpg --card-edit. Type in admin to enabled administration functions. All available commands can now be listed by issuing the help command. Use the name and sex commands to set some unimportant meta data.

To create a new key pair just type in generate. Create a 3072 Bits key that does not expire and enter your data according to this example:

Real name: Pierre Schmitz
Email address: pierre@master-key.archlinux.org
Comment: Arch Linux Master Key

Confirm that your USER-ID looks like "Pierre Schmitz (Arch Linux Master Key) <pierre@master-key.archlinux.org>". Generating the key will take some time. Note that the encryption key will be reduced to 1024 Bits.

If you created a backup of your key during creation you should secure it on an offline device and remove the key from your hard drive. E.g. use shred:

shred -u /home/pierre/.gnupg/sk_8DFDBF1F86872C2F.gpg

Now create a revoke key:

gpg -o master-key-revoke.asc --gen-revoke 6AC6A4C2

Choose no reason (0) if you are asked for one. Make sure to save this key on a secure and offline device (e.g. print it or use a thumb drive).

Signing the master key

Sign the master key using your packager key. For example using the master key id:

gpg --sign-key 6AC6A4C2

Double check you are using the right keys here!

Upload your master key now using:

gpg --send-keys 6AC6A4C2

You may also want to create a copy of your public key to publish elsewhere:

gpg --export --armor 6AC6A4C2 > pierre@master-key.archlinux.org.asc

Signing your own packager key

As you should trust yourself the most, just go ahead and sign your own packager key:

gpg --sign-key -u 6AC6A4C2 9741E8AC

Note that in this example your master key id is first and your packager key id last.

Upload your public key using:

gpg --send-keys 9741E8AC

Revoking a master key

Signing developer keys

Revoking developer keys

Open questions

  • Using the smartcard generates following errors without any apparent effect:
libusb couldn't open USB device /dev/bus/usb/001/006: Permission denied.
libusb requires write access to USB device nodes.

Cause: gnupg has an internal ccid driver. This driver accesses the USB device node directly, without going through pcscd. However, gnupg's internal driver does not support the Gemalto USB reader anyway, so this message can be ignored.

  • udev/packaging issue:
udevd[273]: specified group 'pcscd' unknown

This is unproblematic: the pcscd daemon runs as root.

  • Should we advice to create a backup during key creation or rather not?
  • Is the passphrase only used for the backup key?
  • Is the public key also stored on the card?

It probably is, but there is no apparent way to obtain it. Export it to some keyserver quickly.

  • How should the url configuration be set?

A string pointing to a URL that stores your pubkey.

  • What is the impact of setting forcesig?

If you enable forcesig, you must enter the PIN for each single signature. This is recommended.

External documentation

http://wiki.debian.org/Smartcards/OpenPGP