Installing Gnuk on FST-01G running NeuG

The FST-01G device that you order from the FSF shop runs NeuG. To be able to use the device as a OpenPGP smartcard, you need to install Gnuk. While Niibe covers this on his tutorial, I found the steps a bit complicated to follow. The following guides you from buying the device to getting a FST-01G running Gnuk ready for use with GnuPG.

Once you have received the device and inserted it into a USB port, your kernel log (sudo dmesg) will show something like the following:

[628772.874658] usb 1-1.5.1: New USB device found, idVendor=234b, idProduct=0004
[628772.874663] usb 1-1.5.1: New USB device strings: Mfr=1, Product=2, SerialNumber=3
[628772.874666] usb 1-1.5.1: Product: Fraucheky
[628772.874669] usb 1-1.5.1: Manufacturer: Free Software Initiative of Japan
[628772.874671] usb 1-1.5.1: SerialNumber: FSIJ-0.0
[628772.875204] usb-storage 1-1.5.1:1.0: USB Mass Storage device detected
[628772.875452] scsi host6: usb-storage 1-1.5.1:1.0
[628773.886539] scsi 6:0:0:0: Direct-Access     FSIJ     Fraucheky        1.0  PQ: 0 ANSI: 0
[628773.887522] sd 6:0:0:0: Attached scsi generic sg2 type 0
[628773.888931] sd 6:0:0:0: [sdb] 128 512-byte logical blocks: (65.5 kB/64.0 KiB)
[628773.889558] sd 6:0:0:0: [sdb] Write Protect is off
[628773.889564] sd 6:0:0:0: [sdb] Mode Sense: 03 00 00 00
[628773.890305] sd 6:0:0:0: [sdb] No Caching mode page found
[628773.890314] sd 6:0:0:0: [sdb] Assuming drive cache: write through
[628773.902617]  sdb:
[628773.906066] sd 6:0:0:0: [sdb] Attached SCSI removable disk

The device comes up as a USB mass storage device. Conveniently, it contain documentation describing what it is, and you identify the version of NeuG it runs as follows.

jas@latte:~/src/gnuk$ head /media/jas/Fraucheky/README 
NeuG - a true random number generator implementation (for STM32F103)

							  Version 1.0.7
							     2018-01-19
						           Niibe Yutaka
				      Free Software Initiative of Japan

To convert the device into the serial-mode that is required for the software upgrade, use the eject command for the device (above it came up as /dev/sdb): sudo eject /dev/sdb. The kernel log will now contain something like this:

[628966.847387] usb 1-1.5.1: reset full-speed USB device number 27 using ehci-pci
[628966.955723] usb 1-1.5.1: device firmware changed
[628966.956184] usb 1-1.5.1: USB disconnect, device number 27
[628967.115322] usb 1-1.5.1: new full-speed USB device number 28 using ehci-pci
[628967.233272] usb 1-1.5.1: New USB device found, idVendor=234b, idProduct=0001
[628967.233277] usb 1-1.5.1: New USB device strings: Mfr=1, Product=2, SerialNumber=3
[628967.233280] usb 1-1.5.1: Product: NeuG True RNG
[628967.233283] usb 1-1.5.1: Manufacturer: Free Software Initiative of Japan
[628967.233286] usb 1-1.5.1: SerialNumber: FSIJ-1.0.7-67252015
[628967.234034] cdc_acm 1-1.5.1:1.0: ttyACM0: USB ACM device

The strings NeuG True RNG and FSIJ-1.0.7 suggest it is running NeuG version 1.0.7.

Now both Gnuk itself and reGNUal needs to be built, as follows. If you get any error message, you likely don’t have the necessary dependencies installed.

jas@latte:~/src$ git clone https://salsa.debian.org/gnuk-team/gnuk/neug.git
jas@latte:~/src$ git clone https://salsa.debian.org/gnuk-team/gnuk/gnuk.git
jas@latte:~/src$ cd gnuk/src/
jas@latte:~/src/gnuk/src$ git submodule update --init
jas@latte:~/src/gnuk/src$ ./configure --vidpid=234b:0000
...
jas@latte:~/src/gnuk/src$ make
...
jas@latte:~/src/gnuk/src$ cd ../regnual/
jas@latte:~/src/gnuk/regnual$ make
jas@latte:~/src/gnuk/regnual$ cd ../../

You are now ready to flash the device, as follows.

jas@latte:~/src$ sudo neug/tool/neug_upgrade.py -f gnuk/regnual/regnual.bin gnuk/src/build/gnuk.bin 
gnuk/regnual/regnual.bin: 4544
gnuk/src/build/gnuk.bin: 113664
CRC32: 931cab51

Device: 
Configuration: 1
Interface: 1
20000e00:20005000
Downloading flash upgrade program...
start 20000e00
end   20001f00
# 20001f00: 31 : 196
Run flash upgrade program...
Wait 3 seconds...
Device: 
08001000:08020000
Downloading the program
start 08001000
end   0801bc00
jas@latte:~/src$ 

Remove and insert the device and the kernel log should contain something like this:

[629120.399875] usb 1-1.5.1: new full-speed USB device number 32 using ehci-pci
[629120.511003] usb 1-1.5.1: New USB device found, idVendor=234b, idProduct=0000
[629120.511008] usb 1-1.5.1: New USB device strings: Mfr=1, Product=2, SerialNumber=3
[629120.511011] usb 1-1.5.1: Product: Gnuk Token
[629120.511014] usb 1-1.5.1: Manufacturer: Free Software Initiative of Japan
[629120.511017] usb 1-1.5.1: SerialNumber: FSIJ-1.2.14-67252015

The device can now be used with GnuPG as a smartcard device.

jas@latte:~/src/gnuk$ gpg --card-status
Reader ...........: 234B:0000:FSIJ-1.2.14-67252015:0
Application ID ...: D276000124010200FFFE672520150000
Version ..........: 2.0
Manufacturer .....: unmanaged S/N range
Serial number ....: 67252015
Name of cardholder: [not set]
Language prefs ...: [not set]
Sex ..............: unspecified
URL of public key : [not set]
Login data .......: [not set]
Signature PIN ....: forced
Key attributes ...: rsa2048 rsa2048 rsa2048
Max. PIN lengths .: 127 127 127
PIN retry counter : 3 3 3
Signature counter : 0
Signature key ....: [none]
Encryption key....: [none]
Authentication key: [none]
General key info..: [none]
jas@latte:~/src/gnuk$ 

Congratulations!

OpenPGP Smartcards and GNOME

The combination of GnuPG and a OpenPGP smartcard (such as the YubiKey NEO) has been implemented and working well for around a decade. I recall starting to use it when I received a FSFE Fellowship card long time ago. Sadly there has been some regressions when using them under GNOME recently. I reinstalled my laptop with Debian Jessie (beta2) recently, and now took the time to work through the issue and write down a workaround.

To work with GnuPG and smartcards you install GnuPG agent, scdaemon, pscsd and pcsc-tools. On Debian you can do it like this:

apt-get install gnupg-agent scdaemon pcscd pcsc-tools

Use the pcsc_scan command line tool to make sure pcscd recognize the smartcard before continuing, if that doesn’t recognize the smartcard nothing beyond this point will work. The next step is to make sure you have the following line in ~/.gnupg/gpg.conf:

use-agent

Logging out and into GNOME should start gpg-agent for you, through the /etc/X11/Xsession.d/90gpg-agent script. In theory, this should be all that is required. However, when you start a terminal and attempt to use the smartcard through GnuPG you would get an error like this:

jas@latte:~$ gpg --card-status
gpg: selecting openpgp failed: unknown command
gpg: OpenPGP card not available: general error
jas@latte:~$

The reason is that the GNOME Keyring hijacks the GnuPG agent’s environment variables and effectively replaces gpg-agent with gnome-keyring-daemon which does not support smartcard commands (Debian bug #773304). GnuPG uses the environment variable GPG_AGENT_INFO to find the location of the agent socket, and when the GNOME Keyring is active it will typically look like this:

jas@latte:~$ echo $GPG_AGENT_INFO 
/run/user/1000/keyring/gpg:0:1
jas@latte:~$ 

If you use GnuPG with a smartcard, I recommend to disable GNOME Keyring’s GnuPG and SSH agent emulation code. This used to be easy to achieve in older GNOME releases (e.g., the one included in Debian Wheezy), through the gnome-session-properties GUI. Sadly there is no longer any GUI for disabling this functionality (Debian bug #760102). The GNOME Keyring GnuPG/SSH agent replacement functionality is invoked through the XDG autostart mechanism, and the documented way to disable system-wide services for a normal user account is to invoke the following commands.

jas@latte:~$ mkdir ~/.config/autostart
jas@latte:~$ cp /etc/xdg/autostart/gnome-keyring-gpg.desktop ~/.config/autostart/
jas@latte:~$ echo 'Hidden=true' >> ~/.config/autostart/gnome-keyring-gpg.desktop 
jas@latte:~$ cp /etc/xdg/autostart/gnome-keyring-ssh.desktop ~/.config/autostart/
jas@latte:~$ echo 'Hidden=true' >> ~/.config/autostart/gnome-keyring-ssh.desktop 
jas@latte:~$ 

You now need to logout and login again. When you start a terminal, you can look at the GPG_AGENT_INFO environment variable again and everything should be working again.

jas@latte:~$ echo $GPG_AGENT_INFO 
/tmp/gpg-dqR4L7/S.gpg-agent:1890:1
jas@latte:~$ echo $SSH_AUTH_SOCK 
/tmp/gpg-54VfLs/S.gpg-agent.ssh
jas@latte:~$ gpg --card-status
Application ID ...: D2760001240102000060000000420000
...
jas@latte:~$ ssh-add -L
ssh-rsa AAAAB3NzaC1yc2EAAAADAQABAAABAQDFP+UOTZJ+OXydpmbKmdGOVoJJz8se7lMs139T+TNLryk3EEWF+GqbB4VgzxzrGjwAMSjeQkAMb7Sbn+VpbJf1JDPFBHoYJQmg6CX4kFRaGZT6DHbYjgia59WkdkEYTtB7KPkbFWleo/RZT2u3f8eTedrP7dhSX0azN0lDuu/wBrwedzSV+AiPr10rQaCTp1V8sKbhz5ryOXHQW0Gcps6JraRzMW+ooKFX3lPq0pZa7qL9F6sE4sDFvtOdbRJoZS1b88aZrENGx8KSrcMzARq9UBn1plsEG4/3BRv/BgHHaF+d97by52R0VVyIXpLlkdp1Uk4D9cQptgaH4UAyI1vr cardno:006000000042
jas@latte:~$ 

That’s it. Resolving this properly involves 1) adding smartcard code to the GNOME Keyring, 2) disabling the GnuPG/SSH replacement code in GNOME Keyring completely, 3) reorder the startup so that gpg-agent supersedes gnome-keyring-daemon instead of vice versa, so that people who installed the gpg-agent really gets it instead of the GNOME default, or 4) something else. I don’t have a strong opinion on how to solve this, but 3) sounds like a simple way forward.