Gnuk - software for GPG USB Token

							   Version 0.11
							     2011-04-15
						           Niibe Yutaka
				      Free Software Initiative of Japan

What's Gnuk?
============

Gnuk is software implementation of a USB token for GNU Privacy Guard.
Gnuk supports OpenPGP card protocol version 2, and it runs on STM32
processor.

I wish that Gnuk will be a developer's soother who uses GnuPG.  I have
been nervous of storing secret key(s) on usual secondary storage.
While I want to work at different places, but it is not the choice for
me to bring a card reader all the time.  With Gnuk, this issue will be
solved by a USB token which is small enough.

Please look at the graphics of "gnuk.svg" for the software name.  My
son used to be with his NUK(R), always, everywhere.  I will be with a
USB Token by "Gnuk" everywhere.


FAQ
===

Q1: What's kind of key algorithm is supported?
A1: Gnuk only supports 2048-bit RSA.

Q2: How long does it take for digital signing?
A2: It takes two seconds or so. 

Q3: What's your recommendation for target board?
A3: Orthodox choice is Olimex STM32-H103.
    If you have skill of electronics and like DIY, STM32 part of STM8S
    Discovery Kit might be the best choice.

Q4: What's version of GnuPG are you using?
A4: In Debian GNU/Linux system, I use GnuPG 2.0.14-2 (in sid).

Q5: What's version of pcscd and libccid are you using?
A5: In Debian GNU/Linux system, I use pcscd 1.5.5-4 and libccid 1.3.11-2,
    which is in squeeze.  Note that you need to edit /etc/libccid_Info.plist
    when using libccid (< 1.4.1).

Q6: What kinds of hardware is required for development?
A6: You need a target board plus JTAG debugger.  If you just want to
    test Gnuk for target boards with DfuSe, JTAG debugger is not
    the requirement.  Note that for real use, you need JTAG debugger
    to enable flash ROM protection.


Release notes
=============

This is twelfth release of Gnuk.  While it works well for specific
usages and it is considered stable, it is still somewhat experimental.
Note that you need to write random bits after installation of gnuk
executable to the chip.  This procedure is required to share a single
executable among multiple devices.

Tested features are:

	* Personalization of the card

	  * Changing Login name, URL, Name, Sex, Language, etc.

	* Password handling (PW1, RC, PW3)

	* Key import for three types:

	  * key for digital signing

	  * key for decryption

	  * key for authentication

	* PSO: Digital Signature

	* PSO: Decipher

	* INTERNAL AUTHENTICATE

	* Changing value of password status bytes (0x00C4)

	* Verify with pin pad

	* Modify with pin pad

It is known not-working well:

	* For some version of kernel and libccid, --enable-debug can't
          work well.  Please disable DEBUG option if it doesn't work well.

	* Card holder certificate
	  It is implemented in Gnuk side.  But its size matters (>
	  1KB).  GnuPG cannot handle a data object of large size with
	  PC/SC backend.  Specifically, handle_transmit function in
	  pcsc-wrapper.c uses the buffer of size 1024-byte.

Not supported feature(s):

	* Overriding key import.  You need to remove all keys first.

	* Key generation


Targets
=======

We use Olimex STM32-H103 board.  We also use STM32 part of STM8S
Discovery Kit.

With DfuSe support, CQ STARM, STBee, and STBee Mini are also our
targets.  But those targets with DfuSe are basically not for normal
use but for experiments, because it would be impossible for DfuSe to
disable read from flash.  For real use, please consider killing DfuSe
and enable read protection using JTAG debugger.

I think that it could run on Olimex STM32-P103, or other boards with
STM32F103.  Besides, we are porting it to STM32 Primer 2.

For PIN-pad support, I connect a consumer IR receive module to STBee
Mini and STM8S Discovery Kit, and use controller for TV.  PIN
verification is supported by this configuration.  Yes, it is not
secure at all, since it is very easy to monitor IR output of the
controllers.  It is just an experiment.  Note that hardware needed for
this experiment is only a consumer IR receive module which is as cheap
as 50 JPY.

Another PIN-pad support is connecting rotary encoder, push switch and
7-segment LED display.  Both of PIN verification and PIN modification
are supported for this circuit extension.


Souce code
==========

Gnuk source code is under src/ directory.


License
=======

It is distributed under GNU General Public Licence version 3 or later
(GPLv3+).  Please see src/COPYING.

Please note that it is distributed with external source code too.
Please read relevant licenses for external source code, too.

The author(s) of Gnuk expect users of Gnuk will be able to access the
source code of Gnuk, so that users can study the code and can modify
if needed.  This doesn't mean person who has a USB Token by Gnuk
should be able to acess everything on the Token, regardless of its
protections.  Private keys, random bytes, and other information should
be protected properly.


External source code
====================

Gnuk is distributed with external source code.

* ChibiOS_2.0.8/  -- ChibiOS/RT 2.0.8

  Taken from http://chibios.sourceforge.net/
  Note that CRLF is converted to LF in this repository.
  We use ChibiOS/RT as the kernel for Gnuk.

* polarssl-0.14.0/  -- PolarSSL 0.14.0

  Taken from http://polarssl.org/
  We use PolarSSL for RSA computation, AES encryption/decryption
  and SHA-1 computation.

* STM32_USB-FS-Device_Driver/ -- a part of USB-FS-Device_Lib
* Virtual_COM_Port/ -- a part of USB-FS-Device_Lib

  STM32F10x USB Full Speed Device Library (USB-FS-Device_Lib)
  is a STM32F10x library for USB functionality.

  I took Libraries/STM32_USB-FS-Device_Driver and 
  Project/Virtual_COM_Port in STM32_USB-FS-Device_Lib distribution.
  See http://www.st.com/ for detail.


Host Requirements
=================

For GNU/Linux, libccid version >= 1.3.11 is required.
libccid version == 1.3.9 is known not working well by the issue [r4235].

I think that it should not be requirment but the kernel version of my use is:
Linux version 2.6.32-5-686 (Debian 2.6.32-18) (ben@decadent.org.uk) (gcc version 4.3.5 (Debian 4.3.5-2) ) #1 SMP Sat Jul 24 02:27:10 UTC 2010

Linux 2.6.30 is known *NOT* working well with DEBUG option.
Linux 2.6.24 is known working well with DEBUG option.


How to compile
==============

You need GNU toolchain and newlib for 'arm-none-eabi' target.

See http://github.com/esden/summon-arm-toolchain/ for preparation of
GNU Toolchain for 'arm-none-eabi' target.

Change directory to `src':

  $ cd gnuk-VERSION/src

Then, run `configure':

  $ ./configure

Type:

  $ make

Then, we will have "gnuk.elf".


How to install
==============

Olimex STM32-H103 board
-----------------------

If you are using Olimex JTAG-Tiny, type following to invoke OpenOCD:

  $ openocd -f interface/olimex-jtag-tiny.cfg -f board/olimex_stm32_h103.cfg

Then, with another terminal, type following to write "gnuk.elf" to Flash ROM:

  $ telnet localhost 4444
  > reset halt
  > flash write_image erase gnuk.elf
  > reset
  > exit
  $ 


STM8S Discovery Kit
-------------------

If you are using FTDI-2232D module and the connection is standard, type:

  $ openocd -f interface/openocd-usb.cfg -f target/stm32.cfg

Initially, the flash ROM of the chip is protected.  you need to do:

  $ telnet localhost 4444
  > reset halt
  > stm32x unlock 0
  > reset
  > shutdown
  $ 

and re-connect the board.  Note that power-off / power-on sequence is
required to reset flash ROM.

Then, invoke OpenOCD again and telnet to connect OpenCD and write
image as above example of Olimex STM32-H103.


CQ STARM
--------

Put jumper for J6 to enable DfuSe.  Connecting the board, and type:

  # cd ../tool
  # ./dfuse.py ../src/gnuk.hex

Then, remove the jumper and reset the board.


STBee and STBee Mini
--------------------

Reset the board with "USER" switch pushed.  Type following to write
to flash:

  # cd ../tool
  # ./dfuse.py ../src/gnuk.hex

Then, reset the board.


How to protect flash ROM
========================

Invoke your OpenOCD and type:

  $ telnet localhost 4444
  > reset halt
  > stm32x lock 0
  > reset
  > shutdown

After power-off / power-on sequence, the contents of flash ROM cannot
be accessible from JTAG debugger.

Note that it would be still possible for some implementation of DfuSe
to access the contents.  If you want to protect, killing DfuSe and
accessing by JTAG debugger is recommended.


How to configure
================

You need python and PyUSB (python-usb package in Debian).

(1) In the 'src' directory, type

  $ make random_bits

In this process, it takes time for the command of

   dd if=/dev/random bs=1 of=random_bits count=1024

Don't just wait, but do some other works on your PC.
/dev/random needs entropy to finish.

(2) Stop the pcsc daemon.

  # /etc/init.d/pcscd stop

(3) Write the random bits to the device

Connect your board to USB port of your PC.  And invoke gnuk_put_binary.py:

  # ../tool/gnuk_put_binary.py -r random_bits
  random_bits: 1024
  Updating random bits
  ...

(4) [Optional] Write fixed serial number

If you use fixed serial number in the file 'GNUK_SERIAL_NUMBER', you can do:

  # EMAIL=<YOUR-EMAIL-ADDRESS> ../tool/gnuk_put_binary.py -s ../GNUK_SERIAL_NUMBER 
  Writing serial number
  ...

(5) [Optional] Write card holder certificate

If you have card holder certificate binary file, you can do:

  # ../tool/gnuk_put_binary.py ../../<YOUR-CERTIFICATE>.bin 
  ../../<YOUR-CERTIFICATE>.bin: <LENGTH-OF-YOUR-CERTIFICATE>
  Updating card holder certificate
  ...


How to run
==========

Debug enabled
-------------

If you compiled with --enable-debug option, Gnuk has two interfaces
(one is CCID/ICCD device and another is virtual COM port).  Open
virtual COM port by:

  $ cu -l /dev/ttyACM0

and you will see debug output of Gnuk.


Libccid fix needed
------------------

For libccid (< 1.4.1), we need following change:

--- /etc/libccid_Info.plist.dpkg-dist	2009-07-29 06:50:20.000000000 +0900
+++ /etc/libccid_Info.plist	2010-09-05 09:09:49.000000000 +0900
@@ -104,6 +104,7 @@
 
 	<key>ifdVendorID</key>
 	<array>
+		<string>0x234B</string>
 		<string>0x08E6</string>
 		<string>0x08E6</string>
 		<string>0x08E6</string>
@@ -237,6 +238,7 @@
 
 	<key>ifdProductID</key>
 	<array>
+		<string>0x0000</string>
 		<string>0x2202</string>
 		<string>0x3437</string>
 		<string>0x3438</string>
@@ -370,6 +372,7 @@
 
 	<key>ifdFriendlyName</key>
 	<array>
+		<string>FSIJ USB Token</string>
 		<string>Gemplus Gem e-Seal Pro</string>
 		<string>Gemplus GemPC Twin</string>
 		<string>Gemplus GemPC Key</string>
------------------

This entry has been added into libccid 1.4.1 already ([r5425]).


Testing Gnuk
------------

Try following to see Gnuk runs:

  $ gpg --card-status


For more, see doc/DEMO.



How to debug
============

We can use GDB.

  $ arm-none-eabi-gdb gnuk.elf


Inside GDB, we can connect OpenOCD by:

  (gdb) target remote localhost:3333


You can see the output of PCSCD:

  # /etc/init.d/pcscd stop
  # LIBCCID_ifdLogLevel=7 /usr/sbin/pcscd --debug --foreground


You can observe the traffic of USB using "usbmon".  See the file:
linux/Documentation/usb/usbmon.txt


Read-only Git Repository
========================

You can get it by:

  $ git clone http://www.gniibe.org/git/gnuk.git/


Information on the Web
======================

Please see: http://www.fsij.org/gnuk/


Your Contributions
==================

FSIJ welcomes your contributions.  Please assign your copyright
to FSIJ (if possible).


Foot note
==========
* NUK(R) is a registered trademark owend by MAPA GmbH, Germany.
--