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. 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 protect 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= ../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 ../../.bin ../../.bin: 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 @@ ifdVendorID + 0x234B 0x08E6 0x08E6 0x08E6 @@ -237,6 +238,7 @@ ifdProductID + 0x0000 0x2202 0x3437 0x3438 @@ -370,6 +372,7 @@ ifdFriendlyName + FSIJ USB Token Gemplus Gem e-Seal Pro Gemplus GemPC Twin Gemplus GemPC Key ------------------ 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. --