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tsaitgaist, 09/24/2019 02:38 PM
typo


Cardem

Card emulation (cardem for short) is a firmware for the SIMtrace v2 board allowing to emulate cards (e.g. SIM).
You then can leave the card adapter cable in the reader (e.g. phone), and have the actual card outside.
This allows to easily change or reprogram the card without having to touch the phone.

This functionality is already implemented and working on sysmoQMOD board.
It is now also available for SIMtrace v2 boards.
This is a beta firmware and still in development.
See limitations for known limitations and issues.

Flashing

You can download the beta firmware for the SIMtrace v2 board here: simtrace-cardem-dfu.bin.

To flash the firmware on the board:

sudo dfu-util --device 1d50:60e3 --cfg 1 --alt 1 --reset --download simtrace-cardem-dfu.bin

For more details about the flashing procedure, read this article.

Software

With the cardem firmware, the SIMtrace v2 board mainly forwards the ISO 7816 card communication over USB.
A software on the host must receive the APDU requests and send the corresponding APDU response.
There are several software available to do that.
Since the USB messages are specified and the software is open source, you could implement your own APDU handler.

simtrace2-remsim

simtrace2-remsim is the simplest solution.
If forwards the APDU request/response to/from a PCSC card reader.

To get simtrace2-remsim:
  • Install required packages to compile the software:
    sudo apt-get install libusb-1.0-0-dev libosmocore-dev libpcsclite-dev
    
  • Get and compile the software:
    git clone git://git.osmocom.org/simtrace2.git
    cd simtrace2/host/
    make
    
To use simtrace2-remsim:
  1. power off phone
  2. insert card adapter cable into phone
  3. insert card adapter cable SIMtrace v2 board
  4. plug SIMtrace v2 board in host computer USB port
  5. connect external card reader to host (any USB CCID reader should do the job)
  6. install PCSC daemon (only needs to be done once)
    sudo apt install pcscd
    
  7. ensure the PCSC daemon is started
    sudo systemctl start pcscd
    
  8. install tool to check reader status
    sudo apt install pcsc-tools
    
  9. check if the card is detected by the reader (use CTRL-C to exit)
    pcsc_scan 
    
    Using reader plug'n play mechanism
    Scanning present readers...
    0: OMNIKEY 6321 CLi USB (OKCM0030506091345044320140749730) 00 00
    
    Tue Sep 10 16:03:49 2019
     Reader 0: OMNIKEY 6321 CLi USB (OKCM0030506091345044320140749730) 00 00
      Event number: 0
      Card state: Card inserted, 
      ATR: 3B 9F 94 80 1F C7 80 31 E0 73 FE 21 1B 67 01 00 00 04 4D 02 01 99
    
  10. get SIMtrace USB path (this step will soon be not required anymore)
    dfu-util -l
    
    ...
    Found Runtime: [1d50:60e3] ver=0002, devnum=59, cfg=1, intf=1, path="1-2.2", alt=0, name="UNKNOWN", serial="UNKNOWN" 
    
  11. start simtrace2-remsim with corresponding USB path (here 1-2.2)
    ./simtrace2-remsim --usb-vendor 1d50 --usb-product 60e3 --usb-path 1-2.2 --usb-config 1
    
    (C) 2010-2017, Harald Welte <laforge@gnumonks.org>
    (C) 2018, sysmocom -s.f.m.c. GmbH, Author: Kevin Redon <kredon@sysmocom.de>
    
    SCardEstablishContext: OK
    
    SCardListReaders: OK
    
    SCardConnect: OK
    
    <- 01 05 00 00 00 00 09 00 01 
    <- 02 02 00 00 00 00 09 00 01 
    <= cardem_request_set_atr(3b 00 )
    <- 01 02 00 00 00 00 0b 00 02 3b 00 
    <- 02 01 00 00 00 00 0b 00 02 2c 01 
    Entering main loop
    
  12. now you can power on the phone (only after simtrace2-remsim is started since simtrace2-remsim can't tell the phone a card has been inserted). you should also see some APDU traffic
    URB: 01 06 00 00 00 00 13 00 01 00 00 00 05 00 a0 a4 00 00 02 
    -> 01 06 00 00 00 00 13 00 01 00 00 00 05 00 a0 a4 00 00 02 
    => DATA: flags=1, a0 a4 00 00 02 : CLA=a0 INS=a4 P1=00 P2=00 P3=02; case=4, lc=2(0), le=0(0)
    <= cardem_request_pb_and_rx(a4, 2)
    <- 01 01 00 00 00 00 0f 00 08 00 00 00 01 00 a4 
    URB: 01 06 00 00 00 00 10 00 02 00 00 00 02 00 7f 20 
    -> 01 06 00 00 00 00 10 00 02 00 00 00 02 00 7f 20 
    => DATA: flags=2, 7f 20 : CLA=a0 INS=a4 P1=00 P2=00 P3=02; case=4, lc=2(2), le=0(0)
    TX: a0 a4 00 00 02 7f 20 
    SCardEndTransaction: OK
    
    RX: 9f 17 
    SW=0x9f17, len_rx=0
    <= cardem_request_sw_tx(9f 17)
    <- 01 01 00 00 00 00 10 00 06 00 00 00 02 00 9f 17 
    URB: 01 06 00 00 00 00 13 00 01 00 00 00 05 00 a0 f2 00 00 17 
    -> 01 06 00 00 00 00 13 00 01 00 00 00 05 00 a0 f2 00 00 17 
    => DATA: flags=1, a0 f2 00 00 17 : CLA=a0 INS=f2 P1=00 P2=00 P3=17; case=2, lc=0(0), le=23(0)
    TX: a0 f2 00 00 17 
    SCardEndTransaction: OK
    

osmo-remsim

osmo-remsim is a separate project allowing to have the card/SIM at a different location than the modem/phone. It also allows to manage multiple cards and emulators. The setup is a bit more complicated though.

  1. add the osmo-remsim repository on each host you want to operator parts of osmo-remsim (so you don't have to compile osmo-remsim yourself)
  2. osmo-remsim uses PCSC to access card readers (this setup only needs to be done once)
    • connect external card readers to host (any USB CCID reader should do the job)
    • install PCSC daemon (will also be needed on the host which will run the bankd)
      sudo apt install pcscd
      
    • ensure the PCSC daemon is started
      sudo systemctl start pcscd
      
    • install tool to get reader name
      sudo apt install pcsc-tools
      
    • get reader name (use CTRL-C to exit)
      pcsc_scan 
      
      Using reader plug'n play mechanism
      Scanning present readers...
      0: OMNIKEY 6321 CLi USB (OKCM0030506091345044320140749730) 00 00
      
    • create a bankd_pcsc_slots.csv file listing the card readers osmo-remsim should use. The CSV format is: user provided bank number (collection of readers/slots), user provided slot number (individual card in reader/bank), PCSC reader name.
      echo << EOF > bankd_pcsc_slots.csv
      "1","1","OMNIKEY 6321 CLi USB (OKCM0030506091345044320140749730) 00 00" 
      EOF
      
  3. run the server. This is the central instance telling the bankd which reader to use, and the client which bankd to contact.
    • install osmo-remsim-server:
      sudo apt install osmo-remsim-server
      
    • run server (the bankd_pcsc_slots.csv file must be in the current working directory)
      osmo-remsim-server
      
  4. the server needs to be additionally configured through its RESTful interface. For that we will use the small tool remsim-apitool.py
    • download remsim-apitool.py
      wget https://git.osmocom.org/osmo-remsim/plain/contrib/remsim-apitool.py
      
    • tell the server client 1 with slot 1 (on the modem side) should use bank 1 slot 1 (on the reader side). This must be done every time after to server is started.
      python remsim-apitool.py --create-slotmap 1 1 1 1
      
  5. run the bankd. This will contact the server (which can be on another host) to know which card reader it will manage.
    • install PCSC daemon (if not already done)
      sudo apt install pcscd
      
    • ensure the PCSC daemon is started
      sudo systemctl start pcscd
      
    • install osmo-remsim-bankd:
      sudo apt install osmo-remsim-bankd
      
    • here we tell it will take care of the card reader from bank 1.
      osmo-remsim-bankd --server-host localhost --server-port 9998 --bank-id 1
      
  6. now we need to actually emulate the card
    • power off phone
    • insert card adapter cable into phone
    • insert card adapter cable SIMtrace v2 board
    • plug SIMtrace v2 board in host computer USB port
    • install osmo-remsim-client:
      sudo apt install osmo-remsim-client
      
    • get SIMtrace USB path (this step will soon be not required anymore)
      dfu-util -l
      
      ...
      Found Runtime: [1d50:60e3] ver=0002, devnum=59, cfg=1, intf=1, path="1-2.2", alt=0, name="UNKNOWN", serial="UNKNOWN" 
      
    • start the osmo-remsim-client-st2 client with corresponding USB path (here 1-2.2). This will contact the server (which can be on another host) to know which bankd to contact. Here we tell it will take care of slot 1 of modem 1 (SIMtrace can only emulate one card).
      osmo-remsim-client-st2 --usb-vendor 1d50 --usb-product 60e3 --usb-path 1-2.2 --usb-config 1 --client-id 1 --client-slot 1 --server-host localhost --server-port 9998
      
    • you can now power on the phone, and should see some APDU traffic on the client and bankd.

Limitations

Here are the known limitations:
  • there is no way for SIMtrace to tell the reader that a new card has been inserted. There is no specified way to do it (e.g. in ISO 7816 standard). This is generally done inside the reader hardware by a mechanical switch. The only way around is to restarted the reader (e.g. phone).
  • the cardem is currently a separate firmware. it is planned to combine it with the trace firmware (the software will then select the right functionality)
  • the firmware ignores the sent ATR (sent by the software, from the card to forward). this is to prevent the reader from switching to a yet untested baud rate
  • the error messages returned by simtrace2-remsim are not very useful
  • simtrace2-remsim does not automatically reconnect to the SIMtrace board when the hardware is reset
  • you have to specify the USB path to simtrace2-remsim
  • no long term tests have been performed (this is already planned)
  • you can't use the card reader built in SIMtrace
  • simtrace2-remsim does not send the APDU to GSMTAP so you can trace the traffic using wireshark
  • simtrace2-remsim-udp does not connect to SIMtrace v2 boards

We are currently working on resolving these issues.
If you found yet unknown issues, you can report them to the main developer at kredon AT sysmocom DOT de.
If possible, please also attach the corresponding debug serial output. To get the serial output, connect a USB to UART cable either to the 2.5 mm stereo headphone connector (tip = TX, ring = RX, sleeve = GND) or the nearby DEBUG port (pin 1 = GND, pin 4 = TX, pin 5 = RX). Open the serial port with the following configuration: 921600 8N1.

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