Friday, May 20, 2022

ATR parsing in JSON

I updated my ATR parsing web site at https://smartcard-atr.apdu.fr/ to add the option to get the result not in an HTML page but as a JSON document.

If you do not yet know this service you can read "Parsing an ATR: new web site URL" to get some history. 


JSON

The URL for the JSON service is https://smartcard-atr.apdu.fr/V1/parse2json?ATR=3BFF9700008131FE4380318065B0846160FB120FFD8290000D.

It is the same as for the HTML output https://smartcard-atr.apdu.fr/parse?ATR=3BFF9700008131FE4380318065B0846160FB120FFD8290000D except you replace "parse" by "V1/parse2json" in the URL.

Of course you update the ATR parameter value to use the ATR value you want to parse.

Examples

You can use it to get the description of a particular field by piping the result in the jq command.

jq is a lightweight and flexible command-line JSON processor.

For example to get the meaning of the TA1 byte you can use:

$ curl -s https://smartcard-atr.apdu.fr/V1/parse2json?ATR=3B12953606 | jq '.TA."1"'
{
  "description": "Fi=512, Di=16, 32 cycles/ETU (125000 bits/s at 4.00 MHz, 156250 bits/s for fMax=5 MHz)",
  "value": 149
}

Or for just the TA1 description:

$ curl -s https://smartcard-atr.apdu.fr/V1/parse2json?ATR=3B90160187 | jq '.TA."1".description'
"Fi=372, Di=32, 11.625 cycles/ETU (344086 bits/s at 4.00 MHz, 430107 bits/s for fMax=5 MHz)"

 

Card matching

I also added the possibility to get the cards matching a given ATR.

For example: https://smartcard-atr.apdu.fr/V1/match?ATR=3B8F800180318065B0850300EF120FFE82900072

$ curl -s https://smartcard-atr.apdu.fr/V1/match?ATR=3B8F800180318065B0850300EF120FFE82900072 | jq
{
  "3B 8F 80 01 80 31 80 65 B0 .. .. .. .. 12 0F FE 82 90 00 ..": [
    "IDPrime MD 3810 T=Contactless (Prox DU)"
  ],
  "3B 8F 80 01 80 31 80 65 B0 85 03 00 EF 12 0F FE 82 90 00 72": [
    "Gemalto IDPrime MD 3840",
    "http://www.gemalto.com/dwnld/6891_IDPrimeMD3840_Product_Datasheet_May14.pdf"
  ]
}

Because of the joker mechanism using the character '.' it is possible that one ATR matches more than one "card".


Conclusion

If you have ideas how to improve the service just tell me.

Saturday, May 14, 2022

SCardListReaders() and non-initialized pcchReaders parameter

Sample C sample

We start with the following sample.c program:

01: #include <stdio.h>
02: #include <stdlib.h>
03: #include <winscard.h>
04: 
05: #define CHECK(f, rv) \
06:  if (SCARD_S_SUCCESS != rv) \
07:  { \
08:   printf(f ": %s\n", pcsc_stringify_error(rv)); \
09:   return -1; \
10:  }
11: 
12: int main(void)
13: {
14:     LONG rv;
15: 
16:     SCARDCONTEXT hContext;
17:     LPTSTR mszReaders;
18:     DWORD dwReaders;
19: 
20:     rv = SCardEstablishContext(SCARD_SCOPE_SYSTEM, NULL, NULL, &hContext);
21:     CHECK("SCardEstablishContext", rv)
22: 
23:     rv = SCardListReaders(hContext, NULL, NULL, &dwReaders);
24:     CHECK("SCardListReaders", rv)
25: 
26:     mszReaders = calloc(dwReaders, sizeof(char));
27:     rv = SCardListReaders(hContext, NULL, mszReaders, &dwReaders);
28:     CHECK("SCardListReaders", rv)
29:     printf("1st reader name: %s\n", mszReaders);
30: 
31:     free(mszReaders);
32: 
33:     rv = SCardReleaseContext(hContext);
34:     CHECK("SCardReleaseContext", rv)
35: 
36:     return 0;
37: }
38: 

Makefile

I used this Makefile

# Linux
PCSC_CFLAGS := $(shell pkg-config --cflags libpcsclite)
LDLIBS := $(shell pkg-config --libs libpcsclite)

CFLAGS = $(PCSC_CFLAGS) -g

sample: sample.c

clean:
	rm -f sample

Output

Compilation and execution give:

$ make
cc -pthread -I/usr/include/PCSC -g   sample.c  -lpcsclite -o sample
$ ./sample 
1st reader name: Alcor Micro AU9540 00 00

It looks like everything is correct.

But can you find the problem?

 

Valgrind is your friend

valgrind is a very nice tool to debug issues.

Valgrind is an instrumentation framework for building dynamic analysis tools. There are Valgrind tools that can automatically detect many memory management and threading bugs, and profile your programs in detail. You can also use Valgrind to build new tools.

valgrind sees a problem:

$ valgrind --track-origins=yes ./sample 
==99878== Memcheck, a memory error detector
==99878== Copyright (C) 2002-2017, and GNU GPL'd, by Julian Seward et al.
==99878== Using Valgrind-3.18.1 and LibVEX; rerun with -h for copyright info
==99878== Command: ./sample
==99878== 
==99878== Conditional jump or move depends on uninitialised value(s)
==99878==    at 0x486E02E: SCardListReaders (in /usr/lib/x86_64-linux-gnu/libpcsclite.so.1.0.0)
==99878==    by 0x109210: main (sample.c:23)
==99878==  Uninitialised value was created by a stack allocation
==99878==    at 0x109199: main (sample.c:13)
==99878== 
1st reader name: Alcor Micro AU9540 00 00
==99878== 
==99878== HEAP SUMMARY:
==99878==     in use at exit: 112 bytes in 4 blocks
==99878==   total heap usage: 10 allocs, 6 frees, 1,434 bytes allocated
==99878== 
==99878== LEAK SUMMARY:
==99878==    definitely lost: 0 bytes in 0 blocks
==99878==    indirectly lost: 0 bytes in 0 blocks
==99878==      possibly lost: 0 bytes in 0 blocks
==99878==    still reachable: 112 bytes in 4 blocks
==99878==         suppressed: 0 bytes in 0 blocks
==99878== Rerun with --leak-check=full to see details of leaked memory
==99878== 
==99878== For lists of detected and suppressed errors, rerun with: -s
==99878== ERROR SUMMARY: 1 errors from 1 contexts (suppressed: 0 from 0)

Using uninitialized variables is bad. It creates bugs that declare at random time and are not easy to find.


SCardListReaders

The problem is at line 23 which is:

23:     rv = SCardListReaders(hContext, NULL, NULL, &dwReaders);

If we read the documentation for SCardListReaders() we have:

Returns a list of currently available readers on the system.

mszReaders is a pointer to a character string that is allocated by the application. If the application sends mszGroups and mszReaders as NULL then this function will return the size of the buffer needed to allocate in pcchReaders.

If *pcchReaders is equal to SCARD_AUTOALLOCATE then the function will allocate itself the needed memory. Use SCardFreeMemory() to release it.

Parameters
[in] hContext Connection context to the PC/SC Resource Manager.
[in] mszGroups List of groups to list readers (not used).
[out] mszReaders Multi-string with list of readers.
[in,out] pcchReaders Size of multi-string buffer including NULL's.

You can note that the parameter pcchReaders is in and out. This is because the value is compared to SCARD_AUTOALLOCATE. So the value of pcchReaders shall be set before calling SCardListReaders().

The fix is simple. Just update line 18 like this:

18: DWORD dwReaders = 0;

 

Looking for problems

What happens if we initialize dwReaders to the special value SCARD_AUTOALLOCATE instead of 0?

18: DWORD dwReaders = SCARD_AUTOALLOCATE;

We build and run the sample:

$ ./sample 
SCardListReaders: Invalid parameter given.

The execution of SCardListReaders() fails.

23:     rv = SCardListReaders(hContext, NULL, NULL, &dwReaders);

This is because we are asking SCardListReaders() to allocate and store the result in the parameter mszReaders. But in our sample this parameter is NULL. pcsc-lite has a check for that and returns an error code.

Instead of using NULL we could use something else like 0x1234.

23:     rv = SCardListReaders(hContext, NULL, 0x1234, &dwReaders);

This time we have a nice crash:

$ ./sample 
Segmentation fault

This is because we asked SCardListReaders() to write at the address 0x1234. This address is, in general, not valid.

This problem could happen if you use something like:

23:     rv = SCardListReaders(hContext, NULL, mszReaders, &dwReaders);

And both variables mszReaders and dwReaders are uninitialized, and by a total lack of luck dwReaders has the value SCARD_AUTOALLOCATE (i.e. -1).

 

GnuPG

The problem was found in by oddlama and reported to PCSC at "pcscd fails to read future yubikeys after removing a yubikey, until restarted #125".

The problem is not in pcsc-lite but in GnugPG. So I reported the problem at "SCardListReaders: Conditional jump or move depends on uninitialised value(s)".


WinSCard API

macOS does not support (yet) the value SCARD_AUTOALLOCATE. But pcsc-lite and Windows WinSCard do.

I agree the API to use SCARD_AUTOALLOCATE is ugly. We pass the address of a buffer pointer in a parameter that is a buffer pointer. We have to cast the variable like I did in the C sample like:

  dwReaders = SCARD_AUTOALLOCATE;
  rv = SCardListReaders(hContext, NULL, (LPTSTR)&mszReaders, &dwReaders);

This feature is a Microsoft extension that is not present in the PCSC workgroup specification.


Conclusion

I think the problem is not very known and should be better documented. That was my motivation for writting this blog article.

Morality: in C language, always initialize your variables to a known/safe value (like 0).

Friday, May 13, 2022

New version of pcsc-lite: 1.9.7

I just released a new version of pcsc-lite 1.9.7.
pcsc-lite is a Free Software implementation of the PC/SC (or WinSCard) API for Unix systems. 

 

 Changes

1.9.7: Ludovic Rousseau
13 May 2022

  • disable strict compilation by default
  • fix 3 warnings


Issues with strict compilation

In the previous version (1.9.6) I enabled a strict compilation option by default. The compiler was configured to use the -Werror argument. The effect is to transform warnings into errors. The compilation would fail instead of just displaying a warning.

On my side I had no warnings so I was confident.

But some build systems use a different set of default compilation arguments. For example Arch Linux or openSUSE Tumbleweed use the argument -flto=auto to perform some link-time optimizer.

This option generated 3 warnings. The warnings are minor but since the compilation used -Werror they were treated as errors and the compilation failed.

Sorry for generating the problem. Thanks to Axel Braun and frederik for reporting the failure.

Wednesday, May 11, 2022

New version of pcsc-lite: 1.9.6

I just released a new version of pcsc-lite 1.9.6.
pcsc-lite is a Free Software implementation of the PC/SC (or WinSCard) API for Unix systems. 

 

Changes:

1.9.6: Ludovic Rousseau
11 May 2022
  • do not fail reader removal in some specific cases (USB/Thunderbolt port)
  • improve documentation regarding /etc/reader.conf.d/
  • SCardGetStatusChange: speedup the case DISABLE_AUTO_POWER_ON
  • configure:
    • add --disable-strict option
      By default the compiler arguments are now:
      -Wall -Wextra -Wno-unused-parameter -Werror ${CFLAGS}
    • fail if flex is not found
  • fix different data races
  • pcscdaemon: -v displays internal constants values: MAX_READERNAME & PCSCLITE_MAX_READERS_CONTEXTS
  • Some other minor improvements

 

Reader removal issue

The problem with reader removal is that, with some hardware configurations, the USB bus is removed when the USB device is disconnected. You can see that using the libusb command.

Before connecting the device:

Bus 002 Device 002: ID 0bda:0328 Realtek Semiconductor Corp. USB3.0-CRW
Bus 002 Device 001: ID 1d6b:0003 Linux Foundation 3.0 root hub
Bus 001 Device 003: ID 1bcf:2c6b Sunplus Innovation Technology Inc. HD WebCam
Bus 001 Device 005: ID 1044:7a39 Chu Yuen Enterprise Co., Ltd USB-HID Keyboard
Bus 001 Device 004: ID 8087:0a2b Intel Corp. Bluetooth wireless interface
Bus 001 Device 001: ID 1d6b:0002 Linux Foundation 2.0 root hub

After connecting the Yubikey token

Bus 004 Device 001: ID 1d6b:0003 Linux Foundation 3.0 root hub
Bus 003 Device 002: ID 1050:0407 Yubico.com Yubikey 4/5 OTP+U2F+CCID
Bus 003 Device 001: ID 1d6b:0002 Linux Foundation 2.0 root hub
Bus 002 Device 002: ID 0bda:0328 Realtek Semiconductor Corp. USB3.0-CRW
Bus 002 Device 001: ID 1d6b:0003 Linux Foundation 3.0 root hub
Bus 001 Device 003: ID 1bcf:2c6b Sunplus Innovation Technology Inc. HD WebCam
Bus 001 Device 005: ID 1044:7a39 Chu Yuen Enterprise Co., Ltd USB-HID Keyboard
Bus 001 Device 004: ID 8087:0a2b Intel Corp. Bluetooth wireless interface
Bus 001 Device 001: ID 1d6b:0002 Linux Foundation 2.0 root hub

The new lines are: 

  • Bus 004 Device 001: ID 1d6b:0003 Linux Foundation 3.0 root hub
  • Bus 003 Device 002: ID 1050:0407 Yubico.com Yubikey 4/5 OTP+U2F+CCID
  • Bus 003 Device 001: ID 1d6b:0002 Linux Foundation 2.0 root hub

2 new USB buses are created 003 & 004. The Yubikey token is connected on the bus 003.

After removing the Yubikey

Bus 002 Device 002: ID 0bda:0328 Realtek Semiconductor Corp. USB3.0-CRW
Bus 002 Device 001: ID 1d6b:0003 Linux Foundation 3.0 root hub
Bus 001 Device 003: ID 1bcf:2c6b Sunplus Innovation Technology Inc. HD WebCam
Bus 001 Device 005: ID 1044:7a39 Chu Yuen Enterprise Co., Ltd USB-HID Keyboard
Bus 001 Device 004: ID 8087:0a2b Intel Corp. Bluetooth wireless interface
Bus 001 Device 001: ID 1d6b:0002 Linux Foundation 2.0 root hub

The USB buses 3 & 4 have disappeared. This confused pcsc-lite. The token was not removed for pcsc-lite and caused the generation of log errors. This is now fixed.

    It looks like the problem occurred with a USB-C + Thunderbolt port and was reported in "pcscd fails to read future yubikeys after removing a yubikey, until restarted #125" and "Yubikey 5c Reader "stuck" #57".

    Wednesday, April 27, 2022

    30 shades of PC/SC

    In 2010 I started to write about the different programming languages you can use to talk to a smart card and a smart card reader.

    12 years later I have 30 languages in the list.

    They are, in alphabetical order:

    1. Ada
    2. C
    3. C#
    4. C for UEFI
    5. Common Lisp
    6. Elixir
    7. Erlang
    8. Flutter/Dart
    9. Free Pascal (Lazarus)
    10. go
    11. Java
    12. JavaScript (Node.js)
    13. Java using intarsys smartcard-io
    14. Kotlin
    15. lua
    16. Objective-C (synchronous)
    17. Objective-C (using Crypto Token Kit)
    18. OCaml
    19. Perl
    20. PHP5
    21. PHP (dead upstream as 11 January 2015)
    22. Prolog
    23. Python
    24. Python (using python-pcsclite)
    25. Ruby
    26. Rust
    27. Scala
    28. scriptor
    29. Smart Card Connector on Chromebook
    30. Swift (using Crypto Token Kit)

    Top Computer Languages

    Different lists exist for the top computer languages popularity. I will use the TIOBE Index for April 2022.

    The "support" column indicates if the language has a smart card API available.

    #
    Language support
    1 Python Yes
    2 C Yes
    3 Java Yes
    4 C++ Yes
    5 C# Yes
    6 Visual Basic ?
    7 JavaScript Yes
    8 Assembly ?
    9 SQL ?
    10 PHP Yes
    11 R ?
    12 Pascal Yes
    13 Go Yes
    14 Swift Yes
    15 Ruby Yes
    16 Classic Visual Basic ?
    17 Objective-C Yes
    18 Perl Yes
    19 Lua Yes
    20 Mathlab ?
    21 SAS ?
    22 Prolog Yes
    23 (Visual) FoxPro ?
    24 Scratch ?
    25 COBOL ?
    26 Julia ?
    27 Kotlin Yes
    28 Rust Yes
    29 Ada Yes
    30 Lisp Yes
    31 Fortran ?
    32 Groovy ?
    33 VBScript ?
    34 PL/SQL ?
    35 D ?
    36 Scala Yes
    37 Haskell ?
    38 Dart Yes


    Comments

    It should be easy to call the C WinSCard API from assembly language. So the answer could be "yes". I learned assembly language with a Motorola 6809 and then a Motorola 68000. I am not a fan of the Intel x86 assembly language with its very strange register names (to be backward compatible). Yes, I could also use ARM or RISC-V CPUs. I let the exercise to write an example in assembly language to the readers.

    Not listed

    Some programming languages are not listed in the TIOBE index but do provide a PC/SC wrapper:

    • Elixir
    • Erlang
    • OCaml

    Windows technologies

    Some languages are specific to the Microsoft Windows system. I can't use them since I do not use Windows. They are:

    • Visual Basic
    • Classic Visual Basic
    • VBScript
    • Visual FoxPro.

    It looks like Visual Basic is also available for GNU/Linux. But I don't want to invest time in these technologies.

    Also note that all the computer languages with PC/SC support exist in a Free Software implementation. I am not sure for the Microsoft languages.

    Language I would be surprised to get PC/SC support

    R and SAS are languages used for statistics.

    Scratch is used for education.

    Mathlab is for numeric computing.

    COBOL is very old. I do not expect any COBOL program needing access to smart cards. Same remark for Fortran. COBOL and Fortran are still used and it looks like it is possible to call C functions from both of them. So there is hope .

    Languages that could have a PC/SC wrapper

    What I had not yet found

    SQL: (SQL Server) PC/SC List Smart Card Readers (and USB Tokens)

    This is for SQL Server, so may be limited to the Microsoft product and not the SQL language.

    Conclusion

    It was a lot of fun to discover and write a sample codes for all the 30 languages.

    For some (4) of the PC/SC wrappers I am the maintainer so writing a sample code was easy.

    The list is not finished and may never be as new programming languages are created from time to time. If you want me to add a new language please contact me.

    Thursday, April 14, 2022

    PC/SC sample in Erlang

    To continue the list of PC/SC wrappers initiated in 2010 with "PC/SC sample in different languages" I now present a new sample code in Erlang.

    I use the PC/SC wrapper for Erlang: erlang-pcsc from Alex Wilson. The project description is "libpcsc NIF binding for erlang". The license is BSD 2 clause.

    This is the same wrapper I used in the previous blog article "PC/SC sample in Elixir".

    The wrapper is available on Hex.pm (The package manager for the Erlang ecosystem) at https://hex.pm/packages/pcsc.

    API documentation is available at https://arekinath.github.io/erlang-pcsc/index.html

     

    Create a new application

    $ rebar3 new app blog
    ===> Writing blog/src/blog_app.erl
    ===> Writing blog/src/blog_sup.erl
    ===> Writing blog/src/blog.app.src
    ===> Writing blog/rebar.config
    ===> Writing blog/.gitignore
    ===> Writing blog/LICENSE
    ===> Writing blog/README.md

    Install pcsc module

    Edit the file rebar.config to use:

    {deps, [pcsc]}.
    {erl_opts, [{i, "_build/default/lib/pcsc/include/"}]}. 

    The erl_opts option is needed because we will include one header file from the pcsc module. Maybe it is possible to have a less ugly/hardcoded path.

    Upgrade the dependencies:

    $ rebar3 upgrade --all
    ===> Verifying dependencies...
    ===> Fetching pcsc v1.3.1
    ===> Fetching rebar3_hex v7.0.1
    ===> Fetching hex_core v0.8.4
    ===> Fetching verl v1.1.1
    ===> Analyzing applications...
    ===> Compiling verl
    ===> Compiling hex_core
    ===> Compiling rebar3_hex
    _build/default/plugins/rebar3_hex/src/rebar3_hex_organization.erl:391:5: Warning: public_key:ssh_encode/2 is deprecated and will be removed in OTP 26; use ssh_file:encode/2 instead
    
    ===> Fetching lager v3.9.2
    ===> Fetching goldrush v0.1.9
    ===> No upgrade needed for pcsc
    ===> No upgrade needed for lager
    ===> No upgrade needed for goldrush

    Build the dependencies:

    $ rebar3 compile
    ===> Verifying dependencies...
    make : on entre dans le répertoire « /home/rousseau/Documents/blog/erlang/_build/default/lib/pcsc/c_src »
    cc  -Wall -g -O2 -Wextra -pipe -funsigned-char -fstrict-aliasing -Wchar-subscripts -Wundef -Wshadow -Wcast-align -Wwrite-strings -Wunused -Wuninitialized -Wpointer-arith -Wredundant-decls -Winline -Wformat -Wformat-security -Wswitch-enum -Winit-self -Wmissing-include-dirs -Wempty-body -fdiagnostics-color=auto -Wmissing-prototypes -Wstrict-prototypes -Wold-style-definition -Wbad-function-cast -Wnested-externs  -Wmissing-declarations -fPIC -I /usr/lib/erlang/erts-12.3.1/include/ -I /usr/lib/erlang/lib/erl_interface-5.2.2/include -pthread -I/usr/include/PCSC  -c -o /home/rousseau/Documents/blog/erlang/_build/default/lib/pcsc/c_src/pcsc_nif.o /home/rousseau/Documents/blog/erlang/_build/default/lib/pcsc/c_src/pcsc_nif.c
    [...]
    cc /home/rousseau/Documents/blog/erlang/_build/default/lib/pcsc/c_src/pcsc_nif.o -shared -L /usr/lib/erlang/lib/erl_interface-5.2.2/lib -lei -lpcsclite -o /home/rousseau/Documents/blog/erlang/_build/default/lib/pcsc/c_src/../priv/pcsc_nif.so
    make : on quitte le répertoire « /home/rousseau/Documents/blog/erlang/_build/default/lib/pcsc/c_src »
    ===> Analyzing applications...
    ===> Compiling goldrush
    ===> Compiling lager
    ===> Compiling pcsc
    ===> Analyzing applications... ===> Compiling blog

    Edit the file src/blog.app.src to declare the pcsc application.

    It should look like:

    [...]
      {applications,
       [kernel,
        stdlib,
        pcsc
       ]},
    [...]

    Sample code

    Create the source code file src/blog.erl with the content:

    -module(blog).
    -export([main/0]).
    
    -include("iso7816.hrl").
    
    main() ->
      % get all the available readers
      {ok, Readers} = pcsc_card_db:list_readers(),
    
      % use the first reader
      [Reader | _] = Readers,
      io:fwrite("Using: ~s~n", [Reader]),
    
      % connect
      {ok, Card} = pcsc_card:start_link(Reader, shared, [t1, t0]),
    
      % select applet
      Aid = << 160, 0, 0, 0, 98, 3, 1, 12, 6, 1 >>,
      Select_apdu = #apdu_cmd{cla = iso, ins = select, p1 = 4, p2 = 0, data = Aid},
      {ok, Select_replies} = pcsc_card:command(Card, Select_apdu),
      io:write(Select_replies),
      io:fwrite("~n"),
    
      % command
      Command_apdu = #apdu_cmd{ cla = iso, ins = 0, p1 = 0, p2 = 0 },
      {ok, Command_replies} = pcsc_card:command(Card, Command_apdu),
      io:write(Command_replies),
      io:fwrite("~n"),
    
      % extract the answer
      [Reply | _] = Command_replies,
      case Reply of
        {apdu_reply, _, ok, Msg} ->
          io:write(binary_to_atom(Msg)),
          io:fwrite("~n");
        {apdu_reply, _, error, _} ->
          io:fwrite("Error~n")
      end.
    

    Output

    Generating a standalone Erlang application looks complex. But you can test your code using the interactive shell.

    $ rebar3 shell
    ===> Verifying dependencies...
    ===> Analyzing applications...
    ===> Compiling blog
    Erlang/OTP 24 [erts-12.3.1] [source] [64-bit] [smp:4:4] [ds:4:4:10] [async-threads:1] [jit]
    
    Eshell V12.3.1  (abort with ^G)
    ===> Booted syntax_tools
    ===> Booted compiler
    ===> Booted goldrush
    ===> Booted lager
    ===> Booted pcsc
    ===> Booted blog
     
    1> blog:main().
    Using: Gemalto PC Twin Reader 00 00
    [{apdu_reply,t1,ok,none}]
    [{apdu_reply,t1,ok,<<72,101,108,108,111,32,119,111,114,108,100,33>>}]
    'Hello world!'
    ok
    2> 
    

    Comments

    ehecatl

    An older github project also exist at https://github.com/zgbjgg/ehecatl
    Its description is "An erlang library for read/write nfc smart cards".

    I filed 2 issues in 2020: Missing <PCSC/winscard.h>? and More complete PC/SC wrapper? but got no answer.

    This project has not seen any commit since 2014.

    So I guess this project is dead.

    erlang-pcsc 

    The only problem I have with erlang-pcsc is that, if no smart card reader is connected, I get:

    $ rebar3 shell
    ===> Verifying dependencies...
    ===> Analyzing applications...
    ===> Compiling blog
    Erlang/OTP 24 [erts-12.3.1] [source] [64-bit] [smp:4:4] [ds:4:4:10] [async-threads:1] [jit]
    
    Eshell V12.3.1  (abort with ^G)
    1> ===> Booted syntax_tools
    ===> Booted compiler
    ===> Booted goldrush
    ===> Booted lager
    ===> Booted pcsc
    ===> Booted blog
    23:31:49.563 [warning] got pcsc_reader_error: {error,{pcsc_error,-2146435026,no_readers,"Cannot find a smart card reader."}}; restarted ok
    23:31:49.622 [warning] got pcsc_reader_error: {error,{pcsc_error,-2146435026,no_readers,"Cannot find a smart card reader."}}; restarted ok
    23:31:49.677 [warning] got pcsc_reader_error: {error,{pcsc_error,-2146435026,no_readers,"Cannot find a smart card reader."}}; restarted ok
    23:31:49.729 [warning] got pcsc_reader_error: {error,{pcsc_error,-2146435026,no_readers,"Cannot find a smart card reader."}}; restarted ok
    23:31:49.782 [warning] got pcsc_reader_error: {error,{pcsc_error,-2146435026,no_readers,"Cannot find a smart card reader."}}; restarted ok
    23:31:49.836 [warning] got pcsc_reader_error: {error,{pcsc_error,-2146435026,no_readers,"Cannot find a smart card reader."}}; restarted ok
    23:31:49.889 [warning] got pcsc_reader_error: {error,{pcsc_error,-2146435026,no_readers,"Cannot find a smart card reader."}}; restarted ok
    23:31:49.941 [warning] got pcsc_reader_error: {error,{pcsc_error,-2146435026,no_readers,"Cannot find a smart card reader."}}; restarted ok
    23:31:49.992 [warning] got pcsc_reader_error: {error,{pcsc_error,-2146435026,no_readers,"Cannot find a smart card reader."}}; restarted ok
    23:31:50.044 [warning] got pcsc_reader_error: {error,{pcsc_error,-2146435026,no_readers,"Cannot find a smart card reader."}}; restarted ok
    etc...
    

    The error -2146435026 is SCARD_E_NO_READERS_AVAILABLE and is not really an error for SCardListReaders().

    I filed a github issue [warning] got pcsc_reader_error: {error,{pcsc_error,-2146435026,no_readers,"Cannot find a smart card reader."}}; restarted ok #4 but with no answer so far.

    Conclusion

    Thanks Alex for the Erlang PC/SC wrapper. And thanks tofferoma, from the elixir forum, for your help in writing the Erlang sample code.

    If you work on a Free Software PC/SC wrapper that is not yet in my list please let me know.

    Wednesday, April 13, 2022

    PC/SC sample in Elixir

    To continue the list of PC/SC wrappers initiated in 2010 with "PC/SC sample in different languages" I now present a new sample code in Elixir.

    Elixir uses the Erlang virtual machine: BEAM. I wanted to start with an example in Erlang but Erlang is more complex (for me) so I have not yet a working sample code in Erlang.

    I use the PC/SC wrapper for Erlang: erlang-pcsc from Alex Wilson. The project description is "libpcsc NIF binding for erlang". The license is BSD 2 clause.

    The wrapper is available on Hex.pm (The package manager for the Erlang ecosystem) at https://hex.pm/packages/pcsc.

    API documentation is available at https://arekinath.github.io/erlang-pcsc/index.html

    Elixir sample project

    Create a new Elixir project using mix new ...

    $ mix new blog
    * creating README.md
    * creating .formatter.exs
    * creating .gitignore
    * creating mix.exs
    * creating lib
    * creating lib/blog.ex
    * creating test
    * creating test/test_helper.exs
    * creating test/blog_test.exs
    
    Your Mix project was created successfully.
    You can use "mix" to compile it, test it, and more:
    
        cd blog
        mix test
    
    Run "mix help" for more commands.

    Edit the file mix.exs and add the pcsc dependency. You should have something like:

    [...]
      defp deps do
        [
    	{:pcsc, "~> 1.3"},
        ]
      end
    [...]

    Install the dependency using mix deps.get

    $ mix deps.get
    Resolving Hex dependencies...
    Dependency resolution completed:
    New:
      goldrush 0.1.9
      lager 3.9.2
      pcsc 1.3.1
    * Getting pcsc (Hex package)
    * Getting lager (Hex package)
    * Getting goldrush (Hex package)

    Source code

    Now we create a file blog.exs that contains (sorry, source-highlight does not provide syntax colorization for Elixir):

    # list card readers
    {:ok, readers} = :pcsc_card_db.list_readers()
    
    # use the fist reader
    [reader | _] = readers
    IO.puts("Using reader: " <> reader)
    
    # connect to the card
    {:ok, card} = :pcsc_card.start_link(reader, :shared, [:t1, :t0])
    
    aid = << 160, 0, 0, 0, 98, 3, 1, 12, 6, 1 >>
    select_apdu = {:apdu_cmd, :default, :iso, :select, 4, 0, aid, :none}
    
    # send select APDU
    {:ok, replies} = :pcsc_card.command(card, select_apdu)
    IO.inspect replies
    
    # send command APDU
    command_apdu = {:apdu_cmd, :default, :iso, 0, 0, 0, :none, :none}
    {:ok, replies} = :pcsc_card.command(card, command_apdu)
    IO.inspect replies
    
    # get the first reply only
    [reply | _] = replies
    case reply do
    	{:apdu_reply, _, :ok, msg} -> IO.puts(msg)
    	{:apdu_reply, _, :error, _} -> IO.puts("Failed")
    end
    

    Output

    You can now build and run the code using mix run ...

    The first time you run mix run the pcsc wrapper will be built automatically. After that you only get the build & execution of the sample code.

    $ mix run blog.exs
    
    17:40:50.239 [error] calling logger:remove_handler(default) failed: :error {:badmatch, {:error, {:not_found, :default}}}
    17:40:50.273 [info] Application lager started on node nonode@nohost
    17:40:50.280 [info] Application pcsc started on node nonode@nohost
    17:40:50.281 [info] Application blog started on node nonode@nohost
    Using reader: Gemalto PC Twin Reader 00 00
    [{:apdu_reply, :t1, :ok, :none}]
    [{:apdu_reply, :t1, :ok, "Hello world!"}]
    Hello world!
    

    Remarks

    I do not have any complaints for the Erlang PC/SC wrapper. It built fine on the first try. Nice work Alex.

    As always my sample code is very minimal with no error handling. It is just a short sample.

    Thanks to Stéphane Bortzmeyer for his Elixir training. That gave me the idea to try Elixir.

    A big thank to tofferoma for his help on the Elixir forum on "How to access PCSC card readers via erlang/elixir?".

    Conclusion

    If you work on a Free Software PC/SC wrapper that is not yet in my list please let me know.