SmartCard adapter using smartcard gem with demo

smart_card_adapter.rb

# http://www.rdoc.info/github/costan/smartcard/master/Smartcard
require 'smartcard'

class SmartCardAdapter
  # scope of the smart-card connection; valid values are :system, :user, and :terminal 
  # (see the SCARD_SCOPE_ constants in the PC/SC API)
  def connect(scope = :system)
    @context = Smartcard::PCSC::Context.new(scope)
  end
  
  def readers
    @context.readers
  end
  
  def disconnect
    @card.disconnect if @card
    @context.release if @context
  end
  
  def select_card_in_the_first_reader
    @card = @context.card(@context.readers.first) if @context && @context.readers.any?
  end
  
  def send_APDU_to_current_card(bytes_array)
    # send_data is a string containing the APDU bytes to be sent to the card
    send_data = bytes_array.pack('C*')
    response = @card.transmit(send_data)
    # hex(response[-2, 2])
    hex(response)
  end
  
  def dump_current_card_info
    puts "Dumping Card state and data:"
    puts "card protocol: #{@card.protocol}"
    puts "card sharing mode: #{@card.sharing_mode}"
    info = @card.info
    # puts "\ncard info: #{info}"
    puts "card ATR (hex): #{hex(info[:atr])}"
    puts "card state: #{info[:state].to_a.join(' ')}"
  end
  
  private
  def hex(input)
    input.unpack('C*').map{ |e| e.to_s(16).upcase }.join(' ')
  end
end

smart_card_demo.rb

require_relative 'smart_card_adapter'

begin # demo
  print "Searching for Smart Card..."
  adapter = SmartCardAdapter.new
  readers = adapter.readers if adapter.connect
  abort("No Smart Card readers found") if adapter.nil? || readers.empty?

  puts " found: #{readers}"
  print "connecting to the first reader..."
  card = adapter.select_card_in_the_first_reader
  puts " connected!" if card
  adapter.dump_current_card_info

  apdu_bytes = [0x80, 0xC0, 0x02, 0xA1]
  puts "response: #{adapter.send_APDU_to_current_card(apdu_bytes)}"
  puts "\n"

rescue Smartcard::PCSC::Exception => e
  puts "Ooops: #{e}"

ensure
  adapter.disconnect if adapter
end




# how to format proper APDU bytes string?
# http://web.archive.org/web/20090630004017/http://cheef.ru/docs/HowTo/APDU.info
# http://www.wrankl.de/SCTables/SCTables.html
# apdu_bytes = [0x00, 0xA4, 0x04, 0x00, 0x00]
# apdu_bytes = [0xFF, 0xCA, 0x00, 0x00, 0x00] # get UID
# apdu_bytes = [0xAF, 0x03, 0x16, 0x78] # BH
# apdu_bytes = [0x20, 0x00, 0x82, 0x04, 0x01, 0x02, 0x03, 0x04, 0x00]