smartcard.rb

require 'smartcard'

#UID_CMD = "\xFF\xCA\x00\x00\x00"
UID_CMD = "\xFF\xCA\x00\x00\x00"

def format_readable(sequence)
  sequence.to_s.unpack('C*').join
end

stop = false
until stop
  begin
    context = Smartcard::PCSC::Context.new
    if context.valid?
      readers = context.readers

      if readers.empty?
        puts 'Please attach an PC/SC compliant smart card reader!'
        exit
      else
        queries = Smartcard::PCSC::ReaderStateQueries.new readers.length

        readers.each_with_index do |name, index|
          queries[index].reader_name = name
          queries[index].current_state = :unknown
        end

        # Initial state is "unknown"
        puts
        puts '+' + '-' * 78 + '+'
        puts "| Please insert smart-card card in reader #{@reader_name}"
        puts '+' + '-' * 78 + '+'
        until queries[0].current_state.include?(:present) do
          context.wait_for_status_change(queries)
          queries.ack_changes
        end
        puts
        puts " * Card detected"
        if card = Smartcard::PCSC::Card.new(context, readers[0])

          response = card.transmit(UID_CMD)
          puts " * Response length: #{response.size}\n"
          print " * Status: #{format_readable(response[-2,2])} "
          case response[-2,2]
          when "\x90\x00"
            print "Success"
            puts "   Card ID: #{format_readable(response[0,4])}\n"
          when "\x00\x00"
            puts "No data"
          when "\x67\x00"
            puts "Bad APU"
          when "\x6A\x82"
            puts "Le is greater"
          when "\x6CP1"
            puts "Le is shorter"
          else
            puts "failure"
          end

          card.disconnect

          # Wait until the card has been removed before checking for a new one
          until queries[0].current_state.include?(:empty) do
            context.wait_for_status_change(queries)
            queries.ack_changes
          end
        end
      end
    end
  rescue Smartcard::PCSC::Exception => ex
    puts ex.message
  ensure
    # Disconnect
    context.release
  end
  Signal.trap('INT') { stop = true }
end