random_bytes

# File lib/securerandom.rb, line 50
  def self.random_bytes(n=nil)
    n = n ? n.to_int : 16

    if defined? OpenSSL::Random
      @pid = 0 unless defined?(@pid)
      pid = $$
      unless @pid == pid
        now = Process.clock_gettime(Process::CLOCK_REALTIME, :nanosecond)
        ary = [now, @pid, pid]
        OpenSSL::Random.random_add(ary.join("").to_s, 0.0)
        @pid = pid
      end
      return OpenSSL::Random.random_bytes(n)
    end

    if !defined?(@has_urandom) || @has_urandom
      flags = File::RDONLY
      flags |= File::NONBLOCK if defined? File::NONBLOCK
      flags |= File::NOCTTY if defined? File::NOCTTY
      begin
        File.open("/dev/urandom", flags) {|f|
          unless f.stat.chardev?
            raise Errno::ENOENT
          end
          @has_urandom = true
          ret = f.read(n)
          unless ret.length == n
            raise NotImplementedError, "Unexpected partial read from random device: only #{ret.length} for #{n} bytes"
          end
          return ret
        }
      rescue Errno::ENOENT
        @has_urandom = false
      end
    end

    unless defined?(@has_win32)
      begin
        require 'Win32API'

        crypt_acquire_context = Win32API.new("advapi32", "CryptAcquireContext", 'PPPII', 'L')
        @crypt_gen_random = Win32API.new("advapi32", "CryptGenRandom", 'VIP', 'L')

        hProvStr = " " * DL::SIZEOF_VOIDP
        prov_rsa_full = 1
        crypt_verifycontext = 0xF0000000

        if crypt_acquire_context.call(hProvStr, nil, nil, prov_rsa_full, crypt_verifycontext) == 0
          raise SystemCallError, "CryptAcquireContext failed: #{lastWin32ErrorMessage}"
        end
        type = DL::SIZEOF_VOIDP == DL::SIZEOF_LONG_LONG ? 'q' : 'l'
        @hProv, = hProvStr.unpack(type)

        @has_win32 = true
      rescue LoadError
        @has_win32 = false
      end
    end
    if @has_win32
      bytes = " ".force_encoding("ASCII-8BIT") * n
      if @crypt_gen_random.call(@hProv, bytes.size, bytes) == 0
        raise SystemCallError, "CryptGenRandom failed: #{lastWin32ErrorMessage}"
      end
      return bytes
    end

    raise NotImplementedError, "No random device"
  end