random_bytes

# File activesupport/lib/active_support/secure_random.rb, line 59
      def self.random_bytes(n=nil)
        n ||= 16

        unless defined? OpenSSL
          begin
            require 'openssl'
          rescue LoadError
          end
        end

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

        if !defined?(@has_win32)
          begin
            require 'Win32API'

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

            hProvStr = " " * 4
            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
            @hProv, = hProvStr.unpack('L')

            @has_win32 = true
          rescue LoadError
            @has_win32 = false
          end
        end
        if @has_win32
          bytes = " " * 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