code: def read(self, b=-1):
          
          # Any negative value for b is interpreted as a full read
          # None is also accepted for legacy compatibility
          if b is None or b < 0:
              b = -1
  
          _LOGGER.debug("Stream read called, requesting %d bytes", b)
          output = io.BytesIO()
  
          if not self._message_prepped:
              self._prep_message()
  
          if self.closed:
              raise ValueError("I/O operation on closed file")
  
          if b >= 0:
              self._read_bytes(b)
              output.write(self.output_buffer[:b])
              self.output_buffer = self.output_buffer[b:]
          else:
              while True:
                  line = self.readline()
                  if not line:
                      break
                  output.write(line)
  
          self.bytes_read += output.tell()
          _LOGGER.debug("Returning %d bytes of %d bytes requested", output.tell(), b)
          return output.getvalue()
docs: Returns either the requested number of bytes or the entire stream.
  
          :param int b: Number of bytes to read
          :returns: Processed (encrypted or decrypted) bytes from source stream
          :rtype: bytes