def _parse_iv_length(self, byte_array, off):
self._iv_length = utils.bytes_to_int(byte_array[off])
if self._iv_length < 0:
raise exceptions.BadCipherTextError(
'Invalid IV length ({})'.format(self._iv_length))
return 1
def _parse_frame_content_length(self, byte_array, off):
self.frame_content_length = utils.bytes_to_int(byte_array[off:off + 4])
if self.frame_content_length < 0:
raise exceptions.BadCipherTextError(
'Invalid frame length ({})'.format(self.frame_content_length))
return 4
def _parse_content_type(self, byte_array, off):
self.content_type = utils.bytes_to_int(byte_array[off])
if self.content_type not in (1, 2):
raise exceptions.BadCipherTextError(
'Invalid content type ({})'.format(self.content_type))
return 1
def _parse_type(self, byte_array, off):
self.type = utils.bytes_to_int(byte_array[off])
if self.type != 0x80:
raise exceptions.BadCipherTextError(
'Invalid message type ({})'.format(self.type))
return 1
def _parse_version(self, byte_array, off):
self.version = utils.bytes_to_int(byte_array[off])
if self.version != 1:
raise exceptions.BadCipherTextError(
'Invalid version number ({})'.format(self.version))
return 1
def _parse_reserved_field(self, byte_array, off):
self.reserved_field = utils.bytes_to_int(byte_array[off:off + 4])
if self.reserved_field != 0:
raise exceptions.BadCipherTextError(
'Invalid value for reserved field ({})'.format(
self.reserved_field))
return 4
def _parse_encryption_context_length(self, byte_array, off):
self._encryption_context_length = utils.bytes_to_int(
byte_array[off:off + 2])
if self._encryption_context_length < 0:
raise exceptions.BadCipherTextError(
'Invalid encryption context length ({})'.format(
self._encryption_context_length))
return 2