Don't use subclass
diff --git a/src/cryptography/hazmat/primitives/padding.py b/src/cryptography/hazmat/primitives/padding.py
index c6fe656..77fb8f8 100644
--- a/src/cryptography/hazmat/primitives/padding.py
+++ b/src/cryptography/hazmat/primitives/padding.py
@@ -28,108 +28,77 @@
"""
-class _BytePadding(object):
+def _byte_padding_check(block_size):
+ if not (0 <= block_size < 256):
+ raise ValueError("block_size must be in range(0, 256).")
+
+ if block_size % 8 != 0:
+ raise ValueError("block_size must be a multiple of 8.")
+
+
+def _byte_padding_update(buffer_, data, block_size):
+ if buffer_ is None:
+ raise AlreadyFinalized("Context was already finalized.")
+
+ if not isinstance(data, bytes):
+ raise TypeError("data must be bytes.")
+
+ buffer_ += data
+
+ finished_blocks = len(buffer_) // (block_size // 8)
+
+ result = buffer_[:finished_blocks * (block_size // 8)]
+ buffer_ = buffer_[finished_blocks * (block_size // 8):]
+
+ return buffer_, result
+
+
+def _byte_padding_pad(buffer_, block_size, paddingfn):
+ if buffer_ is None:
+ raise AlreadyFinalized("Context was already finalized.")
+
+ pad_size = block_size // 8 - len(buffer_)
+ return buffer_ + paddingfn(pad_size)
+
+
+def _byte_unpadding_update(buffer_, data, block_size):
+ if buffer_ is None:
+ raise AlreadyFinalized("Context was already finalized.")
+
+ if not isinstance(data, bytes):
+ raise TypeError("data must be bytes.")
+
+ buffer_ += data
+
+ finished_blocks = max(len(buffer_) // (block_size // 8) - 1, 0)
+
+ result = buffer_[:finished_blocks * (block_size // 8)]
+ buffer_ = buffer_[finished_blocks * (block_size // 8):]
+
+ return buffer_, result
+
+
+def _byte_unpadding_check(buffer_, block_size, checkfn):
+ if buffer_ is None:
+ raise AlreadyFinalized("Context was already finalized.")
+
+ if len(buffer_) != block_size // 8:
+ raise ValueError("Invalid padding bytes.")
+
+ valid = checkfn(buffer_, block_size // 8)
+
+ if not valid:
+ raise ValueError("Invalid padding bytes.")
+
+ pad_size = six.indexbytes(buffer_, -1)
+ return buffer_[:-pad_size]
+
+
+class PKCS7(object):
def __init__(self, block_size):
- if not (0 <= block_size < 256):
- raise ValueError("block_size must be in range(0, 256).")
-
- if block_size % 8 != 0:
- raise ValueError("block_size must be a multiple of 8.")
-
+ _byte_padding_check(block_size)
self.block_size = block_size
-
-@six.add_metaclass(abc.ABCMeta)
-class _BytePaddingContext(object):
- def __init__(self, block_size):
- self.block_size = block_size
- # TODO: more copies than necessary, we should use zero-buffer (#193)
- self._buffer = b""
-
- def update(self, data):
- if self._buffer is None:
- raise AlreadyFinalized("Context was already finalized.")
-
- if not isinstance(data, bytes):
- raise TypeError("data must be bytes.")
-
- self._buffer += data
-
- finished_blocks = len(self._buffer) // (self.block_size // 8)
-
- result = self._buffer[:finished_blocks * (self.block_size // 8)]
- self._buffer = self._buffer[finished_blocks * (self.block_size // 8):]
-
- return result
-
- @abc.abstractmethod
- def _padding(self, size):
- """
- Returns the padding for the size.
- """
-
- def finalize(self):
- if self._buffer is None:
- raise AlreadyFinalized("Context was already finalized.")
-
- pad_size = self.block_size // 8 - len(self._buffer)
- result = self._buffer + self._padding(pad_size)
- self._buffer = None
- return result
-
-
-@six.add_metaclass(abc.ABCMeta)
-class _ByteUnpaddingContext(object):
- def __init__(self, block_size):
- self.block_size = block_size
- # TODO: more copies than necessary, we should use zero-buffer (#193)
- self._buffer = b""
-
- def update(self, data):
- if self._buffer is None:
- raise AlreadyFinalized("Context was already finalized.")
-
- if not isinstance(data, bytes):
- raise TypeError("data must be bytes.")
-
- self._buffer += data
-
- finished_blocks = max(
- len(self._buffer) // (self.block_size // 8) - 1,
- 0
- )
-
- result = self._buffer[:finished_blocks * (self.block_size // 8)]
- self._buffer = self._buffer[finished_blocks * (self.block_size // 8):]
-
- return result
-
- @abc.abstractmethod
- def _check_padding(self):
- """
- Returns if the padding is valid.
- """
-
- def finalize(self):
- if self._buffer is None:
- raise AlreadyFinalized("Context was already finalized.")
-
- if len(self._buffer) != self.block_size // 8:
- raise ValueError("Invalid padding bytes.")
-
- valid = self._check_padding()
-
- if not valid:
- raise ValueError("Invalid padding bytes.")
-
- pad_size = six.indexbytes(self._buffer, -1)
- res = self._buffer[:-pad_size]
- self._buffer = None
- return res
-
-
-class PKCS7(_BytePadding):
-
def padder(self):
return _PKCS7PaddingContext(self.block_size)
@@ -138,22 +107,51 @@
@utils.register_interface(PaddingContext)
-class _PKCS7PaddingContext(_BytePaddingContext):
+class _PKCS7PaddingContext(object):
+ def __init__(self, block_size):
+ self.block_size = block_size
+ # TODO: more copies than necessary, we should use zero-buffer (#193)
+ self._buffer = b""
+
+ def update(self, data):
+ self._buffer, result = _byte_padding_update(
+ self._buffer, data, self.block_size)
+ return result
def _padding(self, size):
return six.int2byte(size) * size
+ def finalize(self):
+ result = _byte_padding_pad(
+ self._buffer, self.block_size, self._padding)
+ self._buffer = None
+ return result
+
@utils.register_interface(PaddingContext)
-class _PKCS7UnpaddingContext(_ByteUnpaddingContext):
+class _PKCS7UnpaddingContext(object):
+ def __init__(self, block_size):
+ self.block_size = block_size
+ # TODO: more copies than necessary, we should use zero-buffer (#193)
+ self._buffer = b""
- def _check_padding(self):
- return lib.Cryptography_check_pkcs7_padding(
- self._buffer, self.block_size // 8
- )
+ def update(self, data):
+ self._buffer, result = _byte_unpadding_update(
+ self._buffer, data, self.block_size)
+ return result
+
+ def finalize(self):
+ result = _byte_unpadding_check(
+ self._buffer, self.block_size,
+ lib.Cryptography_check_pkcs7_padding)
+ self._buffer = None
+ return result
-class ANSIX923(_BytePadding):
+class ANSIX923(object):
+ def __init__(self, block_size):
+ _byte_padding_check(block_size)
+ self.block_size = block_size
def padder(self):
return _ANSIX923PaddingContext(self.block_size)
@@ -163,16 +161,42 @@
@utils.register_interface(PaddingContext)
-class _ANSIX923PaddingContext(_BytePaddingContext):
+class _ANSIX923PaddingContext(object):
+ def __init__(self, block_size):
+ self.block_size = block_size
+ # TODO: more copies than necessary, we should use zero-buffer (#193)
+ self._buffer = b""
+
+ def update(self, data):
+ self._buffer, result = _byte_padding_update(
+ self._buffer, data, self.block_size)
+ return result
def _padding(self, size):
return six.int2byte(0) * (size - 1) + six.int2byte(size)
+ def finalize(self):
+ result = _byte_padding_pad(
+ self._buffer, self.block_size, self._padding)
+ self._buffer = None
+ return result
+
@utils.register_interface(PaddingContext)
-class _ANSIX923UnpaddingContext(_ByteUnpaddingContext):
+class _ANSIX923UnpaddingContext(object):
+ def __init__(self, block_size):
+ self.block_size = block_size
+ # TODO: more copies than necessary, we should use zero-buffer (#193)
+ self._buffer = b""
- def _check_padding(self):
- return lib.Cryptography_check_ansix923_padding(
- self._buffer, self.block_size // 8
- )
+ def update(self, data):
+ self._buffer, result = _byte_unpadding_update(
+ self._buffer, data, self.block_size)
+ return result
+
+ def finalize(self):
+ result = _byte_unpadding_check(
+ self._buffer, self.block_size,
+ lib.Cryptography_check_ansix923_padding)
+ self._buffer = None
+ return result