/usr/lib64/python2.6/site-packages/cryptography/hazmat/primitives
Edit: /usr/lib64/python2.6/site-packages/cryptography/hazmat/primitives/padding.py (3635B)
# This file is dual licensed under the terms of the Apache License, Version
# 2.0, and the BSD License. See the LICENSE file in the root of this repository
# for complete details.
from __future__ import absolute_import, division, print_function
import abc
import six
from cryptography import utils
from cryptography.exceptions import AlreadyFinalized
from cryptography.hazmat.bindings._padding import lib
@six.add_metaclass(abc.ABCMeta)
class PaddingContext(object):
@abc.abstractmethod
def update(self, data):
"""
Pads the provided bytes and returns any available data as bytes.
"""
@abc.abstractmethod
def finalize(self):
"""
Finalize the padding, returns bytes.
"""
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.")
self.block_size = block_size
def padder(self):
return _PKCS7PaddingContext(self.block_size)
def unpadder(self):
return _PKCS7UnpaddingContext(self.block_size)
@utils.register_interface(PaddingContext)
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):
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
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 + six.int2byte(pad_size) * pad_size
self._buffer = None
return result
@utils.register_interface(PaddingContext)
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 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
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 = lib.Cryptography_check_pkcs7_padding(
self._buffer, self.block_size // 8
)
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