/usr/lib/python3/dist-packages/cryptography/hazmat/primitives/padding.py is in python3-cryptography 2.1.4-1ubuntu1.1.
This file is owned by root:root, with mode 0o644.
The actual contents of the file can be viewed below.
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77 78 79 80 81 82 83 84 85 86 87 88 89 90 91 92 93 94 95 96 97 98 99 100 101 102 103 104 105 106 107 108 109 110 111 112 113 114 115 116 117 118 119 120 121 122 123 124 125 126 127 128 129 130 131 132 133 134 135 136 137 138 139 140 141 142 143 144 145 146 147 148 149 150 151 152 153 154 155 156 157 158 159 160 161 162 163 164 165 166 167 168 169 170 171 172 173 174 175 176 177 178 179 180 181 182 183 184 185 186 187 188 189 190 191 192 193 194 195 196 197 198 199 200 201 202 | # 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.
"""
def _byte_padding_check(block_size):
if not (0 <= block_size <= 2040):
raise ValueError("block_size must be in range(0, 2041).")
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):
_byte_padding_check(block_size)
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):
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(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_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(object):
def __init__(self, block_size):
_byte_padding_check(block_size)
self.block_size = block_size
def padder(self):
return _ANSIX923PaddingContext(self.block_size)
def unpadder(self):
return _ANSIX923UnpaddingContext(self.block_size)
@utils.register_interface(PaddingContext)
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(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_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
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