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# 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 annotations
import abc
from cryptography import utils
from cryptography.hazmat.bindings._rust import (
ANSIX923PaddingContext,
ANSIX923UnpaddingContext,
PKCS7PaddingContext,
PKCS7UnpaddingContext,
)
class PaddingContext(metaclass=abc.ABCMeta):
@abc.abstractmethod
def update(self, data: utils.Buffer) -> bytes:
"""
Pads the provided bytes and returns any available data as bytes.
"""
@abc.abstractmethod
def finalize(self) -> bytes:
"""
Finalize the padding, returns bytes.
"""
def _byte_padding_check(block_size: int) -> None:
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.")
class PKCS7:
def __init__(self, block_size: int):
_byte_padding_check(block_size)
self.block_size = block_size
def padder(self) -> PaddingContext:
return PKCS7PaddingContext(self.block_size)
def unpadder(self) -> PaddingContext:
return PKCS7UnpaddingContext(self.block_size)
PaddingContext.register(PKCS7PaddingContext)
PaddingContext.register(PKCS7UnpaddingContext)
class ANSIX923:
def __init__(self, block_size: int):
_byte_padding_check(block_size)
self.block_size = block_size
def padder(self) -> PaddingContext:
return ANSIX923PaddingContext(self.block_size)
def unpadder(self) -> PaddingContext:
return ANSIX923UnpaddingContext(self.block_size)
PaddingContext.register(ANSIX923PaddingContext)
PaddingContext.register(ANSIX923UnpaddingContext)
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