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-# -*- coding: utf-8 -*-
-#
-# Copyright 2011 Sybren A. Stüvel <sybren@stuvel.eu>
-#
-# Licensed under the Apache License, Version 2.0 (the "License");
-# you may not use this file except in compliance with the License.
-# You may obtain a copy of the License at
-#
-# https://www.apache.org/licenses/LICENSE-2.0
-#
-# Unless required by applicable law or agreed to in writing, software
-# distributed under the License is distributed on an "AS IS" BASIS,
-# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
-# See the License for the specific language governing permissions and
-# limitations under the License.
-
-"""VARBLOCK file support
-
-.. deprecated:: 3.4
-
- The VARBLOCK format is NOT recommended for general use, has been deprecated since
- Python-RSA 3.4, and will be removed in a future release. It's vulnerable to a
- number of attacks:
-
- 1. decrypt/encrypt_bigfile() does not implement `Authenticated encryption`_ nor
- uses MACs to verify messages before decrypting public key encrypted messages.
-
- 2. decrypt/encrypt_bigfile() does not use hybrid encryption (it uses plain RSA)
- and has no method for chaining, so block reordering is possible.
-
- See `issue #19 on Github`_ for more information.
-
-.. _Authenticated encryption: https://en.wikipedia.org/wiki/Authenticated_encryption
-.. _issue #19 on Github: https://github.com/sybrenstuvel/python-rsa/issues/13
-
-
-The VARBLOCK file format is as follows, where || denotes byte concatenation:
-
- FILE := VERSION || BLOCK || BLOCK ...
-
- BLOCK := LENGTH || DATA
-
- LENGTH := varint-encoded length of the subsequent data. Varint comes from
- Google Protobuf, and encodes an integer into a variable number of bytes.
- Each byte uses the 7 lowest bits to encode the value. The highest bit set
- to 1 indicates the next byte is also part of the varint. The last byte will
- have this bit set to 0.
-
-This file format is called the VARBLOCK format, in line with the varint format
-used to denote the block sizes.
-
-"""
-
-import warnings
-
-from rsa._compat import byte, b
-
-ZERO_BYTE = b('\x00')
-VARBLOCK_VERSION = 1
-
-warnings.warn("The 'rsa.varblock' module was deprecated in Python-RSA version "
- "3.4 due to security issues in the VARBLOCK format. See "
- "https://github.com/sybrenstuvel/python-rsa/issues/13 for more information.",
- DeprecationWarning)
-
-
-def read_varint(infile):
- """Reads a varint from the file.
-
- When the first byte to be read indicates EOF, (0, 0) is returned. When an
- EOF occurs when at least one byte has been read, an EOFError exception is
- raised.
-
- :param infile: the file-like object to read from. It should have a read()
- method.
- :returns: (varint, length), the read varint and the number of read bytes.
- """
-
- varint = 0
- read_bytes = 0
-
- while True:
- char = infile.read(1)
- if len(char) == 0:
- if read_bytes == 0:
- return 0, 0
- raise EOFError('EOF while reading varint, value is %i so far' %
- varint)
-
- byte = ord(char)
- varint += (byte & 0x7F) << (7 * read_bytes)
-
- read_bytes += 1
-
- if not byte & 0x80:
- return varint, read_bytes
-
-
-def write_varint(outfile, value):
- """Writes a varint to a file.
-
- :param outfile: the file-like object to write to. It should have a write()
- method.
- :returns: the number of written bytes.
- """
-
- # there is a big difference between 'write the value 0' (this case) and
- # 'there is nothing left to write' (the false-case of the while loop)
-
- if value == 0:
- outfile.write(ZERO_BYTE)
- return 1
-
- written_bytes = 0
- while value > 0:
- to_write = value & 0x7f
- value >>= 7
-
- if value > 0:
- to_write |= 0x80
-
- outfile.write(byte(to_write))
- written_bytes += 1
-
- return written_bytes
-
-
-def yield_varblocks(infile):
- """Generator, yields each block in the input file.
-
- :param infile: file to read, is expected to have the VARBLOCK format as
- described in the module's docstring.
- @yields the contents of each block.
- """
-
- # Check the version number
- first_char = infile.read(1)
- if len(first_char) == 0:
- raise EOFError('Unable to read VARBLOCK version number')
-
- version = ord(first_char)
- if version != VARBLOCK_VERSION:
- raise ValueError('VARBLOCK version %i not supported' % version)
-
- while True:
- (block_size, read_bytes) = read_varint(infile)
-
- # EOF at block boundary, that's fine.
- if read_bytes == 0 and block_size == 0:
- break
-
- block = infile.read(block_size)
-
- read_size = len(block)
- if read_size != block_size:
- raise EOFError('Block size is %i, but could read only %i bytes' %
- (block_size, read_size))
-
- yield block
-
-
-def yield_fixedblocks(infile, blocksize):
- """Generator, yields each block of ``blocksize`` bytes in the input file.
-
- :param infile: file to read and separate in blocks.
- :returns: a generator that yields the contents of each block
- """
-
- while True:
- block = infile.read(blocksize)
-
- read_bytes = len(block)
- if read_bytes == 0:
- break
-
- yield block
-
- if read_bytes < blocksize:
- break