Add support for ISO 32000-2 AES256 encryption (#614)
* feat: Add support for ISO 32000-2 AES256 encryption * feat: Applies review suggestionspull/661/head
Raphaël Cohen
GitHub
parent
8ea9f1091a
commit
c3e3499a6b
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@ -6,6 +6,7 @@ The format is based on [Keep a Changelog](https://keepachangelog.com/en/1.0.0/).
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## [Unreleased]
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### Added
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- Add support for PDF 2.0 (ISO 32000-2) AES-256 encryption ([#614](https://github.com/pdfminer/pdfminer.six/pull/614))
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- Support for Paeth PNG filter compression (predictor value = 4) ([#537](https://github.com/pdfminer/pdfminer.six/pull/537))
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### Fixed
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@ -51,3 +51,8 @@ Contributing
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------------
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Be sure to read the [contribution guidelines](https://github.com/pdfminer/pdfminer.six/blob/master/CONTRIBUTING.md).
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Acknowledgement
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---------------
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This repository includes code from `pyHanko` ; the original license has been included [here](/docs/licenses/LICENSE.pyHanko).
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@ -0,0 +1,23 @@
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This package contains various elements based on code from the pyHanko project, of which we reproduce the license below.
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MIT License
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Copyright (c) 2020 Matthias Valvekens
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Permission is hereby granted, free of charge, to any person obtaining a copy
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of this software and associated documentation files (the "Software"), to deal
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in the Software without restriction, including without limitation the rights
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to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
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copies of the Software, and to permit persons to whom the Software is
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furnished to do so, subject to the following conditions:
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The above copyright notice and this permission notice shall be included in all
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copies or substantial portions of the Software.
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THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
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IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
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FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
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AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
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LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
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OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
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SOFTWARE.
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@ -0,0 +1,94 @@
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# Copyright 2016-present MongoDB, Inc.
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#
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# Licensed under the Apache License, Version 2.0 (the "License");
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# you may not use this file except in compliance with the License.
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# You may obtain a copy of the License at
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#
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# http://www.apache.org/licenses/LICENSE-2.0
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#
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# Unless required by applicable law or agreed to in writing, software
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# distributed under the License is distributed on an "AS IS" BASIS,
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# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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# See the License for the specific language governing permissions and
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# limitations under the License.
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#
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# Some changes copyright 2021-present Matthias Valvekens,
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# licensed under the license of the pyHanko project (see LICENSE file).
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"""An implementation of RFC4013 SASLprep."""
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__all__ = ['saslprep']
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import stringprep
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import unicodedata
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# RFC4013 section 2.3 prohibited output.
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_PROHIBITED = (
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# A strict reading of RFC 4013 requires table c12 here, but
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# characters from it are mapped to SPACE in the Map step. Can
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# normalization reintroduce them somehow?
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stringprep.in_table_c12,
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stringprep.in_table_c21_c22,
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stringprep.in_table_c3,
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stringprep.in_table_c4,
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stringprep.in_table_c5,
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stringprep.in_table_c6,
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stringprep.in_table_c7,
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stringprep.in_table_c8,
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stringprep.in_table_c9)
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def saslprep(data: str, prohibit_unassigned_code_points=True) -> str:
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"""An implementation of RFC4013 SASLprep.
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:param data:
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The string to SASLprep.
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:param prohibit_unassigned_code_points:
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RFC 3454 and RFCs for various SASL mechanisms distinguish between
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`queries` (unassigned code points allowed) and
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`stored strings` (unassigned code points prohibited). Defaults
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to ``True`` (unassigned code points are prohibited).
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:return: The SASLprep'ed version of `data`.
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"""
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if prohibit_unassigned_code_points:
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prohibited = _PROHIBITED + (stringprep.in_table_a1,)
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else:
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prohibited = _PROHIBITED
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# RFC3454 section 2, step 1 - Map
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# RFC4013 section 2.1 mappings
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# Map Non-ASCII space characters to SPACE (U+0020). Map
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# commonly mapped to nothing characters to, well, nothing.
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in_table_c12 = stringprep.in_table_c12
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in_table_b1 = stringprep.in_table_b1
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data = "".join(
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["\u0020" if in_table_c12(elt) else elt
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for elt in data if not in_table_b1(elt)])
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# RFC3454 section 2, step 2 - Normalize
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# RFC4013 section 2.2 normalization
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data = unicodedata.ucd_3_2_0.normalize('NFKC', data)
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in_table_d1 = stringprep.in_table_d1
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if in_table_d1(data[0]):
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if not in_table_d1(data[-1]):
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# RFC3454, Section 6, #3. If a string contains any
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# RandALCat character, the first and last characters
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# MUST be RandALCat characters.
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raise ValueError("SASLprep: failed bidirectional check")
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# RFC3454, Section 6, #2. If a string contains any RandALCat
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# character, it MUST NOT contain any LCat character.
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prohibited = prohibited + (stringprep.in_table_d2,)
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else:
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# RFC3454, Section 6, #3. Following the logic of #3, if
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# the first character is not a RandALCat, no other character
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# can be either.
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prohibited = prohibited + (in_table_d1,)
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# RFC3454 section 2, step 3 and 4 - Prohibit and check bidi
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for char in data:
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if any(in_table(char) for in_table in prohibited):
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raise ValueError(
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"SASLprep: failed prohibited character check")
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return data
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@ -1,7 +1,7 @@
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import logging
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import re
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import struct
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from hashlib import sha256, md5
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from hashlib import sha256, md5, sha384, sha512
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from cryptography.hazmat.backends import default_backend
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from cryptography.hazmat.primitives.ciphers import Cipher, algorithms, modes
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@ -477,7 +477,7 @@ class PDFStandardSecurityHandlerV4(PDFStandardSecurityHandler):
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class PDFStandardSecurityHandlerV5(PDFStandardSecurityHandlerV4):
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supported_revisions = (5,)
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supported_revisions = (5, 6)
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def init_params(self):
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super().init_params()
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@ -499,29 +499,84 @@ class PDFStandardSecurityHandlerV5(PDFStandardSecurityHandlerV4):
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return None
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def authenticate(self, password):
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password = password.encode('utf-8')[:127]
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hash = sha256(password)
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hash.update(self.o_validation_salt)
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hash.update(self.u)
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if hash.digest() == self.o_hash:
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hash = sha256(password)
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hash.update(self.o_key_salt)
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hash.update(self.u)
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cipher = Cipher(algorithms.AES(hash.digest()),
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password = self._normalize_password(password)
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hash = self._password_hash(password, self.o_validation_salt, self.u)
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if hash == self.o_hash:
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hash = self._password_hash(password, self.o_key_salt, self.u)
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cipher = Cipher(algorithms.AES(hash),
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modes.CBC(b'\0' * 16),
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backend=default_backend())
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return cipher.decryptor().update(self.oe)
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hash = sha256(password)
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hash.update(self.u_validation_salt)
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if hash.digest() == self.u_hash:
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hash = sha256(password)
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hash.update(self.u_key_salt)
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cipher = Cipher(algorithms.AES(hash.digest()),
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hash = self._password_hash(password, self.u_validation_salt)
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if hash == self.u_hash:
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hash = self._password_hash(password, self.u_key_salt)
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cipher = Cipher(algorithms.AES(hash),
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modes.CBC(b'\0' * 16),
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backend=default_backend())
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return cipher.decryptor().update(self.ue)
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return None
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def _normalize_password(self, password):
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if self.r == 6:
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# saslprep expects non-empty strings, apparently
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if not password:
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return b''
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from ._saslprep import saslprep
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password = saslprep(password)
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return password.encode('utf-8')[:127]
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def _password_hash(self, password, salt, vector=None):
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"""
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Compute password hash depending on revision number
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"""
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if self.r == 5:
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return self._r5_password(password, salt, vector)
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return self._r6_password(password, salt[0:8], vector)
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def _r5_password(self, password, salt, vector):
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"""
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Compute the password for revision 5
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"""
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hash = sha256(password)
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hash.update(salt)
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if vector is not None:
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hash.update(vector)
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return hash.digest()
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def _r6_password(self, password, salt, vector):
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"""
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Compute the password for revision 6
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"""
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initial_hash = sha256(password)
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initial_hash.update(salt)
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if vector is not None:
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initial_hash.update(vector)
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k = initial_hash.digest()
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hashes = (sha256, sha384, sha512)
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round_no = last_byte_val = 0
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while round_no < 64 or last_byte_val > round_no - 32:
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k1 = (password + k + (vector or b'')) * 64
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e = self._aes_cbc_encrypt(
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key=k[:16], iv=k[16:32], data=k1
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)
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# compute the first 16 bytes of e,
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# interpreted as an unsigned integer mod 3
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next_hash = hashes[self._bytes_mod_3(e[:16])]
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k = next_hash(e).digest()
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last_byte_val = e[len(e) - 1]
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round_no += 1
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return k[:32]
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@staticmethod
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def _bytes_mod_3(input_bytes):
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# 256 is 1 mod 3, so we can just sum 'em
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return sum(b % 3 for b in input_bytes) % 3
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def _aes_cbc_encrypt(self, key, iv, data):
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cipher = Cipher(algorithms.AES(key), modes.CBC(iv))
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encryptor = cipher.encryptor()
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return encryptor.update(data) + encryptor.finalize()
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def decrypt_aes256(self, objid, genno, data):
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initialization_vector = data[:16]
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ciphertext = data[16:]
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Binary file not shown.
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@ -96,6 +96,12 @@ class TestPdf2Txt():
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def test_encryption_aes256m(self):
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run('encryption/aes-256-m.pdf', '-P foo')
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def test_encryption_aes256_r6_user(self):
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run('encryption/aes-256-r6.pdf', '-P usersecret')
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def test_encryption_aes256_r6_owner(self):
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run('encryption/aes-256-r6.pdf', '-P ownersecret')
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def test_encryption_base(self):
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run('encryption/base.pdf', '-P foo')
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