ENH: Use cryptography for encryption/decryption as a fallback for P…

…yCryptodome (#2000)

Use the [`cryptography` package](https://pypi.org/project/cryptography/) (maintained by the Python Cryptographic Authority, pyca) as a fallback if [PyCryptodome](https://pypi.org/project/pycryptodome/) (maintained by Legrandin / Helder Eijs) is not installed.

Closes #1998

.github/workflows/github-ci.yaml

@@ -22,10 +22,12 @@ jobs:
  strategy:
  matrix:
  python-version: ["3.6", "3.7", "3.8", "3.9", "3.10", "3.11"]
- use-cryptodome: [""]
+ use-crypto-lib: ["pycryptodome"]
  include:
+ - python-version: "3.9"
+ use-crypto-lib: "cryptography"
  - python-version: "3.10"
- use-cryptodome: "false"
+ use-crypto-lib: ""
  steps:
  - name: Checkout Code
  uses: actions/checkout@v3
@@ -62,10 +64,14 @@ jobs:
  run: |
  pip install -r requirements/ci-3.11.txt
  if: matrix.python-version == '3.11'
- - name: Remove cryptodome
+ - name: Remove pycryptodome
  run: |
  pip uninstall pycryptodome -y
- if: matrix.use-cryptodome == 'false'
+ if: matrix.use-crypto-lib != 'pycryptodome'
+ - name: Install cryptography
+ run: |
+ pip install cryptography
+ if: matrix.use-crypto-lib == 'cryptography'
  - name: Install pypdf
  run: |
  pip install .

pypdf/_crypt_providers/__init__.py

@@ -0,0 +1,76 @@
+# Copyright (c) 2023, exiledkingcc
+# All rights reserved.
+#
+# Redistribution and use in source and binary forms, with or without
+# modification, are permitted provided that the following conditions are
+# met:
+#
+# * Redistributions of source code must retain the above copyright notice,
+# this list of conditions and the following disclaimer.
+# * Redistributions in binary form must reproduce the above copyright notice,
+# this list of conditions and the following disclaimer in the documentation
+# and/or other materials provided with the distribution.
+# * The name of the author may not be used to endorse or promote products
+# derived from this software without specific prior written permission.
+#
+# THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
+# AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
+# IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
+# ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR CONTRIBUTORS BE
+# LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
+# CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
+# SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
+# INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
+# CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
+# ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
+# POSSIBILITY OF SUCH DAMAGE.
+
+from pypdf._crypt_providers._base import CryptBase, CryptIdentity
+
+try:
+ from pypdf._crypt_providers._pycryptodome import (
+ CryptAES,
+ CryptRC4,
+ aes_cbc_decrypt,
+ aes_cbc_encrypt,
+ aes_ecb_decrypt,
+ aes_ecb_encrypt,
+ rc4_decrypt,
+ rc4_encrypt,
+ )
+except ImportError:
+ try:
+ from pypdf._crypt_providers._cryptography import ( # type: ignore
+ CryptAES,
+ CryptRC4,
+ aes_cbc_decrypt,
+ aes_cbc_encrypt,
+ aes_ecb_decrypt,
+ aes_ecb_encrypt,
+ rc4_decrypt,
+ rc4_encrypt,
+ )
+ except ImportError:
+ from pypdf._crypt_providers._fallback import ( # type: ignore
+ CryptAES,
+ CryptRC4,
+ aes_cbc_decrypt,
+ aes_cbc_encrypt,
+ aes_ecb_decrypt,
+ aes_ecb_encrypt,
+ rc4_decrypt,
+ rc4_encrypt,
+ )
+
+__all__ = [
+ "CryptBase",
+ "CryptIdentity",
+ "CryptRC4",
+ "CryptAES",
+ "rc4_encrypt",
+ "rc4_decrypt",
+ "aes_ecb_encrypt",
+ "aes_ecb_decrypt",
+ "aes_cbc_encrypt",
+ "aes_cbc_decrypt",
+]

pypdf/_crypt_providers/_base.py

@@ -0,0 +1,38 @@
+# Copyright (c) 2023, exiledkingcc
+# All rights reserved.
+#
+# Redistribution and use in source and binary forms, with or without
+# modification, are permitted provided that the following conditions are
+# met:
+#
+# * Redistributions of source code must retain the above copyright notice,
+# this list of conditions and the following disclaimer.
+# * Redistributions in binary form must reproduce the above copyright notice,
+# this list of conditions and the following disclaimer in the documentation
+# and/or other materials provided with the distribution.
+# * The name of the author may not be used to endorse or promote products
+# derived from this software without specific prior written permission.
+#
+# THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
+# AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
+# IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
+# ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR CONTRIBUTORS BE
+# LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
+# CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
+# SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
+# INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
+# CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
+# ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
+# POSSIBILITY OF SUCH DAMAGE.
+
+
+class CryptBase:
+ def encrypt(self, data: bytes) -> bytes: # pragma: no cover
+ return data
+
+ def decrypt(self, data: bytes) -> bytes: # pragma: no cover
+ return data
+
+
+class CryptIdentity(CryptBase):
+ pass

pypdf/_crypt_providers/_cryptography.py

@@ -0,0 +1,109 @@
+# Copyright (c) 2023, exiledkingcc
+# All rights reserved.
+#
+# Redistribution and use in source and binary forms, with or without
+# modification, are permitted provided that the following conditions are
+# met:
+#
+# * Redistributions of source code must retain the above copyright notice,
+# this list of conditions and the following disclaimer.
+# * Redistributions in binary form must reproduce the above copyright notice,
+# this list of conditions and the following disclaimer in the documentation
+# and/or other materials provided with the distribution.
+# * The name of the author may not be used to endorse or promote products
+# derived from this software without specific prior written permission.
+#
+# THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
+# AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
+# IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
+# ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR CONTRIBUTORS BE
+# LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
+# CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
+# SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
+# INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
+# CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
+# ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
+# POSSIBILITY OF SUCH DAMAGE.
+
+import secrets
+
+from cryptography.hazmat.primitives import padding # type: ignore[import]
+from cryptography.hazmat.primitives.ciphers.algorithms import AES, ARC4 # type: ignore[import]
+from cryptography.hazmat.primitives.ciphers.base import Cipher # type: ignore[import]
+from cryptography.hazmat.primitives.ciphers.modes import CBC, ECB # type: ignore[import]
+
+from pypdf._crypt_providers._base import CryptBase
+
+
+class CryptRC4(CryptBase):
+ def __init__(self, key: bytes) -> None:
+ self.cipher = Cipher(ARC4(key), mode=None)
+
+ def encrypt(self, data: bytes) -> bytes:
+ encryptor = self.cipher.encryptor()
+ return encryptor.update(data) + encryptor.finalize()
+
+ def decrypt(self, data: bytes) -> bytes:
+ decryptor = self.cipher.decryptor()
+ return decryptor.update(data) + decryptor.finalize()
+
+
+class CryptAES(CryptBase):
+ def __init__(self, key: bytes) -> None:
+ self.alg = AES(key)
+
+ def encrypt(self, data: bytes) -> bytes:
+ iv = secrets.token_bytes(16)
+ pad = padding.PKCS7(128).padder()
+ data = pad.update(data) + pad.finalize()
+
+ cipher = Cipher(self.alg, CBC(iv))
+ encryptor = cipher.encryptor()
+ return iv + encryptor.update(data) + encryptor.finalize()
+
+ def decrypt(self, data: bytes) -> bytes:
+ iv = data[:16]
+ data = data[16:]
+ # for empty encrypted data
+ if not data:
+ return data
+
+ # just for robustness, it does not happen under normal circumstances
+ if len(data) % 16 != 0:
+ pad = padding.PKCS7(128).padder()
+ data = pad.update(data) + pad.finalize()
+
+ cipher = Cipher(self.alg, CBC(iv))
+ decryptor = cipher.decryptor()
+ d = decryptor.update(data) + decryptor.finalize()
+ return d[: -d[-1]]
+
+
+def rc4_encrypt(key: bytes, data: bytes) -> bytes:
+ encryptor = Cipher(ARC4(key), mode=None).encryptor()
+ return encryptor.update(data) + encryptor.finalize()
+
+
+def rc4_decrypt(key: bytes, data: bytes) -> bytes:
+ decryptor = Cipher(ARC4(key), mode=None).decryptor()
+ return decryptor.update(data) + decryptor.finalize()
+
+
+def aes_ecb_encrypt(key: bytes, data: bytes) -> bytes:
+ encryptor = Cipher(AES(key), mode=ECB()).encryptor()
+ return encryptor.update(data) + encryptor.finalize()
+
+
+def aes_ecb_decrypt(key: bytes, data: bytes) -> bytes:
+ decryptor = Cipher(AES(key), mode=ECB()).decryptor()
+ return decryptor.update(data) + decryptor.finalize()
+
+
+def aes_cbc_encrypt(key: bytes, iv: bytes, data: bytes) -> bytes:
+ encryptor = Cipher(AES(key), mode=CBC(iv)).encryptor()
+ return encryptor.update(data) + encryptor.finalize()
+
+
+def aes_cbc_decrypt(key: bytes, iv: bytes, data: bytes) -> bytes:
+ decryptor = Cipher(AES(key), mode=CBC(iv)).decryptor()
+ return decryptor.update(data) + decryptor.finalize()

pypdf/_crypt_providers/_fallback.py

@@ -0,0 +1,90 @@
+# Copyright (c) 2023, exiledkingcc
+# All rights reserved.
+#
+# Redistribution and use in source and binary forms, with or without
+# modification, are permitted provided that the following conditions are
+# met:
+#
+# * Redistributions of source code must retain the above copyright notice,
+# this list of conditions and the following disclaimer.
+# * Redistributions in binary form must reproduce the above copyright notice,
+# this list of conditions and the following disclaimer in the documentation
+# and/or other materials provided with the distribution.
+# * The name of the author may not be used to endorse or promote products
+# derived from this software without specific prior written permission.
+#
+# THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
+# AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
+# IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
+# ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR CONTRIBUTORS BE
+# LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
+# CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
+# SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
+# INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
+# CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
+# ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
+# POSSIBILITY OF SUCH DAMAGE.
+
+from pypdf._crypt_providers._base import CryptBase
+from pypdf.errors import DependencyError
+
+_DEPENDENCY_ERROR_STR = "PyCryptodome is required for AES algorithm"
+
+
+class CryptRC4(CryptBase): # type: ignore
+ def __init__(self, key: bytes) -> None:
+ self.S = bytearray(range(256))
+ j = 0
+ for i in range(256):
+ j = (j + self.S[i] + key[i % len(key)]) % 256
+ self.S[i], self.S[j] = self.S[j], self.S[i]
+
+ def encrypt(self, data: bytes) -> bytes:
+ S = bytearray(self.S)
+ out = [0 for _ in range(len(data))]
+ i, j = 0, 0
+ for k in range(len(data)):
+ i = (i + 1) % 256
+ j = (j + S[i]) % 256
+ S[i], S[j] = S[j], S[i]
+ x = S[(S[i] + S[j]) % 256]
+ out[k] = data[k] ^ x
+ return bytes(bytearray(out))
+
+ def decrypt(self, data: bytes) -> bytes:
+ return self.encrypt(data)
+
+
+class CryptAES(CryptBase): # type: ignore
+ def __init__(self, key: bytes) -> None:
+ pass
+
+ def encrypt(self, data: bytes) -> bytes:
+ raise DependencyError(_DEPENDENCY_ERROR_STR)
+
+ def decrypt(self, data: bytes) -> bytes:
+ raise DependencyError(_DEPENDENCY_ERROR_STR)
+
+
+def rc4_encrypt(key: bytes, data: bytes) -> bytes:
+ return CryptRC4(key).encrypt(data)
+
+
+def rc4_decrypt(key: bytes, data: bytes) -> bytes:
+ return CryptRC4(key).decrypt(data)
+
+
+def aes_ecb_encrypt(key: bytes, data: bytes) -> bytes:
+ raise DependencyError(_DEPENDENCY_ERROR_STR)
+
+
+def aes_ecb_decrypt(key: bytes, data: bytes) -> bytes:
+ raise DependencyError(_DEPENDENCY_ERROR_STR)
+
+
+def aes_cbc_encrypt(key: bytes, iv: bytes, data: bytes) -> bytes:
+ raise DependencyError(_DEPENDENCY_ERROR_STR)
+
+
+def aes_cbc_decrypt(key: bytes, iv: bytes, data: bytes) -> bytes:
+ raise DependencyError(_DEPENDENCY_ERROR_STR)