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)