MAINT: Mark cryptography as default (#2186)

.github/workflows/github-ci.yaml

@@ -22,11 +22,13 @@ jobs:
     runs-on: ubuntu-20.04
     strategy:
       matrix:
-        python-version: ["3.6", "3.7", "3.8", "3.9", "3.10", "3.11", "3.12"]
-        use-crypto-lib: ["pycryptodome"]
+        python-version: ["3.7", "3.8", "3.9", "3.10", "3.11", "3.12"]
+        use-crypto-lib: ["cryptography"]
         include:
+          - python-version: "3.6"
+            use-crypto-lib: "pycryptodome"
           - python-version: "3.9"
-            use-crypto-lib: "cryptography"
+            use-crypto-lib: "pycryptodome"
           - python-version: "3.10"
             use-crypto-lib: ""
     steps:
@@ -72,14 +74,17 @@ jobs:
       run: |
         pip install -r requirements/ci-3.11.txt
       if: matrix.python-version == '3.11' || matrix.python-version == '3.12'
-    - name: Remove pycryptodome
+    - name: Remove pycryptodome and cryptography
       run: |
-        pip uninstall pycryptodome -y
-      if: matrix.use-crypto-lib != 'pycryptodome'
+        pip uninstall pycryptodome cryptography -y
     - name: Install cryptography
       run: |
         pip install cryptography
       if: matrix.use-crypto-lib == 'cryptography'
+    - name: Install pycryptodome
+      run: |
+        pip install pycryptodome
+      if: matrix.use-crypto-lib == 'pycryptodome'
     - name: Install pypdf
       run: |
         pip install .

pypdf/_crypt_providers/_fallback.py

@@ -28,7 +28,7 @@
 from pypdf._crypt_providers._base import CryptBase
 from pypdf.errors import DependencyError
 
-_DEPENDENCY_ERROR_STR = "PyCryptodome is required for AES algorithm"
+_DEPENDENCY_ERROR_STR = "cryptography>=3.1 is required for AES algorithm"
 
 
 crypt_provider = ("local_crypt_fallback", "0.0.0")

tests/test_encryption.py

@@ -6,25 +6,14 @@
 
 import pypdf
 from pypdf import PasswordType, PdfReader, PdfWriter
+from pypdf._crypt_providers import crypt_provider
+from pypdf._crypt_providers._fallback import _DEPENDENCY_ERROR_STR
 from pypdf._encryption import AlgV5, CryptAES, CryptRC4
 from pypdf.errors import DependencyError, PdfReadError
 
-try:
-    from Crypto.Cipher import AES  # noqa: F401
-
-    HAS_PYCRYPTODOME = True
-except ImportError:
-    HAS_PYCRYPTODOME = False
-
-try:
-    from cryptography.hazmat.primitives import padding  # noqa: F401
-
-    HAS_CRYPTOGRAPHY = True
-except ImportError:
-    HAS_CRYPTOGRAPHY = False
-
-
-HAS_AES = HAS_CRYPTOGRAPHY or HAS_PYCRYPTODOME
+USE_CRYPTOGRAPHY = crypt_provider[0] == "cryptography"
+USE_PYCRYPTODOME = crypt_provider[0] == "pycryptodome"
+HAS_AES = USE_CRYPTOGRAPHY or USE_PYCRYPTODOME
 TESTS_ROOT = Path(__file__).parent.resolve()
 PROJECT_ROOT = TESTS_ROOT.parent
 RESOURCE_ROOT = PROJECT_ROOT / "resources"
@@ -95,7 +84,7 @@ def test_encryption(name, requires_aes):
             ipdf = pypdf.PdfReader(inputfile)
             ipdf.decrypt("asdfzxcv")
             dd = dict(ipdf.metadata)
-        assert exc.value.args[0] == "PyCryptodome is required for AES algorithm"
+        assert exc.value.args[0] == _DEPENDENCY_ERROR_STR
         return
     else:
         ipdf = pypdf.PdfReader(inputfile)
@@ -193,7 +182,7 @@ def test_merge_encrypted_pdfs(names):
 
 
 @pytest.mark.skipif(
-    HAS_CRYPTOGRAPHY,
+    USE_CRYPTOGRAPHY,
     reason="Limitations of cryptography. see https://github.com/pyca/cryptography/issues/2494",
 )
 @pytest.mark.parametrize(
@@ -286,7 +275,7 @@ def test_pdf_encrypt(pdf_file_path, alg, requires_aes):
             )
             with open(pdf_file_path, "wb") as output_stream:
                 writer.write(output_stream)
-        assert exc.value.args[0] == "PyCryptodome is required for AES algorithm"
+        assert exc.value.args[0] == _DEPENDENCY_ERROR_STR
         return
 
     writer.encrypt(

tests/test_reader.py

@@ -7,6 +7,7 @@
 import pytest
 
 from pypdf import PdfReader
+from pypdf._crypt_providers import crypt_provider
 from pypdf._reader import convert_to_int, convertToInt
 from pypdf.constants import ImageAttributes as IA
 from pypdf.constants import PageAttributes as PG
@@ -29,13 +30,7 @@
 
 from . import get_data_from_url, normalize_warnings
 
-try:
-    from Crypto.Cipher import AES  # noqa: F401
-
-    HAS_PYCRYPTODOME = True
-except ImportError:
-    HAS_PYCRYPTODOME = False
-
+HAS_AES = crypt_provider[0] in ["pycryptodome", "cryptography"]
 TESTS_ROOT = Path(__file__).parent.resolve()
 PROJECT_ROOT = TESTS_ROOT.parent
 RESOURCE_ROOT = PROJECT_ROOT / "resources"
@@ -834,7 +829,7 @@ def test_read_not_binary_mode(caplog):
 
 
 @pytest.mark.enable_socket()
-@pytest.mark.skipif(not HAS_PYCRYPTODOME, reason="No pycryptodome")
+@pytest.mark.skipif(not HAS_AES, reason="No AES algorithm available")
 def test_read_form_416():
     url = (
         "https://www.fda.gov/downloads/AboutFDA/ReportsManualsForms/Forms/UCM074728.pdf"