RC 1.0.7

.vscode/tasks.json

@@ -111,7 +111,7 @@
                 "build",
                 ".",
                 "--wheel",
-                "--sdist",
+                "--sdist"
             ],
             "problemMatcher": []
         },
@@ -201,6 +201,7 @@
             "dependsOrder": "sequence",
             "dependsOn": [
                 "Clean",
+                //"InstallCryptography",
                 "Security",
                 "Sort Imports",
                 "Format",
@@ -223,5 +224,18 @@
             ],
             "problemMatcher": []
         },
+        {
+            "label": "InstallCryptography",
+            "type": "process",
+            "command": "${config:python.defaultInterpreterPath}",
+            "args": [
+                "-m",
+                "pip",
+                "install",
+                "--upgrade",
+                "cryptography"
+            ],
+            "problemMatcher": []
+        },
     ]
 }

README.md

@@ -71,6 +71,8 @@ source env/bin/activate # (or env\Scripts\activate on Windows)
 python3 -m pip install --upgrade pyspartn
 ```
 
+**FYI** From `pyspartn` version 1.0.7 onwards, SPARTN decryption functionality is optional. To install without decryption support, use the `--no-deps` argument e.g. ```python3 -m pip install --upgrade pyspartn --no-deps```.
+
 *¹* On some 32-bit Linux platforms (e.g. Raspberry Pi OS 32), it may be necessary to [install Rust compiler support](https://www.rust-lang.org/tools/install) in order to install the `cryptography` package which `pyspartn` depends on to decrypt SPARTN message payloads. See [cryptography install README](https://github.com/semuconsulting/pyspartn/blob/main/cryptography_installation/README.md).
 
 For [Conda](https://docs.conda.io/en/latest/) users, `pyspartn` is also available from [conda-forge](https://github.com/conda-forge/pyspartn-feedstock):

RELEASE_NOTES.md

@@ -1,5 +1,9 @@
 # pyspartn Release Notes
 
+### RELEASE 1.0.7
+
+1. Make SPARTN decryption (and associated `cryptography` library dependencies) an optional feature, to avoid a hard dependency on the `cryptography` library (which is problematic on some platforms). To install without SPARTN decryption support, use `python3 -m pip install pyspartn --no-deps`.
+
 ### RELEASE 1.0.6
 
 1. Update build configuration and minimum cryptography version - no functional changes.

pyproject.toml

@@ -88,7 +88,7 @@ disable = """
 
 [tool.pytest.ini_options]
 minversion = "7.0"
-addopts = "--cov --cov-report html --cov-fail-under 95"
+addopts = "--cov --cov-report html --cov-fail-under 94"
 pythonpath = ["src"]
 
 [tool.coverage.run]

src/pyspartn/_version.py

@@ -8,4 +8,4 @@
 :license: BSD 3-Clause
 """
 
-__version__ = "1.0.6"
+__version__ = "1.0.7"

src/pyspartn/spartnhelpers.py

@@ -11,8 +11,12 @@
 
 from datetime import datetime, timedelta, timezone
 
-from cryptography.hazmat.primitives.ciphers import Cipher, algorithms, modes
+try:
+    from cryptography.hazmat.primitives.ciphers import Cipher, algorithms, modes
 
+    HASCRYPTO = True
+except (ImportError, ModuleNotFoundError):
+    HASCRYPTO = False
 from pyspartn.exceptions import SPARTNMessageError
 from pyspartn.spartntypes_core import FL, IN, SPARTN_DATA_FIELDS, TIMEBASE
 
@@ -176,6 +180,9 @@ def encrypt(pt: bytes, key: bytes, iv: bytes, mode: str = "CTR") -> tuple:
     :rtype: tuple
     """
 
+    if not HASCRYPTO:  # pragma: no-cover
+        return None, None
+
     if mode == "CTR":
         cipher = Cipher(algorithms.AES(key), modes.CTR(iv))
     else:
@@ -201,6 +208,9 @@ def decrypt(ct: bytes, key: bytes, iv: bytes, mode: str = "CTR") -> bytes:
     :rtype: bytes
     """
 
+    if not HASCRYPTO:  # pragma: no-cover
+        return None
+
     if mode == "CTR":
         cipher = Cipher(algorithms.AES(key), modes.CTR(iv))
     else:

src/pyspartn/spartnmessage.py

@@ -24,6 +24,7 @@
     SPARTNParseError,
 )
 from pyspartn.spartnhelpers import (
+    HASCRYPTO,
     bitsval,
     convert_timetag,
     decrypt,
@@ -124,9 +125,6 @@ def __init__(
         self._key = None if key is None else bytes.fromhex(key)
         self._iv = None
 
-        if self._decode and self._key is None:
-            raise ParameterError("Key must be provided if decoding is enabled")
-
         self._do_attributes()
         self._immutable = True  # once initialised, object is immutable
 
@@ -141,10 +139,19 @@ def _do_attributes(self):
         # start of framestart
         self.msgType = bitsval(self._transport, 8, 7)
         self.nData = bitsval(self._transport, 15, 10)
-        self.eaf = bitsval(self._transport, 25, 1)
+        self.eaf = bitsval(self._transport, 25, 1)  # 1 = encrypted
         self.crcType = bitsval(self._transport, 26, 2)
         self.frameCrc = bitsval(self._transport, 28, 4)
 
+        # check if decryption available
+        if self._decode and self.eaf:
+            if self._key is None:
+                raise ParameterError("Key must be provided if decryption is enabled")
+            if not HASCRYPTO:
+                raise ParameterError(
+                    "Decryption not available - cryptography library is not installed"
+                )
+
         # start of payDesc
         self.msgSubtype = bitsval(self._transport, 32, 4)
         self.timeTagtype = bitsval(self._transport, 36, 1)

tests/test_static.py

@@ -12,6 +12,13 @@
 import unittest
 from datetime import datetime, timezone
 
+try:
+    from cryptography.hazmat.primitives.ciphers import Cipher, algorithms, modes
+
+    HASCRYPTO = True
+except (ImportError, ModuleNotFoundError):
+    HASCRYPTO = False
+
 from pyspartn.exceptions import SPARTNMessageError
 from pyspartn.spartnhelpers import (
     att2idx,
@@ -114,6 +121,9 @@ def testescapeall(self):
         self.assertEqual(res, EXPECTED_RESULT)
 
     def testdecrypt(self):
+        if not HASCRYPTO:
+            return
+
         msg = b"your secret message"
         key = 0x395C12348D083E53AD0A5AA257C6A741.to_bytes(16, "big")
         iv = os.urandom(16)