feat: add new class method to suss out key from string

Closes #59

python/py_vapid/__init__.py

@@ -125,6 +125,22 @@ def from_file(cls, private_key_file=None):
             logging.error("Could not open private key file: %s", repr(exc))
             raise VapidException(exc)
 
+    @classmethod
+    def from_string(cls, private_key):
+        """Initialize VAPID using a string containing the private key. This
+        will try to determine if the key is in RAW or DER format.
+
+        :param private_key: String containing the key info
+        :type private_key: str
+
+        """
+
+        pkey = private_key.encode().replace(b"\n", b"")
+        key = b64urldecode(pkey)
+        if len(key) == 32:
+            return cls.from_raw(pkey)
+        return cls.from_der(pkey)
+
     @classmethod
     def verify(cls, key, auth):
         """Verify a VAPID authorization token.

python/py_vapid/tests/test_vapid.py

@@ -122,8 +122,14 @@ def test_from_raw(self):
         v = Vapid01.from_raw(T_RAW)
         self.check_keys(v)
 
+    def test_from_string(self):
+        v1 = Vapid01.from_string(T_DER)
+        v2 = Vapid01.from_string(T_RAW.decode())
+        self.check_keys(v1)
+        self.check_keys(v2)
+
     def test_sign_01(self):
-        v = Vapid01.from_file("/tmp/private")
+        v = Vapid01.from_string(T_DER)
         claims = {"aud": "https://example.com",
                   "sub": "mailto:[email protected]"}
         result = v.sign(claims, "id=previous")

python/requirements.txt

@@ -1,2 +1,2 @@
 ecdsa==0.13
-cryptography>=1.8.2,<=2.0.3
+cryptography>=1.8.2

python/setup.py

@@ -3,7 +3,7 @@
 
 from setuptools import setup, find_packages
 
-__version__ = "1.2.6"
+__version__ = "1.3.0"
 
 
 def read_from(file):