Add Vapid.from_raw. Closes #35.

Author: Kit Cambridge

python/py_vapid/__init__.py

@@ -16,6 +16,10 @@
 VERSION = "VAPID-DRAFT-02/ECE-DRAFT-07"
 
 
+def b64urldecode(data):
+    return base64.urlsafe_b64decode(data + "===="[:len(data) % 4])
+
+
 class VapidException(Exception):
     """An exception wrapper for Vapid."""
     pass
@@ -42,6 +46,13 @@ def __init__(self, private_key=None):
         """
         self.private_key = private_key
 
+    @classmethod
+    def from_raw(cls, private_key):
+        key = ecdsa.SigningKey.from_string(b64urldecode(private_key),
+                                           curve=cls._curve,
+                                           hashfunc=cls._hasher)
+        return cls(key)
+
     @classmethod
     def from_pem(cls, private_key):
         """Initialize VAPID using a private key in PEM format.

python/py_vapid/tests/test_vapid.py

@@ -21,6 +21,12 @@
 T_PRIVATE = ("-----BEGIN EC PRIVATE KEY-----{}"
              "-----END EC PRIVATE KEY-----\n").format(T_DER)
 
+# This is the same private key, as a point in uncompressed form. This should
+# be Base64url-encoded without padding.
+T_RAW = """
+943WICKkdu3z78pnY0gXw143biOoCacwsVkQyhxjxFs
+"""
+
 # This is a public key in PEM form.
 T_PUBLIC = """-----BEGIN PUBLIC KEY-----
 MFkwEwYHKoZIzj0CAQYIKoZIzj0DAQcDQgAEEJwJZq/GN8jJbo1GGpyU70hmP2hb
@@ -104,6 +110,11 @@ def test_same_public_key(self):
         v.save_public_key("/tmp/p2")
         os.unlink("/tmp/p2")
 
+    def test_from_raw(self):
+        v = Vapid01.from_raw(T_RAW)
+        eq_(v.private_key.to_pem(), T_PRIVATE.encode('utf8'))
+        eq_(v.public_key.to_pem(), T_PUBLIC.encode('utf8'))
+
     def test_validate(self):
         v = Vapid01.from_file("/tmp/private")
         msg = "foobar".encode('utf8')