Add option to pass Auth Key as base64 string

Pass the base64 encoded Auth Key string to TokenCredentials rather than
the file path. This can be useful when the Auth Key is not stored in a
file for security reasons.

apns2/credentials.py

@@ -1,5 +1,6 @@
 import time
 from typing import Optional, Tuple, TYPE_CHECKING
+from base64 import b64decode
 
 import jwt
 
@@ -43,9 +44,13 @@ def __init__(self, cert_file: Optional[str] = None, password: Optional[str] = No
 # Credentials subclass for JWT token based authentication
 class TokenCredentials(Credentials):
     def __init__(self, auth_key_path: str, auth_key_id: str, team_id: str,
+                 auth_key_base64: Optional[str] = None,
                  encryption_algorithm: str = DEFAULT_TOKEN_ENCRYPTION_ALGORITHM,
                  token_lifetime: int = DEFAULT_TOKEN_LIFETIME) -> None:
-        self.__auth_key = self._get_signing_key(auth_key_path)
+        if auth_key_base64 is not None:
+            self.__auth_key = self._decode_signing_key(auth_key_base64)
+        else:
+            self.__auth_key = self._get_signing_key(auth_key_path)
         self.__auth_key_id = auth_key_id
         self.__team_id = team_id
         self.__encryption_algorithm = encryption_algorithm
@@ -71,6 +76,13 @@ def _get_signing_key(key_path: str) -> str:
                 secret = f.read()
         return secret
 
+    @staticmethod
+    def _decode_signing_key(key_base64: str) -> str:
+        secret = ''
+        if key_base64:
+            secret = b64decode(key_base64).decode()
+        return secret
+
     def _get_or_create_topic_token(self) -> str:
         # dict of topic to issue date and JWT token
         token_pair = self.__jwt_token

test/test_credentials.py

@@ -4,6 +4,7 @@
 # - timing out of the token
 # - creating multiple tokens for different topics
 
+from base64 import b64encode
 import pytest
 from freezegun import freeze_time
 
@@ -21,6 +22,10 @@ def token_credentials():
         token_lifetime=30,  # seconds
     )
 
+def test_auth_key_base64():
+    with open('test/eckey.pem', 'rb') as f:
+        auth_key_base64 = b64encode(f.read())
+    assert TokenCredentials._get_signing_key('test/eckey.pem') == TokenCredentials._decode_signing_key(auth_key_base64)
 
 def test_token_expiration(token_credentials):
     with freeze_time('2012-01-14 12:00:00'):