Merge pull request #158 from pusher/base64-master-key

Base64 master key

Author: mdpye

CHANGELOG.md

@@ -1,3 +1,10 @@
+### next (major)
+
+* [ADDED] option `encryption_master_key_base64`
+* [DEPRECATED] option `encryption_master_key`
+
+* [REMOVED] old support for Push Notifications, see https://github.com/pusher/push-notifications-python
+
 ### 2.1.4 2019-08-09
 
 * [FIXED] TypeError in AuthenticationClient when using encrypted channels

README.md

@@ -86,7 +86,8 @@ pusher_client = pusher.Pusher(app_id, key, secret, cluster=u'cluster')
 |host `String`    | **Default:`None`** <br> The host to connect to |
 |port `int`       | **Default:`None`** <br>Which port to connect to |
 |ssl `bool`       | **Default:`True`** <br> Use HTTPS |
-|encryption_master_key `String`       | **Default:`None`** <br> The encryption master key for End-to-end Encryption |
+|~~encryption_master_key~~ `String` | **Default:`None`** <br> *Deprecated*, see `encryption_master_key_base64` |
+|encryption_master_key_base64 `String` | **Default:`None`** <br> The encryption master key for End-to-end Encryption |
 |backend `Object` | an object that responds to the `send_request(request)` method. If none is provided, a `pusher.requests.RequestsBackend` instance is created. |
 |json_encoder `Object` | **Default: `None`**<br> Custom JSON encoder. |
 |json_decoder `Object` | **Default: `None`**<br> Custom JSON decoder.
@@ -287,32 +288,51 @@ auth = pusher_client.authenticate(
 
 ## End to End Encryption (Beta)
 
-This library supports end to end encryption of your private channels. This means that only you and your connected clients will be able to read your messages. Pusher cannot decrypt them. You can enable this feature by following these steps:
+This library supports end to end encryption of your private channels. This
+means that only you and your connected clients will be able to read your
+messages. Pusher cannot decrypt them. You can enable this feature by following
+these steps:
 
-1. You should first set up Private channels. This involves [creating an authentication endpoint on your server](https://pusher.com/docs/authenticating_users).
+1. You should first set up Private channels. This involves [creating an
+   authentication endpoint on your
+   server](https://pusher.com/docs/authenticating_users).
 
-2. Next, Specify your 32 character `encryption_master_key`. This is secret and you should never share this with anyone. Not even Pusher.
+2. Next, generate a 32 byte master encryption key, base64 encode it and store
+   it securely.
 
-```python
+   This is secret and you should never share this with anyone. Not even Pusher.
 
-import pusher
+   To generate a suitable key from a secure random source, you could use:
 
-pusher_client = pusher.Pusher(
-  app_id='yourappid',
-  key='yourkey',
-  secret='yoursecret',
-  encryption_master_key='XXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXX',
-  cluster='yourclustername',
-  ssl=True
-)
+   ```bash
+   openssl rand -base64 32
+   ```
 
-pusher_client.trigger('private-encrypted-my-channel', 'my-event', {
-  'message': 'hello world'
-})
-```
-3. Channels where you wish to use end to end encryption must be prefixed with `private-encrypted-`.
+3. Pass your master key to the SDK constructor
+
+   ```python
+   import pusher
+
+   pusher_client = pusher.Pusher(
+     app_id='yourappid',
+     key='yourkey',
+     secret='yoursecret',
+     encryption_master_key_base64='<output from command above>',
+     cluster='yourclustername',
+     ssl=True
+   )
+
+   pusher_client.trigger('private-encrypted-my-channel', 'my-event', {
+     'message': 'hello world'
+   })
+   ```
+
+4. Channels where you wish to use end to end encryption must be prefixed with
+   `private-encrypted-`.
 
-4. Subscribe to these channels in your client, and you're done! You can verify it is working by checking out the debug console on the https://dashboard.pusher.com/ and seeing the scrambled ciphertext.
+5. Subscribe to these channels in your client, and you're done! You can verify
+   it is working by checking out the debug console on the
+   https://dashboard.pusher.com/ and seeing the scrambled ciphertext.
 
 **Important note: This will not encrypt messages on channels that are not prefixed by private-encrypted-.**
 

pusher/authentication_client.py

@@ -31,22 +31,37 @@
 
 class AuthenticationClient(Client):
     def __init__(
-            self, app_id, key, secret, ssl=True, host=None, port=None,
-            timeout=5, cluster=None, encryption_master_key=None, json_encoder=None, json_decoder=None,
-            backend=None, **backend_options):
+            self,
+            app_id,
+            key,
+            secret,
+            ssl=True,
+            host=None,
+            port=None,
+            timeout=5,
+            cluster=None,
+            encryption_master_key=None,
+            encryption_master_key_base64=None,
+            json_encoder=None,
+            json_decoder=None,
+            backend=None,
+            **backend_options):
+
         super(AuthenticationClient, self).__init__(
-            app_id, key, secret, ssl, host, port, timeout, cluster, encryption_master_key,
-            json_encoder, json_decoder, backend, **backend_options)
-
-        if host:
-            self._host = ensure_text(host, "host")
-
-        elif cluster:
-            self._host = (
-                six.text_type("api-%s.pusher.com") %
-                ensure_text(cluster, "cluster"))
-        else:
-            self._host = six.text_type("api.pusherapp.com")
+            app_id,
+            key,
+            secret,
+            ssl,
+            host,
+            port,
+            timeout,
+            cluster,
+            encryption_master_key,
+            encryption_master_key_base64,
+            json_encoder,
+            json_decoder,
+            backend,
+            **backend_options)
 
 
     def authenticate(self, channel, socket_id, custom_data=None):

pusher/client.py

@@ -9,13 +9,27 @@
 import six
 
 from pusher.util import ensure_text, ensure_binary, app_id_re
+from pusher.crypto import parse_master_key
 
 
 class Client(object):
     def __init__(
-            self, app_id, key, secret, ssl=True, host=None, port=None,
-            timeout=5, cluster=None, encryption_master_key=None, json_encoder=None, json_decoder=None,
-            backend=None, **backend_options):
+            self,
+            app_id,
+            key,
+            secret,
+            ssl=True,
+            host=None,
+            port=None,
+            timeout=5,
+            cluster=None,
+            encryption_master_key=None,
+            encryption_master_key_base64=None,
+            json_encoder=None,
+            json_decoder=None,
+            backend=None,
+            **backend_options):
+
         if backend is None:
               from .requests import RequestsBackend
               backend = RequestsBackend
@@ -32,6 +46,15 @@ def __init__(
 
         self._ssl = ssl
 
+        if host:
+            self._host = ensure_text(host, "host")
+        elif cluster:
+            self._host = (
+                six.text_type("api-%s.pusher.com") %
+                ensure_text(cluster, "cluster"))
+        else:
+            self._host = six.text_type("api.pusherapp.com")
+
         if port and not isinstance(port, six.integer_types):
               raise TypeError("port should be an integer")
 
@@ -44,14 +67,11 @@ def __init__(
         self._json_encoder = json_encoder
         self._json_decoder = json_decoder
 
-
-        if encryption_master_key is not None:
-            encryption_master_key = ensure_binary(encryption_master_key, "encryption_master_key")
-
-        self._encryption_master_key = encryption_master_key
+        self._encryption_master_key = parse_master_key(encryption_master_key, encryption_master_key_base64)
 
         self.http = backend(self, **backend_options)
 
+
     @property
     def app_id(self):
         return self._app_id

pusher/crypto.py

@@ -9,11 +9,14 @@
 import hashlib
 import nacl
 import base64
+import binascii
+import warnings
 
 from pusher.util import (
     ensure_text,
     ensure_binary,
-    data_to_string)
+    data_to_string,
+    is_base64)
 
 import nacl.secret
 import nacl.utils
@@ -29,27 +32,46 @@ def is_encrypted_channel(channel):
         return True
     return False
 
-def is_encryption_master_key_valid(encryption_master_key):
+def parse_master_key(encryption_master_key, encryption_master_key_base64):
     """
-    is_encryption_master_key_valid() checks if the provided encryption_master_key is valid by checking its length
-    the key is assumed to be a six.binary_type (python2 str or python3 bytes)
+    parse_master_key validates, parses and returns the bytes of the encryption master key
+    from the constructor arguments.
+    At present there is a deprecated "raw" key and a suggested base64 encoding.
     """
-    if encryption_master_key is not None and len(encryption_master_key) == 32:
-        return True
-
-    return False
+    if encryption_master_key is not None and encryption_master_key_base64 is not None:
+        raise ValueError("Do not provide both encryption_master_key and encryption_master_key_base64. " +
+                "encryption_master_key is deprecated, provide only encryption_master_key_base64")
+
+    if encryption_master_key is not None:
+        warnings.warn("`encryption_master_key` is deprecated, please use `encryption_master_key_base64`")
+        if len(encryption_master_key) == 32:
+            return ensure_binary(encryption_master_key, "encryption_master_key")
+        else:
+            raise ValueError("encryption_master_key must be 32 bytes long")
+
+    if encryption_master_key_base64 is not None:
+        if is_base64(encryption_master_key_base64):
+            decoded = base64.b64decode(encryption_master_key_base64)
+
+            if len(decoded) == 32:
+                return decoded
+            else:
+                raise ValueError("encryption_master_key_base64 must be a base64 string which decodes to 32 bytes")
+        else:
+            raise ValueError("encryption_master_key_base64 must be valid base64")
+
+    return None
 
 def generate_shared_secret(channel, encryption_master_key):
     """
     generate_shared_secret() takes a six.binary_type (python2 str or python3 bytes) channel name and encryption_master_key
     and returns the sha256 hash in six.binary_type format
     """
-    if is_encryption_master_key_valid(encryption_master_key):
-        # the key has to be 32 bytes long
-        hashable = channel + encryption_master_key
-        return hashlib.sha256(hashable).digest()
+    if encryption_master_key is None:
+        raise ValueError("No master key was provided for use with encrypted channels. Please provide encryption_master_key_base64 as an argument to the Pusher SDK")
 
-    raise ValueError("Provided encryption_master_key is not 32 char long")
+    hashable = channel + encryption_master_key
+    return hashlib.sha256(hashable).digest()
 
 def encrypt(channel, data, encryption_master_key, nonce=None):
     """