Removed PyJWT dependency.

PyJWT is a very brittle and cumbersome dependency that expects several
cryptography libraries to be already installed on the system, and it can
lead to hard-to-debug errors when ported to different systems.

Moreover, it installs the whole `cryptography` package, which is several
MBs in size, takes time to compile, and it requires a Rust compiler to
be present on the target machine.

Platypush will now use the Python-native `rsa` module to handle JWT
tokens.

platypush/user/__init__.py

@@ -1,17 +1,14 @@
+import base64
 import datetime
 import hashlib
+import json
 import random
+import rsa
 import time
 from typing import Optional, Dict
 
 import bcrypt
 
-try:
-    from jwt.exceptions import PyJWTError
-    from jwt import encode as jwt_encode, decode as jwt_decode
-except ImportError:
-    from jwt import PyJWTError, encode as jwt_encode, decode as jwt_decode
-
 from sqlalchemy import Column, Integer, String, DateTime, ForeignKey
 from sqlalchemy.orm import sessionmaker, scoped_session
 from sqlalchemy.ext.declarative import declarative_base
@@ -197,17 +194,20 @@ class UserManager:
         if not user:
             raise InvalidCredentialsException()
 
-        pub_key, priv_key = get_or_generate_jwt_rsa_key_pair()
-        payload = {
-            'username': username,
-            'created_at': datetime.datetime.now().timestamp(),
-            'expires_at': expires_at.timestamp() if expires_at else None,
-        }
+        pub_key, _ = get_or_generate_jwt_rsa_key_pair()
+        payload = json.dumps(
+            {
+                'username': username,
+                'created_at': datetime.datetime.now().timestamp(),
+                'expires_at': expires_at.timestamp() if expires_at else None,
+            },
+            sort_keys=True,
+            indent=None,
+        )
 
-        token = jwt_encode(payload, priv_key, algorithm='RS256')
-        if isinstance(token, bytes):
-            token = token.decode()
-        return token
+        return base64.b64encode(
+            rsa.encrypt(payload.encode('ascii'), pub_key)
+        ).decode()
 
     @staticmethod
     def validate_jwt_token(token: str) -> Dict[str, str]:
@@ -227,12 +227,17 @@ class UserManager:
 
         :raises: :class:`platypush.exceptions.user.InvalidJWTTokenException` in case of invalid token.
         """
-        pub_key, priv_key = get_or_generate_jwt_rsa_key_pair()
+        _, priv_key = get_or_generate_jwt_rsa_key_pair()
 
         try:
-            payload = jwt_decode(token.encode(), pub_key, algorithms=['RS256'])
-        except PyJWTError as e:
-            raise InvalidJWTTokenException(str(e))
+            payload = json.loads(
+                rsa.decrypt(
+                    base64.b64decode(token.encode('ascii')),
+                    priv_key
+                ).decode('ascii')
+            )
+        except (TypeError, ValueError) as e:
+            raise InvalidJWTTokenException(f'Could not decode JWT token: {e}')
 
         expires_at = payload.get('expires_at')
         if expires_at and time.time() > expires_at:

platypush/utils/__init__.py

@@ -7,6 +7,7 @@ import logging
 import os
 import pathlib
 import re
+import rsa
 import signal
 import socket
 import ssl
@@ -15,6 +16,7 @@ from typing import Optional, Tuple, Union
 
 from dateutil import parser, tz
 from redis import Redis
+from rsa.key import PublicKey, PrivateKey
 
 logger = logging.getLogger('utils')
 
@@ -366,7 +368,8 @@ def run(action, *args, **kwargs):
     return response.output
 
 
-def generate_rsa_key_pair(key_file: Optional[str] = None, size: int = 2048) -> Tuple[str, str]:
+def generate_rsa_key_pair(key_file: Optional[str] = None, size: int = 2048) \
+        -> Tuple[PublicKey, PrivateKey]:
     """
     Generate an RSA key pair.
 
@@ -384,28 +387,11 @@ def generate_rsa_key_pair(key_file: Optional[str] = None, size: int = 2048) -> T
     :param size: Key size (default: 2048 bits).
     :return: A tuple with the generated ``(priv_key_str, pub_key_str)``.
     """
-    from cryptography.hazmat.primitives import serialization
-    from cryptography.hazmat.primitives.asymmetric import rsa
-    from cryptography.hazmat.backends import default_backend
-
-    public_exp = 65537
-    private_key = rsa.generate_private_key(
-        public_exponent=public_exp,
-        key_size=size,
-        backend=default_backend()
-    )
-
-    logger.info('Generating RSA {} key pair'.format(size))
-    private_key_str = private_key.private_bytes(
-        encoding=serialization.Encoding.PEM,
-        format=serialization.PrivateFormat.TraditionalOpenSSL,
-        encryption_algorithm=serialization.NoEncryption()
-    ).decode()
-
-    public_key_str = private_key.public_key().public_bytes(
-        encoding=serialization.Encoding.PEM,
-        format=serialization.PublicFormat.PKCS1,
-    ).decode()
+    logger.info('Generating RSA keypair')
+    pub_key, priv_key = rsa.newkeys(size)
+    logger.info('Generated RSA keypair')
+    public_key_str = pub_key.save_pkcs1('PEM').decode()
+    private_key_str = priv_key.save_pkcs1('PEM').decode()
 
     if key_file:
         logger.info('Saving private key to {}'.format(key_file))
@@ -415,7 +401,7 @@ def generate_rsa_key_pair(key_file: Optional[str] = None, size: int = 2048) -> T
             f2.write(public_key_str)
             os.chmod(key_file, 0o600)
 
-    return public_key_str, private_key_str
+    return pub_key, priv_key
 
 
 def get_or_generate_jwt_rsa_key_pair():
@@ -426,9 +412,14 @@ def get_or_generate_jwt_rsa_key_pair():
     pub_key_file = priv_key_file + '.pub'
 
     if os.path.isfile(priv_key_file) and os.path.isfile(pub_key_file):
-        with open(pub_key_file, 'r') as f1, \
-                open(priv_key_file, 'r') as f2:
-            return f1.read(), f2.read()
+        with (
+            open(pub_key_file, 'r') as f1,
+            open(priv_key_file, 'r') as f2
+        ):
+            return (
+                rsa.PublicKey.load_pkcs1(f1.read().encode()),
+                rsa.PrivateKey.load_pkcs1(f2.read().encode()),
+            )
 
     pathlib.Path(key_dir).mkdir(parents=True, exist_ok=True, mode=0o755)
     return generate_rsa_key_pair(priv_key_file, size=2048)

requirements.txt

@@ -14,8 +14,7 @@ frozendict
 requests
 sqlalchemy
 bcrypt
-cryptography
-pyjwt
+rsa
 zeroconf
 paho-mqtt
 websocket-client

setup.py

@@ -64,8 +64,7 @@ setup(
         'zeroconf>=0.27.0',
         'tz',
         'python-dateutil',
-        # 'cryptography',
-        'pyjwt',
+        'rsa',
         'marshmallow',
         'frozendict',
         'flask',