refactor(backend): replace python-jose and passlib with PyJWT and bcrypt for security and simplicity

- Migrated JWT token handling from `python-jose` to `PyJWT`, reducing dependencies and improving error clarity.
- Replaced `passlib` bcrypt integration with direct `bcrypt` usage for password hashing.
- Updated `Makefile`, removing unused CVE ignore based on the replaced dependencies.
- Reflected changes in `ARCHITECTURE.md` and adjusted function headers in `auth.py`.
- Cleaned up `uv.lock` and `pyproject.toml` to remove unused dependencies (`ecdsa`, `rsa`, etc.) and add `PyJWT`.
- Refactored tests and services to align with the updated libraries (`PyJWT` error handling, decoding, and validation).

backend/app/core/auth.py

@@ -1,23 +1,21 @@
 import asyncio
-import logging
 import uuid
 from datetime import UTC, datetime, timedelta
 from functools import partial
 from typing import Any
 
-from jose import JWTError, jwt
-from passlib.context import CryptContext
+import bcrypt
+import jwt
+from jwt.exceptions import (
+    ExpiredSignatureError,
+    InvalidTokenError,
+    MissingRequiredClaimError,
+)
 from pydantic import ValidationError
 
 from app.core.config import settings
 from app.schemas.users import TokenData, TokenPayload
 
-# Suppress passlib bcrypt warnings about ident
-logging.getLogger("passlib").setLevel(logging.ERROR)
-
-# Password hashing context
-pwd_context = CryptContext(schemes=["bcrypt"], deprecated="auto")
-
 
 # Custom exceptions for auth
 class AuthError(Exception):
@@ -37,13 +35,16 @@ class TokenMissingClaimError(AuthError):
 
 
 def verify_password(plain_password: str, hashed_password: str) -> bool:
-    """Verify a password against a hash."""
-    return pwd_context.verify(plain_password, hashed_password)
+    """Verify a password against a bcrypt hash."""
+    return bcrypt.checkpw(
+        plain_password.encode("utf-8"), hashed_password.encode("utf-8")
+    )
 
 
 def get_password_hash(password: str) -> str:
-    """Generate a password hash."""
-    return pwd_context.hash(password)
+    """Generate a bcrypt password hash."""
+    salt = bcrypt.gensalt()
+    return bcrypt.hashpw(password.encode("utf-8"), salt).decode("utf-8")
 
 
 async def verify_password_async(plain_password: str, hashed_password: str) -> bool:
@@ -60,9 +61,9 @@ async def verify_password_async(plain_password: str, hashed_password: str) -> bo
     Returns:
         True if password matches, False otherwise
     """
-    loop = asyncio.get_event_loop()
+    loop = asyncio.get_running_loop()
     return await loop.run_in_executor(
-        None, partial(pwd_context.verify, plain_password, hashed_password)
+        None, partial(verify_password, plain_password, hashed_password)
     )
 
 
@@ -80,8 +81,8 @@ async def get_password_hash_async(password: str) -> str:
     Returns:
         Hashed password string
     """
-    loop = asyncio.get_event_loop()
-    return await loop.run_in_executor(None, pwd_context.hash, password)
+    loop = asyncio.get_running_loop()
+    return await loop.run_in_executor(None, get_password_hash, password)
 
 
 def create_access_token(
@@ -121,11 +122,7 @@ def create_access_token(
         to_encode.update(claims)
 
     # Create the JWT
-    encoded_jwt = jwt.encode(
-        to_encode, settings.SECRET_KEY, algorithm=settings.ALGORITHM
-    )
-
-    return encoded_jwt
+    return jwt.encode(to_encode, settings.SECRET_KEY, algorithm=settings.ALGORITHM)
 
 
 def create_refresh_token(
@@ -154,11 +151,7 @@ def create_refresh_token(
         "type": "refresh",
     }
 
-    encoded_jwt = jwt.encode(
-        to_encode, settings.SECRET_KEY, algorithm=settings.ALGORITHM
-    )
-
-    return encoded_jwt
+    return jwt.encode(to_encode, settings.SECRET_KEY, algorithm=settings.ALGORITHM)
 
 
 def decode_token(token: str, verify_type: str | None = None) -> TokenPayload:
@@ -198,7 +191,7 @@ def decode_token(token: str, verify_type: str | None = None) -> TokenPayload:
 
         # Reject weak or unexpected algorithms
         # NOTE: These are defensive checks that provide defense-in-depth.
-        # The python-jose library rejects these tokens BEFORE we reach here,
+        # PyJWT rejects these tokens BEFORE we reach here,
         # but we keep these checks in case the library changes or is misconfigured.
         # Coverage: Marked as pragma since library catches first (see tests/core/test_auth_security.py)
         if token_algorithm == "NONE":  # pragma: no cover
@@ -219,10 +212,11 @@ def decode_token(token: str, verify_type: str | None = None) -> TokenPayload:
         token_data = TokenPayload(**payload)
         return token_data
 
-    except JWTError as e:
-        # Check if the error is due to an expired token
-        if "expired" in str(e).lower():
-            raise TokenExpiredError("Token has expired")
+    except ExpiredSignatureError:
+        raise TokenExpiredError("Token has expired")
+    except MissingRequiredClaimError as e:
+        raise TokenMissingClaimError(f"Token missing required claim: {e}")
+    except InvalidTokenError:
         raise TokenInvalidError("Invalid authentication token")
     except ValidationError:
         raise TokenInvalidError("Invalid token payload")

backend/app/services/oauth_provider_service.py

@@ -25,8 +25,8 @@ from datetime import UTC, datetime, timedelta
 from typing import Any
 from uuid import UUID
 
-from jose import JWTError, jwt
-from jose.exceptions import ExpiredSignatureError
+import jwt
+from jwt.exceptions import ExpiredSignatureError, InvalidTokenError
 from sqlalchemy.ext.asyncio import AsyncSession
 
 from app.core.config import settings
@@ -704,7 +704,7 @@ async def revoke_token(
                         "Revoked refresh token via access token JTI %s...", jti[:8]
                     )
                     return True
-        except JWTError:
+        except InvalidTokenError:
             pass
         except Exception:  # noqa: S110 - Intentional: invalid JWT not an error
             pass
@@ -827,7 +827,7 @@ async def introspect_token(
             }
         except ExpiredSignatureError:
             return {"active": False}
-        except JWTError:
+        except InvalidTokenError:
             pass
         except Exception:  # noqa: S110 - Intentional: invalid JWT falls through to refresh token check
             pass

backend/app/services/oauth_service.py

@@ -537,8 +537,9 @@ class OAuthService:
             AuthenticationError: If verification fails
         """
         import httpx
-        from jose import jwt as jose_jwt
-        from jose.exceptions import JWTError
+        import jwt as pyjwt
+        from jwt.algorithms import RSAAlgorithm
+        from jwt.exceptions import InvalidTokenError
 
         try:
             # Fetch Google's public keys (JWKS)
@@ -552,24 +553,27 @@ class OAuthService:
                 jwks = jwks_response.json()
 
             # Get the key ID from the token header
-            unverified_header = jose_jwt.get_unverified_header(id_token)
+            unverified_header = pyjwt.get_unverified_header(id_token)
             kid = unverified_header.get("kid")
             if not kid:
                 raise AuthenticationError("ID token missing key ID (kid)")
 
             # Find the matching public key
-            public_key = None
+            jwk_data = None
             for key in jwks.get("keys", []):
                 if key.get("kid") == kid:
-                    public_key = key
+                    jwk_data = key
                     break
 
-            if not public_key:
+            if not jwk_data:
                 raise AuthenticationError("ID token signed with unknown key")
 
+            # Convert JWK to a public key object for PyJWT
+            public_key = RSAAlgorithm.from_jwk(jwk_data)
+
             # Verify the token signature and decode claims
-            # jose library will verify signature against the JWK
-            payload = jose_jwt.decode(
+            # PyJWT will verify signature against the RSA public key
+            payload = pyjwt.decode(
                 id_token,
                 public_key,
                 algorithms=["RS256"],  # Google uses RS256
@@ -597,7 +601,7 @@ class OAuthService:
             logger.debug("Google ID token verified successfully")
             return payload
 
-        except JWTError as e:
+        except InvalidTokenError as e:
             logger.warning("Google ID token verification failed: %s", e)
             raise AuthenticationError("Invalid ID token signature")
         except httpx.HTTPError as e: