fix: drop passlib, hash with bcrypt directly (#595)

passlib 1.7.4 imports bcrypt.__about__ at module load to detect the
bcrypt version. That attribute was removed in bcrypt 4.x, so once
the dependabot bcrypt 5.0.0 bump lands, passlib raises AttributeError
on import and the backend fails its health check at startup.

passlib is effectively unmaintained (last release 2020). Rather than
work around the import, replace the CryptContext usage in
src/app/core/security.py with direct bcrypt calls — the API surface
we use is just hashpw/checkpw plus a salt.

To stay drop-in compatible with hashes generated by the previous
passlib-based code, hash_password / verify_password silently truncate
the password to 72 bytes (bcrypt's hard limit, which passlib used to
swallow) and verify_password catches the ValueError that bcrypt 5.x
now raises on malformed stored hashes, returning False instead — so a
corrupt DB row produces 401, not 500. Both behaviours are covered by
new regression tests in src/tests/test_security.py.

Co-authored-by: Mateo Lostanlen <mateo@pyronear.org>

Author: dependabot[bot]

pyproject.toml

@@ -22,8 +22,7 @@ server = [
     "pydantic-settings>=2.0.0,<3.0.0",
     "requests>=2.32.0,<3.0.0",
     "PyJWT>=2.12.0,<3.0.0",
-    "passlib[bcrypt]>=1.7.4,<2.0.0",
-    "bcrypt==3.1.7",
+    "bcrypt==5.0.0",
     "uvicorn>=0.11.1,<1.0.0",
     "asyncpg>=0.25.0,<1.0.0",
     "alembic>=1.8.1,<2.0.0",
@@ -49,7 +48,6 @@ quality = [
     "types-requests>=2.33.0.20260513",
     "types-python-dateutil>=2.8.0,<3.0.0",
     "sqlalchemy-stubs>=0.4,<0.5",
-    "types-passlib>=1.7.0",
 ]
 test = [
     "pytest==9.0.3",

src/app/core/security.py

@@ -6,16 +6,14 @@
 from datetime import timedelta
 from typing import Any, Dict, Optional
 
+import bcrypt
 import jwt
-from passlib.context import CryptContext
 
 from app.core.config import settings
 from app.core.time import utcnow
 
 __all__ = ["create_access_token", "hash_password", "verify_password"]
 
-pwd_context = CryptContext(schemes=["bcrypt"], deprecated="auto")
-
 
 def create_access_token(content: Dict[str, Any], expires_minutes: Optional[int] = None) -> str:
     """Encode content dict using security algorithm, setting expiration."""
@@ -24,9 +22,21 @@ def create_access_token(content: Dict[str, Any], expires_minutes: Optional[int]
     return jwt.encode({**content, "exp": expire}, settings.JWT_SECRET, algorithm=settings.JWT_ALGORITHM)
 
 
+def _encode_password(password: str) -> bytes:
+    # bcrypt only hashes the first 72 bytes of the password. passlib's
+    # CryptContext used to silently truncate; mirror that here so hashes
+    # generated under the previous implementation keep verifying.
+    return password.encode("utf-8")[:72]
+
+
 def verify_password(plain_password: str, hashed_password: str) -> bool:
-    return pwd_context.verify(plain_password, hashed_password)
+    try:
+        return bcrypt.checkpw(_encode_password(plain_password), hashed_password.encode("utf-8"))
+    except ValueError:
+        # Malformed stored hash — match the previous CryptContext.verify
+        # behaviour which returned False rather than raising.
+        return False
 
 
 def hash_password(password: str) -> str:
-    return pwd_context.hash(password)
+    return bcrypt.hashpw(_encode_password(password), bcrypt.gensalt()).decode("utf-8")

src/tests/test_security.py

@@ -26,6 +26,23 @@ def test_verify_password():
     assert not verify_password("another_try", hash_pwd1)
 
 
+def test_password_longer_than_72_bytes_is_truncated():
+    # bcrypt only hashes the first 72 bytes. The previous passlib
+    # implementation silently truncated, so we keep the same contract to
+    # stay backward-compatible with hashes already in the DB.
+    base = "a" * 72
+    hashed = hash_password(base)
+    assert verify_password(base + "extra_ignored_bytes", hashed)
+    assert not verify_password("a" * 71 + "b", hashed)
+
+
+def test_verify_password_returns_false_on_malformed_hash():
+    # bcrypt.checkpw raises ValueError on malformed hashes; passlib used
+    # to swallow it and return False. We preserve that behaviour so a
+    # corrupt DB row produces 401, not 500.
+    assert not verify_password("anything", "not-a-bcrypt-hash")
+
+
 @pytest.mark.parametrize(
     ("content", "expires_minutes", "expected_delta"),
     [