InvalidPaddingError in StringEncryptedType

[igordertigor]

I use the StringEncryptedType to encrypt user credentials like this:

class Credentials(SQLModel, AsyncAttrs, table=True):  # type: ignore
    email: str = Field(
        sa_column=Column(
            StringEncryptedType(
                sqlalchemy.Unicode,
                constants.email_encryption_key,
                AesEngine,
                'pkcs5',
            ),
            unique=True,
        )
    )
    hashed_password: str

After using this for a few days, I get an InvalidPaddingError when reading the credentials (only end of traceback):

  File "/backend/.venv/lib/python3.11/site-packages/sqlalchemy/engine/result.py", line 548, in _allrows
    rows = self._fetchall_impl()
           ^^^^^^^^^^^^^^^^^^^^^
  File "/backend/.venv/lib/python3.11/site-packages/sqlalchemy/engine/result.py", line 1674, in _fetchall_impl
    return self._real_result._fetchall_impl()
           ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "/backend/.venv/lib/python3.11/site-packages/sqlalchemy/engine/result.py", line 2268, in _fetchall_impl
    return list(self.iterator)
           ^^^^^^^^^^^^^^^^^^^
  File "/backend/.venv/lib/python3.11/site-packages/sqlalchemy/orm/loading.py", line 219, in chunks
    fetch = cursor._raw_all_rows()
            ^^^^^^^^^^^^^^^^^^^^^^
  File "/backend/.venv/lib/python3.11/site-packages/sqlalchemy/engine/result.py", line 541, in _raw_all_rows
    return [make_row(row) for row in rows]
           ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "/backend/.venv/lib/python3.11/site-packages/sqlalchemy/engine/result.py", line 541, in <listcomp>
    return [make_row(row) for row in rows]
            ^^^^^^^^^^^^^
  File "lib/sqlalchemy/cyextension/resultproxy.pyx", line 22, in sqlalchemy.cyextension.resultproxy.BaseRow.__init__
  File "lib/sqlalchemy/cyextension/resultproxy.pyx", line 79, in sqlalchemy.cyextension.resultproxy._apply_processors
  File "/backend/.venv/lib/python3.11/site-packages/sqlalchemy/sql/type_api.py", line 2144, in process
    return fixed_process_value(value, dialect)
           ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "/backend/.venv/lib/python3.11/site-packages/sqlalchemy_utils/types/encrypted/encrypted_type.py", line 425, in process_result_value
    decrypted_value = self.engine.decrypt(value)
                      ^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "/backend/.venv/lib/python3.11/site-packages/sqlalchemy_utils/types/encrypted/encrypted_type.py", line 124, in decrypt
    decrypted = self.padding_engine.unpad(decrypted)
                ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "/backend/.venv/lib/python3.11/site-packages/sqlalchemy_utils/types/encrypted/padding.py", line 46, in unpad
    raise InvalidPaddingError()
sqlalchemy_utils.types.encrypted.padding.InvalidPaddingError

Because this happens after a bit of time, it's very difficult to reproduce. Is this a known issue? Is there a known fix?

So far, my only solution has been to reset the database, but that's obviously not a great solution once this goes to production.