code: async def check_passwd(self, 
          identity: str, 
          passwd: str
      ) -> SessionIdentity :
          
          assert identity
  
          value, _ = await self._client.get(f"{self._prefix_identity}/{identity}")
          if value is None:
              logger.debug(f'Not found identity: {identity}')
              raise Unauthorized(f"无此登录身份'{identity}'")
  
          profile = json.loads(value.decode('utf-8'))
  
          user_id = profile['user_id']
          identity = profile['identity']
          hashed = profile['hashed']
  
          if sha256_crypt.verify(passwd, hashed):
              return SessionIdentity(user_id=user_id, identity=identity)
          else:
              raise Unauthorized(f"登录身份'{identity}'认证失败")
docs: 通过密码检查身份