Add rate limiting for encryption

**Feature request**
It would be great to have timeout for handlers.

**Use case**
Many users need this functionality for production deployments.

**Implementation idea**
Add a new config option `enable_timeout` with default `false`.

No file, test, timeout duration, or handler entry point is named. Start by locating the handler and configuration entry points, then clarify how `enable_timeout` applies; done means the option defaults to `false` and the timeout behavior is covered by tests.

Written by the indexing model from the issue text.