I believe judges can, in fact, hold a defendant for refusing to give up their own passwords, and that the contempt could be indefinite. This is a point of law that is not settled at the federal level yet, and at the state level it varies from jurisdiction to jurisdiction.

In one case, the appellate court at the federal level simply refused to hear the case that had been decided at the sate supreme court level.

https://www.reuters.com/business/legal/us-supreme-court-nixe...