That would be far too direct and brutal. Put them in prison until they talk and let the inmates know that they are refusing to decrypt their PC. The inmates w

That would be far too direct and brutal. Put them in prison until they talk and let the inmates know that they are refusing to decrypt their PC. The inmates will soon enough make their own assumptions why and do the beating themselves. Of course protective custody would be an option, but that is just even further isolation and mental torture.