We've had secure SSL (HTTPS) upload for years via our web-based Case Manager application. And Service Now (part of Junos Space) also does secure file attachments. But for those of you who just really love a CLI we've now introduced a secure FTP service as well. So three secure methods and of course "old faithful" - ftp.juniper.net as well.
But do give sftp.juniper.net a try (Secure FTP is FTP over SSH and a number of clients are available - many free and open-source). We've not only improved security, but it also automatically attaches the files to the case and notifies the case owner to support faster turnaround times. You should also notice improved performance, particularly in areas with high-latency.
For more details see KB23337 (http://kb.juniper.net/KB23337) - How to upload large files to a JTAC Case.