Is RD Gateway obsolutely required for secure communication

Hi all,

Sorry if this is a noob question.

Environment:  RDS 2012 on Windows 2012 R2, Using Web Access server to grant user access to remote apps and session based desktops.

I want users from outside the organization to access the Web Access server throught an internet connection.  Is the RD Gateway absolutely required to garantee encrypted communication? Assuming that I have a fonctionnal SSL certificate for the Web Access server, will this be sufficient for secure/encrypted remote apps and session based desktops?

Thanks,

Jesmat.