They work if you're running in Shockwave (piggy-backs on the browser's ability). Otherwise there is SecureNet xtra (discontinued?), or ... ?
This is a desktop application, so it's not using Shockwave.
The SecureNet is discontinued I believe. Also, I don't believe that it's cross-platform.
I'm afraid you're out of luck.
Adobe could have been woking on this, among other long-standing issues, alongside their iOS publishing and 3D updates but their focus seems to be on game developers not desktop publishers.
SecureNet Xtra is cross platform and supported up to Director 11. I contacted them and they said it "might" work on Dir 12 but they don't offer support for it. In my case I needed it for an iOS app and they said that is definitely NOT supported. So I'm debating if I want to encrypt info on client side and transfer unsecurely, or move on from Director. Good luck to all.