What is the best SSO Single Sign On mechanism for Xenforo?

[BubbaLovesCheese]

Does xenforo easily support any SSO mechanism, like oAuth or something similar?

I currently have vBulletin 4 integrated with my website's authentication infrastructure. (both need to be updated)

So what would be the best way to integrated Xenforo with an SSO?

Thanks!
What is the best SSO Single Sign On mechanism for Xenforo?

free plugins
minecraft paid for free
mcmarket
mc-market
free minecraft paid plugins
free minecraft plugins
spigotmc
SpigotMC
aac free
ewg free
Minecraft Premium Plugins
ewg free download
litebans free
epicworldgenerator free
free schematics
leaked schematics minecraft
schematics
schematics leaked
schematics free
minecraft schematics free
paid minecraft schematics free
paid minecraft schematics for free
free cracked plugins
free cracked minecraft plugins
plugins
featherboard download
featherboard plugin download
antiaura download
xenforo leaked
xenforo for free
xenforo addons